Cancer Risk and Vegetarian Diets

Various aspects of vegetarian diets might affect the risk for several types of cancer. Direct evidence for this comes from a few prospective epidemiological studies. The total amount of data available is relatively small and has not shown convincing differences in cancer risk between vegetarians and nonvegetarians. For cancers of the gastrointestinal tract the data are inconsistent, but some studies have shown a lower risk for stomach cancer and colorectal cancer in vegetarians. The data do not suggest any substantial differences in risk for breast cancer or prostate cancer between lactovegetarians and nonvegetarians. One study has shown that vegetarians may have a lower risk for cancers of the lymphatic and hematopoietic tissue than nonvegetarians. Few data are available for vegans, but these suggest that they might have a reduced risk for prostate cancer and perhaps of all cancers combined. For most types of cancer, there is little evidence, and much more research is needed.