Zinc is one of the most versatile of all the minerals in the human body. This trace element affects many systems in the body, including disease resistance and cellular metabolism. Zinc is required as a cofactor by more than 100 enzymes in the eyes, skin, muscles, bones, kidneys, and other organs. A cofactor is a non-protein molecule bound to an enzyme to help it work properly. Zinc, bound together with a very specific enzyme called superoxide dismutase (SOD) helps to make this trace element a potent antioxidant, capable of preventing free radicals from forming in the body and damaging cellular structures.
Because zinc is found in high concentrations in the eye, it is known to play a large part in eye health. In theAREDS trial, sponsored by the National Eye Institute, researchers discovered that taking zinc, along with various other antioxidants, could lower the risk of developing advanced age-related macular degeneration by about 25%. Zinc supplementation alone was nearly as effective as the mixture of zinc and other antioxidants at reducing the risk of developing advanced AMD in subjects at high risk for the disease in AREDS.
In the African Journal of Food, Agricultural, Nutrition and Development, it was found that zinc deficiency may be implicated in the high prevalence of cataract formation. The incidence of cataract development is more common in tropical countries due to the pronounced exposure to sunlight, and zinc has the ability to protect the lens of the eye from oxidative damage.
Zinc plays an important role in immune function and in normal growth and development. It has an effect on behavior and learning, works together with platelets in blood clotting, is associated with insulin in the pancreas, and influences the function of the thyroid gland. Zinc is vital to wound healing, especially in reducing healing time after surgery. It is also helpful in treating male and female productive problems. When zinc deficiency occurs, it weakens all these and other functions.
Among its many other roles in the body, zinc has been found to preserve the integrity of the skin and the mucus membranes. It is used to maintain healthy skin cells and generate new skin after burns or surgery. It’s been demonstrated that patients with leg ulcers and other serious wounds have lower than normal serum zinc levels. A study in The Lancet showed that healing rates were two-and-one-half times quicker in the group taking zinc, than they were in the control group.
Sucking on zinc lozenges has been shown to decrease the length and severity of colds and sore throats, and can also prevent the progression of viral flu symptoms. A study published in the Journal of the American Pharmacists Association showed that zinc supplements can shorten the duration of the common cold if taken within 24 hours of onset. Individuals with allergies may benefit from zinc supplementation as well.
One of the functions of zinc is to help maintain a healthy appetite. Zinc deficiencies can play an important role in certain eating behaviors. Supplementing with zinc has been shown to be effective in improving the appetite in people with anorexia. Many of the symptoms of anorexia can also be symptoms of zinc deficiency. In adults, common zinc deficiencies can produce a poor appetite and reduced taste sensitivity.
Zinc plays a crucial role in various phases of insulin production. When experimental animals are fed zinc-deficient diets, they develop impaired glucose tolerance. A study performed at the Department of Medicine at the University Central Hospital in Finland showed that diabetics had low levels of zinc in their blood. Many of the side effects and complications of diabetes are strikingly similar to the effects of a zinc deficiency, including poor wound healing and increased risk of infections.
Zinc can be helpful in many diseases of the elderly. Older adults usually do not get enough zinc in their diets. A study of 33 nursing homes published in the American Journal of Clinical Nutrition was performed to see if blood levels of zinc were associated with an increased risk of pneumonia. The study showed that those residents who had normal blood levels of zinc had a decreased prevalence and duration of the disease. Another experiment found that high doses of zinc enhanced the immune function of healthy aging adults.
Older adults lose up to 80 percent of their taste buds as they age, with much of this loss due to zinc deficiency. A 2008 study in the British Journal of Nutrition found that the loss of ability to taste was observed in cases of zinc deficiency and that supplementing zinc was shown to improve taste disorders in zinc-depleted groups. Zinc deficiency appears to be associated with reduced appetite and may lead to decreased intake of zinc-rich foods.
Many older adults are easily bruised, and their bruises heal very slowly. Low zinc levels may be somewhat responsible for the purple spot bruising, called purpura, which seems so common among the elderly.
Zinc can be helpful in the treatment of arthritis. People with arthritis frequently have lower than normal zinc levels in their blood. A study in the 2009 Pakistan Journal of Biological Sciences showed that zinc serum levels in patients with rheumatoid arthritis were considerably lower than those in the sample group. Zinc supplements were therefore suggested to treat those patients.
Zinc is essential for both maternal and fetal health. Zinc levels are a very important factor when it comes to the cell division that occurs in pregnancy. When zinc levels are optimal, cell division occurs normally.
Some researchers feel that zinc deficiency can initiate benign prostatic hyperplasia, or prostate enlargement. Zinc is one of the more common deficiencies, especially as we age. Mild zinc deficiency can also lead to a low sperm count, and supplementing with zinc has been shown to increase this count in normal healthy males who have only a mild zinc deficiency.
Chronic zinc deficiency is fairly common due to the loss of this trace mineral in our soil, and this depletion can cause a wide range of symptoms. Even a mild zinc deficiency can result in metabolic changes such as an impaired immune response, vision problems, and a weakened sense of smell and taste.
Some evidence implies that zinc intake among older adults might be too low. An investigation of NHANES III data found that “35%-45% of adults aged 60 years or older had zinc intakes below the estimated average requirement of 6.8 mg/day for elderly females and 9.4 mg/day for elderly males”. When the researchers took into consideration amounts from both food and supplements, they found that almost 25% of older adults still had inadequate zinc intake.
Acute zinc deficiency may cause hair loss or thinning, poor appetite, and growth impairment. Brittleness of the nails and white spots on the nails are very common signs of zinc deficiency. Skin problems, including acne, rashes, dry skin, and slow wound healing may result from too little zinc.
Deficiency can cause delayed menstruation in female teenagers, or, in later years, cause menstrual problems. Male teens with low zinc levels may have a delay in sexual development, causing a decline in testosterone levels and a diminishing sperm count. Prostate problems are also more prevalent with zinc deficiency.
Children have especially high zinc needs because they are growing rapidly. They may present with fatigue, insufficient appetite, delayed development, poor attention spans, and increased susceptibility to infection. These and most other symptoms can be corrected with supplemental zinc.
Zinc can be toxic if too much is consumed. Excessive zinc intake causes the intestinal cells to produce a certain type of protein that binds copper more strongly than zinc and captures it in a non usable form. This hinders copper absorption and may result in a condition called copper-deficiency anemia.
When taking higher amounts of zinc, it’s important to get adequate amounts of copper to prevent copper deficiency. Taking excessive amounts of zinc can cause abdominal cramping, diarrhea, vomiting and dizziness. It can also inhibit the proper functioning of iron in the body.
Zinc is most prevalent in foods of high protein content, such as shellfish, meats and liver. Oysters have more zinc than any other food, but red meat, poultry, eggs, and whole-grain products are good sources of zinc as well.
The recommended daily allowance for zinc is 15 mg per day for men and 12 mg per day for women, although these amounts are believed to be too low. We probably need 15-30 mg of elemental (available) zinc daily for maintenance and about 30-60 mg if a deficiency is suspected. With certain conditions, like macular degeneration for example, therapeutic levels up to 80 mgs may be necessary. Zinc is required for the conversion of beta-carotene into Vitamin A, so more may be needed when additional vitamin A is required, as is the case with specific eye diseases. Zinc should be taken every day, because the body has no specialized system to store it. The standard American diet, high in refined foods, provides only about one-half the recommended dietary allowance for zinc. It’s best to take zinc on an empty stomach, either one hour before or two hours after meals, to help increase absorption.