Kelp May Reduce Women's Cancer Risk

The study, published in the Journal of Nutrition (2005, vol. 135, no. 2), found that the anti-estrogenic effects of kelp may reduce estradiol levels, the hormone linked with estrogen-related cancers. Researchers at the University of California, Berkeley administered bladderwrack seaweed (Fucus vesiculosus), the most common form of kelp, to 3 groups of 24 female rats. Two different doses of kelp were administered daily to the rats. A placebo was given to the control rats.

At the end of the study, researchers found that menstrual cycles were lengthened from an average of 4.3 days to 5.4 days and estradiol levels were reduced from 48.9 nanograms per liter to 36.7 nanograms per liter in rats that consumed 175mg of kelp daily. Menstrual cycles were lengthened to 5.9 days in rats that consumed 350mg of kelp daily.

"Kelp extract inhibited the binding of estradiol to estrogen receptor alpha and beta and that of progesterone to the progesterone receptor," write the study authors. "These data show endocrine modulating effects of kelp at relevant doses and suggest that dietary kelp may contribute to the lower incidence of hormone-dependent cancers among the Japanese."