You may have heard the expression knowledge is power.
Well, today we’re going to give you more power
to control your diet and lifestyle by giving you the facts.
Welcome to the Nutrition Facts Podcast.
I’m your host, Dr. Michael Greger.
Today we continue our series
looking at the human health effects of plant based meats.
We start out with the effects of plant-based meats
on premature puberty, childhood obesity,
and hip fracture risk.
As noted in an editorial in the Journal of the American Medical Association
on plant-based meat alternatives, just looking at the nutrition facts info
of a regular burger versus Beyond Meat or the Impossible Burger
you wouldn't necessarily be able to predict the health consequences
without further studies. But we've had plant-based meat alternatives
for over a century. I mean, who wouldn't want a can of good eatin' Protose?
It is, after all, the modern vegetable meat,
patent filed by Dr. John Harvey Kellogg in 1899. Of course, products such
as tofu and tempeh have existed in Asia for centuries,
but I think of those as separate foods in their own right,
as opposed to products intentionally designed to mimic
the taste and texture of meat.
With such a rich history, harkening back to the days of pass-the-Proteena,
you'd think there'd be some studies of consumers.
And indeed, there are. For example, girls who eat meat
may start their periods six months earlier than girls who don't.
Is it just because they're eating lots of protein and fat?
Evidently not, because girls who instead are eating meat analogues,
like veggie burgers and veggie dogs, are able to delay menstruation
by nine months. Of course, it's hard to tease out how much of that
is just from avoiding meat.
But compared with girls who eat meat just a few times a week,
those who ate meat a few times a day had a significantly earlier age
of first menstruation, which also may help provide an explanation
for why childhood meat consumption is linked to breast cancer later in life,
since the earlier you start your period, the higher your lifetime risk.
Now obesity itself may contribute to the early onset of puberty in girls,
so that could be another factor.
Studies have suggested vegetarian children tend to be leaner
than nonvegetarian children.
They aren't smaller in general, though. Vegetarian boys and girls may measure
up to be about an inch taller than their classmates; they just aren't as wide.
So the fact that girls who eat plant- based meats may be less likely to suffer
from premature puberty may, in part, be because they were leaner.
Indeed, childhood obesity research found meat consumption seemed
to double the odds of schoolchildren becoming overweight, compared
to the consumption of plant-based meat.
Now, whole plant food sources of protein, such as beans, did even better though,
associated with cutting in half the odds of kids becoming overweight.
So that's why I consider these kinds of plant-based meats
more of a useful stepping stone towards a healthier diet,
rather than the endgame ideal. The same amount of protein
in a bean burrito would be better in nearly every way.
Similarly, in terms of hip fracture risk, in the Adventist 2 study
following tens of thousands of men and women for years, daily intake
of plant-based meats appeared to reduce the risk of hip fracture
by nearly half, but daily legume intake--- beans, split peas, chickpeas, and lentils---
may drop risk of hip fracture by even more, nearly two thirds.
In our next story, clinical trials on Quorn show that it can improve satiety
and help people control cholesterol, blood sugar, and insulin levels.
You may have heard about meat made out of wheat protein,
meat made out of soybean protein, and meats made out of pea protein,
but mycoprotein is a relatively new addition—meat made from
the mushroom kingdom—popular in Europe, commercialized as Quorn,
which makes not just meat-free beef, but chicken-free chicken,
fishless fish and pig-free pork, just in case someone would like
to eat plant-based but can’t give up their cocktail weenies.
Environmental impact-wise, Quorn beef has at least
a 10 times smaller carbon footprint than beef;
Quorn chicken at least four times better than chicken-chicken.
And health-wise, it’s high in protein and ﬁber, and low in fat,
cholesterol, sodium, and sugar as one would expect.
But, most importantly, there have been clinical trials
showing it may help people control cholesterol, blood sugar,
and insulin levels, and improve satiety.
No surprise given that not only the fiber
but the mycoprotein itself is fermentable by our good gut bugs,
so can also act as a prebiotic for our friendly flora.
There have been rare authenticated reports of people
with mycoprotein allergies, and even more with unvalidated
complaints, but given how many billions of packages have been sold,
the rate of allergic reactions may be
on the order of like 1 in 9 million.
Here’s the cholesterol data, converted into US numbers.
So significant drops in total and LDL cholesterol—
more than 30 points within 8 weeks.
In terms of satiety, as I noted in my Evidence-Based
Weight Loss presentation, both tofu and Quorn have been found
to have satiating qualities that are stronger than chicken;
for Quorn, among both lean subjects and overweight
and obese individuals, cutting down on subsequent
meal intake hours later.
You know, it’s funny when the meat industry funds obesity studies
on chicken, they choose for their head-to-head comparison foods
like cookies and “sugar-coated chocolates.”
This is a classic drug industry trick where you make
your product look better by comparing it against something worse.
(Apparently, just regular chocolate,
was not enough to make chicken look better.)
But what happens when chicken is pitted against a real control,
like chicken without the actual chicken?
Chicken chickens out.
For example, feed people a chicken and rice lunch,
and four and a half hours later they eat 18% more of a dinner buffet
than those who instead who got a Quorn and rice lunch,
cutting about 200 calories on average.
Part of the reason plant-based meats may be less fattening
is that they cause less of an insulin spike.
A meat-free chicken like Quorn causes up to 41% less
of an immediate insulin reaction.
It turns out animal protein causes almost exactly
as much insulin release as pure sugar.
Just adding some egg whites to your diet can increase insulin output
60% within four days. And fish may be even worse.
Why would adding tuna to mashed potatoes spike up insulin levels,
but adding broccoli instead drop the insulin response
by about 40%? It’s not the fiber, since giving the same amount
of broccoli fiber alone provided no significant benefit.
So, why does animal protein make things worse,
but plant protein make things better?
Plant proteins tend to be lower in the branched-chain amino acids,
which are associated with insulin resistance—
the cause of type 2 diabetes. You can show this experimentally.
Give some vegans branched-chain amino acids,
and you can make them as insulin resistant as omnivores.
Or, take omnivores and put them through even a 48-hour
vegan diet challenge, and within two days you can see
the opposite—significant improvements in metabolic signatures. Why?
Because “decreased consumption of branched-chain amino acids
improves metabolic health.”
Check this out. Those randomized to restrict their protein intake
were averaging literally hundreds more calories per day;
so, they should have become fatter, right?
But no, they actually lost more body fat.
Restricting their protein enabled them to eat more calories,
while at the same time they lost more weight.
More calories, yet a loss of body fat!
And this magic “protein restriction”?
They were just having people eat the recommended amount of protein.
So, maybe they should have called this
the normal protein group, or the recommended protein group,
and the group that was eating the more typical American
protein levels, and suffering because of it,
the excess protein group.
Given the “restoration of metabolic health by decreased consumption
of branched-chain amino acids,” leaders in the field
have suggested the invention of drugs to block their absorption,
to “promote metabolic health and treat diabetes and obesity
without reducing caloric intake.”
Or, we can just try not to eat so many
branched-chain amino acids in the first place.
They are found mostly in meat, including chicken and fish,
dairy products, and eggs, perhaps explaining why animal protein
has been associated with higher diabetes risk,
whereas plant protein appears protective.
So, defining the “appropriate upper limits” of animal protein intake
“may offer a great chance for the prevention
of type 2 diabetes and obesity.”
Finally today we ask: is heme just an innocent bystander
in the link between meat intake and breast cancer,
diabetes, heart disease, stroke, and high blood pressure?
In an editorial in the Journal of the American Medical Association,
the chair of nutrition at Harvard pointed out that many
plant-based meat alternatives, such as Beyond Meat and
the Impossible Burger, can be high in sodium.
But an issue specific to the Impossible Burger was the heme they add, derived
from soybean plants to enhance the product's meaty flavor and appearance.
Safety analyses have failed to find any toxicity risk specific to the soy heme
they have yeast churn out. The FDA has agreed both
for use as a flavor and color enhancer: safe.
In other words, just as safe as the heme found in blood and muscle in meat.
But how much is that really saying?
The concern raised in the op-ed, for example, was that higher intake of heme
has been associated with an elevated risk of developing type 2 diabetes.
But not just diabetes, killer #7 in the United States, higher dietary
intake of heme iron is associated
with an increased risk of cardiovascular disease as well,
killers #1, 4 and 13: heart disease, stroke, and high blood pressure.
But since heme is found mostly in meat,
heme intake may just be a marker for meat intake.
It's like with diabetes: three meta-analyses published to date,
and they all reported the same link.
But there's lots of reasons why meat may increase diabetes risk,
like advanced glycation end products, produced when animal products
are baked, broiled, grilled, fried, or barbequed.
So how do we know that the heme isn't just some innocent bystander?
The same issue arises about the link between heme intake
and increased breast cancer risk.
Since heme iron is coming from animal foods, it could be any
of the other meat components, like animal fat or meat mutagens,
compounds in meat that can cause DNA mutations.
And hey, what about all the hormonal steroids implanted into cattle
that may play a role in the development of breast cancer?
A study in Japan found that beef imported from the United States
contained up to 600 times the levels of estrogens like estradiol.
And higher consumption of estrogen-rich beef due to hormone implantation
may facilitate estrogen accumulation in the human body
and thus affecting women's risk for breast cancer.
So yeah, heme iron intake was associated with breast cancer risk,
but maybe that's just because the heme and the hormones are traveling together
in the same package: meat.
The NIH-AARP study is the largest prospective study on diet and health
ever, following more than a half million men and women for over a decade now.
With such a huge dataset they could take advantage of the fact that
different meats have different amounts of heme, so they could try to tease out
the heme components by, in effect, comparing people eating different
amounts of heme, but the same amount of meat
to see if heme is independently associated with disease.
And indeed, that's what they showed: an independent association not only
from nitrites in processed meat, but heme and mortality from almost all causes:
death from diabetes, heart disease, stroke, respiratory disease,
kidney disease, liver disease, cancer, and all causes put together.
They calculated that about one-fifth of the association between
like eating burgers and the shortening of your lifespan
could be statistically accounted for by just the heme itself,
but that's assuming cause-and-effect.
Even an independent association is still an association. You can't
prove cause and effect until you put it to the test in interventional studies.
Normally, we don't necessarily care about the mechanism.
When the World Health Organization designated bacon, ham, hot dogs,
luncheon meat, sausage to be Group 1 carcinogens,
meaning we know these products cause cancer in human beings,
who cares if it's the heme iron, or the heterocyclic aromatic amines,
or the polycyclic aromatic hydrocarbons, or the N-nitrosamines.
They're all wrapped up in the same place, processed meat,
which we know causes cancer.
So we should just try to stay away from it, regardless of the mechanism.
But with the advent of the Impossible Burger, we really do have to know,
because for the first time we have lots of heme without any actual meat.
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