Back in the day, in 1946, we were right to like meat, it was the fun way to get our proteins,
it came in cans. Sometimes with a sack of sauce! And people knew meat was good, but
thanks to the American Meat Institute, they then learned that it was this good.
Fast forward to 2019, for one reason or another various public figures from celebrities, companies
and even New York Public Schools want people eating less meat. There are many studies showing
that people who eat more meat seem to have more heart disease, more diabetes more cancer
and other health issues.
And when it comes down to the specifics of why meat is bad, compounds in meat are often
investigated - things like heterocyclic amines, TMAO, Neu5GC, Arachadonic acid, and the list
goes on.
Too much iron in your blood.
In the first Chapter of “Survival of the Sickest,” Dr. Sharon Moalem tells the story
of how long distance runner Aaron Gordon found himself in a very peculiar situation while
training for a 150 mile race across the Sahara desert. He was tired all the time. His joints
hurt and his heart seemed to be skipping beats. After 3 years of trying to figure out the
cause, his doctors found that An abnormal buildup of iron in his blood and liver was
rusting him to death. He had 5 years left to live.
So, the first “bad” compound in meat we’ll have a look at is heme iron. You may be familiar
with news headlines like this: ”Breaking news linking meat and cancer. The World Health
Organization publishing a report on the dangers of processed and red meat." The WHO’s IARC
report identified heme iron as one of the suspect compounds in meat. Heme iron is said
to increase your risk for heart disease, and even cancer, particularly colon cancer.
But, I think everyone knows that we need iron.
The WHO estimates 25% of the population to be anemic.
Plants provide non-heme iron whereas meat and fish gives us heme-iron which is absorbed
much more easily. Depending on the person and their lifestyle, iron stores can deplete
rapidly when you stop ingesting heme iron.
Youtuber Liam Thompson tried eating no meat or fish for one year. Near the end of the
first six months, he noticed he was a bit tired and was requiring more sleep, so he
went to get a blood test. The test showed his iron level had halved. Liam happens to
run alot, so his iron requirements are higher, but in the last 3 months of his diet experiment,
despite having taken supplements and using other strategies for increasing his iron,
his iron level halved ...again.
Sure, iron absorption is great, but what about cancer? Well, one of the initial studies looking
at that idea that heme iron causes cancer, fed calcium deficient rats a heme iron rich
diet and found that indeed these rats developed precancerous lesions in their colon. ...but
if you gave these calcium deficient rats some calcium, they had no such increase in precancerous
lesions. There’s another interesting thing about this study, as it says: “[the rats
were] given control diet before being injected with .dimethylhydrazine (Dimethylhydrazine
is a carcinogen, a cancer causing substance). ...We chose to initiate all rats with the
carcinogen, [because another study found] that a [high heme iron diet] does not [cause
colon cancer] in rats.”
In fact, in that WHO report that told us processed meat causes cancer, is a study that found
that bacon protects against azoxymethane induced colon cancer. Actually, the report even says
“There is inadequate evidence in experimental animals that red meat or processed meat cause
cancer,"
“As of this coming September, Meatless mondays will be in effect in all 1800 New York City
public schools. And we are proud of that.”
A different WHO report found that globally, 47% of iron deficiencies come from pre-kindergarten
children. Unfortunately, iron deficiency anemia in growing children has been associated with
cognitive deficits due to abnormal brain development
"Supper time, boys!" “Oh Boy, liver! Iron helps us play!”
Bradley Peterson, director of the Institute for the Developing Mind at Children's Hospital
Los Angeles in California, wanted to see why low iron levels in children are correlated
with lower IQ and poor concentration. Peterson and his colleagues used an MRI to see what
was happening in the brains of newborn infants and 40 healthy adolescent mothers — a group
known to be at high risk for iron deficiency.
The brain images that his team took showed a correlation between neuron complexity in
an infant and the amount of iron in the mother's diet, meaning: “The higher the iron intake
throughout pregnancy, the more complex the grey matter [of the brain] was at the time
of birth.”
Clearly, iron is especially important for mothers and their children. And, the iron
source is very important too. As this paper explains, “...during pregnancy there appears
to be preferential fetal use of maternally ingested iron derived from a dietary, animal-based
heme source…”
Unfortunately, it looks like iron supplements don’t cut it for pregnant women. Despite
taking prenatal vitamins with iron, 58% of the women had iron levels below normal.
Due to heme iron’s superior absorption, this review found that despite heme iron constituting
only one third of the iron that is actually digested, it makes up two thirds of the average
person’s total iron stores.
This review of 13 studies found that people who don’t eat meat, people who don’t have
a steady supply of heme iron, had consistently lower levels of iron and had consistently
higher rates of anemia - this was especially the case for women who could become pregnant.
OK So what about the iron overloaded guy with only 5 years to live? The long distance runner
Aaron Gordon was suffering from a genetic condition called “hemochromatosis.” where
your body holds onto too much iron. Iron is good, but we really don’t want our bodies
overloaded with it - hemochromatosis causes various problems like metabolic issues, liver
damage, heart palpitations and more. This condition is found commonly adult men with
North or West European ancestry - but around only 0.5% of those men actually suffer from
the condition, though the risk does increase with age.
However, there is evidence that iron accumulates can accumulate with age, even in people without
hemochromatosis genes. Dr. Leo Zacharski says increasing concentration of body iron is common
with aging.
Though accumulating too much iron might be the consequence of an unhealthy lifestyle.
There seems to be an association between iron and obesity. Two studies, one looking at a
Japanese population and a Mexican population found that the body’s storage form of iron,
ferritin, correlated with visceral fat and insulin resistance - two hallmarks of the
metabolic syndrome. Paul Adams, professor of medicine at the University of Western Ontario
says “In a large multiethnic population, the most common causes of elevated ferritin,
[the storage form of iron] levels are likely obesity, inflammation, and daily alcohol consumption.”
So, should adult men or post-menopausal women avoid meat or iron rich plant foods to prevent
iron overload just in case? Well, Chris Masterjohn, PhD in nutritional sciences recommends specifically
not to lower iron rich foods in your diet even if you have hemochromatosis because those
foods often have very valuable nutrients packed with them like copper, zinc, vitamin A, and
vitamin B12.
Now The reason hemochromatosis is more prevalent in men is because premenopausal women lose
a lot of iron through a natural monthly loss of blood. The key treatment for people with
iron overload is phlebotomy - therapeutic blood removal or blood donation. So, the rusting
long distance runner Aaron Gordon had his life saved and his health returned to normal
with one of the oldest medical practices - blood letting.
But here’s the thing: Why was bloodletting so popular in so many places for so long?
It’s thought to have been around as a medical practice for as long as 5000 years up until
the late 1800’s. In the 18th and 19th century, pretty much any ailment you had from hypertension
to headache to shortness of breath, the cure would be to bleed you.
In the earlier mentioned book, survival of the sickest, Dr. Moalem says that surely blood
letting must have conferred some benefit since it was so widespread and practiced for so
long.
In this short book by P.D. Mangan, prefaced by Dr. Leo Zacharski, he lists various studies
on the detrimental effects of excess iron in people without hemochromatosis, for example
studies that show blood donors have lower rates of heart disease and cancer. One study
showed therapeutic blood letting improved biomarkers for patients with non-alcoholic
fatty liver disease, a condition that commonly appears with diabetes.[R]
Maybe all those blood letting patients from the past didn’t understand what improvements
in biomarkers meant, but found that they felt a little better.
So, why wouldn’t the body be adapted to deal with excess iron?
For 99.6% of human’s existence we were hunter gatherers until we figured out how to do agriculture.
And, back when we were still hunter gatherers we had to have ingested a ton of heme iron
in the form of hunted animals. A paper by Loren Cordain, supported by fossil isotope
data, found that a majority of hunter gatherers were getting 56 to 65% of their nourishment
from animal foods with at least 20% of calories and as much as 50% of their calories coming
from animal protein. That’s a lot of heme iron.
So there’s two ideas to consider: First, it could be the case paleolithic humans
were at far higher risk of being low on iron, so having a mechanism by which the body could
dispose of excess iron wouldn’t be worth having. Being infected by hookworms, roundworms,
bacteria like H. Pylori and other pathogens, getting wounded from accidents or animal attacks,
ticks, leeches and so on would all be great ways to lose blood and iron for paleolithic
humans.
In fact, the inuit, have a big concern for anemia despite and abundance intake of heme
iron in the form of fish and animal meat.
Some of the proposed reasons are flatworm and hookworm infection, H. Pylori infection,
gastrointestinal bleeding and their vitamin intake being disrupted by the incorporation
of modern high-starch foods to the diet.
On the other hand, this paper suggests that after the agriculture gave us iron poor diets
10,000 years or so ago, our genetics started developing ways to hold on to that iron for
dear life.
There are still several question marks orbiting the topic of iron overload but we can safely
say a nuanced approach to dietary iron is very important. Growing people and people
who are growing people, surely need more easily absorbed iron, but older people might be tempted
to avoid good sources of heme iron for some of the reasons I talked about. Though, older
people are at risk for sarcopenia, muscle wasting, which is linked to a higher risk
for death from all causes. Iron isn’t the only thing in meat that’s easily absorbed.
Several studies have shown that the more easily absorbed animal protein is good for maintaining
muscle mass in the elderly.
Before we forget about the heme in heme iron, let me just add that heme itself is essential
for a ton of things. Heme of course is the reason your blood can carry oxygen, it’s
also essential for many other things like regulation of your circadian rhythm and it
is important for several enzyme systems for example the detoxification enzymes in your
liver. In fact, one component of cognitive decline and Azlheimer’s disease is thought
to be a heme deficiency . Research has found that hemoglobin and heme itself help reduce
inflammation in the brain and clear out the problematic amyloid plaques found in the brain
of Alzheimer’s patients.
But you don’t have to get your heme from the diet, your body makes it.
Though process to create heme requires 8 enzymes and uses up the main protein for collagen,
glycine, as well as vitamin B6, zinc and of course, iron. What’s funny is all those
nutrients are in meat.
In any case, it seems like the times have changed. Whereas a doctor from the American
College of Obstetricians and Gynecologists said in 2017 that yes absolutely you can have
a healthy pregnancy without meat, a 1946 paper from the Journal of the American Medical Association
was recommending pregnant women to add an extra generous portion of meat to their typical
daily diet.