For years the scientific community has debated the link between diet and cancer. Now the argument of a causal relationship is getting a second airing—with convincing results.

At the American Association for Cancer Research’s Frontiers in Cancer Prevention Research Meeting, held in Boston in November, the presentation of three studies illustrated a positive correlation between cancer prevention or severity and the consumption of soy, fish and vitamin E.

In the one study, soy consumption among Asian American girls was investigated as a preventive measure against future breast cancer. Past studies looking at cancer risk and soy consumption among adult women have had mixed results. But when researchers followed the diets of girls starting from ages 5 through 11 through adulthood, they saw that the highest consumption of soy reduced risk of developing the disease later on by 58 percent.

Another study looked at fish consumption and colon cancer, and found that men who ate fish five times a week or more had a 40 percent lower risk of developing the disease. Among men who ate fish twice a week, cancer risk was reduced by 20 percent, and among those who ate it less than twice a week, the risk was 13 percent lower.

Researchers say they believe the reduced risk may be due to the presence of fatty acids in fish that can inhibit an enzyme believed to be associated with cancer development.

A third study looked at the relationship between smoking and consumption of the antioxidant vitamin E. Male smokers who consumed vitamin E in the forms of vegetable oils, nuts, fish, whole grains and green leafy vegetables, had lower levels of oxidative-DNA damage in their white blood cells. Such damage can increase the risk of developing cancer.