December 2, 2025 • 53 mins
We ended last week’s episode on a bit of a cliffhanger: is salt actually bad for us and if so, why does there still seem to be a debate? This week’s episode holds all the answers. We’re sifting through the noise to figure out what salt actually does in our bodies, how it might impact our health, and why we crave this delicious substance. If you’ve ever wondered how we’ve arrived at the maximum daily sodium intake (2300 mg for adults) and why salt impacts blood pressure, then this is the episode for you!
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Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:00):
Intake of salt is a biological imperative inextricably woven into
physiological systems, human societies, and global culture. However, excessive salt
intake is associated with high blood pressure. The crucial question
is whether salt exerts a causal influence on patient centered
health outcomes such as myocardial infection, stroke, and death. However,
(00:25):
this issue is controversial and fiercely debated. Despite the controversy,
two broad points of consensus exist. The first is that
the uncertainty could be resolved by better quality data, that is, large,
randomized clinical trials with sufficient follow up to assess robust
cardiovascular outcomes. The second is that the barriers to performing
(00:48):
such trials are so substantial that they will be rarely,
if ever surmounted.
Speaker 2 (01:43):
Okay, so many questions.
Speaker 1 (01:45):
What was that? From?
Speaker 2 (01:47):
When was that? From? Who wrote that?
Speaker 1 (01:50):
I can't wait to tell you? Okay? So that was
I pulled clips like little bits from the intro and
from later in a paper, from a very very recent paper.
I have just scrolled. Why didn't I put this up?
I'm scrolling all the way to the bottom of my
notes from Nature Reviews Nephrology from twenty twenty two by
(02:11):
hunter at All titled the Impact of Excessive Salt Intake
on Human Health, and this paper that little intro, that's
the end of my.
Speaker 2 (02:24):
I mean, that's what like, That's what kills me, is
that I feel like since that could The reason I
asked where when is it from? Is because that could
have been from so many different points in history over
the salt debate. We need better data, we need randomized
control trials, we need long term data sets and follow up.
Speaker 1 (02:45):
And it is from twenty twenty two. So that's what
we're going to talk about today in this episode.
Speaker 2 (02:56):
Hi, I'm Aaron Welsh.
Speaker 1 (02:58):
And I'm Aaron Allman updight.
Speaker 2 (03:00):
And this is this podcast will kill you. Welcome back
to Salt Salt. Here we go again, Yeah.
Speaker 1 (03:07):
We go again. I'm really excited about today's episode. I
don't know how many answer any of your questions, but
I think I think we'll come to some clarity. I
honestly really actually do at the end of this.
Speaker 2 (03:19):
I am hopeful. I know that if there is a
thread to be pulled, you will find it and yank
it out from the yank Yeah, yeah, I do. I'm
thrilled for this. Yeah, I already want to start asking questions,
and that is a first like that is early for me,
(03:39):
so good.
Speaker 1 (03:41):
I can't wait. I can't wait for you to ask
me questions and then I'll be like that's the one
I don't have an answer for, or like, oh my god,
now I have to scroll one hundred years in my notes.
I can't wait. I have fifteen pages of notes here
erin so like, I've got to have answers to something.
But firstarantiny time it is?
Speaker 2 (04:01):
It is we're again drinking the grains of salts, which
is based on a salty dog. I mean it is
a salty dog, which is great fruit juice and vodka
or gin, whichever you prefer. Make sure your rim is
salted unless you're dealing with high blood pressure. No, just kidding,
I don't know, but that is the technical recipe. Also,
(04:23):
this reminds me that if you are just now tuning in,
then you didn't see at the top that it says
Salt Part two. You really don't have to listen to
the first episode, but you should. It's not like there's
a narrative that you'll miss, but you'll miss a lot.
You'll miss some. It'll help you with trivia. It's got
some cool It's a great episode. Do you want to
(04:43):
learn where the term grain of salt comes from? Check
it out.
Speaker 1 (04:47):
You've got to listen to that episode. We're not going
to tell you now.
Speaker 2 (04:49):
Yeah.
Speaker 1 (04:51):
Anyways, we'll post the recipe for the drink on our website.
This podcast with you dot com and our social media
is so make sure you're following us there. You find
lots of other cool stuff on our website too, like
trans scripts and a bookshop dot orgiphiliated account, and a
good Reads list and merch and all the sources from
all of these episodes. Boy do I have a long
list for this one bloodmobile? Who does our music? You know?
(05:13):
Contact us form.
Speaker 2 (05:14):
Lots of things.
Speaker 1 (05:15):
I'll check it out.
Speaker 2 (05:18):
Is there any other business or can we like get
straight to things? Let's do this?
Speaker 1 (05:22):
Oh yes, very short break life evolved in the oceans,
(05:51):
which are salty.
Speaker 2 (05:53):
I loved this. I'm like, wait a second, have I
said this before?
Speaker 1 (05:57):
No, you haven't, but it is the most Aaron Welsh
way to start the thing. Ever that I was like
thrilled that you didn't start that way and that I
could do it.
Speaker 2 (06:05):
I did think about going into the evolutionary origins and
then I was like stop.
Speaker 1 (06:09):
Yeah, no, no, I'm not going any further than that. Life
evolved in the oceans. Yeah, the oceans are salty, and
with the evolution from single celled organisms to multicellular organisms,
salt became a major component of our extracellular fluid, that is,
the fluid that is on the outside rather than the
inside of our cells. Our bodies are basically just made
(06:35):
up of tiny little water balloons bathing in more water. Yeah, okay,
and all of the water inside and outside of our
cells is salty water. Yeah, but the salt on the
inside of our cells is mostly potassium. So the ions
that make up the salt mostly are potassium, and the
(06:57):
salts outside of our cells most are made up of sodium. So,
as we moved from our ocean homes to land, and
by we I mean like, you know, creatures and not
like humans.
Speaker 2 (07:10):
Global evolutionary we yeah.
Speaker 1 (07:12):
Exactly, we were no longer bathing in sodium all the time, right,
and thus we had to find ways to ingest it. Yeah.
So animals evolved taste receptors to be able to detect salt,
and in general, like you kind of mentioned, Aaron, most
(07:32):
animals have actually a pretty consistent like upside down U
shaped preference curve for saltiness, right, but I think it's yeah,
upside down you so like it's delicious right in the middle.
If it's not salty enough, it doesn't taste good. If
there's too much salt also doesn't taste good. Right. So
when we talk about salt in this episode, like you
(07:53):
said last week as well too, I'm talking about sodium
chloride NaCl uh huh. I mean when I set it
in the bodies where there's other salts in your bodies,
and there's other ions that are important, But from now
on out, I'm just talking about sodium chloride.
Speaker 2 (08:07):
Okay, Can I already ask a question? Yeah, Garby, you
mentioned potassium is on the inside and sodium is on
the outside.
Speaker 1 (08:15):
Huh.
Speaker 2 (08:18):
And what happens then?
Speaker 1 (08:20):
Like okay, yeah, let me let's sorry.
Speaker 2 (08:23):
Yeah, well it's not a question. It was more just
like tell me more.
Speaker 1 (08:28):
Yes, let me continue setting the scene and then I
will I will get into that, okay, very shortly. Well,
we're talking mostly about sodium chloride today. Lots of other
salts exist in chemistry, salt like table salt, Sodium chloride
is about forty percent sodium. Yeah, like by weight, so
(08:49):
ten grams of salt. This is important for one work
because like all of the dietary guidelines and things talk
about sodium, right, But then a lot of studies just
talk about salt. So we can use these interchange ten
grams of salt four grams of sodium. That's the equivalence there.
Speaker 2 (09:04):
Okay, guess what there are like online calculators that I
had to use to be like how much sodium are wet?
I would be like how much salt does the average
American eat? Oh? You know, however thirty two hundred milligrams
of salt or sodium, So like right, no, but how
much salt are we eating?
Speaker 1 (09:19):
How much salt does that? Yeah? Exactly. Also, then some
studies like to use millimals just to make them sound
more smart, and you're just like, now I have to
take it from mills to milligrams, Like stop it, it's unnecessary.
But so the questions that I want to answer today
in this episode are number one, why do we give
a crap about sodium? And that's going to get it
your question of like sodium potassium, what does that mean?
(09:40):
What does it do in our bodies? Why do we
actually need it. What is the problem or is there
a problem with excess sodium and how much? What does
excess actually mean? And why is there so much debate
about this? Yeah, that's going to be a big part
of the episode. What I am not going to talk
about is hypo and hyper natremia. That is when your
(10:03):
blood sodium is too low or too high. I'm not
going to talk about it in any great detail. If
you are a medical student or a resident, you're welcome
for not making you listen to that. If you don't
know what that means, you can watch some doctor Glalcum
Flecken videos because they sum up both my knowledge and
also why I have no interest in talking about those things, because.
Speaker 2 (10:23):
Are those acute stages.
Speaker 1 (10:26):
They can be acute or chronic. Okay, okay, yeah, and
it's all just a mess. But you will understand why
it's important when I tell you why do we have
to give a crap about sodium? Right at its core,
at its most important, sodium is what determines our total
body fluid balance. So because it is the most abundant
(10:48):
cat ion, positively charged ion in our extracellular fluid, it
is what determines how much fluid volume we actually have
in our bodies. Right, Because the salt on the inside
of our cell bags is mostly potassium and the salt
on the outside is mostly sodium, it doesn't matter which
(11:09):
is which as long as their concentrations are the same.
Our bodies have to keep a balance of these fluids.
So the concentration of particles on the inside of our
cell has to match the concentration on the outside if
they don't, Like if you were to dump a bunch
of sodium into your bloodstream into your extracellular fluid, then
your body would have to compensate by extracting fluid from
(11:33):
cells in order to make up for that.
Speaker 2 (11:35):
Right, Okay, And the identity of sodium versus potassium doesn't
necessarily matter, I imagine it does at a point.
Speaker 1 (11:44):
It does, absolutely, but it doesn't for the purposes of
just understanding that, like at its core, you just have
to have balance. It so happens that potassium is what
exists inside of our cells, and sodium primarily exists outside
of our cells, And our cells do a lot of
transmitting sodium and potassium back and forth through these atp
ion channels, and that is all very important. But to
(12:09):
understand fluid balance. You need to know that potassiums on
the inside and sodiums on the outside, and they got
to be concentration wise balanced.
Speaker 2 (12:16):
Right.
Speaker 1 (12:18):
Sodium is also an incredibly important cad on outside of
fluid balance. It's a neurotransmitter. It is essential for our
muscles to be able to contract, and so it's something
that our cells also use in communication with other cells. So,
make no mistake, we cannot exist without sodium.
Speaker 2 (12:38):
It's necessary for life.
Speaker 1 (12:40):
It is necessary for life, and the volume of our
fluid in our bodies is proportional to our total body
content of sodium. Right, So, in order to if you
lose a bunch of volume, for example, if you're bleeding,
or if you're even just peeing out way too much,
(13:00):
or you're sweating or you're having diarrhea, in order to
replace the volume that you've lost of fluid, you have
to also replace sodium. You cannot replace it with just water,
it will not work. Right. We lose sodium predominantly through
our kidneys. In fact, shout out to our kidneys. They
(13:22):
are so stellar at this that they excrete about ninety
to ninety five percent of what we ingest regardless of
how much we ingest. Isn't that interesting?
Speaker 2 (13:33):
Wait? So okay, but you said it's a proportion that
they excrete out or.
Speaker 1 (13:38):
Is it ninety to ninety five percent of what you
ingest you're going to pee out in your kidneys.
Speaker 2 (13:44):
So let's say we're talking about sodium sodium. Yeah, so
let's say that you, you know, going back to last
week's episode when the ridiculous estimate, shocking estimate of one
hundred grams of salt a day a day, let's say, so,
that's forty grams of sodium oday. Yeah, that ninety percent
(14:05):
that's excreted out. You've got a lot more salt remaining
in your body than if you're.
Speaker 1 (14:09):
Oh, Aaron, you're so right.
Speaker 2 (14:14):
Thank you for leading me perfectly to that.
Speaker 1 (14:17):
You did it all on your own. Oh my god, Yes, exactly,
exactly right. Proportionally percent of what we ingest, regardless of
what we're ingesting. Right, we're gonna lose some through our
gi tract, via your poop. You're gonna lose some via sweat,
et cetera. Okay, most of its kidneys, Most of it's kidneys,
and our kidneys. They do a really good job of
(14:38):
deciding how much to kick out and how much to
keep depending on how much we eat, because it is
going to be variable. Right, if you're not getting enough,
if you are deficient in your sodium intake, or if
you've got other reasons that your body decides, hey, we
need to hold onto this. Your kidneys can actually keep
almost all of it. They can They can keep almost
(14:59):
one hundred percent of your sodium if they need to.
Speaker 2 (15:15):
Two questions, Okay, what are some of the conditions that
your kidneys might keep more sodium than is necessary? And
how often does someone actually not consume enough sodium in
like the your like a normal day to.
Speaker 1 (15:30):
Day you know, such great questions. How often in the
year twenty twenty five is someone not getting enough sodium?
Very rare? Okay, it's very hard to not get enough
sodium for most people. You If you, for example, were
to lose a lot of blood or lose a lot
of volume for any reason, then your blood pressure would
probably drop. Then your kidneys would say, hey, we need
(15:52):
to hold onto blood pressure. We're going to do that
by holding on all of our sodium. We're not going
to let any sodium go, and that's going to help.
You're going to need to ingest sodium, either via like
ivy fluids or just eating salt in order to make
up for those losses. But your kidneys are also going
to react very quickly to hold on to as much
as possible. There's other like disease states. For example, if
you have issues with your adrenals where you're not producing
(16:14):
certain hormones. Because it's a lot of very complicated it's
your kidneys, it's your brain, it's your blood vessels and
sensors that are in your blood vessels. It's hormones that
are controlling all of this. So if you have deficiencies
in certain hormones, then your kidneys might flip on and say, hey,
we need to hold on to all the sodium that's
possible because we are you know, at risk of losing
it or whatever. Or maybe you have deficiencies and hormones
(16:37):
and you can't do that and so you're losing a
lot of sodiums. So then you might have what so
many animals have big bone lick stake park and that
is what's called sodium appetite. Yes, and sodium appetite is
this idea that we know exists in animals that in
a state of sodium deficiency. Animals will exhibit these pretty
(17:00):
extreme sodium seeking behaviors and they will do extra work
to seek out and consume salt. And we see this
in a lot of different animals, mice, rats, rabbits, pigeons, goats,
we learned, kangaroos, sheep, cattle, monkeys, horses. So the question
is does this sodium appetite exist in humans, And we
(17:22):
think probably yes, though the data is based on a
few cases of like, for example, kids who had no
functional adrenals, so they were salt wasting. Their kidneys could
not hold on to salt, and so they had an
increased need for salt and exhibited these kinds of salt
(17:42):
seeking behaviors. In the literature, these are like really old
single case type studies. Yea, but then yeah, so those
individuals in those studies did exhibit that kind of sodium
seeking what we would call sodium appetite. That's not the
same thing as what we experience now, which is sodium
preference where we like it so we eat it because
(18:05):
it tastes good. That does not mean that we are
sodium deficient.
Speaker 2 (18:09):
Right, even though it feels sometimes like the same thing.
Speaker 1 (18:12):
Right, hard to distinguish perhaps.
Speaker 2 (18:18):
Okay, I have a question about you said like salt appetite,
this instinctual drive to find salt, and you said that
they tested out in kids that lacked adrenals. Tell me
why that would. What's happening there is their kidneys aren't
holding on like yeah.
Speaker 1 (18:35):
Yes, exactly that. So your adrenals they do a lot,
but one of the hormones that they make is called aldosterone,
which is a very important part of mediating the resorption
of sodium in your kidneys. And so without being able
to make that particular hormone, then you can't have a
signal to tell your kidneys to hold on to sodium,
(18:57):
and so you're basically sodium wasting. And there's other conditions
as well too. There's like genetic conditions, or there's maybe
damage to the kidney. There's medications that can make you
lose more sodium in your urine through your kidneys. Okay, yeah,
but a lot of it is under that hormonal control.
So that's why it was in kids who had like
(19:17):
not either they didn't have adrenals or they had non
functional adrenals. I can't remember which one. Okay, And your
drenals do a lot more than just teldosterone, but that's
important for salt.
Speaker 2 (19:27):
And your kidneys do a lot more than just sodium too, yes, Vato.
Speaker 1 (19:33):
But so this all begs the question how much sodium
do we actually need?
Speaker 2 (19:43):
How much?
Speaker 1 (19:44):
Aaron? This is my favorite question that I've asked myself, yeah,
in a while, and it is very hard to come
to an actual answer on this. So you mentioned, and
I'm so glad that you did in last episode, that
our early hominid ancestors, their estimated amount of salt intake
(20:09):
was about one gram of salt per day or less.
That's four hundred milligrams of sodium. Now, there also was
a study that came out in the late eighties called
inter Salt, and this was this one of these big,
big observational studies that first showed a relationship. Not first
(20:30):
because you said it was like you know, in the
early nineteen hundreds.
Speaker 2 (20:33):
Twenty six, if you're talking, you know, correct hard hard
pulse that hardens.
Speaker 1 (20:39):
Yeah, But this was one of like a big important
observational study that looked at a bunch of different populations
with variation in their average salt intake and found a
very strong relationship between higher salt intake and blood pressure.
In this study, they also looked at several remote human
populations in Brazil, Kenya, and Papula, New Guinea, and in
(21:02):
those populations, people, yes, had very low blood pressure, but
they also had substantially lower sodium intakes compared to what
we see today, one to three grams of salt on average,
which is four hundred milligrams to one point two grams
of sodium per day.
Speaker 2 (21:17):
I mean, it's to be hard, I feel like, in
our like in the US, to eat that, to select
that diet, right.
Speaker 1 (21:24):
Listen, we'll get there. It's very hard, Okay, But this
all becomes really important because, as I'm going to talk
about later, there is a lot of weird debate about
what our quote unquote physiologic need actually is. Okay, and
we'll get into the people who are claiming things that
they're claiming, but it is very clear from these early
(21:47):
you know, these estimates of early hominid we can't we
can't have exact data on that, right, but these estimates
based on the sodium content of the types of foods
that early hominids would be eating, plus the fact that
there are, or at least in the eighties and seventies
were societies in which people were consuming very minimal amounts
of salt and they were living, surviving, maybe thriving, I
(22:10):
don't know, but their bodies were functioning just fine. So physiologically,
most estimates say we need at a minimum about five
hundred milligrams of sodium a day in order to continue
our bodily functionings, to keep up with losses from our kidneys,
from our sweat, from our GI tract. And that's going
to vary based on how much you're sweating, how much
you're pooping, and how great your kidneys are at retaining sodium.
Speaker 2 (22:33):
What about potassium, great question.
Speaker 1 (22:36):
Potassium is incredibly important and actually plays a huge role
in this sodium blood pressure, et cetera debate. And I
didn't write down the exact like what the RDA the
recommended amount of potassium that you get is, so I
don't know the exact numbers of that, but potassium is
absolutely essential to consume every day as well.
Speaker 2 (22:57):
And we're but I'm asking about the intrasalt study. Were
those populations, the remote populations, were they consuming some other
types of salt, you know, potassium or whatever.
Speaker 1 (23:07):
They were probably consuming more potassium than what we consume
or what a lot of other populations consume. Because foods
that tend to be low in sodium are often high
in potassium. That's very interesting, because whole foods are very
high like fruits, vegetables, these kinds of things tend to
be very high in potassium. Harm. Okay, we'll get there, Okay, okay,
(23:31):
So that's how much salt we need, like bare minimum
to survive. We think, right, how much salt do we get?
On average? Global daily salt intake is estimated. Most estimates
and by the World Health Organization are about ten grams
of salt per day, which is about four grams of sodium.
There is a lot of variation, so the average ranges
(23:53):
from just over two grams to just over five grams
per day based on different populations, and of course there's
a lot of individual and day to day variation. Now,
the World Health Organization recommends a limit of no more
than two grams of sodium a day two thousand milligrams,
that's five grams of salt. The American Heart Association in
(24:18):
the US recommends for all adults absolutely no more than
two point three grams of sodium, and for anyone with
high blood pressure or at high risk for cardiovascular disease.
They recommend a limit of one point five grams of sodium.
Other countries have slightly different recommendations, but they're all in
(24:38):
this ballpark of around two grams of sodium, around five
grams of salt, and yet globally, on average, we are
getting more than double the amount of what most major
medical societies recommend. Why is that? What impact is this having?
And why is there so much controversy about this? Still?
Speaker 2 (24:58):
This is so fascinating because I think question being how
much salt do we need? Versus how much salt is
too much? I feel like is really different. Those are
two entirely different questions.
Speaker 1 (25:10):
They are, And I.
Speaker 2 (25:12):
Also want to understand how we arrived at this number,
these recommended numbers, which have been revised down over the
past fifty years.
Speaker 1 (25:24):
Yes, they have been revised down. To me, most of
the data that has led to the revising down of
these numbers is based on blood pressure, because there is
honestly very little at this point controversy left about the
data that pretty clearly shows that a reduction in salt
intake from that about four grams of sodium, which is
(25:47):
our average. Reduction from that reduces blood pressure, especially on
a population level, and in most studies it reduces it
to what would be considered a clinically relevant to so
like about the same amount that you would see if
you were starting someone on an anti hypertensive medication at
(26:07):
a low dose, right, so not quite as good as
blood pressure medicine, but you know at a population level
you're going to be reducing blood pressure by reducing sodium
intake from that current average of about four grams. The
exact amount that you're going to get is going to
very study to study. There's a lot of individual variation.
Not every person gets the same degree of benefit, but
(26:29):
across the board, like studies don't argue that lower sodium diets,
Both interventional studies and observational studies agree that a reduction
in sodium intake and lower sodium diets reduce blood pressure. Now,
blood pressure is one of the major risk factors for
(26:50):
cardiovascular disease, including heart attack, heart failure, stroke, and death
from cardiovascular disease. High blood pressure is one of the
major risk factors, so the biggest risk of diets that
are high in sodium is an increased risk of cardiovascular disease,
and this is where so much of this controversy lies.
Speaker 2 (27:14):
Is now the time to ask what the mechanism is
between sodium intake and blood pressure?
Speaker 1 (27:24):
Great question? Yes, now is a great time to ask.
So there's a complicated answer, which is a lot of
like we don't quite know and the mechanisms da da
da da. And then there's a simple answer, which is
that when you consume more salt, because you're not excreting
one hundred percent of it, some additional salt is going
to stay in your body and that is going to
(27:47):
tell your kidneys to hold not even tell your kidneys,
kind of force your kidneys to hold on to water
because water follows sodium yep. And so as your blood
volume spans and your extracellular fluid volume expands because it
will because you're holding on to water. By holding on
to sodium, that is going to cause an increase in
(28:10):
your blood pressure because you're increasing the volume in your
blood and.
Speaker 2 (28:15):
Just more is shooting through those vessels.
Speaker 1 (28:18):
Right, you've got more sodium or holding onto more water,
So now you have more fluids, so you have more pressure. Okay, Now,
most of the time, if you're kidneys, which sense this
increase in volume and sense this increase in blood pressure.
What they should do is excrete more sodium because they
(28:38):
can sense this and they can say, oh, we need
to get rid of some sodium in order to get
rid of some water because our pressure is too high.
So what exactly happens in these especially long term high
sodium diets, because this is not like a today tomorrow
type of situation. This is like a long term trend
that we see, Okay, especially in places where there are
(29:01):
high sodium diets for a very long time. There's in
like an increasing effect of high sodium diet with age
and with time, And so what exactly is going on
and what other miscommunications are happening between you know, our
reunnin and geotensin system and aldosterone and all of these
hormones and our kidneys and the receptors in our carotids
(29:24):
that are also telling our kidneys in our brain how
much blood pressure we have. Like there's some miscommunication that's
going on that leads to over time and increase in
blood pressure.
Speaker 2 (29:34):
And so our kidneys are just is it our kidneys
that aren't responding as well?
Speaker 1 (29:38):
Or is it that's part of what we think is
that it's like, for some reason or another there's a
loss of some of this feedback where they're not able
to sense this increase in blood pressure, or in some
cases they even maybe go, hey, let's activate this system
and actually increase blood pressure more or something weird, like
a like a paradoxical kind of response. So it's not
like a super clear cut but and it's most basic.
(30:01):
You can think of it as you're increasing the amount
of sodium, therefore you're increasing fluid, therefore you're increasing pressure.
Speaker 2 (30:24):
Why does age play a role?
Speaker 1 (30:27):
I mean, age plays such a huge role in our
cardiovascular health overall. We see like a decrease in elasticity
of the vessels. So is it that they're not able
to expand to that increasing volume. There's a chronic inflammation
that's going on, Like there's so there's so much So
that's that's a different question. But yeah, so that's how
(30:47):
we think that blood pressure is like involved with sodium. Right,
So then the question is if we know that blood
pressure is such a huge risk for cardiovascular disease, and
diets that are high end sodium increase your blood pressure,
do they increase the risk of cardiovascular disease, and that
(31:09):
question has been fracked with so much controversy. Yeah, it has,
so let me try and break it down a little bit. Okay,
nearly all of the large scale meta analyzes that have
been done to look at this question, does reducing sodium
(31:29):
intake decrease cardiovascular mortality? All of these large scale meta
analyzes do show a significant reduction in risk of stroke,
heart attack, cardiovascular disease, and mortality from cardiovascular disease. The quality, though,
of this data is not as good as the strength
(31:52):
of the data that we have for this direct association
between sodium and blood pressure. We don't have long term
randomized clinical trial because that is very hard to do.
As I said, at the first hand account, the estimates
that I have seen are that to get really good
data on this, you would have to enroll between seventeen
(32:12):
thousand and thirty seven thousand people. You'd have to follow
them for a number of years because you need to
have enough unfortunately bad cardiovascular outcomes to be able to
get that data, and it would cost between four hundred
and nine hundred million dollars. So I know some people
who could fund that, you know what I'm saying. Not
like personally.
Speaker 2 (32:31):
But but are they willing?
Speaker 1 (32:35):
Are they willing? No? But what it also seems to
me is that a lot of this controversy about the
strength of this data and whether it is real or
not hinges on a couple of types of data and
a couple of studies that have come out. One of
them is not just one study but a few studies.
(32:58):
Like one type of study has found that there might
be an increased risk of cardiovascular disease or death from
cardiovascular disease at very low sodium intakes, closer to that
one point two grams of sodium that a lot of
people actually recommend, right right right, So there are some
studies that suggest who have looked at like the lowest,
(33:19):
the intermediate, and high sodium intake levels, some studies suggest
that actually the risk of cardiovascar disease is very clear
above like four to five grams of sodium intake a day. Okay,
so like eight to ten grams of salt that is
too much, But the recommendation should be more like three
to four grams of intake and not this super restrictive
(33:42):
one point five to two point three grams of sodium intake.
That's what some of these studies say, okay, now the critics,
I know you have questions like why what the critics,
what's the mechanism? Yeah, yeah, what's the mechanism? Great question.
I don't know. Okay, I don't know. They have not
offered a mechanistic explanation. And some of the critics of
these studies that have looked at what they call this
(34:04):
J shaped curve right where like lowest intake is potentially
harmful and higher intake is potentially harmful, so there's a
sweet spot in the middle. Some of the critics of
this say, look, in those studies that have looked at
low intake or that have shown low intake to be
potentially dangerous, that could actually be from what's called reverse causality,
(34:25):
because in those studies they included a lot of people
who also already had known cardiovascular disease or high blood
pressure or heart failure. Those people might be more likely
to be on a low sodium diet because they've been
advised to cut out salt from their diet, and then
they die from cardiovascular disease.
Speaker 2 (34:45):
It's very interesting that that is not something that would
have been controlled for or right, you know, in those studies.
Speaker 1 (34:51):
Yeah, yeah, exactly, so mays like, actually need some better
studies on this stuff. It's bananas. They also criticize some
of the like methodological issues with some of those studies
because they relied more on like spot urine rather than
twenty four hour urine, which is how we measure sodium
intake more reliably. But that's just like a lot of
like it all just points to the fact that like
(35:13):
these people say this data is not strong enough to
show a strong link, and these people say this data
is not strong enough to show a strong link, and
it's like, my goodness, Okay, oh.
Speaker 2 (35:23):
It's really interesting. I think, like also in the context
of evolutionary history, like our hominin ancestors. But at the
same time, though, like how cardio of I don't even
want to like this is like such a can of worms.
Speaker 1 (35:38):
Okay, listen, Yeah, there's multiple kinds of worms that you're
about to talk about, and I want to get at
one that you're saying this evolutionary history thing, because listen,
the other camp of people who seem super adamant that
we should not be pushing for lower sodium, that we
should not be having our medical societies have a push
for sodium. It should not be a public health goal.
(35:58):
They seem to be in this group. Get ready for this?
I get I'm too excited, they claim based on their data,
they have done all these studies. They've looked at like
fifty thousand people using these really great, high quality twenty
four hour year in studies across a number of different
countries with different cultures, et cetera. And over the last
(36:21):
fifty years they say there's been no substantial change in
our salt intake over time, and it follows a normal
distribution between about two point six grams and four point
eight grams of sodium a day. And therefore they say
that is our physiologic need of salt because for the
(36:44):
last fifty years it hasn't changed, and because it follows
a normal distribution, that is what our physiological requirements are.
This is a true argument that people are making in
a bunch of studies. It seems to be mostly one
dude who makes this arm and then get cited over
and over and over in all the studies that are saying, well,
(37:04):
this J shaped curve and don't you know our physiologic need?
And I'm like, you cannot tell a human's physiologic need
from fifty years of data. That's a post industrial revolutionary
You're kidding me, m I was aghast.
Speaker 2 (37:19):
I mean, I'm not surprised the this is one of
the most heated debates. I really is. It's like it
also doesn't feel like a debate too it or like
it feels like the arguments for we are like that
is a ridiculous claim.
Speaker 1 (37:40):
To me, and yet Aaron, it is so cited. Okay,
this J shaped curve, it seems like we need to
investigate a little bit more. What is the ideal amount
of assault consumption? That is, at its core the major question.
There is no doubt that diets very high in sodium,
especially over that four g of sodium, which is what's average,
(38:01):
are going to increase your risk for blood pressure, and
almost all the data also agrees that that will increase
your risk for cardiovascular disease between this like one point
five to four grams. There's people who just want to
like fine tune this debate, which makes sense at a
public health level, like we need to have recommendations, right, sure,
but like I just the arguments that are trying to
(38:23):
be made, I just I'm like, I get.
Speaker 2 (38:25):
I mean, in the past fifty years, how many people
are smoking cigarettes? Like, does that mean that that's a
physiological need? Right?
Speaker 1 (38:35):
Do you know what? Also, the rates of hypertension have
also been stable over that exact same time period in
which our salt consumption has been stable. So like, that
doesn't tell us anything. It literally doesn't tell us anything.
Our awareness and treatment have actually improved. So that's nice,
but like, come on, it's not just blood pressure. Also,
(38:56):
there are more and more studies and more and more
data coming out that dietheset a high end sodium are
also linked to a number of other potential diseases or
whole body system changes that might result in disease. We
see increases in inflammation, we see a potential for increased
risk in autoimmune diseases. We see changes in the gut microbiome,
(39:17):
and we see associations with certain cancers, especially stomach cancer.
And we don't fully understand the mechanisms of these, but
we know that more and more data is coming out
that these exist, and so people are looking into like
what could these mechanisms be. It seems to be that
there's like changes in our T cell response, there's this
(39:38):
like pro inflammatory state there's an increased in scret muscle contraction,
et cetera.
Speaker 2 (39:44):
That's I think that's that's interesting too, This argument about well,
this is our physiological need. If we have less than this,
then we'll die and this is what we whatever. Like
that also, I think, doesn't it dismisses these health these
potential health res as something that is not linked to salt.
(40:04):
But it because otherwise we would be eating less salt,
right because otherwise, or we would have adapted to consume
more salt somehow, the human species over the past five
thousand years. But the other thing too, is that these
all of these chronic conditions for the most part, like
you said, there's this age component to it, yes, and
so in which case, like it just is, yeah, it
doesn't make sense.
Speaker 1 (40:25):
I know. It's there's also an argument that's like, well,
we can't consume a lower sodium diet in our current
society and it would require such a societal shift that
therefore we shouldn't recommend it. Like what, it's too hard
to do, so we shouldn't do it. High sodium intake
is also associated with an increased risk of osteoporosis and
(40:48):
kidney stones, and we think that it's by a similar mechanism,
because when you are consuming more sodium, then you will
have increased excretion of sodium, and calcium follows sodium the
same way that water does soday. Okay, and overall, the
World Health Organization estimates that there are nearly two million,
the most reason data I saw said one point eight
(41:09):
nine million excess deaths every year that are due to
excessive sodium consumption.
Speaker 2 (41:16):
Okay, So I have some questions now, uh huh, give
it to me. So, like we talked about, there is
variation in individual sensitivity to sodium and the impact of sodium.
What are some of the reasons for that, and how
does that sort of just come out in the wash
when we're talking about the levels of sodium that we're
(41:37):
talking about.
Speaker 1 (41:38):
This is a really important question. So there's this phenomenon
that is talked about in the literature of like salt sensitivity,
so called salt sensitivity, right, And the thought is that
maybe it's like fifty percent or or less, or some
studies say more of people whose blood pressure specifically actually
responds to an increase in dietary sodium. So they call
(42:02):
those people salt sensitive. That is not a term that
can be easily measured. There is not an agreed upon
degree of salt sensitivity. How much of an increase in
your blood pressure do you need to have to be
considered salt sensitive. That's not a there's not a metric
for that. But overall, yes, it is the case that
not everyone's blood pressure is going to increase necessarily as
(42:25):
a result of an increase in salt intake. Some people
might have very low blood pressure on average, and in
fact need more salt in their diet in order to
maintain their blood pressure, and they could be at risk
of hypotension having too low of blood pressure if they're
not getting enough dietary sodium.
Speaker 2 (42:44):
What is clinical hypotension?
Speaker 1 (42:46):
Oh, it depends on your age, but and it depends
on your if you're symptomatic or not.
Speaker 2 (42:51):
But yeah, okay, symptomatic meaning you're faint or like you could.
Speaker 1 (42:55):
Faint, you could pass out. But it kind of depends.
Usually if you're talking about like under an nineties over sixties,
that's that's pretty low, ok But someone who's you know,
always quite a lot higher than that and suddenly drops,
then you might consider that hypertensive. It kind of just
cost okay, Okay, but yeah, so it does depend. But
there it is the case that not every person needs
(43:18):
the exact amount of salt in their diet. Public health
recommendations don't apply exactly to every single individual. Equally, if
you have certain conditions, you might need to follow slightly
different recommendations. Then what is like the World Health Organization,
(43:39):
the CDC, the FDA, they are making recommendations for the
general public, and it's estimated that over seventy to eighty
percent of adults are consuming significantly more than two point
three grams of sodium per day. So the advice to
reduce sodium applies to most people, not to everyone, which
is also why you shouldn't be taking medical advice from
(43:59):
podcasts or Instagram content creators because it doesn't apply to everyone.
There's also another huge confounder that we haven't even talked
about yet, and that is that this is true of
all nutritional studies. But it's very true in all of
these studies that look at blood pressure and cardiovascular disease
and sodium, and that is that you cannot change only
(44:23):
your sodium intake.
Speaker 2 (44:25):
Yeah, how different? Like what, Yeah, the foods that you're eating.
Speaker 1 (44:29):
The foods that you eat will change there is a
very solid amount of data that shows an inverse relationship
between potassium intake, for example, and blood pressure and cardiovascular disease,
meaning for most people. Not true for everyone, because if
you have kidney disease, this might not apply. But for
most people, increasing your potassium intake can reduce your blood
(44:50):
pressure and in some cases offset some of the effects
of sodium. A lot of our nutrient dense whole foods,
like fruits, vegetables, legumes, whole grains, these are high in potassium. Also,
many of our salt substitutes. If people are going to
swap out their salt that they're sprinkling or cooking with
(45:12):
for a salt substitute, they're switching their sodium for potassium.
Speaker 2 (45:15):
What are some of these salt substitutes.
Speaker 1 (45:18):
Oh, I don't know. You just buy them at the grocery. Toot.
It's called like substitutional substitute. It's a potassium salt. Sometimes
it's just like pure what they're Yeah, sometimes they're pure potassium.
Sometimes they're like a mixture of sodium chloride and like
a potassium chloride or a potassium another potassium salt. There's
been some really interesting data actually on using those, and
then some of the really strong data is from like
(45:39):
a big study in China where they took entire villages
and they were like, you guys are getting salt substitute
and you guys are getting real salt. And they saw
significant decreases in cardiovascular mortality and strokes and all of
these things, and decreases in blood pressure in the salt
substitute group. But you can't quite disentangle the effects of
potassium and sodium in that right, because they're connected.
Speaker 2 (46:00):
They're connected. And also, like you do a sub salt substitute,
but most people don't. Most of the dietary salt that
we consume is not from salt that we sprinkle on foods.
It's from the salt that's in the foods.
Speaker 1 (46:12):
In the US, that's absolutely true. In this part of
China where they were doing it, most of their sodium
actually does come from discretionary sources. So that's why it's
an interesting study in that case. But yes, you're right,
for us, for most people in the US, in Canada,
in Europe, our sodium consumption is mostly coming from things
that are not the salt shaker on our table. I
(46:33):
think it's most estimates are like fifteen percent or something
of our sodium intake comes from adding salt to our foods.
Most of it comes from the fact that every single
food that comes in a package has sodium added to it.
Speaker 2 (46:46):
Yeah.
Speaker 1 (46:47):
Yeah, And so there is something to be said for
the fact that all of the trials that have looked
at long term sodium trends do not find that people
are able to reliably stick to low sodium diets. Usually
less than ten percent of people in these studies can
stick to these limits of less than two grams or so.
I do not buy the argument that this is physiologically
(47:09):
driven at like an evolutionary level. This is a reflection
of our food systems and the fact that it is
very difficult even when you're trying to avoid sodium. But
that doesn't mean it's not an important conversation, right, because
if you're recommending fifteen hundred milligrams of sodium and it's
impossible to do that in our grocery stores, you're setting
(47:30):
people up for failure. So that's a problem too.
Speaker 2 (47:32):
Yeah, And it's also like more time consuming, more expensive.
Often it's like you're yeah, it's hard.
Speaker 1 (47:38):
Yeah, here, and like at the bottom line, to me, okay, Kenna,
if I can conclude, please, the biggest problem, the unspoken
piece in all of these conversations about sodium and health
and blood pressure is the same story as food dies.
Speaker 2 (47:59):
Yeah, what about food?
Speaker 1 (48:01):
Does single piece of our food system arin?
Speaker 2 (48:04):
Yeah?
Speaker 1 (48:05):
Yeah, there's some really interesting data that there's these long
term studies that have been done on Japanese Americans living
in Hawaii and Japanese people living in Japan, and they
look at cardiovascular disease and blood pressure and all of
these rates. We have and die from cardiovascular disease in
the US at substantially higher rates than people in Japan.
(48:28):
Like when you compare US to japan data, Japan has
some of the best health metrics out there. They also
consume so much sodium, significantly more sodium on average than
in America than in the US. And in these studies
that have looked at Japanese men and women and Japanese
American men and women living in Hawaii, we see higher
blood pressure in Japanese populations living in Japan, and yet
(48:51):
higher cardiovascular disease in Japanese Americans living in Hawaii. Because
guess what, it's not just sodium that's different in their diets.
There's higher intakes of omega three fatty acids, there's higher
total cholesterol intakes. There's also interestingly higher rates of smoking
and alcohol use, but lower intakes of total calories and
protein and fat including saturated fatty acids. Nothing that we
(49:14):
eat is in isolation. Ye right, Yeah, so, yes, it
is important to have these dietary guidelines, but these exist
in the context of so many other foods, and it
is one single part of your overall food system.
Speaker 2 (49:32):
This is fascinating and I feel like there is a
to me, there is like a clear answer in many ways.
Your sodium, yeah, am I Yeah, Honestly, while I was reading,
I was trying to use less. I use a lot
of salt. But I think I think you're right, Like
(49:53):
my Yes, I can reduce my discretionary salt, but am
I still gonna want, you know, salty crackers and stuff. Yeah,
so I'm going to try to less or at least
try to eat more whole foods.
Speaker 1 (50:08):
Like I mean, we all need to be doing that,
that's true.
Speaker 2 (50:12):
Yeah, but yeah, I think I think it's like because
I feel like I have. The more salt I eat,
the more I want, and then it becomes like a problem.
So maybe I'll try you know what, you know what,
I do kind of want to try it. To the
salt alternatives, Yeah yeah.
Speaker 1 (50:29):
My husband Trek got really into those for a while.
We had a lot of potassium salt in the house
for a while.
Speaker 2 (50:33):
Yeah, I'm intrigued.
Speaker 1 (50:35):
Yeah yeah, Well, if you're also intrigued and want to
learn more about this debate or whether you should reduce
your salt intake or not. My favorite paper, honestly was
the one that I pulled that first hand account from,
and it was by Hunter at All in Nature of
Views and Nephrology twenty twenty two, The Impact of Excessive
Salt Intake on Human Health. I thought that they did
(50:56):
a really good job of explaining all of the controversy
of providing the data. I know, not on quote unquote
both sides, but like providing all of the data. They
definitely have a bent, they think that we're eating too
much salt. But I really enjoyed that paper. I also
read it piecemeal, and I wish I had just read
it all the way through at the beginning, because it
was most of my stuff ended up putting from there.
(51:17):
But I was like reading it and then I found others. Anyways,
it's a great paper. There's also some interesting ones about
like our regulation of salt appetite and like the you know,
the salt drive and everything. So I have a couple
of papers on that. And then literally, I mean so
just so many papers. I think. Another great one was
from twenty eighteen by he at All the Role or
(51:38):
He and McGregor. It was the role of salt intake
in prevention of cardiovascular disease Controversies and challenges. I enjoyed
that one, but there's so many, including all of the
controversial ones. You can find them on our website this
podcast wkay dot com under the episode's tab.
Speaker 2 (51:54):
Thank you to Bloodmobile for providing the music for this
episode and all of our episodes.
Speaker 1 (51:58):
Thank you to Leon and Tom and Pete and Brent
and Jessica and everyone else that is exactly right for
making all of this possible.
Speaker 2 (52:06):
Thank you, thank you, and thank you to you listeners.
I hope you liked these episodes. Let us know what
you think.
Speaker 1 (52:13):
Yeah, I'm very curious. Yeah, how much sodium do you eat?
You don't have to tell me that you don't. There's
no judgment here. And a special shout out as always
to our patrons, thank you so much for your support.
It means the world to us.
Speaker 2 (52:31):
Until next time, wash your hands, you filthy animals.
Intake of salt is a biological imperative inextricably woven into
physiological systems, human societies, and global culture. However, excessive salt
intake is associated with high blood pressure. The crucial question
is whether salt exerts a causal influence on patient centered
health outcomes such as myocardial infection, stroke, and death. However,
(00:25):
this issue is controversial and fiercely debated. Despite the controversy,
two broad points of consensus exist. The first is that
the uncertainty could be resolved by better quality data, that is, large,
randomized clinical trials with sufficient follow up to assess robust
cardiovascular outcomes. The second is that the barriers to performing
(00:48):
such trials are so substantial that they will be rarely,
if ever surmounted.
Speaker 2 (01:43):
Okay, so many questions.
Speaker 1 (01:45):
What was that? From?
Speaker 2 (01:47):
When was that? From? Who wrote that?
Speaker 1 (01:50):
I can't wait to tell you? Okay? So that was
I pulled clips like little bits from the intro and
from later in a paper, from a very very recent paper.
I have just scrolled. Why didn't I put this up?
I'm scrolling all the way to the bottom of my
notes from Nature Reviews Nephrology from twenty twenty two by
(02:11):
hunter at All titled the Impact of Excessive Salt Intake
on Human Health, and this paper that little intro, that's
the end of my.
Speaker 2 (02:24):
I mean, that's what like, That's what kills me, is
that I feel like since that could The reason I
asked where when is it from? Is because that could
have been from so many different points in history over
the salt debate. We need better data, we need randomized
control trials, we need long term data sets and follow up.
Speaker 1 (02:45):
And it is from twenty twenty two. So that's what
we're going to talk about today in this episode.
Speaker 2 (02:56):
Hi, I'm Aaron Welsh.
Speaker 1 (02:58):
And I'm Aaron Allman updight.
Speaker 2 (03:00):
And this is this podcast will kill you. Welcome back
to Salt Salt. Here we go again, Yeah.
Speaker 1 (03:07):
We go again. I'm really excited about today's episode. I
don't know how many answer any of your questions, but
I think I think we'll come to some clarity. I
honestly really actually do at the end of this.
Speaker 2 (03:19):
I am hopeful. I know that if there is a
thread to be pulled, you will find it and yank
it out from the yank Yeah, yeah, I do. I'm
thrilled for this. Yeah, I already want to start asking questions,
and that is a first like that is early for me,
(03:39):
so good.
Speaker 1 (03:41):
I can't wait. I can't wait for you to ask
me questions and then I'll be like that's the one
I don't have an answer for, or like, oh my god,
now I have to scroll one hundred years in my notes.
I can't wait. I have fifteen pages of notes here
erin so like, I've got to have answers to something.
But firstarantiny time it is?
Speaker 2 (04:01):
It is we're again drinking the grains of salts, which
is based on a salty dog. I mean it is
a salty dog, which is great fruit juice and vodka
or gin, whichever you prefer. Make sure your rim is
salted unless you're dealing with high blood pressure. No, just kidding,
I don't know, but that is the technical recipe. Also,
(04:23):
this reminds me that if you are just now tuning in,
then you didn't see at the top that it says
Salt Part two. You really don't have to listen to
the first episode, but you should. It's not like there's
a narrative that you'll miss, but you'll miss a lot.
You'll miss some. It'll help you with trivia. It's got
some cool It's a great episode. Do you want to
(04:43):
learn where the term grain of salt comes from? Check
it out.
Speaker 1 (04:47):
You've got to listen to that episode. We're not going
to tell you now.
Speaker 2 (04:49):
Yeah.
Speaker 1 (04:51):
Anyways, we'll post the recipe for the drink on our website.
This podcast with you dot com and our social media
is so make sure you're following us there. You find
lots of other cool stuff on our website too, like
trans scripts and a bookshop dot orgiphiliated account, and a
good Reads list and merch and all the sources from
all of these episodes. Boy do I have a long
list for this one bloodmobile? Who does our music? You know?
(05:13):
Contact us form.
Speaker 2 (05:14):
Lots of things.
Speaker 1 (05:15):
I'll check it out.
Speaker 2 (05:18):
Is there any other business or can we like get
straight to things? Let's do this?
Speaker 1 (05:22):
Oh yes, very short break life evolved in the oceans,
(05:51):
which are salty.
Speaker 2 (05:53):
I loved this. I'm like, wait a second, have I
said this before?
Speaker 1 (05:57):
No, you haven't, but it is the most Aaron Welsh
way to start the thing. Ever that I was like
thrilled that you didn't start that way and that I
could do it.
Speaker 2 (06:05):
I did think about going into the evolutionary origins and
then I was like stop.
Speaker 1 (06:09):
Yeah, no, no, I'm not going any further than that. Life
evolved in the oceans. Yeah, the oceans are salty, and
with the evolution from single celled organisms to multicellular organisms,
salt became a major component of our extracellular fluid, that is,
the fluid that is on the outside rather than the
inside of our cells. Our bodies are basically just made
(06:35):
up of tiny little water balloons bathing in more water. Yeah, okay,
and all of the water inside and outside of our
cells is salty water. Yeah, but the salt on the
inside of our cells is mostly potassium. So the ions
that make up the salt mostly are potassium, and the
(06:57):
salts outside of our cells most are made up of sodium. So,
as we moved from our ocean homes to land, and
by we I mean like, you know, creatures and not
like humans.
Speaker 2 (07:10):
Global evolutionary we yeah.
Speaker 1 (07:12):
Exactly, we were no longer bathing in sodium all the time, right,
and thus we had to find ways to ingest it. Yeah.
So animals evolved taste receptors to be able to detect salt,
and in general, like you kind of mentioned, Aaron, most
(07:32):
animals have actually a pretty consistent like upside down U
shaped preference curve for saltiness, right, but I think it's yeah,
upside down you so like it's delicious right in the middle.
If it's not salty enough, it doesn't taste good. If
there's too much salt also doesn't taste good. Right. So
when we talk about salt in this episode, like you
(07:53):
said last week as well too, I'm talking about sodium
chloride NaCl uh huh. I mean when I set it
in the bodies where there's other salts in your bodies,
and there's other ions that are important, But from now
on out, I'm just talking about sodium chloride.
Speaker 2 (08:07):
Okay, Can I already ask a question? Yeah, Garby, you
mentioned potassium is on the inside and sodium is on
the outside.
Speaker 1 (08:15):
Huh.
Speaker 2 (08:18):
And what happens then?
Speaker 1 (08:20):
Like okay, yeah, let me let's sorry.
Speaker 2 (08:23):
Yeah, well it's not a question. It was more just
like tell me more.
Speaker 1 (08:28):
Yes, let me continue setting the scene and then I
will I will get into that, okay, very shortly. Well,
we're talking mostly about sodium chloride today. Lots of other
salts exist in chemistry, salt like table salt, Sodium chloride
is about forty percent sodium. Yeah, like by weight, so
(08:49):
ten grams of salt. This is important for one work
because like all of the dietary guidelines and things talk
about sodium, right, But then a lot of studies just
talk about salt. So we can use these interchange ten
grams of salt four grams of sodium. That's the equivalence there.
Speaker 2 (09:04):
Okay, guess what there are like online calculators that I
had to use to be like how much sodium are wet?
I would be like how much salt does the average
American eat? Oh? You know, however thirty two hundred milligrams
of salt or sodium, So like right, no, but how
much salt are we eating?
Speaker 1 (09:19):
How much salt does that? Yeah? Exactly. Also, then some
studies like to use millimals just to make them sound
more smart, and you're just like, now I have to
take it from mills to milligrams, Like stop it, it's unnecessary.
But so the questions that I want to answer today
in this episode are number one, why do we give
a crap about sodium? And that's going to get it
your question of like sodium potassium, what does that mean?
(09:40):
What does it do in our bodies? Why do we
actually need it. What is the problem or is there
a problem with excess sodium and how much? What does
excess actually mean? And why is there so much debate
about this? Yeah, that's going to be a big part
of the episode. What I am not going to talk
about is hypo and hyper natremia. That is when your
(10:03):
blood sodium is too low or too high. I'm not
going to talk about it in any great detail. If
you are a medical student or a resident, you're welcome
for not making you listen to that. If you don't
know what that means, you can watch some doctor Glalcum
Flecken videos because they sum up both my knowledge and
also why I have no interest in talking about those things, because.
Speaker 2 (10:23):
Are those acute stages.
Speaker 1 (10:26):
They can be acute or chronic. Okay, okay, yeah, and
it's all just a mess. But you will understand why
it's important when I tell you why do we have
to give a crap about sodium? Right at its core,
at its most important, sodium is what determines our total
body fluid balance. So because it is the most abundant
(10:48):
cat ion, positively charged ion in our extracellular fluid, it
is what determines how much fluid volume we actually have
in our bodies. Right, Because the salt on the inside
of our cell bags is mostly potassium and the salt
on the outside is mostly sodium, it doesn't matter which
(11:09):
is which as long as their concentrations are the same.
Our bodies have to keep a balance of these fluids.
So the concentration of particles on the inside of our
cell has to match the concentration on the outside if
they don't, Like if you were to dump a bunch
of sodium into your bloodstream into your extracellular fluid, then
your body would have to compensate by extracting fluid from
(11:33):
cells in order to make up for that.
Speaker 2 (11:35):
Right, Okay, And the identity of sodium versus potassium doesn't
necessarily matter, I imagine it does at a point.
Speaker 1 (11:44):
It does, absolutely, but it doesn't for the purposes of
just understanding that, like at its core, you just have
to have balance. It so happens that potassium is what
exists inside of our cells, and sodium primarily exists outside
of our cells, And our cells do a lot of
transmitting sodium and potassium back and forth through these atp
ion channels, and that is all very important. But to
(12:09):
understand fluid balance. You need to know that potassiums on
the inside and sodiums on the outside, and they got
to be concentration wise balanced.
Speaker 2 (12:16):
Right.
Speaker 1 (12:18):
Sodium is also an incredibly important cad on outside of
fluid balance. It's a neurotransmitter. It is essential for our
muscles to be able to contract, and so it's something
that our cells also use in communication with other cells. So,
make no mistake, we cannot exist without sodium.
Speaker 2 (12:38):
It's necessary for life.
Speaker 1 (12:40):
It is necessary for life, and the volume of our
fluid in our bodies is proportional to our total body
content of sodium. Right, So, in order to if you
lose a bunch of volume, for example, if you're bleeding,
or if you're even just peeing out way too much,
(13:00):
or you're sweating or you're having diarrhea, in order to
replace the volume that you've lost of fluid, you have
to also replace sodium. You cannot replace it with just water,
it will not work. Right. We lose sodium predominantly through
our kidneys. In fact, shout out to our kidneys. They
(13:22):
are so stellar at this that they excrete about ninety
to ninety five percent of what we ingest regardless of
how much we ingest. Isn't that interesting?
Speaker 2 (13:33):
Wait? So okay, but you said it's a proportion that
they excrete out or.
Speaker 1 (13:38):
Is it ninety to ninety five percent of what you
ingest you're going to pee out in your kidneys.
Speaker 2 (13:44):
So let's say we're talking about sodium sodium. Yeah, so
let's say that you, you know, going back to last
week's episode when the ridiculous estimate, shocking estimate of one
hundred grams of salt a day a day, let's say, so,
that's forty grams of sodium oday. Yeah, that ninety percent
(14:05):
that's excreted out. You've got a lot more salt remaining
in your body than if you're.
Speaker 1 (14:09):
Oh, Aaron, you're so right.
Speaker 2 (14:14):
Thank you for leading me perfectly to that.
Speaker 1 (14:17):
You did it all on your own. Oh my god, Yes, exactly,
exactly right. Proportionally percent of what we ingest, regardless of
what we're ingesting. Right, we're gonna lose some through our
gi tract, via your poop. You're gonna lose some via sweat,
et cetera. Okay, most of its kidneys, Most of it's kidneys,
and our kidneys. They do a really good job of
(14:38):
deciding how much to kick out and how much to
keep depending on how much we eat, because it is
going to be variable. Right, if you're not getting enough,
if you are deficient in your sodium intake, or if
you've got other reasons that your body decides, hey, we
need to hold onto this. Your kidneys can actually keep
almost all of it. They can They can keep almost
(14:59):
one hundred percent of your sodium if they need to.
Speaker 2 (15:15):
Two questions, Okay, what are some of the conditions that
your kidneys might keep more sodium than is necessary? And
how often does someone actually not consume enough sodium in
like the your like a normal day to.
Speaker 1 (15:30):
Day you know, such great questions. How often in the
year twenty twenty five is someone not getting enough sodium?
Very rare? Okay, it's very hard to not get enough
sodium for most people. You If you, for example, were
to lose a lot of blood or lose a lot
of volume for any reason, then your blood pressure would
probably drop. Then your kidneys would say, hey, we need
(15:52):
to hold onto blood pressure. We're going to do that
by holding on all of our sodium. We're not going
to let any sodium go, and that's going to help.
You're going to need to ingest sodium, either via like
ivy fluids or just eating salt in order to make
up for those losses. But your kidneys are also going
to react very quickly to hold on to as much
as possible. There's other like disease states. For example, if
you have issues with your adrenals where you're not producing
(16:14):
certain hormones. Because it's a lot of very complicated it's
your kidneys, it's your brain, it's your blood vessels and
sensors that are in your blood vessels. It's hormones that
are controlling all of this. So if you have deficiencies
in certain hormones, then your kidneys might flip on and say, hey,
we need to hold on to all the sodium that's
possible because we are you know, at risk of losing
it or whatever. Or maybe you have deficiencies and hormones
(16:37):
and you can't do that and so you're losing a
lot of sodiums. So then you might have what so
many animals have big bone lick stake park and that
is what's called sodium appetite. Yes, and sodium appetite is
this idea that we know exists in animals that in
a state of sodium deficiency. Animals will exhibit these pretty
(17:00):
extreme sodium seeking behaviors and they will do extra work
to seek out and consume salt. And we see this
in a lot of different animals, mice, rats, rabbits, pigeons, goats,
we learned, kangaroos, sheep, cattle, monkeys, horses. So the question
is does this sodium appetite exist in humans, And we
(17:22):
think probably yes, though the data is based on a
few cases of like, for example, kids who had no
functional adrenals, so they were salt wasting. Their kidneys could
not hold on to salt, and so they had an
increased need for salt and exhibited these kinds of salt
(17:42):
seeking behaviors. In the literature, these are like really old
single case type studies. Yea, but then yeah, so those
individuals in those studies did exhibit that kind of sodium
seeking what we would call sodium appetite. That's not the
same thing as what we experience now, which is sodium
preference where we like it so we eat it because
(18:05):
it tastes good. That does not mean that we are
sodium deficient.
Speaker 2 (18:09):
Right, even though it feels sometimes like the same thing.
Speaker 1 (18:12):
Right, hard to distinguish perhaps.
Speaker 2 (18:18):
Okay, I have a question about you said like salt appetite,
this instinctual drive to find salt, and you said that
they tested out in kids that lacked adrenals. Tell me
why that would. What's happening there is their kidneys aren't
holding on like yeah.
Speaker 1 (18:35):
Yes, exactly that. So your adrenals they do a lot,
but one of the hormones that they make is called aldosterone,
which is a very important part of mediating the resorption
of sodium in your kidneys. And so without being able
to make that particular hormone, then you can't have a
signal to tell your kidneys to hold on to sodium,
(18:57):
and so you're basically sodium wasting. And there's other conditions
as well too. There's like genetic conditions, or there's maybe
damage to the kidney. There's medications that can make you
lose more sodium in your urine through your kidneys. Okay, yeah,
but a lot of it is under that hormonal control.
So that's why it was in kids who had like
(19:17):
not either they didn't have adrenals or they had non
functional adrenals. I can't remember which one. Okay, And your
drenals do a lot more than just teldosterone, but that's
important for salt.
Speaker 2 (19:27):
And your kidneys do a lot more than just sodium too, yes, Vato.
Speaker 1 (19:33):
But so this all begs the question how much sodium
do we actually need?
Speaker 2 (19:43):
How much?
Speaker 1 (19:44):
Aaron? This is my favorite question that I've asked myself, yeah,
in a while, and it is very hard to come
to an actual answer on this. So you mentioned, and
I'm so glad that you did in last episode, that
our early hominid ancestors, their estimated amount of salt intake
(20:09):
was about one gram of salt per day or less.
That's four hundred milligrams of sodium. Now, there also was
a study that came out in the late eighties called
inter Salt, and this was this one of these big,
big observational studies that first showed a relationship. Not first
(20:30):
because you said it was like you know, in the
early nineteen hundreds.
Speaker 2 (20:33):
Twenty six, if you're talking, you know, correct hard hard
pulse that hardens.
Speaker 1 (20:39):
Yeah, But this was one of like a big important
observational study that looked at a bunch of different populations
with variation in their average salt intake and found a
very strong relationship between higher salt intake and blood pressure.
In this study, they also looked at several remote human
populations in Brazil, Kenya, and Papula, New Guinea, and in
(21:02):
those populations, people, yes, had very low blood pressure, but
they also had substantially lower sodium intakes compared to what
we see today, one to three grams of salt on average,
which is four hundred milligrams to one point two grams
of sodium per day.
Speaker 2 (21:17):
I mean, it's to be hard, I feel like, in
our like in the US, to eat that, to select
that diet, right.
Speaker 1 (21:24):
Listen, we'll get there. It's very hard, Okay, But this
all becomes really important because, as I'm going to talk
about later, there is a lot of weird debate about
what our quote unquote physiologic need actually is. Okay, and
we'll get into the people who are claiming things that
they're claiming, but it is very clear from these early
(21:47):
you know, these estimates of early hominid we can't we
can't have exact data on that, right, but these estimates
based on the sodium content of the types of foods
that early hominids would be eating, plus the fact that
there are, or at least in the eighties and seventies
were societies in which people were consuming very minimal amounts
of salt and they were living, surviving, maybe thriving, I
(22:10):
don't know, but their bodies were functioning just fine. So physiologically,
most estimates say we need at a minimum about five
hundred milligrams of sodium a day in order to continue
our bodily functionings, to keep up with losses from our kidneys,
from our sweat, from our GI tract. And that's going
to vary based on how much you're sweating, how much
you're pooping, and how great your kidneys are at retaining sodium.
Speaker 2 (22:33):
What about potassium, great question.
Speaker 1 (22:36):
Potassium is incredibly important and actually plays a huge role
in this sodium blood pressure, et cetera debate. And I
didn't write down the exact like what the RDA the
recommended amount of potassium that you get is, so I
don't know the exact numbers of that, but potassium is
absolutely essential to consume every day as well.
Speaker 2 (22:57):
And we're but I'm asking about the intrasalt study. Were
those populations, the remote populations, were they consuming some other
types of salt, you know, potassium or whatever.
Speaker 1 (23:07):
They were probably consuming more potassium than what we consume
or what a lot of other populations consume. Because foods
that tend to be low in sodium are often high
in potassium. That's very interesting, because whole foods are very
high like fruits, vegetables, these kinds of things tend to
be very high in potassium. Harm. Okay, we'll get there, Okay, okay,
(23:31):
So that's how much salt we need, like bare minimum
to survive. We think, right, how much salt do we get?
On average? Global daily salt intake is estimated. Most estimates
and by the World Health Organization are about ten grams
of salt per day, which is about four grams of sodium.
There is a lot of variation, so the average ranges
(23:53):
from just over two grams to just over five grams
per day based on different populations, and of course there's
a lot of individual and day to day variation. Now,
the World Health Organization recommends a limit of no more
than two grams of sodium a day two thousand milligrams,
that's five grams of salt. The American Heart Association in
(24:18):
the US recommends for all adults absolutely no more than
two point three grams of sodium, and for anyone with
high blood pressure or at high risk for cardiovascular disease.
They recommend a limit of one point five grams of sodium.
Other countries have slightly different recommendations, but they're all in
(24:38):
this ballpark of around two grams of sodium, around five
grams of salt, and yet globally, on average, we are
getting more than double the amount of what most major
medical societies recommend. Why is that? What impact is this having?
And why is there so much controversy about this? Still?
Speaker 2 (24:58):
This is so fascinating because I think question being how
much salt do we need? Versus how much salt is
too much? I feel like is really different. Those are
two entirely different questions.
Speaker 1 (25:10):
They are, And I.
Speaker 2 (25:12):
Also want to understand how we arrived at this number,
these recommended numbers, which have been revised down over the
past fifty years.
Speaker 1 (25:24):
Yes, they have been revised down. To me, most of
the data that has led to the revising down of
these numbers is based on blood pressure, because there is
honestly very little at this point controversy left about the
data that pretty clearly shows that a reduction in salt
intake from that about four grams of sodium, which is
(25:47):
our average. Reduction from that reduces blood pressure, especially on
a population level, and in most studies it reduces it
to what would be considered a clinically relevant to so
like about the same amount that you would see if
you were starting someone on an anti hypertensive medication at
(26:07):
a low dose, right, so not quite as good as
blood pressure medicine, but you know at a population level
you're going to be reducing blood pressure by reducing sodium
intake from that current average of about four grams. The
exact amount that you're going to get is going to
very study to study. There's a lot of individual variation.
Not every person gets the same degree of benefit, but
(26:29):
across the board, like studies don't argue that lower sodium diets,
Both interventional studies and observational studies agree that a reduction
in sodium intake and lower sodium diets reduce blood pressure. Now,
blood pressure is one of the major risk factors for
(26:50):
cardiovascular disease, including heart attack, heart failure, stroke, and death
from cardiovascular disease. High blood pressure is one of the
major risk factors, so the biggest risk of diets that
are high in sodium is an increased risk of cardiovascular disease,
and this is where so much of this controversy lies.
Speaker 2 (27:14):
Is now the time to ask what the mechanism is
between sodium intake and blood pressure?
Speaker 1 (27:24):
Great question? Yes, now is a great time to ask.
So there's a complicated answer, which is a lot of
like we don't quite know and the mechanisms da da
da da. And then there's a simple answer, which is
that when you consume more salt, because you're not excreting
one hundred percent of it, some additional salt is going
to stay in your body and that is going to
(27:47):
tell your kidneys to hold not even tell your kidneys,
kind of force your kidneys to hold on to water
because water follows sodium yep. And so as your blood
volume spans and your extracellular fluid volume expands because it
will because you're holding on to water. By holding on
to sodium, that is going to cause an increase in
(28:10):
your blood pressure because you're increasing the volume in your
blood and.
Speaker 2 (28:15):
Just more is shooting through those vessels.
Speaker 1 (28:18):
Right, you've got more sodium or holding onto more water,
So now you have more fluids, so you have more pressure. Okay, Now,
most of the time, if you're kidneys, which sense this
increase in volume and sense this increase in blood pressure.
What they should do is excrete more sodium because they
(28:38):
can sense this and they can say, oh, we need
to get rid of some sodium in order to get
rid of some water because our pressure is too high.
So what exactly happens in these especially long term high
sodium diets, because this is not like a today tomorrow
type of situation. This is like a long term trend
that we see, Okay, especially in places where there are
(29:01):
high sodium diets for a very long time. There's in
like an increasing effect of high sodium diet with age
and with time, And so what exactly is going on
and what other miscommunications are happening between you know, our
reunnin and geotensin system and aldosterone and all of these
hormones and our kidneys and the receptors in our carotids
(29:24):
that are also telling our kidneys in our brain how
much blood pressure we have. Like there's some miscommunication that's
going on that leads to over time and increase in
blood pressure.
Speaker 2 (29:34):
And so our kidneys are just is it our kidneys
that aren't responding as well?
Speaker 1 (29:38):
Or is it that's part of what we think is
that it's like, for some reason or another there's a
loss of some of this feedback where they're not able
to sense this increase in blood pressure, or in some
cases they even maybe go, hey, let's activate this system
and actually increase blood pressure more or something weird, like
a like a paradoxical kind of response. So it's not
like a super clear cut but and it's most basic.
(30:01):
You can think of it as you're increasing the amount
of sodium, therefore you're increasing fluid, therefore you're increasing pressure.
Speaker 2 (30:24):
Why does age play a role?
Speaker 1 (30:27):
I mean, age plays such a huge role in our
cardiovascular health overall. We see like a decrease in elasticity
of the vessels. So is it that they're not able
to expand to that increasing volume. There's a chronic inflammation
that's going on, Like there's so there's so much So
that's that's a different question. But yeah, so that's how
(30:47):
we think that blood pressure is like involved with sodium. Right,
So then the question is if we know that blood
pressure is such a huge risk for cardiovascular disease, and
diets that are high end sodium increase your blood pressure,
do they increase the risk of cardiovascular disease, and that
(31:09):
question has been fracked with so much controversy. Yeah, it has,
so let me try and break it down a little bit. Okay,
nearly all of the large scale meta analyzes that have
been done to look at this question, does reducing sodium
(31:29):
intake decrease cardiovascular mortality? All of these large scale meta
analyzes do show a significant reduction in risk of stroke,
heart attack, cardiovascular disease, and mortality from cardiovascular disease. The quality, though,
of this data is not as good as the strength
(31:52):
of the data that we have for this direct association
between sodium and blood pressure. We don't have long term
randomized clinical trial because that is very hard to do.
As I said, at the first hand account, the estimates
that I have seen are that to get really good
data on this, you would have to enroll between seventeen
(32:12):
thousand and thirty seven thousand people. You'd have to follow
them for a number of years because you need to
have enough unfortunately bad cardiovascular outcomes to be able to
get that data, and it would cost between four hundred
and nine hundred million dollars. So I know some people
who could fund that, you know what I'm saying. Not
like personally.
Speaker 2 (32:31):
But but are they willing?
Speaker 1 (32:35):
Are they willing? No? But what it also seems to
me is that a lot of this controversy about the
strength of this data and whether it is real or
not hinges on a couple of types of data and
a couple of studies that have come out. One of
them is not just one study but a few studies.
(32:58):
Like one type of study has found that there might
be an increased risk of cardiovascular disease or death from
cardiovascular disease at very low sodium intakes, closer to that
one point two grams of sodium that a lot of
people actually recommend, right right right, So there are some
studies that suggest who have looked at like the lowest,
(33:19):
the intermediate, and high sodium intake levels, some studies suggest
that actually the risk of cardiovascar disease is very clear
above like four to five grams of sodium intake a day. Okay,
so like eight to ten grams of salt that is
too much, But the recommendation should be more like three
to four grams of intake and not this super restrictive
(33:42):
one point five to two point three grams of sodium intake.
That's what some of these studies say, okay, now the critics,
I know you have questions like why what the critics,
what's the mechanism? Yeah, yeah, what's the mechanism? Great question.
I don't know. Okay, I don't know. They have not
offered a mechanistic explanation. And some of the critics of
these studies that have looked at what they call this
(34:04):
J shaped curve right where like lowest intake is potentially
harmful and higher intake is potentially harmful, so there's a
sweet spot in the middle. Some of the critics of
this say, look, in those studies that have looked at
low intake or that have shown low intake to be
potentially dangerous, that could actually be from what's called reverse causality,
(34:25):
because in those studies they included a lot of people
who also already had known cardiovascular disease or high blood
pressure or heart failure. Those people might be more likely
to be on a low sodium diet because they've been
advised to cut out salt from their diet, and then
they die from cardiovascular disease.
Speaker 2 (34:45):
It's very interesting that that is not something that would
have been controlled for or right, you know, in those studies.
Speaker 1 (34:51):
Yeah, yeah, exactly, so mays like, actually need some better
studies on this stuff. It's bananas. They also criticize some
of the like methodological issues with some of those studies
because they relied more on like spot urine rather than
twenty four hour urine, which is how we measure sodium
intake more reliably. But that's just like a lot of
like it all just points to the fact that like
(35:13):
these people say this data is not strong enough to
show a strong link, and these people say this data
is not strong enough to show a strong link, and
it's like, my goodness, Okay, oh.
Speaker 2 (35:23):
It's really interesting. I think, like also in the context
of evolutionary history, like our hominin ancestors. But at the
same time, though, like how cardio of I don't even
want to like this is like such a can of worms.
Speaker 1 (35:38):
Okay, listen, Yeah, there's multiple kinds of worms that you're
about to talk about, and I want to get at
one that you're saying this evolutionary history thing, because listen,
the other camp of people who seem super adamant that
we should not be pushing for lower sodium, that we
should not be having our medical societies have a push
for sodium. It should not be a public health goal.
(35:58):
They seem to be in this group. Get ready for this?
I get I'm too excited, they claim based on their data,
they have done all these studies. They've looked at like
fifty thousand people using these really great, high quality twenty
four hour year in studies across a number of different
countries with different cultures, et cetera. And over the last
(36:21):
fifty years they say there's been no substantial change in
our salt intake over time, and it follows a normal
distribution between about two point six grams and four point
eight grams of sodium a day. And therefore they say
that is our physiologic need of salt because for the
(36:44):
last fifty years it hasn't changed, and because it follows
a normal distribution, that is what our physiological requirements are.
This is a true argument that people are making in
a bunch of studies. It seems to be mostly one
dude who makes this arm and then get cited over
and over and over in all the studies that are saying, well,
(37:04):
this J shaped curve and don't you know our physiologic need?
And I'm like, you cannot tell a human's physiologic need
from fifty years of data. That's a post industrial revolutionary
You're kidding me, m I was aghast.
Speaker 2 (37:19):
I mean, I'm not surprised the this is one of
the most heated debates. I really is. It's like it
also doesn't feel like a debate too it or like
it feels like the arguments for we are like that
is a ridiculous claim.
Speaker 1 (37:40):
To me, and yet Aaron, it is so cited. Okay,
this J shaped curve, it seems like we need to
investigate a little bit more. What is the ideal amount
of assault consumption? That is, at its core the major question.
There is no doubt that diets very high in sodium,
especially over that four g of sodium, which is what's average,
(38:01):
are going to increase your risk for blood pressure, and
almost all the data also agrees that that will increase
your risk for cardiovascular disease between this like one point
five to four grams. There's people who just want to
like fine tune this debate, which makes sense at a
public health level, like we need to have recommendations, right, sure,
but like I just the arguments that are trying to
(38:23):
be made, I just I'm like, I get.
Speaker 2 (38:25):
I mean, in the past fifty years, how many people
are smoking cigarettes? Like, does that mean that that's a
physiological need? Right?
Speaker 1 (38:35):
Do you know what? Also, the rates of hypertension have
also been stable over that exact same time period in
which our salt consumption has been stable. So like, that
doesn't tell us anything. It literally doesn't tell us anything.
Our awareness and treatment have actually improved. So that's nice,
but like, come on, it's not just blood pressure. Also,
(38:56):
there are more and more studies and more and more
data coming out that dietheset a high end sodium are
also linked to a number of other potential diseases or
whole body system changes that might result in disease. We
see increases in inflammation, we see a potential for increased
risk in autoimmune diseases. We see changes in the gut microbiome,
(39:17):
and we see associations with certain cancers, especially stomach cancer.
And we don't fully understand the mechanisms of these, but
we know that more and more data is coming out
that these exist, and so people are looking into like
what could these mechanisms be. It seems to be that
there's like changes in our T cell response, there's this
(39:38):
like pro inflammatory state there's an increased in scret muscle contraction,
et cetera.
Speaker 2 (39:44):
That's I think that's that's interesting too, This argument about well,
this is our physiological need. If we have less than this,
then we'll die and this is what we whatever. Like
that also, I think, doesn't it dismisses these health these
potential health res as something that is not linked to salt.
(40:04):
But it because otherwise we would be eating less salt,
right because otherwise, or we would have adapted to consume
more salt somehow, the human species over the past five
thousand years. But the other thing too, is that these
all of these chronic conditions for the most part, like
you said, there's this age component to it, yes, and
so in which case, like it just is, yeah, it
doesn't make sense.
Speaker 1 (40:25):
I know. It's there's also an argument that's like, well,
we can't consume a lower sodium diet in our current
society and it would require such a societal shift that
therefore we shouldn't recommend it. Like what, it's too hard
to do, so we shouldn't do it. High sodium intake
is also associated with an increased risk of osteoporosis and
(40:48):
kidney stones, and we think that it's by a similar mechanism,
because when you are consuming more sodium, then you will
have increased excretion of sodium, and calcium follows sodium the
same way that water does soday. Okay, and overall, the
World Health Organization estimates that there are nearly two million,
the most reason data I saw said one point eight
(41:09):
nine million excess deaths every year that are due to
excessive sodium consumption.
Speaker 2 (41:16):
Okay, So I have some questions now, uh huh, give
it to me. So, like we talked about, there is
variation in individual sensitivity to sodium and the impact of sodium.
What are some of the reasons for that, and how
does that sort of just come out in the wash
when we're talking about the levels of sodium that we're
(41:37):
talking about.
Speaker 1 (41:38):
This is a really important question. So there's this phenomenon
that is talked about in the literature of like salt sensitivity,
so called salt sensitivity, right, And the thought is that
maybe it's like fifty percent or or less, or some
studies say more of people whose blood pressure specifically actually
responds to an increase in dietary sodium. So they call
(42:02):
those people salt sensitive. That is not a term that
can be easily measured. There is not an agreed upon
degree of salt sensitivity. How much of an increase in
your blood pressure do you need to have to be
considered salt sensitive. That's not a there's not a metric
for that. But overall, yes, it is the case that
not everyone's blood pressure is going to increase necessarily as
(42:25):
a result of an increase in salt intake. Some people
might have very low blood pressure on average, and in
fact need more salt in their diet in order to
maintain their blood pressure, and they could be at risk
of hypotension having too low of blood pressure if they're
not getting enough dietary sodium.
Speaker 2 (42:44):
What is clinical hypotension?
Speaker 1 (42:46):
Oh, it depends on your age, but and it depends
on your if you're symptomatic or not.
Speaker 2 (42:51):
But yeah, okay, symptomatic meaning you're faint or like you could.
Speaker 1 (42:55):
Faint, you could pass out. But it kind of depends.
Usually if you're talking about like under an nineties over sixties,
that's that's pretty low, ok But someone who's you know,
always quite a lot higher than that and suddenly drops,
then you might consider that hypertensive. It kind of just
cost okay, Okay, but yeah, so it does depend. But
there it is the case that not every person needs
(43:18):
the exact amount of salt in their diet. Public health
recommendations don't apply exactly to every single individual. Equally, if
you have certain conditions, you might need to follow slightly
different recommendations. Then what is like the World Health Organization,
(43:39):
the CDC, the FDA, they are making recommendations for the
general public, and it's estimated that over seventy to eighty
percent of adults are consuming significantly more than two point
three grams of sodium per day. So the advice to
reduce sodium applies to most people, not to everyone, which
is also why you shouldn't be taking medical advice from
(43:59):
podcasts or Instagram content creators because it doesn't apply to everyone.
There's also another huge confounder that we haven't even talked
about yet, and that is that this is true of
all nutritional studies. But it's very true in all of
these studies that look at blood pressure and cardiovascular disease
and sodium, and that is that you cannot change only
(44:23):
your sodium intake.
Speaker 2 (44:25):
Yeah, how different? Like what, Yeah, the foods that you're eating.
Speaker 1 (44:29):
The foods that you eat will change there is a
very solid amount of data that shows an inverse relationship
between potassium intake, for example, and blood pressure and cardiovascular disease,
meaning for most people. Not true for everyone, because if
you have kidney disease, this might not apply. But for
most people, increasing your potassium intake can reduce your blood
(44:50):
pressure and in some cases offset some of the effects
of sodium. A lot of our nutrient dense whole foods,
like fruits, vegetables, legumes, whole grains, these are high in potassium. Also,
many of our salt substitutes. If people are going to
swap out their salt that they're sprinkling or cooking with
(45:12):
for a salt substitute, they're switching their sodium for potassium.
Speaker 2 (45:15):
What are some of these salt substitutes.
Speaker 1 (45:18):
Oh, I don't know. You just buy them at the grocery. Toot.
It's called like substitutional substitute. It's a potassium salt. Sometimes
it's just like pure what they're Yeah, sometimes they're pure potassium.
Sometimes they're like a mixture of sodium chloride and like
a potassium chloride or a potassium another potassium salt. There's
been some really interesting data actually on using those, and
then some of the really strong data is from like
(45:39):
a big study in China where they took entire villages
and they were like, you guys are getting salt substitute
and you guys are getting real salt. And they saw
significant decreases in cardiovascular mortality and strokes and all of
these things, and decreases in blood pressure in the salt
substitute group. But you can't quite disentangle the effects of
potassium and sodium in that right, because they're connected.
Speaker 2 (46:00):
They're connected. And also, like you do a sub salt substitute,
but most people don't. Most of the dietary salt that
we consume is not from salt that we sprinkle on foods.
It's from the salt that's in the foods.
Speaker 1 (46:12):
In the US, that's absolutely true. In this part of
China where they were doing it, most of their sodium
actually does come from discretionary sources. So that's why it's
an interesting study in that case. But yes, you're right,
for us, for most people in the US, in Canada,
in Europe, our sodium consumption is mostly coming from things
that are not the salt shaker on our table. I
(46:33):
think it's most estimates are like fifteen percent or something
of our sodium intake comes from adding salt to our foods.
Most of it comes from the fact that every single
food that comes in a package has sodium added to it.
Speaker 2 (46:46):
Yeah.
Speaker 1 (46:47):
Yeah, And so there is something to be said for
the fact that all of the trials that have looked
at long term sodium trends do not find that people
are able to reliably stick to low sodium diets. Usually
less than ten percent of people in these studies can
stick to these limits of less than two grams or so.
I do not buy the argument that this is physiologically
(47:09):
driven at like an evolutionary level. This is a reflection
of our food systems and the fact that it is
very difficult even when you're trying to avoid sodium. But
that doesn't mean it's not an important conversation, right, because
if you're recommending fifteen hundred milligrams of sodium and it's
impossible to do that in our grocery stores, you're setting
(47:30):
people up for failure. So that's a problem too.
Speaker 2 (47:32):
Yeah, And it's also like more time consuming, more expensive.
Often it's like you're yeah, it's hard.
Speaker 1 (47:38):
Yeah, here, and like at the bottom line, to me, okay, Kenna,
if I can conclude, please, the biggest problem, the unspoken
piece in all of these conversations about sodium and health
and blood pressure is the same story as food dies.
Speaker 2 (47:59):
Yeah, what about food?
Speaker 1 (48:01):
Does single piece of our food system arin?
Speaker 2 (48:04):
Yeah?
Speaker 1 (48:05):
Yeah, there's some really interesting data that there's these long
term studies that have been done on Japanese Americans living
in Hawaii and Japanese people living in Japan, and they
look at cardiovascular disease and blood pressure and all of
these rates. We have and die from cardiovascular disease in
the US at substantially higher rates than people in Japan.
(48:28):
Like when you compare US to japan data, Japan has
some of the best health metrics out there. They also
consume so much sodium, significantly more sodium on average than
in America than in the US. And in these studies
that have looked at Japanese men and women and Japanese
American men and women living in Hawaii, we see higher
blood pressure in Japanese populations living in Japan, and yet
(48:51):
higher cardiovascular disease in Japanese Americans living in Hawaii. Because
guess what, it's not just sodium that's different in their diets.
There's higher intakes of omega three fatty acids, there's higher
total cholesterol intakes. There's also interestingly higher rates of smoking
and alcohol use, but lower intakes of total calories and
protein and fat including saturated fatty acids. Nothing that we
(49:14):
eat is in isolation. Ye right, Yeah, so, yes, it
is important to have these dietary guidelines, but these exist
in the context of so many other foods, and it
is one single part of your overall food system.
Speaker 2 (49:32):
This is fascinating and I feel like there is a
to me, there is like a clear answer in many ways.
Your sodium, yeah, am I Yeah, Honestly, while I was reading,
I was trying to use less. I use a lot
of salt. But I think I think you're right, Like
(49:53):
my Yes, I can reduce my discretionary salt, but am
I still gonna want, you know, salty crackers and stuff. Yeah,
so I'm going to try to less or at least
try to eat more whole foods.
Speaker 1 (50:08):
Like I mean, we all need to be doing that,
that's true.
Speaker 2 (50:12):
Yeah, but yeah, I think I think it's like because
I feel like I have. The more salt I eat,
the more I want, and then it becomes like a problem.
So maybe I'll try you know what, you know what,
I do kind of want to try it. To the
salt alternatives, Yeah yeah.
Speaker 1 (50:29):
My husband Trek got really into those for a while.
We had a lot of potassium salt in the house
for a while.
Speaker 2 (50:33):
Yeah, I'm intrigued.
Speaker 1 (50:35):
Yeah yeah, Well, if you're also intrigued and want to
learn more about this debate or whether you should reduce
your salt intake or not. My favorite paper, honestly was
the one that I pulled that first hand account from,
and it was by Hunter at All in Nature of
Views and Nephrology twenty twenty two, The Impact of Excessive
Salt Intake on Human Health. I thought that they did
(50:56):
a really good job of explaining all of the controversy
of providing the data. I know, not on quote unquote
both sides, but like providing all of the data. They
definitely have a bent, they think that we're eating too
much salt. But I really enjoyed that paper. I also
read it piecemeal, and I wish I had just read
it all the way through at the beginning, because it
was most of my stuff ended up putting from there.
(51:17):
But I was like reading it and then I found others. Anyways,
it's a great paper. There's also some interesting ones about
like our regulation of salt appetite and like the you know,
the salt drive and everything. So I have a couple
of papers on that. And then literally, I mean so
just so many papers. I think. Another great one was
from twenty eighteen by he at All the Role or
(51:38):
He and McGregor. It was the role of salt intake
in prevention of cardiovascular disease Controversies and challenges. I enjoyed
that one, but there's so many, including all of the
controversial ones. You can find them on our website this
podcast wkay dot com under the episode's tab.
Speaker 2 (51:54):
Thank you to Bloodmobile for providing the music for this
episode and all of our episodes.
Speaker 1 (51:58):
Thank you to Leon and Tom and Pete and Brent
and Jessica and everyone else that is exactly right for
making all of this possible.
Speaker 2 (52:06):
Thank you, thank you, and thank you to you listeners.
I hope you liked these episodes. Let us know what
you think.
Speaker 1 (52:13):
Yeah, I'm very curious. Yeah, how much sodium do you eat?
You don't have to tell me that you don't. There's
no judgment here. And a special shout out as always
to our patrons, thank you so much for your support.
It means the world to us.
Speaker 2 (52:31):
Until next time, wash your hands, you filthy animals.
Hosts And Creators
Erin Welsh
Erin Allmann Updyke
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