Soy Compounds Could Protect Against Breast Cancer Comeback

Compounds from soy and other plant sources could protect against breast cancer recurrence or affect survival, researchers report.

Investigators in Australia, Denmark, England, Norway, and the US reviewed 22 published observational studies that examined the impact of dietary intake of soybeans, lignans, cruciferous/cabbage-family vegetables, and green tea on breast cancer recurrence and mortality, as well as on mortality from all causes.

Soy isoflavones were associated with a 26% reduced risk of breast cancer recurrence, according to a meta-analysis that included six of the studies reviewed by investigators. The results were most notable among post-menopausal survivors.

The greatest risk reduction was seen at 60 milligrams per day, equivalent to two to three servings per day. However, the effect of soy consumption on risk of mortality was smaller (12%) and not statistically significant, and was seen mostly at 20-40 mg per day, or one to two servings.

Another finding relates to enterolactone, a compound metabolized from lignans. High levels are found in flaxseeds, cashew nuts, broccoli, and brussels sprouts, among other sources.