A hundred years ago, The New York Times reported on a rather sophisticated study for the time: 4,600 cases of cancer studied over seven years, suggesting that the increased consumption of animal foods was to blame. A century later, the latest review on the subject concluded that mortality from all causes put together, ischemic heart disease, and circulatory and cerebrovascular disease (such as stroke) was significantly lower in those eating meat-free diets, in addition to less cancer and diabetes.
I’m surprised they found such significant results given that people in these studies typically didn’t stop eating meat until late in life. For example, in the largest study done up until that time, up to a third ate vegetarian for less than five years, yet they still ended up with lower rates of heart disease whether they were young or old—under 60, or over 60. Whether they were normal weight or overweight, whether they used to smoke or never smoked, regardless–those who had stopped eating meat had lower risk, suggesting that decades of higher risk dietary behavior could be reversed within just years of eating healthier.
If you look at countries that switched from eating traditional, more plant-based diets to more Westernized diets, it may take 20 years for cancer rates to shoot up. It takes decades for most tumors to grow. For example, if you look in Asia, their dietary shift was accompanied by a remarkable increase in mortality rates of breast, colon, and prostate cancers. For example death from breast cancer in Japan or from prostate cancer: the line just goes straight up, but again, it can take years of a cancer-promoting diet and lifestyle. Same thing shown with migration studies. Men moving from rural China to the U.S. experience a dramatic increase in cancer risk, but tumors take time to grow.
So it’s remarkable to me that after most of a lifetime eating the standard Western diet, one can turn it around, reverse chronic disease risk with a healthier diet, even late in the game.
So, should we all start eating vegetarian? This was the editorial that accompanied the results from the largest study ever published on Americans eating plant-based diets, which found vegetarian diets associated with lower all-cause mortality, meaning those who started eating vegetarian live, on average, longer lives. Now this analysis included so-called semi-vegetarians, who ate meat at least once a month (but no more than once a week), so it’s not yet clear how bad eating meat a few times a month is for our longevity. What we can all agree on, though, is that we should limit our intake of junk food and animal fat, and eat more fruits and vegetables. Most authorities will also agree that diets should include whole grains, beans, and nuts. Instead of fighting over whose diet’s the best, it’s time to acknowledge these common features of diets associated with less disease, and instead focus our attention on helping patients avoid the intense commercial pressures to eat otherwise.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
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