Comment by zngtk4 | Hacker News Reader

Comment by zngtk4 | Hacker News Reader

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There are zero controlled studies showing this, however, and all of these studies are epidemiological/observational. It's confounded by things such as the fact that many of the groups that are vegetarian also essentially engage in calorie restriction (which has been shown in controlled animal studies to work). Meat eating, however, hasn't even been shown in animal studies to necessarily be bad, because it entirely depends on the animal (feed meat to a rabbit, bad things happen, feed grains to a cat, bad things happen). Cultures that engage in significant meat eating also tend to eat a lot of sugar, trans-fats, and other things. These studies are far from conclusive as a result.

Observational studies that are peer reviewed and exhaustive can yield results that are entirely opposite reality. Dozens of peer reviewed, exhaustive observational studies told doctors that hormone replacement therapy reduced the incidence of heart attacks. Only after 16,000 women were enrolled in a double-blind controlled trial of hormone-replacement therapy in the 90s (after 6 million women had received the therapy) did we learn that heart disease, breast cancer, stroke, and dementia actually were more common in people receiving hormone replacement therapy vs placebo. In other words, the exact opposite.

Epidemiology is only of value in formulating hypotheses, not in proving anything.

"Dozens of peer reviewed, exhaustive observational studies told doctors that hormone replacement therapy reduced the incidence of heart attacks. "

Then they weren't exhaustive were they? Virtually nothing is proven ever. In fact, nothing is absolute except abstract mathematics. When there are numerous studies showing a correlation then we can feel somewhat confident in it. When we then look at disease rates in societies that do not eat me and see a clear correlation between meat eating and heart disease then we can feel even more confident.

Also remember that in the china study the group that got more disease (and ate more meat) got roughly the same amount of exercise and had roughly the same lifestyle. This isn't absolute proof, but nothing is every absolutely proven. I always find it fascinating that there is such a knee jerk reaction to this issue.

My "knee jerk reaction" is simply that there isn't enough evidence to provide real nutritional guidance. The types of studies that need to be done have not been done.

And the fact is, there are not numerous studies consistently showing a correlation, there are many studies that do not show that those who eat more meat get more disease. For example, Cretan villagers have lower heart-disease rates than even the Japanese and eat diets consisting of 40% fat. The "French Paradox" is so termed because the French eat high quantities of animal fat but have low heart disease. Tokelauan's, who had a diet high in fat (50% fat) and saturated fat (90% of the fat they ate was saturated), were relatively healthy. After migrating they consumed much less fat and had higher heart disease.

In other words, there's a lot about diet we don't understand yet and you can't boost the relevance of epidemiological studies by saying that "virtually nothing is proven ever" and therefore we should just accept observational science, when it's known that epidemiology has significant flaws as anything other than a hypothesis generator.

the cretan diet is low in meat and the fat mainly comes from olive oil. This is an example that supports the correlation with meat and heart disease.

Now onto the french paradox. First, you again are conflating fat with meat. They aren't the same so at this point you seem to be pushing an agenda through bait and switch.

"French people get up to 80% of their fat intake from dairy and vegetable sources ... The principal aspects of this diet include high olive oil consumption".

There is plenty of evidence and there are some outliers. Using outliers to claim that the abundance of evidence doesn't exist is disingenuous. Also, the american diet is terrible for other reasons such as the high consumption of highly processed foods. One can certainly find people that eat a lot of meat, but little processed food, and show that it's a healthier diet compared to one of highly processed foods. This doesn't mean that a diet low in meat and processed food isn't healthier, and in fact we there is a good deal of evidence showing that it is.

| There are zero controlled studies showing this...

There are animal studies that looks pretty compelling to me. The China Study refers to some of these.

Which animal studies prove that eating meat will decrease longevity in humans? Sure, if you feed meat to rabbits, or other vegetarian animals, but there are just as many animals that are essentially incapable of eating not only grains but even vegetables.

They used omnivorous animals. Yes it's not concrete proof that it will translate to humans but if you take all the evidence together - the animal trials, the cellular-level experiments and the observations in humans - it's enough to convince the author of The China Study. And more importantly it convinced me.

> And more importantly it convinced me.

Huh?

And which type of omnivorous animals? And which type of fat?

Saturated fat has little effect on rats, but polyunsaturated fat induces tumors in rats according to to many studies. Low-fat, high calorie diets lead to more tumors than high-fat, low calorie diets in rats (in fact the high-fat, low calorie diets essentially stopped tumor production entirely). This latter was a major study in the journal Cancer Research. Only in high calorie diets was high-fat worse than low-fat, and in low calorie diets, high-fat was better than low-fat.

Atherosclerosis is often observed in pigs, cats, dogs, sheep, cows, horses, reptiles, rats, and baboons when fed exclusively vegetarian diets.

Monkeys in captivity often become fat and diabetic on high-fiber, low-fat, no-cholesterol diets.

It's entirely possible that a no-meat diet is best for humans, but I don't think we're anywhere near the understanding needed to say this -- and his recommendation to avoid fish as well would be viewed as dangerous by much of the medical and scientific community. What we really need are controlled studies, which are entirely possible to do.

You continue to conflate fat and meat and then make points implying that meat consumption is fine.

I don't see how controlled studies are possible for various reasons. For starters there are far to many variables and we have no idea how they interrelate. Second, we can't control humans to the degree that would be needed to truly isolate a single variable (which I don't think would be too useful anyway) and animal studies are always imperfect. I'm convinced that diet studies are most effective when performed at a higher level of abstraction.

| And which type of omnivorous animals? And which type of fat?

Er... Maybe you should read the book first before you go on a tirade against it.

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