Let's say you're trying to lose 20 pounds, or boost your immunity,
or increase your ability to fight COVID, or even cancer.
Well, the amazing thing is, with the right diet,
you're well on your way to achieving these vital health goals.
Welcome to the Nutrition Facts Podcast. I'm your host, Dr. Michael Greger.
Today we have more information about the mycotoxins found in our food supply.
And as it turns out, the overall cost-benefit ratio for mycotoxins
depends on which food is contaminated.
Ochratoxin has been described as toxic to the immune system,
developing fetus, kidneys, nervous system, as well as
being carcinogenic—but that’s in animal studies.
Ochratoxin causes kidney toxicity in certain animal species,
but there is little documented evidence of adverse effects in humans.
That’s why it’s only considered a possible human carcinogen.
Big Ag assures that current ochratoxin levels are safe
even among those who eat a lot of contaminated foods.
The worst-case scenario may be young children eating a lot
of oat-based cereals, but even then, their lifetime cancer risk
is considered negligible, with those arguing against
regulatory standards suggesting you can eat more than
42 cups of oatmeal a day and not worry about it.
Where do they get these kinds of estimates?
They determine the so-called benchmark dose in animals—
the dose of the toxin that gives a 10% increase in pathology—
and then, because you want to err on the side of caution,
you divide that dose by 500 as a kind of safety fudge factor
to develop the tolerable daily intake.
For cancer risk, you can find the tumor dose—
the dose that increases tumor incidence in lab animals
by 5%—and extrapolate down to the ”negligible cancer risk intake,”
effectively incorporating a 5,000-fold safety factor.
It seems kind of arbitrary, right? But what else are you going to do?
You can’t just intentionally feed people the stuff and see what happens.
Though look, people eat it all the time.
Can’t we just follow people and their diets out over time
and see if people who eat more whole grains like oats, for example,
are more likely to have cancer or live shorter lives?
What is the association between whole grain intake
and all-cause, cardiovascular, and cancer mortality?
Every additional ounce of whole grains a day is associated with
not only a lower risk for cancer but also a lower risk
of dying from all causes put together.
Bottom line is that you don’t find adverse effects
confirmed in these population studies.
This is not to say ochratoxin is necessarily harmless,
but any such risk it does pose doesn’t outweigh
the known beneﬁts of whole grain consumption.
In fact, healthy constituents of the whole grains themselves
like the antioxidants may directly reduce the impacts
of mycotoxins by protecting cells from damage,
so eating lots of fruits and vegetables may also help.
Either way, a healthy diet can play a signiﬁcant role
in mitigating the risk.
In summary, healthy foods like whole grains are good,
but just not as good as they could be because of ochratoxin;
whereas less healthful foods, like wine and pork,
are worse because of the mycotoxin.
Ochratoxin was detected, for example, in 44% of tested pork.
In our next story we ask, is “toxic mold syndrome” a real thing?
And, what do we do about toxic mold contamination of food?
In recent years, mold has been blamed for all sorts
of vague subjective symptoms, but we have little scientific evidence
that mold has anything to do with them.
However, this concept of “toxic mold syndrome” has permeated
the public consciousness, perpetuated by disreputable predatory practices,
by those making money testing homes for mold spores or
testing people’s urine or blood.
But all these tests are said to just further propagate misinformation
and inflict unnecessary, and often exorbitant costs
on patients desperate for a diagnosis.
“The continued belief in this myth is perpetuated by those charlatans
who believe that measles vaccines cause autism, that homeopathy works,
that fluoride in the water should be removed . . .”
Mold toxin contamination of food, however, has emerged
as a legitimate issue of serious concern,
perhaps even more important than other contaminants
that might make their way into the food supply.
Hundreds of different types have been identified, but only one has been
classified as a known human carcinogen, and that’s aflatoxin.
The ochratoxin I talked about before is a possible human carcinogen,
but we know aflatoxin causes cancer in human beings.
In fact, aﬂatoxins are amongst the most powerful
carcinogens we know about.
For example, it has been estimated that about a fifth of all
liver cancer cases may be attributable to aflatoxins,
and since liver cancer is the third-leading cause of
cancer deaths worldwide, and kills so rapidly after diagnosis,
the contribution of aflatoxins to this deadly cancer is quite significant.
And once it makes it into the food, there is almost nothing
you can do to remove it. Cooking, for example, doesn’t help.
So, once it makes it into crops, or the meat, dairy, and eggs
from animals consuming those crops, it’s too late.
So, we have to prevent contamination in the first place,
and that’s what we’ve been doing for decades in this country.
Because of government regulations, companies are almost
“always sampling” for aflatoxin, resulting in nearly a billion dollars
in losses every year, which may get worse if climate change worsens
aflatoxin contamination in the Midwest Corn Belt.
So, on a consumer level it’s really more of a public health problem
in the less industrialized world such as African countries
where conditions are ripe, and farmers can’t afford
to throw away a billion dollars’ worth of crops.
Indeed, aflatoxin remains a public health threat in Africa,
rural China, and Southeast Asia, affecting more than half of humanity,
which explains why the prevalence of liver cancer in those areas
may be 30 times higher, but it is not a major problem in the U.S. or Europe.
For example, only about 1% of Americans have detectible levels
of aflatoxins in their bloodstream. Why even 1%, though?
Well, the FDA works to ensure that the levels of exposure
to these toxins are not kept as low as possible,
but, instead, as low as practical.
For example, in California there has been an increase in unacceptable
aflatoxin levels in pistachios, almonds, and figs.
Unacceptable in Europe, that is, so it affects our ability to export,
but not necessarily unacceptable for U.S. consumers,
as we allow twice as much aflatoxin contamination.
Figs are unique since they’re allowed to dry on the tree.
This makes them particularly susceptible to aﬂatoxin production.
It would be interesting to know about the fig consuming habits
of the 1% of Americans who turned up positive for the toxin.
If figs were to blame, I’d encourage people to diversify
their dried fruit consumption, but nuts are so good for us
that we really want to keep them in our diets.
The cardiovascular health beneﬁts outweigh the carcinogenic effects,
preventing thousands of strokes and heart attacks
for every one case of liver cancer.
“Thus, the population health beneﬁts provided by increased nut consumption
clearly outweigh the risks associated with increased aﬂatoxin exposure.”
So, we’re left with aflatoxin being mostly a problem
in the developing world, and because of that, it remains
a largely and rather shamefully ignored global health issue.
Where attention has been paid, it has been largely driven
by the need to meet stringent import regulations in the richer nations
of the world rather than to protect the billions of people
exposed on a daily basis.
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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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