Eating Soy Foods Linked to Supporting Breast Health in Adult and Adolescent Women

Soy food is a good source of isoflavones—a class of phytoestrogens that has both antiestrogenic and anticarcinogenic properties.

In the current study, researchers evaluated the association of adolescent and adult soy food intake with breast cancer risk. The participants were 73,223 Chinese women who participated in the Shanghai Women’s Health Study.

Adult soy food consumption, measured either by soy protein or isoflavone intake, was associated with a significantly reduced risk of premenopausal breast cancer. Compared to the group with the lowest soy intake, adults with the highest soy protein intake were 59% less likely develop breast cancer. Higher soy isoflavone intake resulted in a 56% reduction in breast cancer risk. High intake of soy foods during adolescence was associated with a 43% reduction in risk of premenopausal breast cancer. Overall, women who regularly consumed a high amount of soy foods during adolescence and adulthood had a substantially reduced risk of breast cancer.

The current study involving a large population of women provides strong evidence of a protective effect of soy foods against premenopausal breast cancer.

Am J Clin Nutr 89: 1920-1926, 2009