Good nutrition, including regular intake of the vitamin folate, reduces one's risk of colon cancer. According to a 16-year study of nearly 90,000 women, the vitamin's protective effect is greatest among women whose families have been affected by the disease.
Between 1980 and 1996, Charles S. Fuchs and his colleagues at Harvard Medical School in Boston questioned thousands of nurses about their dietary habits and whether family members had suffered colon or rectal cancer. The team also identified which nurses developed colon cancer during the study.
Among study volunteers with no family history of colorectal cancer, women who consumed 400 or more micrograms of folate per day in food didn't show significantly lower rates of colon cancer than those who consumed less than 200 micrograms/day. In women with a family history of the cancer, however, higher folate consumption cut risk in half.