June 19, 2025 • 20 mins
Today’s episode of Daily Value questions something fundamental—the guidelines that shape our daily vitamin C intake. What if the rules you've been following were set too low, missing a hidden metabolic reality that affects millions? New evidence suggests that current recommendations may underestimate our true biological needs—impacting energy, immune health, and even cognitive clarity.
This episode will explore how subtle differences in absorption, cellular retention, and even the form of vitamin C you choose, could impact your health. Could your vitamin C strategy use an upgrade? Listen to find out.
00:00 Introduction: Questioning Modern Nutrition Assumptions
01:01 Understanding Subclinical Vitamin C Deficiency
01:43 Neuropsychiatric Impacts of Vitamin C Deficiency
04:11 Reevaluating Vitamin C Intake Recommendations
06:11 Body Weight and Vitamin C Requirements
10:51 Bioavailability of Vitamin C: Food vs. Supplements
13:39 Advanced Vitamin C Supplement Formulations
17:43 Practical Guidance for Optimizing Vitamin C Intake
19:59 Conclusion: Personalized Vitamin C Supplementation
PMID: 39861409
PMID: 38845362
PMID: 24169506
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:00):
There's a quiet assumption woven into modern
nutrition, one that almost noone outside of the nutrition
field questions you meet yourRDA and you're covered.
But what if that assumptionisn't just outdated but
biologically misleading?
What if the very guidelinesmeant to ensure sufficiency
leave entire populationsfunctionally depleted?
And they don't even know it?
(00:21):
Today we're revisiting amolecule that's long been
relegated to preventing scurvy,but whose story has evolved far
beyond that.
This isn't about megadosing,and it's not about miracle cures
.
It's about whether our currentrecommendations for one of the
most studied nutrients in humanbiology still holds up under the
weight of new data, populationshifts and a much deeper
(00:43):
understanding of cellular demand.
The molecule is vitamin C, andthe evidence is more complicated
than what you've been told.
A vitamin C deficiency can beeasy to miss, because it doesn't
(01:05):
always begin with bleeding gumsand bruises.
More often it begins with moodchanges, with fatigue, with a
kind of biological slowdownthat's hard to put your finger
on, until it gets worse.
Subclinical vitamin Cdeficiency or hypovitaminosis C
refers to a state where plasmaascorbate levels are low enough
to impair physiologicalfunctions, but not yet low
(01:26):
enough to trigger overt scurvy.
That's the primary deficiencysyndrome tied to vitamin C
deficiency.
Vitamin C tissue levels declinein response to nearly all forms
of stress.
A subclinical deficiency ismore common than you might think
and more biologicallydisruptive than most clinicians
acknowledge.
A review published in BMCPsychiatry in 2020
(01:48):
systematically examined this andfound that low plasma ascorbate
levels, well above the scurvycutoff, were consistently
associated with depression,irritability and cognitive
dysfunction.
In fact, the threshold at whichthese neuropsychiatric symptoms
appeared often sat between 20to 50 micromoles per liter.
That's higher than the commonlyaccepted definition of even a
(02:10):
subclinical deficiency, which is11 to 23 micromoles per liter.
Mechanistically, this makessense.
Neuroendocrine tissues like theadrenals, pituitary glands and
neurons have the highestconcentrations of vitamin C in
the body.
In fact, one-third of wholebody vitamin C is concentrated
at the sites of catecholaminesynthesis.
(02:30):
Those are sites that synthesizedopamine, adrenaline and
noradrenaline.
These are not subtle systems.
They're central to moodregulation, motivation, working
memory and stress tolerance, andthey're among the first to show
signs of strain when vitamin Clevels drop.
We tend to think of vitamin Cas a physical vitamin collagen,
(02:53):
skin healing but in reality, thecentral nervous system may be
its most sensitive target.
In experimental models, vitaminC deficient animals exhibit not
only fatigue and motor deficits, but also significant
reductions in brain, dopamineand serotonin metabolites.
They show behavioral changesthat closely mirror
depression-like phenotypes.
These effects reverse whenvitamin C is restored.
(03:18):
In humans, case series datingback to the 1960s and reaffirmed
by modern trials report thatdepressive symptoms, confusion
and asthenia that's, generalmuscle weakness often improve
within days of vitamin Crepletion.
But perhaps the most importantpoint here is this the symptoms
of vitamin C deficiency caneasily be misattributed to aging
(03:41):
, to burnout, to psychiatricconditions, to poor sleep.
Rarely is vitamin C status thefirst thing investigated.
And yet in an at-riskpopulation, from the elderly to
patients with diabetes, toindividuals with psychiatric
disorders, the rate ofdeficiency can go beyond 50%.
And in fact, recent data issuggesting that even in people
(04:03):
without any known disorders,vitamin C insufficiency may be a
characteristic of half of thepopulation.
And this is the setup.
Because if suboptimal vitamin Cstatus is this common, the
natural next question becomesare our intake recommendations
too low for modern physiology?
When we suggest that currentvitamin C recommendations might
(04:26):
be inadequate, it's not merespeculation.
We're looking directly atrecent large-scale population
data that shows a disconnectbetween recommended intakes and
actual nutritional adequacy.
A 2025 analysis by Anitra Kaurand colleagues provides
particularly compelling evidence.
(04:46):
This study interrogated datafrom two major population
cohorts the EPIC Norfolk studyin the UK and the NHANES
2017-2018 cohort in the US toevaluate how effectively current
recommended dietary allowancesfor vitamin C translate to
achieving sufficient plasmavitamin C concentrations,
specifically targeting thewidely recognized threshold of
(05:08):
50 micromoles per liter.
This threshold is consideredoptimal not just for preventing
deficiency, but also formaximizing vitamin C's broader
health benefits, includingimproved immunity, metabolic
health and cognitive function.
What this investigationuncovered is that, despite
participants consuming intakesat or even above current RDAs,
(05:30):
only about two-thirds actuallyreached optimal plasma
concentrations.
Interestingly, amongindividuals whose vitamin C
consumption was within 10% ofthe established RDA, that's 40
milligrams per day in the UK and75 to 90 milligrams per day in
the US, the situation wassubstantially worse Just 35% of
(05:51):
the UK participants and about50% of the US participants
reached the target plasmaconcentration.
These figures suggest a seriousmisalignment between standard
nutritional guidance andreal-world physiological
requirements.
The study highlighted animportant factor behind this
disconnect, that being bodyweight.
Historically, vitamin Crecommendations were developed
(06:14):
based on an average adultreference weight of 70 kilograms
, that's approximately 154pounds.
This assumption, however, nolonger reflects the reality of
global population trends, wherebody weight has significantly
increased over time.
The researchers observed clearinverse relationships.
As an individual's body weightrose, their plasma vitamin C
(06:36):
concentration declined, evenwhen dietary vitamin C intake
remained constant.
Specifically, the analysisshowed that for every additional
10 kilograms, about 22 poundsof body weight, plasma vitamin C
concentrations droppedapproximately 2.6 to 3.5
micromoles per liter.
In practical terms, this meansa person weighing approximately
(06:59):
200 pounds would need anadditional 34 to 44 milligrams
per day of vitamin C beyond thecurrent RDA just to reach the
same plasma levels achieved bysomeone who weighs 70 kilograms
or 154 pounds.
The data suggests that thefundamental assumptions
underlying current vitamin CRDAs may themselves be flawed.
(07:20):
Typically, the RDA is derivedfrom the estimated average
requirement, also shortened tothe EAR, which is then adjusted
by a standard deviation of about10%, an arbitrary figure that
may not accurately reflect truepopulation variability.
In fact, the CAR study foundthat the actual variability in
(07:41):
vitamin C requirements toachieve adequate plasma
concentrations was closer to 57%, indicating that to genuinely
cover the needs of 98% of thepopulation, the RDA might need
to be as high as 175 milligramsper day.
That's dramatically higher thanthe existing US guidelines of
75 to 90 milligrams per day.
(08:01):
These findings are not minoradjustments.
They represent a fundamentalshift in our understanding of
vitamin C nutrition.
The data strongly suggests thatour current RDAs, though
sufficient for preventing theovert symptoms of something like
scurvy, are inadequate foraddressing subtler yet important
health functions.
Millions of people maytherefore be unknowingly
(08:23):
suboptimally supplied withvitamin C, not due to negligence
, but precisely because they'refaithfully adhering to
guidelines that were never trulycalibrated to the diverse
metabolic demands of today'spopulation.
We've been talking a lot aboutplasma vitamin C levels, but
plasma vitamin C provides only asnapshot of recent intake,
(08:43):
fluctuating with dietaryconsumption and being tightly
regulated within a limitedphysiological range, typically
30 to 70 micromoles per liter inhealthy adults.
Now, in contrast, tissuesaturation and functional
vitamin C stores are morereliably assessed through
leukocyte concentrations.
Leukocytes are white bloodcells of the immune system.
(09:05):
These cells accumulate thevitamin at significantly higher
levels, often 5 to 100 timesgreater than plasma.
Thanks to active transportmechanisms, leukocyte levels of
vitamin C are a more accuratemeasure of intake and tissue
stores of vitamin C.
Human cells become fullysaturated with vitamin C at
relatively modest intake levels,approximately 100 milligrams
(09:28):
per day, due to these highlyefficient transport systems.
Yet, interestingly, thissaturable active transport
mechanism also means there'sdiminishing bioavailability,
with an increasing dose ofvitamin C At typical nutritional
intakes like 15 to 200milligrams per day, absorption
efficiency is very high, around80 to 90 percent.
(09:49):
However, as intake exceedsroughly 200 milligrams per day,
absorption begins to declinedramatically.
By the time an individualreaches intakes of around 1,000
milligrams, only about 50% ofthe consumed dose is absorbed.
In other words, more at a giventime it's not always
proportionally better.
Moreover, while plasmasaturation typically occurs at
(10:12):
daily doses of around 1,000milligrams or more, this plasma
level doesn't necessarily equateto optimal whole body tissue
saturation.
This plasma level doesn'tnecessarily equate to optimal
whole body tissue saturation.
Total body vitamin C stores areestimated to be around 1.5 to 5
grams in healthy adults and areprimarily distributed in
tissues such as the adrenalglands, pituitary liver and
(10:33):
muscle, which have a high demandfor antioxidant protection and
enzymatic functions.
Thus, achieving full-bodyfunctional saturation and
optimal physiological supportmay require intake levels higher
than our current RDAs, yetsignificantly lower than the
megadoses often promotedcommercially, and this nuance
leads us naturally to considerthe different forms of vitamin C
(10:56):
.
It's not just about how much youtake, but how well your body
absorbs and uses it.
Many assume that gettingnutrients like vitamin C
directly from foods isinherently superior to taking
synthetic supplements.
However, the reality is alittle bit more nuanced.
A question researchers haveexplored is whether food-derived
vitamin C, particularly fromsources rich in bioflavonoids,
(11:19):
differs meaningfully inbioavailability and
effectiveness compared tosynthetic ascorbic acid from
supplements.
Collectively, the data seems toshow that both synthetic and
food-derived vitamin C appearequally bioavailable when
provided in typical nutritionaldoses between 15 to 200
milligrams per day.
This means that at moderatedietary intake levels, our
(11:39):
bodies efficiently absorb andutilize vitamin C regardless of
the source.
However, there's an interestingtwist when intake increases
significantly.
While moderate doses of up toapproximately 200 mg are almost
completely absorbed, higherdoses, around 1,000 mg or more,
begin to show a notable declinein absorption efficiency,
(12:00):
dropping to about 50%utilization.
This shift happens because atlower physiological doses,
vitamin C absorptionpredominantly involves saturable
active transport mechanismsensuring a very high uptake, but
at very high doses, passivediffusion, which is much less
efficient, takes over, leadingto reduced bioavailability, at
(12:21):
least proportionally speaking.
One aspect often touted in favorof food-based sources is the
presence of bioflavonoids.
These are natural plant-basedcompounds found in citrus fruits
and vegetables that usuallyaccompany dietary vitamin C.
Bioflavonoids are believed tohave synergistic effects with
vitamin C, potentially enhancingits antioxidant capacity,
(12:42):
although these claims have somemerit in animal models, it
doesn't seem to matter as muchin humans.
As it stands, data indicatesthat these bioflavonoids,
although beneficial for otherhealth aspects, do not
significantly boost thebioavailability or metabolic
utilization of vitamin C.
Practically, this translates toan important takeaway for
(13:03):
listeners While eating a dietrich in fresh fruits and
vegetables ensures a range ofhealth benefits beyond just
vitamin C, for the specificpurpose of optimizing your
vitamin C status, syntheticsupplements can be equally
effective.
Again, if we are only talkingabout vitamin C as a single
component compound, if food andsynthetic vitamin C at typical
(13:23):
doses show similar biologicalactivities, then why would we
even consider specializedsupplement formulations?
Well, it's possible thatachieving and maintaining
optimal cellular levels can bedone more seamlessly with more
advanced delivery forms.
Recent research from Calder etal 2025 systematically analyzed
(13:45):
various advanced supplementforms, exploring their
comparative bioavailability andretention within plasma and
leukocytes.
One well-studied formulation iscalcium ascorbate EC, commonly
known as ester C.
This is a non-acidic bufferedvitamin C combined with
metabolites such as calciumthreonate.
(14:07):
The evidence consistentlysupports that calcium ascorbate
EC not only matches, but incertain circumstances exceeds
standard ascorbic acid inenhancing leukocyte vitamin C
levels.
Studies found that at doses of500 to 1,000 milligrams calcium
ascorbate EC improved leukocytevitamin C retention
(14:28):
significantly better thanstandard ascorbic acid,
sometimes by up to 24 hours andeven post-24 hours.
Moreover, data indicatesadditional advantages of calcium
ascorbate EC in immunemodulation.
For example, controlled studiesshowed that calcium ascorbate
EC at higher doses 500milligrams and above notably
(14:49):
enhanced immune cell function,specifically neutrophil
phagocytosis and natural killercell activity.
This functional enhancementdirectly translated into fewer
colds and shorter duration ofsevere symptoms compared to a
placebo, suggesting superiorreal-world immune protection.
Another innovative form isliposomal encapsulated vitamin C
(15:11):
, where ascorbic acid isencapsulated in lipid bilayers.
This encapsulation enhancesstability, reduces
gastrointestinal degradation andsignificantly increases
bioavailability.
Clinical trials havedemonstrated that liposomal
vitamin C achieves substantiallyhigher peak plasma levels,
approximately 27% higher andgreater leukocyte concentrations
(15:32):
, compared to conventionalascorbic acid.
Specifically, the liposomalform produces about 20% greater
peak leukocyte concentrations,implying enhanced immune cell
uptake and retention.
An intriguing variationincludes formulations like
vitamin C lipid metabolites,also called PureWay C, combining
(15:53):
vitamin C with fatty acids andbioflavonoids.
In head-to-head comparisons,this form delivered notably
higher serum vitamin Cconcentrations rapidly within
the first few hourspost-consumption, suggesting
superior short-term absorption.
However, whether these serumelevations correspond directly
to improve leukocyte retentionor long-term functional benefits
(16:14):
still requires furthervalidation.
Conversely, sustained releaseformulations often prolong
plasma levels, which can helpmaintain elevated vitamin C
concentrations over extendedperiods.
Although studies confirm theseforms increase plasma levels
effectively, clear evidence onleukocyte retention or immune
enhancement is still emerging,making definitive conclusions
(16:38):
about the immune-relatedbenefits less certain compared
to liposomal or calciumascorbate EC forms.
Across these studies, animportant theme emerges Superior
plasma concentrations don'talways directly reflect improved
leukocyte or tissue vitamin Cstatus.
Leukocyte vitamin C levelsappear more reliable as a
(16:59):
biomarker for immune function,suggesting that certain forms
like calcium ascorbate EC andliposomal may offer functional
advantages beyond simplyelevating plasma concentrations.
Safety and tolerability furtherdifferentiate these advanced
forms.
Calcium ascorbate ECconsistently demonstrated fewer
gastrointestinal adverse effectsdue to its neutral pH and
(17:21):
buffering capacity, even atdoses exceeding 1,000 milligrams
per day.
This better tolerabilitypotentially encourages greater
adherence and compliance.
Those are importantconsiderations for practical
supplementation.
This nuanced understanding setsthe stage for practical
guidance on how listeners mightadjust their own vitamin C
supplementation strategies tooptimize their personal health
(17:43):
outcomes.
Given everything that we'vediscussed, the key question now
is how should you approachvitamin C intake differently?
First, it's clear that thetraditional RDA 75 milligrams a
day for women and 90 milligramsa day for men is built primarily
on preventing scurvy, notoptimizing health.
For many individuals today,especially those with higher
body weight, chronic stress orincreased inflammation, these
(18:05):
recommendations may beinadequate.
Emerging data strongly suggestsrevising typical daily intakes
upward, with practical targetsoften ranging between 200 to 400
milligrams per day for betteroverall saturation and actual
functional efficacy.
Moreover, not all vitamin C isequal in terms of absorption and
retention For everyday dietaryintake.
(18:27):
Foods like kiwis, citrus fruits, berries, bell peppers and
leafy greens remain optimalsources.
They're reliably bioavailableand provide additional
beneficial compounds like fiberand bioflavonoids, even though
these bioflavonoids don'tsignificantly enhance vitamin C
absorption itself.
Supplemental vitamin C becomesespecially valuable under higher
(18:47):
physiological demands, as we'veseen.
Advanced supplementformulations like calcium
ascorbate EC again that's esterC and liposomal vitamin C show
clear advantages in specificscenarios.
Calcium ascorbate ECconsistently demonstrates
enhanced leukocyte retention andimmune support benefits, with
the added advantage ofsignificantly better
(19:08):
gastrointestinal tolerability,especially at doses exceeding
typical dietary levels, again,that's between 500 and 1,000
milligrams.
Meanwhile, liposomal formsoffer superior bioavailability,
achieving higher plasma andleukocyte levels, valuable when
rapid absorption or acute immunesupport is necessary.
For most individuals seekingconsistent everyday support, a
(19:31):
moderate dose of 200 to 400milligrams per day, preferably
split into smaller doses,provides excellent tissue
saturation and sustainedbenefits without the sharp
declines in absorption seen athigher megadoses.
Those facing specific immunechallenges, higher stress or
periods of illness mightstrategically use advanced
supplemental forms at doses upto around 1,000 milligrams per
(19:54):
day to maintain robust immunecell concentrations without
overwhelming absorption pathways.
Ultimately, vitamin Csupplementation should be
personalized.
Consider your weight, stresslevel, general health status and
even your gastrointestinalsensitivity when choosing both
dosage and formulation.
If going the supplement route,monitoring your body's response,
(20:15):
like energy levels, recoveringfrom stress and overall immunity
, can also help guideadjustments.
The takeaway here isn't aboutmegadosing vitamin C.
It's about recognizing thatoptimal health isn't simply
avoiding deficiency.
It's actively pursuing thelevels and forms of nutrients
that best match your uniquephysiological needs.
Vitamin C isn't just aboutpreventing illness.
(20:35):
It's about optimizing wellness.
Thank you for joining me todayon Daily Value.
If this episode was useful toyou, please like and share.
Until next time, stay healthy.
There's a quiet assumption woven into modern
nutrition, one that almost noone outside of the nutrition
field questions you meet yourRDA and you're covered.
But what if that assumptionisn't just outdated but
biologically misleading?
What if the very guidelinesmeant to ensure sufficiency
leave entire populationsfunctionally depleted?
And they don't even know it?
(00:21):
Today we're revisiting amolecule that's long been
relegated to preventing scurvy,but whose story has evolved far
beyond that.
This isn't about megadosing,and it's not about miracle cures
.
It's about whether our currentrecommendations for one of the
most studied nutrients in humanbiology still holds up under the
weight of new data, populationshifts and a much deeper
(00:43):
understanding of cellular demand.
The molecule is vitamin C, andthe evidence is more complicated
than what you've been told.
A vitamin C deficiency can beeasy to miss, because it doesn't
(01:05):
always begin with bleeding gumsand bruises.
More often it begins with moodchanges, with fatigue, with a
kind of biological slowdownthat's hard to put your finger
on, until it gets worse.
Subclinical vitamin Cdeficiency or hypovitaminosis C
refers to a state where plasmaascorbate levels are low enough
to impair physiologicalfunctions, but not yet low
(01:26):
enough to trigger overt scurvy.
That's the primary deficiencysyndrome tied to vitamin C
deficiency.
Vitamin C tissue levels declinein response to nearly all forms
of stress.
A subclinical deficiency ismore common than you might think
and more biologicallydisruptive than most clinicians
acknowledge.
A review published in BMCPsychiatry in 2020
(01:48):
systematically examined this andfound that low plasma ascorbate
levels, well above the scurvycutoff, were consistently
associated with depression,irritability and cognitive
dysfunction.
In fact, the threshold at whichthese neuropsychiatric symptoms
appeared often sat between 20to 50 micromoles per liter.
That's higher than the commonlyaccepted definition of even a
(02:10):
subclinical deficiency, which is11 to 23 micromoles per liter.
Mechanistically, this makessense.
Neuroendocrine tissues like theadrenals, pituitary glands and
neurons have the highestconcentrations of vitamin C in
the body.
In fact, one-third of wholebody vitamin C is concentrated
at the sites of catecholaminesynthesis.
(02:30):
Those are sites that synthesizedopamine, adrenaline and
noradrenaline.
These are not subtle systems.
They're central to moodregulation, motivation, working
memory and stress tolerance, andthey're among the first to show
signs of strain when vitamin Clevels drop.
We tend to think of vitamin Cas a physical vitamin collagen,
(02:53):
skin healing but in reality, thecentral nervous system may be
its most sensitive target.
In experimental models, vitaminC deficient animals exhibit not
only fatigue and motor deficits, but also significant
reductions in brain, dopamineand serotonin metabolites.
They show behavioral changesthat closely mirror
depression-like phenotypes.
These effects reverse whenvitamin C is restored.
(03:18):
In humans, case series datingback to the 1960s and reaffirmed
by modern trials report thatdepressive symptoms, confusion
and asthenia that's, generalmuscle weakness often improve
within days of vitamin Crepletion.
But perhaps the most importantpoint here is this the symptoms
of vitamin C deficiency caneasily be misattributed to aging
(03:41):
, to burnout, to psychiatricconditions, to poor sleep.
Rarely is vitamin C status thefirst thing investigated.
And yet in an at-riskpopulation, from the elderly to
patients with diabetes, toindividuals with psychiatric
disorders, the rate ofdeficiency can go beyond 50%.
And in fact, recent data issuggesting that even in people
(04:03):
without any known disorders,vitamin C insufficiency may be a
characteristic of half of thepopulation.
And this is the setup.
Because if suboptimal vitamin Cstatus is this common, the
natural next question becomesare our intake recommendations
too low for modern physiology?
When we suggest that currentvitamin C recommendations might
(04:26):
be inadequate, it's not merespeculation.
We're looking directly atrecent large-scale population
data that shows a disconnectbetween recommended intakes and
actual nutritional adequacy.
A 2025 analysis by Anitra Kaurand colleagues provides
particularly compelling evidence.
(04:46):
This study interrogated datafrom two major population
cohorts the EPIC Norfolk studyin the UK and the NHANES
2017-2018 cohort in the US toevaluate how effectively current
recommended dietary allowancesfor vitamin C translate to
achieving sufficient plasmavitamin C concentrations,
specifically targeting thewidely recognized threshold of
(05:08):
50 micromoles per liter.
This threshold is consideredoptimal not just for preventing
deficiency, but also formaximizing vitamin C's broader
health benefits, includingimproved immunity, metabolic
health and cognitive function.
What this investigationuncovered is that, despite
participants consuming intakesat or even above current RDAs,
(05:30):
only about two-thirds actuallyreached optimal plasma
concentrations.
Interestingly, amongindividuals whose vitamin C
consumption was within 10% ofthe established RDA, that's 40
milligrams per day in the UK and75 to 90 milligrams per day in
the US, the situation wassubstantially worse Just 35% of
(05:51):
the UK participants and about50% of the US participants
reached the target plasmaconcentration.
These figures suggest a seriousmisalignment between standard
nutritional guidance andreal-world physiological
requirements.
The study highlighted animportant factor behind this
disconnect, that being bodyweight.
Historically, vitamin Crecommendations were developed
(06:14):
based on an average adultreference weight of 70 kilograms
, that's approximately 154pounds.
This assumption, however, nolonger reflects the reality of
global population trends, wherebody weight has significantly
increased over time.
The researchers observed clearinverse relationships.
As an individual's body weightrose, their plasma vitamin C
(06:36):
concentration declined, evenwhen dietary vitamin C intake
remained constant.
Specifically, the analysisshowed that for every additional
10 kilograms, about 22 poundsof body weight, plasma vitamin C
concentrations droppedapproximately 2.6 to 3.5
micromoles per liter.
In practical terms, this meansa person weighing approximately
(06:59):
200 pounds would need anadditional 34 to 44 milligrams
per day of vitamin C beyond thecurrent RDA just to reach the
same plasma levels achieved bysomeone who weighs 70 kilograms
or 154 pounds.
The data suggests that thefundamental assumptions
underlying current vitamin CRDAs may themselves be flawed.
(07:20):
Typically, the RDA is derivedfrom the estimated average
requirement, also shortened tothe EAR, which is then adjusted
by a standard deviation of about10%, an arbitrary figure that
may not accurately reflect truepopulation variability.
In fact, the CAR study foundthat the actual variability in
(07:41):
vitamin C requirements toachieve adequate plasma
concentrations was closer to 57%, indicating that to genuinely
cover the needs of 98% of thepopulation, the RDA might need
to be as high as 175 milligramsper day.
That's dramatically higher thanthe existing US guidelines of
75 to 90 milligrams per day.
(08:01):
These findings are not minoradjustments.
They represent a fundamentalshift in our understanding of
vitamin C nutrition.
The data strongly suggests thatour current RDAs, though
sufficient for preventing theovert symptoms of something like
scurvy, are inadequate foraddressing subtler yet important
health functions.
Millions of people maytherefore be unknowingly
(08:23):
suboptimally supplied withvitamin C, not due to negligence
, but precisely because they'refaithfully adhering to
guidelines that were never trulycalibrated to the diverse
metabolic demands of today'spopulation.
We've been talking a lot aboutplasma vitamin C levels, but
plasma vitamin C provides only asnapshot of recent intake,
(08:43):
fluctuating with dietaryconsumption and being tightly
regulated within a limitedphysiological range, typically
30 to 70 micromoles per liter inhealthy adults.
Now, in contrast, tissuesaturation and functional
vitamin C stores are morereliably assessed through
leukocyte concentrations.
Leukocytes are white bloodcells of the immune system.
(09:05):
These cells accumulate thevitamin at significantly higher
levels, often 5 to 100 timesgreater than plasma.
Thanks to active transportmechanisms, leukocyte levels of
vitamin C are a more accuratemeasure of intake and tissue
stores of vitamin C.
Human cells become fullysaturated with vitamin C at
relatively modest intake levels,approximately 100 milligrams
(09:28):
per day, due to these highlyefficient transport systems.
Yet, interestingly, thissaturable active transport
mechanism also means there'sdiminishing bioavailability,
with an increasing dose ofvitamin C At typical nutritional
intakes like 15 to 200milligrams per day, absorption
efficiency is very high, around80 to 90 percent.
(09:49):
However, as intake exceedsroughly 200 milligrams per day,
absorption begins to declinedramatically.
By the time an individualreaches intakes of around 1,000
milligrams, only about 50% ofthe consumed dose is absorbed.
In other words, more at a giventime it's not always
proportionally better.
Moreover, while plasmasaturation typically occurs at
(10:12):
daily doses of around 1,000milligrams or more, this plasma
level doesn't necessarily equateto optimal whole body tissue
saturation.
This plasma level doesn'tnecessarily equate to optimal
whole body tissue saturation.
Total body vitamin C stores areestimated to be around 1.5 to 5
grams in healthy adults and areprimarily distributed in
tissues such as the adrenalglands, pituitary liver and
(10:33):
muscle, which have a high demandfor antioxidant protection and
enzymatic functions.
Thus, achieving full-bodyfunctional saturation and
optimal physiological supportmay require intake levels higher
than our current RDAs, yetsignificantly lower than the
megadoses often promotedcommercially, and this nuance
leads us naturally to considerthe different forms of vitamin C
(10:56):
.
It's not just about how much youtake, but how well your body
absorbs and uses it.
Many assume that gettingnutrients like vitamin C
directly from foods isinherently superior to taking
synthetic supplements.
However, the reality is alittle bit more nuanced.
A question researchers haveexplored is whether food-derived
vitamin C, particularly fromsources rich in bioflavonoids,
(11:19):
differs meaningfully inbioavailability and
effectiveness compared tosynthetic ascorbic acid from
supplements.
Collectively, the data seems toshow that both synthetic and
food-derived vitamin C appearequally bioavailable when
provided in typical nutritionaldoses between 15 to 200
milligrams per day.
This means that at moderatedietary intake levels, our
(11:39):
bodies efficiently absorb andutilize vitamin C regardless of
the source.
However, there's an interestingtwist when intake increases
significantly.
While moderate doses of up toapproximately 200 mg are almost
completely absorbed, higherdoses, around 1,000 mg or more,
begin to show a notable declinein absorption efficiency,
(12:00):
dropping to about 50%utilization.
This shift happens because atlower physiological doses,
vitamin C absorptionpredominantly involves saturable
active transport mechanismsensuring a very high uptake, but
at very high doses, passivediffusion, which is much less
efficient, takes over, leadingto reduced bioavailability, at
(12:21):
least proportionally speaking.
One aspect often touted in favorof food-based sources is the
presence of bioflavonoids.
These are natural plant-basedcompounds found in citrus fruits
and vegetables that usuallyaccompany dietary vitamin C.
Bioflavonoids are believed tohave synergistic effects with
vitamin C, potentially enhancingits antioxidant capacity,
(12:42):
although these claims have somemerit in animal models, it
doesn't seem to matter as muchin humans.
As it stands, data indicatesthat these bioflavonoids,
although beneficial for otherhealth aspects, do not
significantly boost thebioavailability or metabolic
utilization of vitamin C.
Practically, this translates toan important takeaway for
(13:03):
listeners While eating a dietrich in fresh fruits and
vegetables ensures a range ofhealth benefits beyond just
vitamin C, for the specificpurpose of optimizing your
vitamin C status, syntheticsupplements can be equally
effective.
Again, if we are only talkingabout vitamin C as a single
component compound, if food andsynthetic vitamin C at typical
(13:23):
doses show similar biologicalactivities, then why would we
even consider specializedsupplement formulations?
Well, it's possible thatachieving and maintaining
optimal cellular levels can bedone more seamlessly with more
advanced delivery forms.
Recent research from Calder etal 2025 systematically analyzed
(13:45):
various advanced supplementforms, exploring their
comparative bioavailability andretention within plasma and
leukocytes.
One well-studied formulation iscalcium ascorbate EC, commonly
known as ester C.
This is a non-acidic bufferedvitamin C combined with
metabolites such as calciumthreonate.
(14:07):
The evidence consistentlysupports that calcium ascorbate
EC not only matches, but incertain circumstances exceeds
standard ascorbic acid inenhancing leukocyte vitamin C
levels.
Studies found that at doses of500 to 1,000 milligrams calcium
ascorbate EC improved leukocytevitamin C retention
(14:28):
significantly better thanstandard ascorbic acid,
sometimes by up to 24 hours andeven post-24 hours.
Moreover, data indicatesadditional advantages of calcium
ascorbate EC in immunemodulation.
For example, controlled studiesshowed that calcium ascorbate
EC at higher doses 500milligrams and above notably
(14:49):
enhanced immune cell function,specifically neutrophil
phagocytosis and natural killercell activity.
This functional enhancementdirectly translated into fewer
colds and shorter duration ofsevere symptoms compared to a
placebo, suggesting superiorreal-world immune protection.
Another innovative form isliposomal encapsulated vitamin C
(15:11):
, where ascorbic acid isencapsulated in lipid bilayers.
This encapsulation enhancesstability, reduces
gastrointestinal degradation andsignificantly increases
bioavailability.
Clinical trials havedemonstrated that liposomal
vitamin C achieves substantiallyhigher peak plasma levels,
approximately 27% higher andgreater leukocyte concentrations
(15:32):
, compared to conventionalascorbic acid.
Specifically, the liposomalform produces about 20% greater
peak leukocyte concentrations,implying enhanced immune cell
uptake and retention.
An intriguing variationincludes formulations like
vitamin C lipid metabolites,also called PureWay C, combining
(15:53):
vitamin C with fatty acids andbioflavonoids.
In head-to-head comparisons,this form delivered notably
higher serum vitamin Cconcentrations rapidly within
the first few hourspost-consumption, suggesting
superior short-term absorption.
However, whether these serumelevations correspond directly
to improve leukocyte retentionor long-term functional benefits
(16:14):
still requires furthervalidation.
Conversely, sustained releaseformulations often prolong
plasma levels, which can helpmaintain elevated vitamin C
concentrations over extendedperiods.
Although studies confirm theseforms increase plasma levels
effectively, clear evidence onleukocyte retention or immune
enhancement is still emerging,making definitive conclusions
(16:38):
about the immune-relatedbenefits less certain compared
to liposomal or calciumascorbate EC forms.
Across these studies, animportant theme emerges Superior
plasma concentrations don'talways directly reflect improved
leukocyte or tissue vitamin Cstatus.
Leukocyte vitamin C levelsappear more reliable as a
(16:59):
biomarker for immune function,suggesting that certain forms
like calcium ascorbate EC andliposomal may offer functional
advantages beyond simplyelevating plasma concentrations.
Safety and tolerability furtherdifferentiate these advanced
forms.
Calcium ascorbate ECconsistently demonstrated fewer
gastrointestinal adverse effectsdue to its neutral pH and
(17:21):
buffering capacity, even atdoses exceeding 1,000 milligrams
per day.
This better tolerabilitypotentially encourages greater
adherence and compliance.
Those are importantconsiderations for practical
supplementation.
This nuanced understanding setsthe stage for practical
guidance on how listeners mightadjust their own vitamin C
supplementation strategies tooptimize their personal health
(17:43):
outcomes.
Given everything that we'vediscussed, the key question now
is how should you approachvitamin C intake differently?
First, it's clear that thetraditional RDA 75 milligrams a
day for women and 90 milligramsa day for men is built primarily
on preventing scurvy, notoptimizing health.
For many individuals today,especially those with higher
body weight, chronic stress orincreased inflammation, these
(18:05):
recommendations may beinadequate.
Emerging data strongly suggestsrevising typical daily intakes
upward, with practical targetsoften ranging between 200 to 400
milligrams per day for betteroverall saturation and actual
functional efficacy.
Moreover, not all vitamin C isequal in terms of absorption and
retention For everyday dietaryintake.
(18:27):
Foods like kiwis, citrus fruits, berries, bell peppers and
leafy greens remain optimalsources.
They're reliably bioavailableand provide additional
beneficial compounds like fiberand bioflavonoids, even though
these bioflavonoids don'tsignificantly enhance vitamin C
absorption itself.
Supplemental vitamin C becomesespecially valuable under higher
(18:47):
physiological demands, as we'veseen.
Advanced supplementformulations like calcium
ascorbate EC again that's esterC and liposomal vitamin C show
clear advantages in specificscenarios.
Calcium ascorbate ECconsistently demonstrates
enhanced leukocyte retention andimmune support benefits, with
the added advantage ofsignificantly better
(19:08):
gastrointestinal tolerability,especially at doses exceeding
typical dietary levels, again,that's between 500 and 1,000
milligrams.
Meanwhile, liposomal formsoffer superior bioavailability,
achieving higher plasma andleukocyte levels, valuable when
rapid absorption or acute immunesupport is necessary.
For most individuals seekingconsistent everyday support, a
(19:31):
moderate dose of 200 to 400milligrams per day, preferably
split into smaller doses,provides excellent tissue
saturation and sustainedbenefits without the sharp
declines in absorption seen athigher megadoses.
Those facing specific immunechallenges, higher stress or
periods of illness mightstrategically use advanced
supplemental forms at doses upto around 1,000 milligrams per
(19:54):
day to maintain robust immunecell concentrations without
overwhelming absorption pathways.
Ultimately, vitamin Csupplementation should be
personalized.
Consider your weight, stresslevel, general health status and
even your gastrointestinalsensitivity when choosing both
dosage and formulation.
If going the supplement route,monitoring your body's response,
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like energy levels, recoveringfrom stress and overall immunity
, can also help guideadjustments.
The takeaway here isn't aboutmegadosing vitamin C.
It's about recognizing thatoptimal health isn't simply
avoiding deficiency.
It's actively pursuing thelevels and forms of nutrients
that best match your uniquephysiological needs.
Vitamin C isn't just aboutpreventing illness.
(20:35):
It's about optimizing wellness.
Thank you for joining me todayon Daily Value.
If this episode was useful toyou, please like and share.
Until next time, stay healthy.
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