Meat, Cooking

Risk Factors

A number of hypotheses have tried to explain the relationship between meat consumption and cancer risk. Meat is devoid of fiber and other nutrients that have a protective effect, and the process of cooking and the content of the meat itself can cause damage. Steady dietary consumption of meat influences carcinogenesis by two methods: (1) the cooking of meat, which induces the production of heterocyclic amines and polycyclic aromatic hydrocarbons, which are potent carcinogenic compounds; and (2) the induction of excessive steroidal hormones, which affect tissues and organs (such as the breast and prostate gland) that are sensitive to these hormones. The presence of carcinogenic compounds and excessive steroidal hormones that induce abnormal cellular growth is a major factor in carcinogenesis.

A report published by the World Health Organization has determined that at least 30 percent of all cancers in the Western Hemisphere are due to dietary factors. The key fact that consistently emerges from studies of cancer is that a diet based on vegetables and fruits helps reduce risk, whereas a diet that derives most nutrients from animal products is frequently found to increase risk.

In large studies conducted in Western Europe, individuals who consume meat regularly are 40 percent more likely than vegetarians to develop cancer.

The Physicians' Health Study, which followed close to 15,000 male physicians in the United States, showed a positive association between prostate-can-cer incidence and meat consumption in individuals who consumed red meat at least five times a week. In these individuals, the relative risk of developing prostate cancer was close to three times higher than in those who rarely ate meat.

In another study conducted in the late 1980s that followed more than 52,000 male health professionals, the data demonstrated a statistically strong positive correlation between red-meat consumption and cancer. In the study, those individuals with advanced stages of prostate cancer were found to have high intakes of red meat. Individuals who ate red meat more than five times a week also had four times the risk of developing colon cancer than those who consumed red meat less than once a month.

For women, a comparable study—the Nurses' Health Study, which followed 122,000 married registered nurses from 30 to 55 years old in the 11 most populous states—showed that those who ate the largest amount of fat derived from animal products were twice as likely to develop colon cancer as nurses who consumed the least.

Why is the consumption of red meat risky? The fat contained in the meat and the carcinogens formed during the cooking process play major roles. Another factor may be the exclusion of vegetables, fibers, and grains from a diet dominated by meat.

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