A Randomized, Controlled Trial on Dried Cruciferous Vegetables for Estrogen Metabolism in Healthy Premenopausal Women

Investigators: Nicole A. Vasilevsky,Heather Schiffke, Patricia Elmer, Sandra L. Szabat, William L. Gregory, Jill R. H. Edwards, Doug Hanes, Heather Zwickey


Background:Consumption of cruciferous vegetables has been linked to many health benefits, including regulation of estrogen metabolism. Previous studies have suggested that ingestion of cruciferous vegetables can increase the ratio of 2:16 hydroestronein premenopausal women, and consumption of cruciferous vegetables is believed to decrease cancer risk.

Objectives:The purpose of this study was to evaluate the effects of a cruciferous vegetable supplement on estrogen metabolism in healthy pre-menopausal women. We hypothesized that consumption of a dehydrated cruciferous vegetable supplement will up-regulate the 2-hydroxylation pathway of estrogen at the expense of the 16-hydroxylation pathway, thus leading to measurable increases in serum levels of 2OHE1 and the 2OHE1:16aOHE1 ratio.

Methods: A randomized, placebo controlled pilot study was conducted in 20 healthy, premenopausal females. Participants took either a 1800-2700 mg dose of dehydrated kale and Brussels sprouts, or a placebo for 60 days. The primary outcome was the ratio of 2OHE1 to 16aOHE1, and the absolute values of 2 OHE1 and 16aOHE1 in serum.

Results:Data from this study did not show any differences in the 2 OHE1:16aOHE1 ratio in pre-menopausal women after treatment with the cruciferous vegetable supplement compared to the placebo control.


While the physiological measures of this study did not show significant effects after ingestion of the cruciferous vegetable supplement, future studies should be conducted at higher doses and/or at a longer duration to further evaluate the effects of cruciferous vegetable supplement on regulating estrogen metabolism. While food sources may have ingredients that have the same mechanism of action as drugs, because they are not administered at pharmacological doses, they are often not as effective. In order to protect the safety of people using phytomedicines, it is as important to publish the negative trials as the positive ones.