Agricultural researchers report that beef raised on the Northern Plains contains unusually high levels of selenium, an important cancer fighter. But they say it's too early to know whether any significant benefit to humans will result.
Their finding is published in the February Journal of Agricultural and Food Chemistry, a monthly peer-reviewed journal of the American Chemical Society, the world's largest scientific society.
A key objective of the study - conducted by U.S. Department of Agriculture researchers - was to determine whether a direct connection exists between concentrations of selenium in the soil and in beef. Specifically, the USDA scientists wanted to know whether beef from areas with soil high in selenium accumulates high concentrations of the mineral.
It does, they learned, and according to lead researcher John W. Finley, a chemist at USDA's Grand Forks Human Research Center in North Dakota, "In some areas the selenium concentrations were high enough to supply more than one day's selenium requirement in a modest 100 gram serving of beef (approximately the size of a hamburger patty)." In contrast, the average burger contains only about one-third of the daily selenium requirement, Finley said.
Researchers consider the finding important in light of a long-term cancer study completed in 1996. The study, reported in the Journal of the American Medical Association, involved the treatment of 1,312 skin cancer patients over 4.5 years plus a 6.4-year follow-up period. According to Finley, selenium had no effect on skin cancer, but the study "found that 200 micrograms per day of supplemental selenium reduced the incidence of all cancers by more than 50 percent and specifically reduced the incidence of lung, colo-rectal and prostate cancers."
On average, beef is the single largest source of selenium in the North American diet at about 20 percent of the total dietary requirement, Finley said. He added that concentrations vary widely from one geographical area to another.
But the researchers warned that confirmation of specific health benefits from selenium-rich beef will depend on further experimentation and require complete and accurate determination of the precise chemical forms of selenium in beef, since not every form of the mineral affects humans in the same way.
"If nutritional experiments that we are currently conducting show the selenium in beef to have similar biological properties to other forms of selenium, then beef produced in these (high selenium) areas could conceivably be marketed as a specialty product, thus enhancing value for consumers and profitability to producers," Finley said.
While red meat has been widely implicated as a risk factor for certain cancers, including cancer of the prostate and others, researchers believe these risks could be ameliorated somewhat by the substitution of high selenium beef for low selenium beef, Finley suggested.
Furthermore, the mineral may have other benefits. Finley noted studies indicating selenium is a mood-enhancer in which "people were more elated/less depressed, more composed/less anxious and more confident/less unsure."
"Selenium is also a powerful antioxidant," he said. "But perhaps the most important function of (selenium) is to be found in work showing it enhances the immune system. A non-virulent virus will mutate into a virulent form in a selenium-deficient host. And selenium is today being investigated as a potentially important component in combating the AIDS virus."
Funding for the above study was provided by the USDA and the North Dakota Beef Commission.
John W. Finley, Ph.D., is a research chemist at the Agricultural Research Service, U.S. Department of Agriculture, Grand Forks Human Nutrition Research Center, in Grand Forks, N.D. He is also an adjunct professor in the animal and range sciences department at North Dakota State University in Fargo.
Materials provided by American Chemical Society. Note: Content may be edited for style and length.
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