A report published in the April 15, 2007 issue of the International Journal of Cancer described the finding of a study funded by the National Cancer Institute that a greater intake of calories, attributable to a higher proportion of animal-sourced protein and fat, is associated with an increased risk of endometrial (uterine) cancer, and plant sources of these nutrients as well as vitamins A, C and E, beta-carotene, fiber and vitamin supplements are associated with a decreased risk.

Researchers in China and at Vanderbilt University in Nashville, Tennessee compared 1,454 Chinese women with newly diagnosed endometrial cancer to 1,212 age-matched women without the disease. Questionnaires completed by the participants provided demographic information, health history and data on macronutrient (protein, fat, carbohydrate, fiber) and micronutrient (vitamin) intake, including the use of vitamin supplements.

Greater consumption of calories, calories from animal food, increased animal protein, and greater animal fat intake were associated with an increased risk of endometrial cancer. Women whose dietary percentage of animal derived food was in the top one-fifth of participants had a 90 percent greater risk of endometrial cancer than those whose percentage was in the lowest fifth. Among women whose percentage of animal protein was highest, the risk was double that of those in the lowest group, and for those whose animal fat was highest, the risk was 50 percent greater. In contrast, women whose percentage of calories from plants was in the top fifth had half the risk of endometrial cancer compared to those in the lowest fifth. Plant sourced protein and fat were also protective, as were fiber, vitamin A, beta-carotene, vitamin C, and vitamin E.

When participants who reported having used vitamin supplements were compared with those who had never used them, their risk of endometrial cancer was found to be 30 percent lower. A similar effect was observed for the use of single vitamin C and vitamin E supplements. Supplementation with B vitamins was associated with a 70 percent reduction in endometrial cancer risk, even though intake of vitamins B1 and B2 from diet had not been found to be related to risk of the disease. Increased duration of any supplement use appeared to further decrease risk.

The authors remark that the associations of dietary macronutrients with endometrial cancer risk may depend on their sources. Micronutrients such as those found to be protective in this study may inhibit tumor development by their antioxidative effects. The authors note that “Inverse associations of vitamin supplement use with cancer risk in our study provide additional evidence on the possible beneficial role of vitamins in the development of the disease.”

Source: Life extension