Study: Flaxseed May Protect Postmenopausal Women Against Breast Cancer

The dietary supplement flaxseed may protect postmenopausal women against breast cancer, according to researchers at the University of Minnesota, St. Paul.

Blood levels of certain estrogens associated with an increased risk for developing breast cancer "decreased significantly with flax," said Dr. Joanne Slavin, lead author of the study.

Previous research has shown that flaxseed may reduce chemical markers linked with an increased risk of breast cancer. The new research is the first to show that flax may be protective against the disease in humans, according to the study presented at the national meeting of the American Chemical Society.

Researchers studied 28 postmenopausal nuns who were chosen because of their strict dietary practices. The nuns were given daily dietary supplements of either zero, 5 or 10 grams of ground flaxseed for seven-week cycles over one year.

The study showed that consuming 5 or 10 grams of flax might significantly decrease blood levels of certain types of estrogen that are characteristic in postmenopausal women and are possibly linked to the development of breast cancer.

Researchers are not clear on what the exact mechanism of flax is but speculate that because flax is the most concentrated food source of lignan, a plant hormone structurally similar to estrogen, it may lower estrogen in humans by inhibiting enzymes that are involved in estrogen synthesis.

Researchers caution that more long-term studies are needed before they recommend flaxseed to women in general but Slavin reports that many women are starting to use flax as an alternative to soy because of its high levels of phytoestrogens.

Other Sources: American Chemical Society