Soy, tea, and cancer benefits

From San Diego, at the Experimental Biology 2000 meeting

Soy-rich diets appear to help fight certain cancers. Tea drinking has been linked to similar benefits. Two studies now find that the combo offers a potent double whammy against cancer of the breast and prostate—at least in mice.

Jin-Rong Zhou and his colleagues at Harvard Medical School in Boston injected a million breast cancer or prostate cancer cells into mice engineered to possess weak immune systems.

Two weeks earlier, they had replaced the drinking water of some animals with green or black tea. Others received chow laced with isoflavones, soy’s biologically active antioxidants. Two groups of mice got both the mix of isoflavones and one or the other tea. Some just ate their normal diet.

Two months after implantation of the cancer cells, the researchers surveyed for tumors and found that all the experimental diets had conferred some benefit. Compared with animals on the normal diet, mice given isoflavones or tea had 25 to 50 percent fewer tumors, and their tumors weighed 15 to 25 percent less. However, benefits from pairing tea and isoflavones equaled or exceeded the sum of either alone—a reduction of between 72 and 87.5 percent in tumor number and a similarly large decrease in each tumor’s size.