Vegetarianism is regarded by many as one of the best ‘eat healthy’ strategies. Epidemiological studies have shown that consuming a vegetarian diet is associated with lower levels of low density lipoprotein cholesterol and a smaller incidence of overweight, hypertension and type 2 diabetes mellitus compared to consuming a diet with meat . Some studies have reported on better longevity in vegetarians as well . Since dietary habits are often mentioned in regard to cancer risk, it became necessary to investigate large populations that consume specific foods. Vegetarians are, of course, a very good model for people with a well-defined nutrition characterized by a higher content of fiber, folic acid, vitamins C and E, many phytochemicals and a fat content that is more unsaturated.
Key and colleagues have examined cancer incidence in a prospective study of 63,550 men and women in the UK and compared vegetarians to meat- and fish-eaters . Participants, who were 20–89 years old, were recruited in the 1990s and followed until the end of 2005. When five types of malignant neoplasms were combined (lung, colorectal, breast, ovary, prostate), and meat-eaters considered as the reference point, fish-eaters had a 17% reduced risk (95% confidence interval (CI) 0.71–0.96) and vegetarians had an 11% reduced risk (95% CI 0.80–1.00) for cancer. However, the incidence of colorectal cancer was higher among vegetarians than in the meat-eaters. Interestingly, the number of cancer patients in this study was much lower than expected according to national rates. Among women, there were 27,652 non-vegetarians and 12,824 vegetarians. The relative risk for breast cancer was similar for all groups (fish-eaters 1.02, vegetarians 0.94) and was insignificantly lower for ovarian cancer (fish-eaters 0.43, 95% CI 0.18–1.01; vegetarians 0.73, 95% CI 0.42–1.28). Key and colleagues also published a pooled analysis from two prospective studies (including the above study) reporting on 20 cancer sites . It was noteworthy that the risk for endometrial cancer was found to be insignificantly lower, and the risk for cervical cancer was insignificantly higher when fish-eaters and vegetarians were compared with meat-eaters.
Department of Medicine T, Ichilov Hospital, Tel-Aviv, Israel
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