Zinc is a trace mineral. Trace metals are minerals present in living tissues in small amounts. Some of them are very essential for our bodies nutritionally. You need very small amounts of trace minerals. Trace minerals required by us include iron, manganese, copper, iodine, zinc, cobalt, fluoride, and selenium. Most of us get the required amount of minerals through our food. In some cases, the doctor may recommend a mineral supplement.
The discovery of zinc deficiency as a human health problem was in 1961. Anemia, hypogonadism, and dwarfism were reported in an Iranian farmer. A similar problem was observed in Egyptian adolescents whose diet was similar. It consisted of flatbread, potatoes, beans, and milk. Administration of zinc supplements improved growth and rectified hypogonadism.
Causes of zinc deficiency
- Inadequate intake of zinc: This may be because of heavy reliance on foods with little or poorly absorbable zinc.
- Malabsorption: Malabsorption may occur due to some health conditions like acrodermatitis enteropathica, and inflammatory diseases of the bowel which lead to poor absorption of zinc. Malabsorption also leads to impaired utilization of zinc in the body.
- Increased requirements: Vegetarians and vegans may need more zinc. Even though plants do have zinc, the bioavailability is less in vegetarian diet. Also, vegetarians eat more of legumes and whole grain, which contains phytates, that inhibits the absorption of zinc. Elderly people, Pregnant and lactating women may also need increased supply of zinc.
- Increased Losses: Zinc deficiency can be caused by medical conditions like diabetes, cancer, kidney disease, alcoholism and also Chron’s disease.
Consequences of zinc deficiency
Zinc deficiency can cause a broad range of physiological signs which may include, epidermal, gastrointestinal, immune, skeletal, and reproductive systems. It may also affect the central nervous system. Zinc deficiency may lead to the following problems.
- Growth and Development: Zinc deficiency leads to the impairment of physical growth and development. This effect is mostly seen during periods of rapid growth, such as pregnancy, infancy, and puberty when the requirement is more.
- Diarrhea: Zinc deficiency also causes diarrhea. Zinc supplements have a beneficial effect.
- Pneumonia: Studies in children have shown that zinc supplements have led to a significant reduction in pneumonia in developing countries.
- Age-related symptoms: Zinc deficiency may also lead to degenerative changes like low immunity, delay in wound healing, and neurological and psychological changes. the consequences of zinc deficiency vary with age. In early infancy, it usually manifests in the form of diarrhea. As the child grows older, skin problems become more common due to zinc deficiency. As mentioned earlier, growth retardation may occur in children.
Bioavailability of zinc
Bio-availability refers to the fraction of intake that can be absorbed into the blood system and used for physiologic functions of the body. Our body does not need a large amount of zinc. The recommended daily allowance for adults is 8 – 11 mg (8mg for women and 11 mg for adult men).
The body absorbs about 20 – 40% of the zinc present in food. Zinc from non-vegetarian foods like red meat, fish, and poultry is more readily absorbed by the body than zinc from plant foods. Zinc is better absorbed when you take it with a meal that contains protein.
We can soak grains and legumes for sometime before cooking to reduce the amount of the phytates in them. This makes it easier for the body to process and absorb zinc. Leavened grain products also help reduce the number of phytates, thus increasing the amount of zinc the body can use.
Several studies have also shown that “high iron concentrations can negatively affect zinc absorption in adults when these trace minerals are given in solution. However, when iron and zinc are given in a meal, this effect is not observed.”
Health benefits of Zinc
Zinc is essential for almost 100 enzymes to carry out important chemical reactions. Zinc plays an important role in the creation of DNA, growth of cells, and building proteins. It also helps heal damaged tissue, while supporting a healthy immune system. Zinc helps cells to grow and multiply, that is why zinc is very necessary in childhood, adolescence, and pregnancy, as fast growth takes place.
- Helps build immunity. Low levels of zinc can lead to an increase in the risk of infections.
- Heals wounds by repairing damaged cells.
- Zinc supplements may help heal diarrhea.
- Zinc may delay age-related macular degeneration.
- Zinc helps in bone formation and may prevent osteoporosis.
- Some studies suggest that zinc lozenges may help to shorten the duration of common cold, if taken within 24 hours after cold symptoms start, but researchers aren’t sure what kind of zinc works best and zinc can decrease the effectiveness of certain drugs. Intranasal zinc could lead to loss of sense of smell.
- Zinc may help treat Wilson’s disease. Wilson’s disease is a condition which causes copper to build up in the body. Zinc has a tendency to reduce copper absorption of the body and hence may help reduce levels of copper in people with Wilson’s disease.
- Zinc can also be topically applied to help improve acne. Zinc oxide is usually used topically. Ointments having zinc oxide in them may be applied to prevent problems such as sunburn and diaper rash.
Food Sources of zinc
The best sources of zinc are oysters, red meats, poultry, cheese like ricotta, Swiss, and gouda, shrimp, crab, and other shellfish. Oysters are the richest source. Some other good but less easily absorbed sources of zinc include legumes such as lima beans, black-eyed peas, pinto beans, soybeans, and peanuts; whole grains, tofu, brewer’s yeast, cooked greens, mushrooms, green beans, and seeds like pumpkin, sunflower and sesame seeds.
Side Effects and Precautions
Oral zinc supplements may cause indigestion, diarrhea, headache and nausea or vomiting.
When zinc supplements are taken for long and in high doses, it may lead copper deficiency.
Intranasal zinc may lead to a loss of sense of smell.
Taking oral zinc may interact with certain medications such as thiazide diuretics, Penicillamine and some antibiotics.