Plant Lignans Reduce Risk of Breast Cancer in Postmenopausal Women
Postmenopausal women whose diet is high in lignans—estrogen-like compounds found in plants—may have a reduced risk of invasive breast cancer, according to a new study by French researchers.
The study included 58,049 postmenopausal women. (Those taking soy isoflavone supplements were excluded from the study, since soy also has estrogen-like properties.) The women’s diets were recorded, and then the women were followed for 7-8 years. During that time, some 1,469 cases of breast cancer were diagnosed. Women with the highest total plant lignan intake (about 1.4 mg or more per day) showed a 28 % reduced risk for estrogen and progesterone-positive breast cancer, compared to women in the lowest intake group.
Lignans are in a group of plant compounds called phytoestrogens. The most common dietary sources of lignans are unrefined grains, seeds such as sesame and flaxseed, and berries, fruits and vegetables. In our intestines, bacteria convert plant lignans into compounds that act like weak estrogen in the body. When natural estrogen is abundant, lignans appear to reduce the activity of natural estrogen hormones by occupying the same cellular estrogen-binding sites. As a result, they tend to help reduce the incidence of hormone-influenced cancers, such as breast, prostate and colon cancer. (Touillard, MS et al. J Natl Cancer Inst, 2007; 99(6):475-86.)
Flaxseed is a great source of lignans, with a two-tablespoon serving offering 100-300 mg of lignans.
