The Benefits of Brassicas
Edible plants in the Brassica family (also know as cruciferous vegetables), are grown all over the world – a partial list includes: broccoli, kale, collards, cauliflower, cabbage, napa cabbage, Brussels sprouts, mustards, bok choy, arugula, turnip, radish, daikon, cress, kohlrabi, horseradish, wasabi. These vegetables contain multiple nutrients with anti-cancer properties. In 1992, Drs. Paul Talalay and Jed Fahey of the Johns Hopkins University School of Medicine founded the Brassica Chemoprotection Laboratory, in order to test and cultivate plants that would have the highest levels of protective enzymes.
They isolated a phytochemical in broccoli called SGS, ‘sulforaphane glucosinolate’, an enzyme that helps neutralize cancer-causing chemicals, as well as free radicals, before they can damage DNA and initiate the development of cancer. They found that SGS blocked the formation of mammary tumors in rats treated with a potent carcinogen: The number of rats that developed tumors was reduced by as much as 60%, the number of tumors in each animal was reduced by 80%, and the size of the tumors that did develop was reduced by 75%. Scientists at the American Health Foundation discovered that SGS inhibited the formation of premalignant lesions in the colons of rats. Researchers in Toulouse, France found that SGS induced cell death in human colon carcinoma cells. This study suggests that in addition to the activation of detoxifying enzymes, induction of apoptosis [cell death] is also involved in the sulforaphane-associated prevention of cancer. These results have not yet been validated in humans.
Dr. Talalay and his team have examined a wide range of broccoli plants to determine which had the highest levels of sulforaphane. Varieties of broccoli were found to differ significantly in the amounts of SGS they contained and, as the plant grows older, the concentration of SGS decreased. Conversely, young plants (three-day-old sprouts) yielded much more concentrated enzyme-induced activity. Findings from this research demonstrated that certain varieties of three-day-old broccoli sprouts contain between 20 and 50 times the concentration of SGS as the mature, cooked vegetable. They are now producing and selling their own variety of broccoli sprouts (broccosprouts.com), and Brassica teas (BrassicaTea.com). You can often find broccoli sprouts in markets and you can buy organic broccoli seed for sprouting at home: http://www.healthyeating.com 800-695-2241. Here’s a good site for learning to sprout: http://www.themindfuleater.com/archives/2007/03/making_sprouts.html
Indole-3-carbinol - another compound in Brassica vegetables has also been found to decrease susceptibility to cancer in laboratory animals. It alters estrogen metabolism in a favorable way, and its metabolite 3'Diindolylmethane is a strong androgen receptor antagonist in human prostate cancer cells. Researchers at the University of California and elsewhere warn that it is too early to start using indole-3-carbinol as a supplement for cancer prevention.
However, it’s always a good time to eat more Brassica vegetables. Grow some of your own. Even if you don’t garden, you can grow radishes in deep pots, or make your own sprouts.
Sadja Greenwood, MD, MPH –back issues on this blog. Leave me a message!
no columns on 8/24/09 or 8/31/09.