Jan. 28, 2000 (Baltimore) -- The type of copper found most often in vitamins and supplements, called cupric oxide, is not a type the body can absorb easily, according to a report published in the December issue of the Journal of Nutrition. "Studies on animals have shown conclusively that cupric oxide is totally worthless," says David H. Baker, PhD, the paper's author. "Yet my survey of all the products on the market reveals that the majority of them are still using [it] to provide copper."
Baker, a professor of comparative nutrition at the University of Illinois at Urbana, is concerned that some people taking copper in this form, along with higher doses of vitamin C or zinc, could actually develop copper deficiency. Vitamin C and zinc are known to inhibit the body's ability to absorb and use copper -- even the copper naturally present in food.
According to Baker, copper has a role in many bodily processes, including blood pressure control, cholesterol and glucose metabolism, and enzyme function. Low copper levels have been implicated in heart disease and osteoporosis.
Baker has conducted numerous studies himself and has looked at the scientific literature on the role of copper in human health. "Copper is simply too important to human health to continue to use cupric oxide in supplements, on which many people depend," he concludes.
"Inadequate copper levels are quite possible in teen-agers and those on diets, as well as vegetarians, since the best sources of dietary copper are of animal origin, and the copper found in plant materials is not very available. These people may think they are getting adequate copper in supplements, but that's not usually true."
Baker suggests that manufacturers may use the inadequate form of copper because it occupies less space in a supplement tablet. Other sources of copper that provide the body with the mineral in a form that it can use are available. "The resulting pill may be larger, but at least it will furnish (copper) in a form that can be utilized." Cupric oxide is no longer used in animal feeds and supplements.
Making sure that the copper in supplements is adequate has been a complicated process, according to Baker. New information may lead to a revision of current recommendations for intake. Current recommendations call for an Estimated Safe and Adequate Daily Dietary Intake (ESADDI) of from 1.5 to 3.0 mg. Low copper intakes based on current recommendations have been reported for several population groups, including infants and older adults.
Jennifer Otten, communications specialist and spokesperson for the Food and Nutrition Board of the Institute of Medicine, National Academy of Sciences, tells WebMD that the old recommendation will be updated when a new report on the micronutrients is released next summer. "Our new paradigm expands on the old RDA and looks at the role of additional factors, such as food components, and is called a DRI, for Dietary Reference Intake."
Otten adds, "Our group has been producing RDAs for the last 50 years, and now we will provide DRIs. These are simply recommendations, however, not government regulations and may have no impact on manufacturing practices. Conforming to these recommendations puts the onus back on the manufacturer."