Healthnotes Newswire (June 21, 2001)—Postmenopausal women consuming 1 to 2 servings (1 to 2 cups) of brassica vegetables (e.g., broccoli, Brussels sprouts, cauliflower, and cabbage) per day were found to have a 20 to 40% decrease in the risk of breast cancer, according to a research letter published in this week’s Journal of the American Medical Association (JAMA).¹

The study, carried out by the Karolinska Institute in Stockholm, Sweden, compared the diets of 2,832 women aged 50 to 74 years diagnosed with invasive breast cancer with 2,650 women of the same age with no history of breast cancer. While there was no relation between total fruit and vegetable consumption and breast cancer risk, women consuming an average of 1 1/2 servings of brassica vegetables daily had a 25% decreased risk of breast cancer.

Brassica vegetables are high in the compound indole-3-carbinol (I3C). In preliminary research, I3C has been reported to affect the metabolism of estrogen in a way that might protect against breast cancer,² an idea supported by animal³ and test tube research.⁴ No research trials have yet investigated the effects of I3C supplementation in women with breast cancer.

In a recent analysis of studies, no association was found between fruit and vegetable consumption and risk of breast cancer.⁵ In a reply to the new study report in JAMA, the authors of this analysis reported finding no association between brassica vegetable consumption and decreased risk of breast cancer.⁶ However, they admit to not being able to “exclude the possibility that very high intakes of brassica vegetables are associated with a modest reduction in breast cancer risk.”

Further research is required to determine the role that brassica vegetables may play in reducing the risk of breast cancer in postmenopausal women.