Anna S. Keck, PhD
Cancer is a leading cause of premature death. Our diet plays an important role in determining the risk of cancer. The American Cancer Society estimates that 1/3 of all of the cancer deaths in the U.S. can be attributed to a poor diet.
In 1996, Larry Clark (formerly at Arizona Cancer Center), Gerald Combs (currently the Center Director at the Grand Forks Human Nutrition Research Center) and coworkers conducted a prolonged study of the effectiveness of selenium supplementation against developing cancer. The study was conducted in the Southeastern U.S.. and included 1312 people with a previous history of skin cancer. For ten years people were given a daily placebo, or 200 micrograms of selenium (this is almost four times the recommended amount of 55 micrograms per day). The selenium was in the form of yeast that had been grown to be high in selenium. People who consumed the selenium supplement had an almost 50% decrease in incidence and death from all cancers. In addition, the scientists found an even greater decrease in the incidence of prostate cancer and colon cancer. They also found an equal decrease in lung cancer, which is the leading cause of cancer death in the U.S. While this study provides the strongest evidence of the ability of selenium to protect against cancer, there are several other human studies and many animal studies that also show a protective benefit of selenium.
At the Grand Forks Human Nutrition Research Center, we are interested in determining whether the selenium in commonly eaten foods such as beef, wheat and broccoli can also provide the same health benefits as the high selenium yeast supplement used in the study. This could be especially important to the state of North Dakota because many areas of North Dakota have soils with high concentrations of selenium and crops grown on these soils become enriched in selenium. For example wheat and beef grown in parts of North and South Dakota contain selenium concentrations that are from 10 to 100 times the U.S. average. Such high selenium crops could help protect against cancer as well as be sold as a specialty crop or help market Dakota wheat and beef. But what we need is well conducted research that provides proof that these Dakota foods actually have the healthful properties that we claim. Consequently, we have designed several human studies that will test these foods in people living in the Grand Forks area.
For these studies, we will use natural levels of selenium present in the soil to produce selenium-enriched broccoli, wheat and beef. Enhancing the selenium concentration of commonly eaten foods will allow the majority of people to increase their intake of selenium without taking supplemental pills or tablets. Although there may be benefits from consuming supplements, the American Dietetic Association recommends that, whenever possible, we should get our nutrients from natural foods and not from supplements.