We have a lot of choices to make about our diet.
Add to that, doing the right thing
when it comes to preventing
and treating a chronic disease,
fighting a virus, or losing weight,
and suddenly our nutrition choices
can seem almost overwhelming.
Well, I’m here to help.
Welcome to the Nutrition Facts Podcast.
I’m your host, Dr. Michael Greger.
More than 10,000 articles have been published on gluten
in medical journals— intimidating even for me!
Today we have a three part series
summarizing the best available science on gluten.
In our first story, we look at how we might prevent
the inflammation that occurs from gluten-free diets.
Over the last decade or so, there’s been a growing interest
in the medical literature on plant-based eating,
beyond just exclusionary terms like vegetarian or vegan.
Previous such studies were somewhat limited
because they just split people up into either
vegetarian or nonvegetarian, excluding some or all animal foods,
but without taking into account the quality of plant foods.
Vegans could be living off of French fries, Oreos, and Coca-Cola.
Enter: “Changes in Plant-Based Diet Quality and Total and
Cause-Specific Mortality,” the first study to investigate
the associations between changes in plant-based diet quality
and subsequent risk of death.
If you look at overall plant-based diet scores,
the more you increase your intake of any plant foods and
decrease your intake of any animal foods,
the lower your risk of death appears to fall,
but that’s because people were adding healthy plant foods
like fruits and vegetables.
If you just look at people who ate more processed,
sugary junk over time, their mortality risk goes up,
the clinical implications being that increasing intake
of healthy plant foods and decreasing intake
of not just animal foods, but also animal crackers,
could lower the future risk of premature death.
Whereas just reducing the intake of carbs in general,
cutting down not just refined carbs and sugars,
but healthy high carb foods like fruits and whole grains
is associated with increased overall mortality,
which would correspond to years of your life being cut short,
as well as the risk of dying specifically
from heart disease, stroke, and cancer.
Why are whole plant foods so good for us?
Much of the benefit may be mediated by our microbiome.
There are all sorts of things threatening our good gut bugs,
like the over prescription of antibiotics, however,
the only factor that has been empirically shown to be important
is a diet low in microbiome- accessible carbohydrates,
in other words prebiotics like fiber and resistant starch
only found one place in abundance, whole plant foods.
We went from high-MAC diets to Big Mac diets
and may be suffering the consequences.
Intake of dietary fiber, which is the main source of MACs in the diet
is negligibly low compared to how we evolved.
Such a low-fiber diet provides insufficient food for our gut microbes,
starving ourselves of all the wonderful things they produce for us.
A low-fiber diet is a key driver of microbiome depletion,
and this loss is implicated in the rampant increase
of chronic diseases that now plague the modern world.
We evolved getting perhaps a hundred grams of fiber a day.
Our gut bugs must have been in heaven.
How do you get even close to that?
A cup of fruit may only have about
3 grams, a cup of vegetables, 5 grams.
Why so little? Because fruits and vegetables
are like 80 to 90 percent water.
One has to go to the drier plant foods to really scale it up,
like beans, at 15 grams, or intact grains like barley,
over 30 grams per cup.
But many people are avoiding common grains these days,
like wheat barley and rye due to gluten,
but there is a dark side of gluten-free diets.
Now, if you have a condition like celiac disease,
then you absolutely have to avoid gluten, but if not,
the downsides include the potential for nutritional deﬁciencies,
like not getting enough fiber, and toxic compounds,
for example the accumulation of heavy metals
in people on gluten-free diets.
Those following a gluten-free diet had signiﬁcantly increased
blood mercury levels, more arsenic flowing through their systems.
The arsenic is likely due to increased rice consumption because
rice is a major ingredient in gluten-free foods,
but you can certainly choose other grains like sorghum—
that’s my favorite rice substitute.
And the higher mercury may just be because people eating
gluten-free diets were tending to eat more fish for some reason.
But the reason that 10 out of 10 of those without celiac disease
or a recognized gluten sensitivity following a gluten-free diet
experienced a pro-inﬂammatory gastrointestinal environment
is likely due to starving your microbial self,
not getting enough prebiotics, not getting enough fiber
because you’re avoiding grains like wheat.
So, whatever diet you choose for whatever reason,
make sure you’re getting enough fiber.
In our next story, we look at how the effects of gluten on our health
have been debated for more than 30 years.
In 1980, researchers in England reported a series of women
who suffered from chronic diarrhea that resolved on a gluten-free diet,
yet did not have evidence of celiac disease,
the autoimmune disorder associated with gluten intolerance.
The medical profession was skeptical at the time, and even 30 years later,
so much so, that much like patients who had irritable bowel syndrome,
patients claiming non-celiac gluten sensitivity were commonly referred to psychiatrists
because they were believed to have an underlying mental illness.
Psychological testing of such patients, however, found no evidence
that they were suffering from some kind of psychosomatic hysteria.
The medical profession has a history of dismissing diseases as all in people’s heads—
PTSD, ulcerative colitis, migraines, ulcers, asthma, Parkinson’s, MS.
Despite resistance from the prevailing medical community at the time,
these health problems have subsequently been confirmed
to be credible physiologically-based disorders
rather than psychologically-based confabulations.
On the flip side, the Internet is rife with unsubstantiated claims about gluten free diets,
which has spilled over into the popular press to make gluten the diet villain du jour
with claims like ‘17 million Americans are gluten sensitive.’
However, it must be remembered that this is also ‘big business.’
When literally billions of dollars are at stake, it’s hard to trust anybody,
so as always, best to stick to the science.
What sort of evidence do we have for the existence of a condition presumed to be so widespread?
Not much.
The evidence base for such claims was unfortunately very thin
because we didn’t have randomized controlled trials
demonstrating that the entity even exists.
The gold-standard for confirming non-celiac gluten sensitivity requires a gluten-free diet,
followed by a double-blind, randomized, placebo-controlled food challenge.
Like you give someone a muffin and they’re not told
if it’s a gluten free muffin or gluten filled muffin – to control for placebo effects –
and see what happens.
The reason this is necessary is because when you actually do this,
a number of quote-unquote “gluten-sensitive” patients don’t react at all to disguised gluten,
and instead react to the gluten-free placebo, so it truly was in their heads.
But we never had that kind of level of evidence until 2011,
when a double-blind, randomized placebo- controlled trial was published,
which tested to see if patients complaining of irritable bowel type symptoms,
who claimed they felt better on a gluten free diet – despite not having celiac disease –
actually could tell if they were given gluten free bread
and muffins or the gluten-containing bread and muffins.
They started out gluten-free and symptom-free for two weeks
and then they were challenged with the bread and muffins.
Here’s what happened to the 15 patients who got the placebo,
meaning they started out on a gluten-free diet and continued on a gluten-free diet.
They got worse.
Just the thought that they may be eating something that was bad for them
made them feel all crampy and bloated.
This is what’s called a nocebo effect.
The placebo effect is when you give someone something useless and they feel better.
The nocebo effect is when you give someone something harmless and they feel worse.
But the small group that got the actual gluten felt worse still.
So, they concluded, this non-celiac gluten intolerance may actually exist.
It was a small study, though, and even though they claimed
the gluten-free bread and muffins were indistinguishable,
maybe at some level the patients could tell which is which.
So in 2012, researchers in Italy took 920 patients that
had been diagnosed with non-celiac gluten sensitivity
and put them to the test with a double-blinded wheat
challenge by giving them not bread and muffins,
but capsules filled with wheat flour or filled with
placebo flour, kind of a placebo powder – no flour at all.
And more than two-thirds failed the test, like they
got worse on the placebo or better on the wheat.
But of those that passed, there was a clear benefit
to staying on the wheat-free diet, confirming the existence of a non-celiac wheat sensitivity.
Now note they said wheat sensitivity, not gluten sensitivity.
Gluten itself may not be causing gut symptoms at all.
See, most people with wheat sensitivity have a variety of other food sensitivities.
Two thirds are sensitive to cow’s milk protein as well,
then eggs were the most common culprit after that.
So if you put people on a diet low in common triggers of irritable bowel symptoms
and then challenge them with gluten, there’s no effect.
Same increase in symptoms with high gluten, low gluten, or no gluten, calling into question
the very existence of non-celiac gluten sensitivity.
Interestingly, despite being informed that avoiding
gluten wasn’t apparently doing a thing for their gut symptoms,
many participants opted to continue following a gluten-free
diet as they just subjectively described “feeling better,”
so the researchers wondered if avoiding gluten might
be improving the mood of those with wheat sensitivity,
and indeed, short-term exposure to gluten appeared
to induce feelings of depression in these patients.
But whether non-celiac gluten sensitivity is a disease of the mind
or the gut, it is no longer a condition that can be dismissed.
Finally today, how common is gluten sensitivity?
Are there benefits to gluten?
Why does the medical profession explicitly advise against people
who might suspect they may be gluten intolerant
from just going on a gluten-free diet?
Let’s find out.
Until only a few years ago, almost the whole of the scientific world
maintained that the wheat protein gluten would provoke negative effects
only in people with rare conditions such as celiac disease or wheat allergies,
but by the early part of 2013, it was largely becoming accepted
that some nonceliac patients could suffer from gluten or wheat sensitivity.
And indeed a consensus panel of experts now officially recognizes
three gluten-related conditions, wheat allergy, celiac disease, and gluten sensitivity.
So what percent of the population should avoid wheat?
Although 1 in a thousand may have a wheat allergy, nearly 1 in a 100 may have celiac disease,
and it appears to be on the rise, though there’s still less than about 1 in 10,000 chance
Americans will get diagnosed with celiac in a given year.
How common is wheat sensitivity?
Our best estimate at this point is in that same kind of general range, slightly higher than 1%,
but still that’s potentially millions of people who may have been suffering for years
who could have been cured by simple dietary means,
yet went unrecognized and unhelped by the medical profession.
Although gluten sensitivity continues to gain medical credibility,
we still don’t know how it works, or how much gluten can be tolerated,
if it’s reversible or not and what the long-term complications
might be of not sticking to the diet.
Considering the lack of knowledge, maybe people with gluten sensitivity
should be trying to reintroduce gluten back into their diet every year
to see if it’s still causing problems.
The reason health professionals don’t want to see people on gluten-free diets
unless absolutely necessary is that for the 98% of people
people that don’t have gluten issues, whole grains—
including the gluten grains - wheat, barley and rye—
are health promoting, linked to the reduced risk of
coronary heart disease, cancer, diabetes, obesity and other chronic diseases.
Just like, because some people have a peanut allergy,
doesn’t mean that everyone should avoid peanuts.
There is no evidence to suggest that following a gluten-free diet
has any significant benefits in the general population.
Indeed, there is some evidence to suggest that a gluten-free diet may adversely affect
gut health in those without celiac disease or gluten sensitivity or allergy.
They’re talking about this study that found that a month on a gluten-free diet
may hurt our gut flora and immune function,
potentially setting those on gluten-free diets up for an overgrowth
of harmful bacteria in their intestines. Why?
Because, ironically, of the beneficial effects of the very components
wheat sensitive people have problems with—like the FODMAP fructans
that act as prebiotics and feed our good bacteria,
or the gluten itself, which may boost immune function.
Less than a week of added gluten protein significantly
increases natural killer cell activity,
which could be expected to improve our body’s ability to fight cancer and viral infections.
High gluten bread improves triglyceride levels better
than regular gluten bread, as another example.
Ironically, one of the greatest threats of gluten-free diets may be the gluten itself.
Self-prescription of a gluten-free diet may undermine our ability to pick up celiac disease,
the much more serious form of gluten intolerance.
The way we diagnose celiac is by looking for the inflammation
caused by gluten in celiac sufferers,
but if they haven’t been eating a lot of gluten, we might miss the disease.
Hence, rather than being on a gluten-free diet,
we want celiac suspects to be on a gluten-loaded diet.
We’re talkin’ 4-6 slices of gluten packed bread a day, every day for at least a month,
so we can definitively diagnose the disease.
Why does it matter so much to get a formal diagnosis if you’re already on a gluten-free diet?
Well, it’s a genetic disease so you’ll know to test the family,
but most importantly many people on gluten-free diets are not actually on gluten-free diets.
Even 20 parts per million can be toxic to someone with celiac.
Many on so-called gluten-free diets inadvertently still eat gluten.
Sometimes there’s contamination of gluten-free products,
so even foods labeled "gluten-free" may still not be safe for celiac sufferers.
That’s why we need to know.
The irony, editorialized in a prominent medical journal,
of many celiac patients not knowing their diagnosis,
while millions of non-sufferers banish gluten from their lives,
can be considered a public health farce.
We would love it if you could share with us your stories
about reinventing your health through evidence-based nutrition.
Go to nutritionfacts.org/testimonials.
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To see any graphs, charts, graphics, images, or studies mentioned here,
please go to the Nutrition Facts Podcast landing page.
There you’ll find all the detailed information you need –
plus, links to all of the sources we cite for each of these topics.
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