Selenium-Enriched Broccoli and Cancer Prevention
A little-noticed study published by a team of U.S. Department of Agriculture (USDA) scientists suggests that selenium-enriched broccoli may have a preventive effect against breast cancer. Previous research has shown that selenium may also have benefits against prostate and certain other cancers.
Selenium is a trace element that is naturally present in grains and vegetables grown in selenium-rich soil, as well as in other foods, especially fish.
Writing in the Journal of Agricultural and Food Chemistry, Dr. John Finley of the USDA's Nutrition Research Center and colleagues reported on their study involving laboratory rats injected with a cancer-causing chemical. The animals were then divided into two groups that were fed either low-selenium broccoli or high-selenium broccoli as part of their regular diet for 22 weeks. A third comparison group was fed selenium supplements without the broccoli.
They found that the rats fed high-selenium broccoli had a significantly lower incidence of breast tumors and fewer tumors overall than the rats in either the low-selenium broccoli or selenium-alone groups.
However, the researchers cautioned against people becoming overzealous with selenium consumption. Sometimes more is not better. Large amounts may become toxic, they warned, resulting in nausea, vomiting, hair and tooth loss, and nail damage.
Selenium and Vitamin E - the SELECT Trial
A major clinical trial was recently launched to determine if selenium and another dietary supplement, vitamin E, can help protect against prostate cancer. The Selenium and Vitamin E Cancer Prevention Trial (SELECT Trial) began enrolling prostate cancer patients in July 2001. It will eventually enroll more than 32,000 men at 400 study sites in the United States, Puerto Rico and Canada.
Selenium was included in the SELECT Trial based on the findings of an earlier decade-long study of patients with skin cancer. During that trial, the researchers noticed that selenium seemed to have a preventive effect on a number of cancers, including those of the prostate, lung and colorectum. (Unfortunately, selenium did not affect the incidence of skin cancer, as was originally hoped.)
SOURCE:
Journal of Agricultural and Food Chemistry, 2001; 49:2679-2683