May 30, 2025 • 11 mins
Bakers, breadlovers, even purported health information authorities such as the Mayo Clinic all spread the claim that all the problems associated with consumption of foods made of wheat are eliminated or significantly reduced by sourdough fermentation. Is this true?
In this episode of the Defiant Health podcast, Let’s take each of those claims made, one by one, and examine the evidence to see if there is any truth behind them.
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Books:
Super Gut: The 4-Week Plan to Reprogram Your Microbiome, Restore Health, and Lose Weight
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:00):
Now, I generally don't like to use words like
lies as clickbait for you towatch something, but in this
case I think you'll see why I'mcalling it lies, or at least
flagrant misinformation, aboutthis thing called sourdough.
Now, how did this happen?
I don't quite know how thesefictions got started.
I suspect it was some kind ofsourdough baker or bakery, maybe
(00:21):
in San Francisco or someplace,who thought or believed that
there was something in sourdoughor different about sourdough
that made it healthier thannon-fermented breads.
Sourdough fermentation, sothat's a fermented bread, and so
some people have claimed thatsourdough fermentation disables
all the adverse effects of wheat.
And if you review my wheatbelly books or recall what I
(00:43):
argued in the wheat belly books,that there are numerous toxic
compounds in wheat, especiallymodern wheat, for various
characteristics, such as analtered form of the gliadin
protein that yields opioidpeptides that stimulate appetite
(01:08):
and initiate the autoimmuneprocess meant for many
conditions like rheumatoidarthritis or type 1 diabetes.
Wheat germagglutinin, which isa very toxic compound in the
human gastrointestinal tract.
Phytates that bind mineralslike calcium, iron, zinc and
magnesium and you pass them outin the toilet and they're
(01:28):
therefore unabsorbed.
They're unabsorbable theamylopectin, a carbohydrate of
wheat that raises blood glucosevery high and stimulates the
formation of small LDL particles, the real cause for heart
disease, not LDL cholesterol.
And so the argument is thatsourdough fermentation by
microbes resident in wheatchanges the characteristics of
(01:51):
the bread and making it healthyor healthier.
Let's take that apart.
One of the sources of thisinformation, oddly, is the Mayo
Clinic, and I'll share anexcerpt from their website.
They say that three provenhealth benefits of sourdough
bread so this is from the MayoClinic website supports a
healthy gut microbiome.
(02:13):
Sourdough bread contains morebeneficial nutrients than other
types of bread Due to thefermentation process.
Fermentation creates probioticsor healthy bacteria that can
aid in digestion.
Another claim they make aboutsourdough bread is that it's
easily digested.
Sourdough fermentationdecreases the amount of gluten
(02:36):
and FODMAP carbohydrates in thebread.
This makes digestion easier andhas proven beneficial for those
with digestive disorders suchas irritable bowel syndrome.
And then the last claim theymake from the Mayo Clinic is
supports better blood sugarcontrol.
Sourdough bread has a lowerglycemic index than white bread,
so it doesn't increase bloodsugar levels quickly.
So those are pretty persuasive,aren't they?
Coming from Mayo Clinic withall these purported benefits?
(02:59):
Let's take those apart one byone Now, if you want the
references, the scientificreferences that bag up these
arguments.
See my williamdavismdcom blog,where it's kind of hard to
provide references ina podcastright.
So I put these in mywilliamdavismdcom blog along
with about 2,500 other blogposts that discuss all the
(03:20):
things I talk about in thispodcast, my YouTube channel and
elsewhere all the things I talkabout in this podcast, my
YouTube channel and elsewhere.
So supports a healthy gutmicrobiome, because sourdough
fermentation with microbesresident in wheat or added for
fermentation yield probioticspecies.
Well, there's so much wrongwith that, but the easiest
argument against that is that tomake sourdough bread they
(03:42):
typically bake at 450 to 500degrees Fahrenheit higher than
usual bread baking.
With that temperature nomicrobe survives.
You know, spore-forming species, like bacillus species, tend to
survive high temperatures, butnot that high.
So 450 degrees Fahrenheit issufficient to kill all organisms
(04:03):
spore-forming microbes,probiotic microbes, fungi
everything dies at 4.
So there are no microbes.
There are no probiotic microbesin sourdough bread.
It does not have any influenceon providing probiotics to your
gastrointestinal tract andsimilar studies have been
(04:25):
conducted where the compositionof the gastrointestinal
microbiome has been looked atpre and post consumption of
sourdough bread and there is nodifference.
Because there are no microbes,because they're all dead in
sourdough bread.
So for the Mayo Clinic andothers to say that sourdough
bread is a source of probioticmicrobes is completely and
(04:45):
utterly false, as common sensewould tell you and has studies
have validated.
The other claim is thatsourdough bread is more easily
digested because it reducesgluten protein.
Well, that's actually not true.
So the most important proteinwithin gluten so recall that
gluten, this protein unique towheat and related proteins and
(05:07):
other grains, has two parts.
It has a globular gliadinprotein, the source of most of
the problems associated withwheat proteins, and a glutenin
protein, that's a long chain orpolymeric protein that gives
wheat dough its stretchability.
Well, when you sourdough,ferment and then bake, you
(05:28):
actually release some of thegliadin protein sequences within
gluten within that gliadin, andyou increase the various
fractions of gliadin,alpha-gliadin, omega-gliadin,
gamma-gliadin, and it increasesthe potential to activate immune
responses, including autoimmuneresponses, and it makes it more
accessible to an enzyme thatlines the gastrointestinal tract
(05:52):
called trans-mortaminase 2,making it more likely to
generate effects such asactivation of celiac disease.
There's a lot of latent peoplewho are susceptible to celiac
disease who haven't yetexperienced it.
This is one of the phenomenathat could unmask that presence
of a genetic predispositiontowards celiac disease.
So the gliadin, and therebygluten, is actually increased by
(06:15):
the fermentation process tomake sourdough bread.
How about this idea that itreduces glycemic index by
reducing carbohydrates?
Not true?
So there's really no change Ifyou look at the carbohydrate
count in sourdough bread versusnon-fermented bread.
If you look at the variousfractions of carbohydrates, but
especially amylopectin A andamylose, there is no difference.
(06:38):
So this idea that sourdoughbread is less likely to trigger
blood glucose rises is patentlyfalse.
And the amylopectin A, becauseit's still there, provokes
formation of the small LDLparticle, the real cause for
heart disease.
So we know with confidence thatsugars, but also wheat, via the
(06:59):
amylopectin A carbohydrateunique to wheat and other grains
, is the trigger for formationof small LDL particles, the real
cause, or among the real causes, for coronary disease, heart
attack, sudden cardiac death anda need for procedures like
stent implantation, bypasssurgery Not saturated fat, by
(07:19):
the way, not LDL cholesterol,ldl particles, but specifically
small LDL particles.
So there's plenty ofamylopectin A left After
sourdough fermentation and afterhigh-temperature baking,
sufficient trigger formation ofthese heart disease-causing
particles that in 55, now todate 55 human clinical trials,
(07:42):
those particles, those small LDLparticles, have been shown to
be superior in predicting yourrisk for heart attack, stent
implantation, sudden cardiacdeath, etc.
Predicting your risk for heartattack, stent implantation,
sudden cardiac death, etc.
How about this idea thatconsuming sourdough bread
reduces the symptoms ofirritable bowel syndrome?
Well, there's a recent Europeanstudy in people with irritable
(08:06):
bowel syndrome, ibs, who weregiven sourdough bread and they
actually had worse symptoms.
And here's a quote from thatstudy.
And they actually had worsesymptoms.
And here's a quote from thatstudy.
There were significantly morefeelings of tiredness, joint
symptoms and decreased alertnesswhen the participants ate the
sourdough bread.
So this idea that sourdoughbread somehow absolves this
(08:27):
bread of all the problemsordinarily associated with wheat
once again completely false.
There is some truth, though.
There's one truth, actually, insome of the claims made by the
Mayo Clinic and other sources ofinformation regarding sourdough
brown.
That is a reduction in phytates.
So phytates are a compound inwheat and grains that bind
(08:47):
minerals.
They bind positively chargedminerals like calcium, magnesium
, iron and zinc, making themunavailable for absorption.
You just pass them into thetoilet.
Iron deficiency is especially aproblem and, for some odd
reason, particularly in femalesnot so much males, mostly
females and so these phytatesare very bad for nutrition.
(09:08):
You're told you need grains,wheat and grains for nutrition.
Actually, the you need grains,wheat and grains for nutrition.
Actually, the opposite is true.
They cause nutrientdeficiencies, especially of
minerals.
Well, the phytates are the onething actually reduced by
sourdough fermentation, not bythe actual process of
fermentation per se, but by theacidification you may notice.
(09:29):
If you ever had some sourdoughbread, it's very acidic.
That's because it has someacids like lactic acid and some
others, and that reduced the phinto the acidic range and that
level of acidity reduces thephytate content.
So that is true.
Another issue is often claimedis wheat germagglutinin, that's
the lectin of wheat.
That's very toxic to the humangastrointestinal tract and
(09:51):
animals.
When a purified one milligram,one little speck of purified
wheat, germ and gluten is givento a laboratory rat, for
instance, it denudes or destroysall the villi, the hair-like
projections lining thegastrointestinal tract.
It denudes them, it removesthem, which is very inflammatory
, very destructive.
Well, humans are subject tothat effect too from wheat
(10:13):
germagglutinin.
What effect does sourdoughfermentation and high
temperature baking have on wheatgermagglutinin?
None, it's still there.
It's as plentiful as it was atthe start.
It's no different than anyother form of bread, fermented
or non-fermented, baked or notbaked.
So a lot of the arguments madeto say that sourdough bread
(10:34):
supports a healthy microbiomebecause of the presence of
probiotic species, or that it'smore easily digested and has
reduced quantities of gluten, orthat it is better for blood
sugar control that's all falseand all you need to do is take a
few minutes to look at theevidence human clinical evidence
to show none of that is true.
(10:55):
The only thing that falls out astrue is that there's a
reduction in phytates.
So don't fall for these lies orat least this misinformation.
Who knows where this gotstarted?
But you know, the Internet isthe vast echo chamber.
It takes only one or a handfulof people to say something.
Let's say a sourdough bakery inSan Francisco.
It gets repeated, gets repeated, gets repeated, picked up by
(11:19):
some writer for the Mayo Clinicwho is too lazy to do background
work and look at the actualscience, not just hear the
repeated claims made by otherbakers, by people interested in
nutrition or people justinterested in eating bread, and
it becomes like it almost seemslike it's true, but it's not
true.
All we need to do is look atthe evidence and find out there
(11:40):
is no such advantage forsourdough bread.
Now, I generally don't like to use words like
lies as clickbait for you towatch something, but in this
case I think you'll see why I'mcalling it lies, or at least
flagrant misinformation, aboutthis thing called sourdough.
Now, how did this happen?
I don't quite know how thesefictions got started.
I suspect it was some kind ofsourdough baker or bakery, maybe
(00:21):
in San Francisco or someplace,who thought or believed that
there was something in sourdoughor different about sourdough
that made it healthier thannon-fermented breads.
Sourdough fermentation, sothat's a fermented bread, and so
some people have claimed thatsourdough fermentation disables
all the adverse effects of wheat.
And if you review my wheatbelly books or recall what I
(00:43):
argued in the wheat belly books,that there are numerous toxic
compounds in wheat, especiallymodern wheat, for various
characteristics, such as analtered form of the gliadin
protein that yields opioidpeptides that stimulate appetite
(01:08):
and initiate the autoimmuneprocess meant for many
conditions like rheumatoidarthritis or type 1 diabetes.
Wheat germagglutinin, which isa very toxic compound in the
human gastrointestinal tract.
Phytates that bind mineralslike calcium, iron, zinc and
magnesium and you pass them outin the toilet and they're
(01:28):
therefore unabsorbed.
They're unabsorbable theamylopectin, a carbohydrate of
wheat that raises blood glucosevery high and stimulates the
formation of small LDL particles, the real cause for heart
disease, not LDL cholesterol.
And so the argument is thatsourdough fermentation by
microbes resident in wheatchanges the characteristics of
(01:51):
the bread and making it healthyor healthier.
Let's take that apart.
One of the sources of thisinformation, oddly, is the Mayo
Clinic, and I'll share anexcerpt from their website.
They say that three provenhealth benefits of sourdough
bread so this is from the MayoClinic website supports a
healthy gut microbiome.
(02:13):
Sourdough bread contains morebeneficial nutrients than other
types of bread Due to thefermentation process.
Fermentation creates probioticsor healthy bacteria that can
aid in digestion.
Another claim they make aboutsourdough bread is that it's
easily digested.
Sourdough fermentationdecreases the amount of gluten
(02:36):
and FODMAP carbohydrates in thebread.
This makes digestion easier andhas proven beneficial for those
with digestive disorders suchas irritable bowel syndrome.
And then the last claim theymake from the Mayo Clinic is
supports better blood sugarcontrol.
Sourdough bread has a lowerglycemic index than white bread,
so it doesn't increase bloodsugar levels quickly.
So those are pretty persuasive,aren't they?
Coming from Mayo Clinic withall these purported benefits?
(02:59):
Let's take those apart one byone Now, if you want the
references, the scientificreferences that bag up these
arguments.
See my williamdavismdcom blog,where it's kind of hard to
provide references ina podcastright.
So I put these in mywilliamdavismdcom blog along
with about 2,500 other blogposts that discuss all the
(03:20):
things I talk about in thispodcast, my YouTube channel and
elsewhere all the things I talkabout in this podcast, my
YouTube channel and elsewhere.
So supports a healthy gutmicrobiome, because sourdough
fermentation with microbesresident in wheat or added for
fermentation yield probioticspecies.
Well, there's so much wrongwith that, but the easiest
argument against that is that tomake sourdough bread they
(03:42):
typically bake at 450 to 500degrees Fahrenheit higher than
usual bread baking.
With that temperature nomicrobe survives.
You know, spore-forming species, like bacillus species, tend to
survive high temperatures, butnot that high.
So 450 degrees Fahrenheit issufficient to kill all organisms
(04:03):
spore-forming microbes,probiotic microbes, fungi
everything dies at 4.
So there are no microbes.
There are no probiotic microbesin sourdough bread.
It does not have any influenceon providing probiotics to your
gastrointestinal tract andsimilar studies have been
(04:25):
conducted where the compositionof the gastrointestinal
microbiome has been looked atpre and post consumption of
sourdough bread and there is nodifference.
Because there are no microbes,because they're all dead in
sourdough bread.
So for the Mayo Clinic andothers to say that sourdough
bread is a source of probioticmicrobes is completely and
(04:45):
utterly false, as common sensewould tell you and has studies
have validated.
The other claim is thatsourdough bread is more easily
digested because it reducesgluten protein.
Well, that's actually not true.
So the most important proteinwithin gluten so recall that
gluten, this protein unique towheat and related proteins and
(05:07):
other grains, has two parts.
It has a globular gliadinprotein, the source of most of
the problems associated withwheat proteins, and a glutenin
protein, that's a long chain orpolymeric protein that gives
wheat dough its stretchability.
Well, when you sourdough,ferment and then bake, you
(05:28):
actually release some of thegliadin protein sequences within
gluten within that gliadin, andyou increase the various
fractions of gliadin,alpha-gliadin, omega-gliadin,
gamma-gliadin, and it increasesthe potential to activate immune
responses, including autoimmuneresponses, and it makes it more
accessible to an enzyme thatlines the gastrointestinal tract
(05:52):
called trans-mortaminase 2,making it more likely to
generate effects such asactivation of celiac disease.
There's a lot of latent peoplewho are susceptible to celiac
disease who haven't yetexperienced it.
This is one of the phenomenathat could unmask that presence
of a genetic predispositiontowards celiac disease.
So the gliadin, and therebygluten, is actually increased by
(06:15):
the fermentation process tomake sourdough bread.
How about this idea that itreduces glycemic index by
reducing carbohydrates?
Not true?
So there's really no change Ifyou look at the carbohydrate
count in sourdough bread versusnon-fermented bread.
If you look at the variousfractions of carbohydrates, but
especially amylopectin A andamylose, there is no difference.
(06:38):
So this idea that sourdoughbread is less likely to trigger
blood glucose rises is patentlyfalse.
And the amylopectin A, becauseit's still there, provokes
formation of the small LDLparticle, the real cause for
heart disease.
So we know with confidence thatsugars, but also wheat, via the
(06:59):
amylopectin A carbohydrateunique to wheat and other grains
, is the trigger for formationof small LDL particles, the real
cause, or among the real causes, for coronary disease, heart
attack, sudden cardiac death anda need for procedures like
stent implantation, bypasssurgery Not saturated fat, by
(07:19):
the way, not LDL cholesterol,ldl particles, but specifically
small LDL particles.
So there's plenty ofamylopectin A left After
sourdough fermentation and afterhigh-temperature baking,
sufficient trigger formation ofthese heart disease-causing
particles that in 55, now todate 55 human clinical trials,
(07:42):
those particles, those small LDLparticles, have been shown to
be superior in predicting yourrisk for heart attack, stent
implantation, sudden cardiacdeath, etc.
Predicting your risk for heartattack, stent implantation,
sudden cardiac death, etc.
How about this idea thatconsuming sourdough bread
reduces the symptoms ofirritable bowel syndrome?
Well, there's a recent Europeanstudy in people with irritable
(08:06):
bowel syndrome, ibs, who weregiven sourdough bread and they
actually had worse symptoms.
And here's a quote from thatstudy.
And they actually had worsesymptoms.
And here's a quote from thatstudy.
There were significantly morefeelings of tiredness, joint
symptoms and decreased alertnesswhen the participants ate the
sourdough bread.
So this idea that sourdoughbread somehow absolves this
(08:27):
bread of all the problemsordinarily associated with wheat
once again completely false.
There is some truth, though.
There's one truth, actually, insome of the claims made by the
Mayo Clinic and other sources ofinformation regarding sourdough
brown.
That is a reduction in phytates.
So phytates are a compound inwheat and grains that bind
(08:47):
minerals.
They bind positively chargedminerals like calcium, magnesium
, iron and zinc, making themunavailable for absorption.
You just pass them into thetoilet.
Iron deficiency is especially aproblem and, for some odd
reason, particularly in femalesnot so much males, mostly
females and so these phytatesare very bad for nutrition.
(09:08):
You're told you need grains,wheat and grains for nutrition.
Actually, the you need grains,wheat and grains for nutrition.
Actually, the opposite is true.
They cause nutrientdeficiencies, especially of
minerals.
Well, the phytates are the onething actually reduced by
sourdough fermentation, not bythe actual process of
fermentation per se, but by theacidification you may notice.
(09:29):
If you ever had some sourdoughbread, it's very acidic.
That's because it has someacids like lactic acid and some
others, and that reduced the phinto the acidic range and that
level of acidity reduces thephytate content.
So that is true.
Another issue is often claimedis wheat germagglutinin, that's
the lectin of wheat.
That's very toxic to the humangastrointestinal tract and
(09:51):
animals.
When a purified one milligram,one little speck of purified
wheat, germ and gluten is givento a laboratory rat, for
instance, it denudes or destroysall the villi, the hair-like
projections lining thegastrointestinal tract.
It denudes them, it removesthem, which is very inflammatory
, very destructive.
Well, humans are subject tothat effect too from wheat
(10:13):
germagglutinin.
What effect does sourdoughfermentation and high
temperature baking have on wheatgermagglutinin?
None, it's still there.
It's as plentiful as it was atthe start.
It's no different than anyother form of bread, fermented
or non-fermented, baked or notbaked.
So a lot of the arguments madeto say that sourdough bread
(10:34):
supports a healthy microbiomebecause of the presence of
probiotic species, or that it'smore easily digested and has
reduced quantities of gluten, orthat it is better for blood
sugar control that's all falseand all you need to do is take a
few minutes to look at theevidence human clinical evidence
to show none of that is true.
(10:55):
The only thing that falls out astrue is that there's a
reduction in phytates.
So don't fall for these lies orat least this misinformation.
Who knows where this gotstarted?
But you know, the Internet isthe vast echo chamber.
It takes only one or a handfulof people to say something.
Let's say a sourdough bakery inSan Francisco.
It gets repeated, gets repeated, gets repeated, picked up by
(11:19):
some writer for the Mayo Clinicwho is too lazy to do background
work and look at the actualscience, not just hear the
repeated claims made by otherbakers, by people interested in
nutrition or people justinterested in eating bread, and
it becomes like it almost seemslike it's true, but it's not
true.
All we need to do is look atthe evidence and find out there
(11:40):
is no such advantage forsourdough bread.
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