The Best Advice on Diet and Cancer

kelsey byers diet

The Best Advice on Diet and Cancer

What the best available balance of evidence says right now about what to eat and avoid to reduce your risk of cancer.


Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

In 1982, a “landmark report on diet, nutrition, and cancer” was released by the National Academy of Sciences, “the first major, institutional, science-based report on this topic.” The report started out saying that yes, scientists must be careful in their choice of words, whenever they are not totally confident about their conclusions. But, for example, by that time, it had become “absolutely clear” that cigarettes were killing people. But, “[if] the population had been persuaded to stop smoking when the association with lung cancer was first reported, these cancer deaths would now not be occurring.” If you wait for absolute certainty, millions of people could die in the meantime. That’s why, sometimes, you have to invoke the “precautionary principle.”

For example, emphasizing that “fruits and vegetables [may] reduce the risk of several common forms of cancer.” We’re not completely sure, but there’s good evidence, and what’s the downside of eating more fruits and vegetables? So, why not give it a try?

The 1982 National Academy of Sciences report continued: “The public is now asking about the causes of cancers that are not associated with smoking. What are these causes, and how can these cancers be avoided? Unfortunately, it is not yet possible to make firm scientific pronouncements about the association between diet and cancer. We are in an interim stage of knowledge similar to that for cigarettes 20 years ago. Therefore, in the judgment of the committee, it is now the time to offer some interim guidelines on diet and cancer.”

For example, they raised concern about processed meats. And, 30 years later, it was confirmed: processed meat was officially declared “carcinogenic to humans.” Maybe if we would have listened back then, maybe we would have been spared Lunchables, which, if taken apart, a CEO of Philip Morris describes reading, “the most healthy item in it is the napkin.”

“The findings of this [diet and cancer] report generated a striking level of disbelief from the cancer community and outright hostility from people and the industries whose livelihood depended on the foods…being questioned,” to the point of accusing one of the authors of the report of “killing people,” with formally organized petitions “to expel [the researchers] from their professional societies…clearly, a very sensitive nerve was touched.”

The American Meat Science Association and other members of the Council for Agricultural Science and Technology criticized the report. Yeah, maybe it would save lives, but the recommended “reductions in meat consumption would sharply reduce incomes to the livestock and meat processing industries.” “The fruit and vegetable industries would clearly benefit…if consumers were to implement the guidelines. However, fruits and vegetables account for less than 15 percent of cash receipts.” Most of the money is in “cattle, hogs, poultry products, feed grains, and oil crops.” That reminds me of the tobacco industry memos where Philip Morris spoke of the tobacco industry going “bankrupt.”

“Maybe it’s not the meat that’s causing cancer,” the industry critique continued, but all the “marihuana” people are smoking these days. “How…can one argue that such an abundant diet causes cancer?” Maybe you’re all just jealous of all the good food we’re eating, like the Puritans that “condemned bear baiting, not because of the pain for the bear but because of the pleasure of the spectators.” You can’t tell us to cut down on meat; “one of mankind’s few remaining pleasures is that of the table.”

The day the National Academy of Sciences report was published was “The Day That Food Was Declared a Poison,” declared Thomas Jukes, the guy who discovered you could speed up the growth of chickens by feeding them antibiotics. How dare the National Academy of Sciences recommend people eat fruits, vegetables, and whole grains daily, which were said to contain “as yet unidentified compounds that may protect us against certain cancers”? “How can one select foods that contain unidentified compounds? This is not a scientific recommendation; it sounds like ‘health food store’ literature.”

My favorite, though, was to think about the human breast. How can animal fat be bad for us if breastfeeding women create so much of it? Women are animals; their mammary glands make fat for breast milk. Therefore, we shouldn’t have to cut down on burgers. Huh?

So, anyway, what did the latest science tell us about nutrition and cancer? What were the other five recommendations? We talked about eating more fruits and vegetables. Consumption of soy products may not only reduce the risk of getting breast cancer, but also increase chances of surviving it. Then, in terms of dietary-guidance-suggestions-on-foods-to cut-down-on, where evidence is sufficiently compelling, recommendations included “limiting or avoiding dairy products to reduce the risk of prostate cancer; limiting or avoiding alcohol to reduce the risk of cancers of the mouth, [throat], esophagus, colon, rectum, and breast; avoiding red and processed meat to reduce the risk of cancers of the colon and rectum; and avoiding grilled, fried, and broiled meats to reduce the risk of cancers of the colon, rectum, breast, prostate, kidney, and pancreas.” In this context, they’re talking about all meat, including poultry and fish.

Look, we all have to make dietary decisions every day. We “cannot wait for the evolution of scientific consensus.” Until we know more, “to protect [ourselves and our families, all we can do is act on] the best available evidence [we have right now].”

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