In 1982, the US National Academy of Sciences released a report entitled “Diet, Nutrition, and Cancer.” This was the first major institutional, science-based report on this topic. This report discusses what levels of scientific certainty should be present before a recommendation is made in the interest of public health. An example given was that at the time of this paper being published, it was absolutely clear that cigarettes were killing people. However, twenty years before that, how many lives would have been saved if the population had been persuaded to stop smoking when the association between smoking and cancer was first made? In other words, how many deaths are worth absolute certainty? The question being asked here is what is called the “Precautionary Principle” meaning there should be a social responsibility to protect the public from exposure to harm because science has found a plausible risk. Only if further scientific findings provide more sound evidence against that risk should the position be reversed.
The report moved on to say the following, “The public is now asking about the causes of cancers that are not associated with smoking. What are these causes, and how can cancers be avoided. Unfortunately, it is not yet possible to make firm scientific pronouncements about the association between diet and cancer. We are in the interim stage of knowledge similar to that for cigarettes 20 years ago. Therefore, in the judgement of the committee, it is now time to offer some interim guidelines on diet and cancer.”
This report seemed to be prophetic in many ways. For example, the report specifically named processed meats as being concerning: “In recent years a number of observations have also led to concern about potential risks to human health resulting from the use of nitrate and nitrite as preservatives in meats and other cured products.” Sound familiar? 30 years after the report, processed meat was classified as a Group 1 carcinogen by the World Health Organization.
How was this report’s recommendation to reduce meat consumption and increase intake of fruits and vegetables received? There were petitions to get the authors expelled from the NAS and have their credentials revoked. One criticism said the following: “The fruit and vegetable industries would clearly benefit from the expanded demand for their products if consumers were to implement the guidelines. However, fruits and vegetables account for less than 15 percent of cash receipts for US agriculture. In contrast, cattle, hogs, poultry products, feed grains, and oil crops account for over 50 percent of cash receipts. Thus, the expanded sales of fruits and vegetables would not overcome the income losses to other segments of US agriculture.”
In 2014, PCRM along with several other university nutrition and medical science departments wrote a paper entitled “Applying the Precautionary Principle to Nutrition and Cancer.” This paper uses the precautionary principle previously discussed and applies it to what science has learned since this 1982 paper to expand recommendations of dietary interventions to prevent or reverse cancer. These recommendations are as follows:
Limit or avoid dairy products to reduce risk of prostate cancer
Limit or avoid alcohol to reduce risk of mouth, throat, colon, rectum, and breast cancers
Avoid red and processed meat to reduce risks of colon and rectum cancers
Avoid grilled, fried, and broiled meats to reduce risk of colon, rectum, breast, prostate, kidney, and pancreas cancers
Consume soy products during adolescence to reduce the risk of breast cancer in adulthood and to reduce the risk of recurrence and mortality of women already treated for breast cancer
Emphasizing fruits and vegetables to reduce risk of several common forms of cancer
Sources:
https://www.ncbi.nlm.nih.gov/pubmed/25032415
https://www.ncbi.nlm.nih.gov/pubmed/24870117
https://nutritionfacts.org/video/the-best-advice-on-diet-and-cancer/