How Excessive Red Meat Consumption Increases Colorectal Cancer Risk
nccs.com.sg
nccs.com.sg
As a thought experiment (I'm completely making up these claims, but they do at least seem plausible), imagine a world in which regular coffee consumption resulted in some small increase in cancer risk, but then also regular coffee consumption was correlated with say, academic success, success at work, had some appetite suppressing effects, etc.
If the latter outweighs the former then the cancer risk is probably worth it even just longevity wise. Like how we know that going out in the sun increases cancer risk but also is just, well, good for us, to a degree.
But of course the media will just run with a headline, which is why it sometimes feels as if the science is constantly "changing".
With red meat the known benefits peaks (way) lower than average consumption. I’m not an expert but that looks to be shown more than the opposite. On a personal anecdote my doctor tells last week optimum is at 1meal/2weeks. He’s maybe not aware of breaking discoveries but this looks to be in range with what’s discussed here and there.
I like critical thinking nevertheless and it would be interesting to learn more.
I chose caffeine as an example because I think that it's completely nontrivial to calculate. The physical pathways of things like "well this makes that molecule do this and have some x% chance to mutate and so on and so you get cancer", or the statistical output of "well people in the coffee cohort have % higher rates of this cancer" are much easier to accurately study than things like "if you drink coffee you are 3% more likely to get into law school and therefore become significantly wealthier and probably live a longer/healthier life and we can measure that impact precisely".
It's also not at all obvious that lifespan above all else is the thing to maximise. e.g. maybe red meat reduces lifespan but makes your 20s-60s more fun because you're likely to be more muscular or whatever.
My personal feeling is that aside from really really bad things like smoking, heavy alcohol use, heroin etc the error bars are too large to make decisions purely on long-term health impact alone.
Correlation != causation and all of that, but as the US has increased meat consumption and processed foods colon cancer has been on the rise, including younger and younger adults.
We only adopted carbs because back in the day, cereals were the most efficient way to feed a large population (compared to say large-scale veggie cultivation) for an active societal workforce. But with us slowly and inevitably turning into lumbering sedentary creatures, it makes no sense to continue eating as many carbs as we are culturally accustomed to, instead resorting to meats and veggies to adequately cover up that deficit. Unfortunately, you need a ton of veggies to make up that deficit, but you can make do with a much smaller sized portion of meat than you're usually accustomed to (as we see with East Asian diets).
You can drastically reduce the “redness” of your diet by eating chicken and fish. Even pork is less “red” though I’m not sure if it counts as red meat for this study.
Coming from a heavily pescetarian culture, I wouldn't recommend a lot of seafood today. Fish are loaded with oceanic carcinogens, not to mention you have even little control over how they're sourced (it's nearly always a factory ship).
Humans need to get most of the energy either from fat or from carbohydrates like starch, otherwise they die.
Even for the speed of obtaining energy from food, nothing beats a mixture of glucose with fructose, like long-distance runners or cyclists have to consume, if they want to win.
Red meat may be very tasty, but it is not the best for any criterion. As a source of proteins, lean white meat is superior, e.g. turkey breast, chicken breast or fillet from various kinds of fish with white meat, e.g. cod or zander.
As a source of energy, any food rich in starch or in oil is superior and also many times cheaper.
During the last few tens of thousands of years, the humans have evolved to be much better at digesting starch than their ancestors and than most other apes or monkeys, by increasing the ability to synthesize the enzymes used in starch digestion.
So our body physiology has already shifted somewhat from being best adapted to a hunter lifestyle to one where the plant seeds can satisfy most of the energy requirements.
Meat still remains one of the best choices as a source of proteins, but not as a source of energy.
That itself is a fallacious notion. Mammals can get energy from a multitude of sources, including carbs, proteins and fats. True, carbs are the fastest source and are prioritized first by the body, and any surplus is converted to fat, which is then stored as lipids. But fats are slower than proteins to digest, which take the second order in priority. The body breaks down protein to generate energy in the absence of carbs.
You could make do with eating a much lower portion of carbs and still cover your energy intake needs, as the world has moved on from an active lifestyle to a sedentary lifestyle. But you can't forgo the protein you get from meat and adequately substitute it, unless you eat exorbitant amounts of legumes. On a societal scale, it's much simpler to just have cattle around and eat on some grass, instead of allocating land to grow a bunch of legumes - one buffalo would be enough to feed a small village and some more.
You're right in that white meat is superior, but white meat in the US has a much higher chance of being factory farmed than white meat. The carcinogenicity of red meat largely comes from the use of chemical preservatives used in cleaning before freezing the meat - something fresh grass fed beef doesn't have to contend with.
Fish and seafood is another good source of protein, unfortunately they might be as carcinogenic as frozen red meat due to the amount of toxic chemicals we dump into our seas.
I’m fine with other people eating less red meat since that means less competition for me, but I’d still encourage healthy skepticism when people tell you to eat less of something that we’ve eaten since the dawn of our being and replace that in any degree with something novel.
Eating "excessive" red meat seems very likely cause high iron concentrations in your lower intestines. Beyond that - YMMV.
Looking at Inuit and Mongolian populations for stuff like this would likely be a good approach to actually learn stuff. Almost a strictly meat diet, but without all the confounding variables of sedentary office workers, industrial chemicals, and highly processed foods with tons of sugar.
In all likelihood, Inuit microbiota is very far from Western one, at least as long as they don't adapt Western diet.
https://www.lodgecastiron.com/cleaning-and-care/cast-iron/sc...
I have Lynch syndrome: a hereditary cell mutation which increases risk of colon cancer. Patients like me get a colonoscopy every eighteen months or so only to remove polyps. For a decade I had not had a single polyp to remove.
Then in 2022, I got another cancer which gave me blood deficiency (low hemoglobin levels), and just to keep myself alive I took strong iron supplements for months. It did of course also stress my immune system. I got colon cancer in record time, which surprised also my doctors. It grew from no visible polyp (my last colonoscopy) to two inches in nine months, and in-between that I had an X-ray that also showed nothing (but which can't detect tumors small enough).
https://www.researchgate.net/figure/Mortality-rate-for-men-a...
Basically, for whatever reason, a larger sex chromosome (X is much bigger than Y) confers a better chance of survival.
Perhaps the riskiness of male behavior in humans is built in at the chromosonal level...
Also, spinach has iron. So excessive spinach consumption at levels that most people couldn't tolerate could also increase colorectal cancer risk? Or no?
It looks like however the absorption of iron in red meat is quite high (15%-35%) compared to spinach (2-5%), so maybe not enough to really be a risk factor.
Interestingly, Vitamin C increases the rate at which you can get iron from greens such as spinach. So maybe a glass or orange juice and a bowl of salad a day keeps the doctor away.
Edit: Let me offer some USDA data points for those who are curious, but not curious enough to bother Googling for themselves.
Red Bell Peppers: https://fdc.nal.usda.gov/fdc-app.html#/food-details/170108/n...
Green Bell Peppers: https://fdc.nal.usda.gov/fdc-app.html#/food-details/2258588/...
Oranges: https://fdc.nal.usda.gov/fdc-app.html#/food-details/746771/n...
Eating one raw red bell pepper per day is pretty much guaranteed to provide enough vitamin C, even when no other food contains any.
If the red bell peppers are cooked, some of the vitamin C will be lost, but there still should be more than is most kinds of food.
Also explains why I crave red meat and vitamin C after a workout. Can't get enough of the stuff.
Vegetarian resource group 2018 https://www.vrg.org/nutrition/iron.php
> Some might expect that […] vegans might be prone to developing iron deficiency anemia. However, surveys of vegans have found that iron deficiency anemia is no more common among vegetarians than among the general population although vegans tend to have lower iron stores.
> In fact, if the amount of iron in these foods is expressed as milligrams of iron per 100 calories, many foods eaten by vegans are superior to animal-derived foods.[…] you would have to eat more than 1700 calories of sirloin steak to get the same amount of iron as found in 100 calories of spinach.
> Another reason for the satisfactory iron status of vegans is that vegan diets are high in vitamin C
2021 Norway health institute https://pubmed.ncbi.nlm.nih.gov/33803700/
> In conclusion, although the participants were eating a plant-based diet, the majority had sufficient iron status
Nutrients 2021 https://www.mdpi.com/2072-6643/13/9/2964
> We did not find differences in the prevalence of iron deficiency between vegetarians and omnivores among men and women who do not menstruate. Among women who menstruate, vegetarians had a higher prevalence of iron deficiency than omnivores did.
In this last one they’ll mixed non-omnivorous together. Not sure why, and how to calculate it.
A vegan diet can provide enough iron, but this is not automatic. One has to actually take care to ensure this.
While some studies like those quoted by you have found vegans who ate enough iron, studies done in other countries have found vegans with iron deficiencies. I have seen at least 2 or 3 such studies, I think one was about vegans in UK.
While there are many vegetables with a relatively high iron content, their iron content is still rather low so you have to eat greater quantities than many people would want to eat. Moreover, many of those vegetables are not cheap and eating large quantities is likely to make the expenses for the daily food greater than when eating food that includes meat.
So yes, vegans can eat enough iron, but they must be aware of the danger of eating too little iron and they must carefully choose their food to avoid this danger. Similar problems are caused by calcium, which exists in vegetables, but also in much smaller amounts than desirable. It is possible to eat a vegan diet with enough iron and calcium, but in many cases it is much less expensive and also easier to eat less food, but complete it with some iron and calcium supplements.
> One has to actually take care to ensure this.
Yes, but not more complex than eating the perfect omnivorous diet, which nobody does. Do you precisely count your omegas intake? Your daily ratio of carbs/protein/fat…? Some nutrition aficionados do, but the vast majority of the population (rich and poor) does not.
If you find the studies you remember please share them. Iron deficiency is a very common anemia, not only for vegans or poor countries.
On the supplement, it’s interesting to note that most cattle and other farms animals are heavely supplemented so they stay relatively healthy during life and their future flesh has the nutriments expected.
https://historiesofecology.blogspot.com/2015/08/on-spinach-i...
https://www5.in.tum.de/~huckle/Sutton_Spinach_Iron_and_Popey...
Those are the proteins with iron that give to blood the ability to transport oxygen and to red muscles the ability to store oxygen. Similar iron proteins, e.g. the so-called cytochromes, exist in all the cells of all aerobic living beings, but only in amounts many times lower than in the blood and red muscles of vertebrates.
Most of the other iron ions that can be found in water, in food or in iron supplements are reduced Fe(II) ions, which are not involved in this cancer-causing process.
Sigh at the clickbait headlines.
This study identifies only the oxidized Fe(III) ions as causing cancer.
The oxidized Fe(III) ions can have any effect in the intestine only when they are bound to organic molecules, like in blood or in red muscles. Otherwise, the oxidized Fe(III) ions form insoluble precipitates, which either pass through the intestine without any interaction, or they are reduced to soluble Fe(II), which is not harmful, but an essential nutrient.
Nevertheless, an excessively high intake of iron supplements can have various harmful effects, like any other excessive food intake.
Really?