At the time the ATBC Study began, the fat content of the Finnish diet was about 38 percent of total calories. However, the national average fat intake has decreased to about 34 percent of calories from fat, equal to the current U.S. average. The Finns also eat a lot of whole-grain products, like dark rye breads, which gives them a higher fiber intake, and they eat more dairy products. Vitamin E and beta-carotene were chosen because epidemiologic studies have linked high dietary intake and high serum levels of these micronutrients to a reduced risk of cancer, particularly lung cancer. The mechanisms by which vitamin E may reduce prostate cancer risk are not clear.
Vitamin E is an antioxidant.
The men in the study took one pill each day, which contained vitamin E, beta-carotene, both, or neither. Vitamin E is found mainly in oils, such as vegetable oils, and in nuts and grains. The amount in the U.S. diet varies, but is estimated to be about 17 mg per day. NCI has never recommended that Americans take supplements. The results of the ATBC Study, while promising, do not answer whether vitamin E supplements would be able to reduce the risk of prostate cancer in men of varying race and ethnicity and in nonsmokers.