Zinc & Copper

Zinc and copper are needed in a 10 to 1 mg ratio for proper absorption and for the maintenance of the human body. The two minerals affect many facets of the regulation of blood cells in the body, and an imbalance can lead to anemia. Copper is responsible mainly for the storage and use of iron in the bloodstream, while zinc is needed for healthy cell function, regulating levels of vitamin A in the blood, immune system maintenance and the production of collagen. Zinc also promotes normal fetal growth, and is therefore an integral part of the diet for pregnant women. For pregnant women, the recommended daily allowance (RDA) of zinc is 20 mg, while the RDA for the average adult is 15 mg. Many of these effects have been downplayed recently as zinc has been touted in the last few years as the modern weapon against the common cold. Some research supports this view, while other studies are less supportive of the popular belief.

The Mayo Clinic published an ambivalent study regarding the efficacy of zinc in fighting the common cold in September 1997. The study was conducted by the Cleveland Clinic in 1996. Participants in the study were instructed to take zinc lozenges within 24 hours of noticing cold symptoms. Colds lasted, on average, for four days for those who took zinc, and for seven days for those who took placebo. However, it was noted that even the study participants were unsure as to whether the zinc had any effect. Many of the participants whose colds lasted only four days said that they probably had a mild cold and that the zinc did not affect their health one way or the other. Drs. Philip Hagen and Donald Hensrud of the Mayo Clinic agreed that the use of zinc as a cold remedy has no significant supportive evidence. Dr. Hensrud states that it is important to begin taking zinc at the onset of a cold, within 24 hours, or it is a moot point. The Mayo clinic doctors also suggested that consumers make sure the zinc in their cold lozenge is created from zinc gluconate, which is a form of zinc easily absorbed through saliva. Dr. Hagen stated the importance of not assuming more is better because there is no evidence that taking zinc actually prevents colds, and there is always the hazard of a zinc overdose.

Zinc toxicity is difficult to induce, as doses of up to 40 times the RDA have not always shown side effects. However, some signs of zinc toxicity are nausea, vomiting, diarrhea, drowsiness, dizziness, difficulty writing and walking, and restlessness. Zinc overdose can also increase chances of developing anemia, decrease mental function of Alzheimer's patients and lower good cholesterol (HDL) levels while raising bad cholesterol (LDL) levels. Signs of zinc deficiency include sterility, low sperm count, delayed wound healing, loss of taste and smell, rashes, loss of hair and skin lesions.

Some food sources of zinc are egg yolk, milk, maple syrup, black-strap molasses, sesame seeds, sunflower seeds, soybeans, whole-grain products, wheat bran, wheat germ and yeast. It is thought, however, that wheat products may decrease the absorption of zinc because of the phytic acid they contain. Dairy products are also thought to decrease zinc absorption, even though they contain the mineral. The best food sources of zinc, which also increase absorption, are beef, lamb, pork, poultry, and seafood, including herring and oysters.

Diuretics, oral contraceptives, alcohol and coffee lower zinc levels in the blood, and tetracycline (when taken within 2 hours of a zinc supplement) can decrease the absorption of zinc. In addition, zinc has been known to interfere with calcium and copper absorption. If zinc supplements are being taken, then copper is needed at a ratio of 1 mg of copper to each 10 mg of zinc because the zinc will hinder the body's ability to absorb copper. It should also be noted that doses of zinc should not exceed 30 mg without a doctor's approval.

Copper is necessary in very small amounts of about 1.5 to 2 mg, not to exceed 3 mg, to store and utilize iron in the blood, manufacture hemoglobin, and to produce various enzymes needed to maintain body tissue. Overdoses of copper cause similar symptoms to those of zinc toxicity. Copper toxicity is manifested in nausea, vomiting, stomach pain, muscle aches and an increased incidence of anemia. A lack of copper can also lead to anemia, as well as weakness, difficulty breathing and skin sores. Copper is found in red meat, nuts, barley, lentils, honey, black-strap molasses, mussels, oysters, salmon, mushrooms, oats and wheat germ.

In September 1999, the United States Department of Agriculture (USDA) and the Agricultural Research Service (ARS) released a study stating that adequate amounts of zinc and copper are necessary for peak athletic performance. The study also stated that vegetarians, ballerinas, gymnasts and wrestlers, because of their diets, tend to be deficient in both minerals. Henry Lukaski, ARS physiologist, conducted an 18-week study involving 12 twenty-something male athletes to determine the effect of zinc deficiency on athletic performance. For the first nine weeks, the men took 18 mg of zinc per day, and for the second nine weeks, the men took only 3 mg of zinc per day. The focus of the study was carbonic anhydrase, a zinc-containing enzyme found in red blood cells. The enzyme is responsible for transporting carbon dioxide to the lungs for exhalation in order to maintain a desirable chemical environment in the muscles, which in turn produce energy. Lukaski's study determined that if carbon dioxide remains in the body for extended periods of time because of zinc deficiency, athletes could not perform at optimal levels.

Cupric oxide, the type of copper found in many dietary supplements and vitamins probably because it takes up less space than other forms of the mineral, is not absorbed easily by the body, according to an article written by Dr. David H. Baker in the December 1999 issue of Journal of Nutrition. Dr. Baker noted that those taking copper supplements also tend to take vitamin C and zinc supplements, both of which inhibit copper absorption in the body. In addition, if the copper supplements being taken are formed from cupric oxide, copper deficiency is a very real concern. Dr. Baker also noted that vegetarians and people on diets tend to be deficient in copper because the best source of the mineral is found in meat, while the copper found in plants is not absorbed as easily, and those people taking supplements may be taking cupric oxide and absorbing very little copper, if any at all.