Zinc is a mineral that you need on a daily basis, but only in very small amounts (50 milligrams or less), which makes it a micromineral. People don’t get sufficient amounts of zinc can have impaired overall growth as well as impaired sexual maturation. Zinc can:

• Regulate genetic activities: Most of your cells contain a nucleus, and inside the nucleus are approximately 100,000 genes. These genes provide instructions for the cell. Zinc is essential for decoding genetic instructions in a process called gene transcription. Without zinc, genetic instructions can get misinterpreted, or not decoded at all. In addition, zinc is vital for normal fetal development and the maturation of sperm.
• Support blood sugar balance and metabolic rate: Insulin, a hormone made by your pancreas, is often required to move sugar from your bloodstream into your cells. When the foods in your diet do not provide you with enough zinc, the response of your cells to insulin (insulin response) decreases, and your blood sugar becomes more difficult to stabilize. Metabolic rate (the rate at which you create and use energy) also depends on zinc for its regulation. When zinc is deficient in your diet, your metabolic rate drops (along with hormonal output by your thyroid gland).
• Support smell and taste sensitivity: Gustin is a small protein that is directly involved in your sense of taste. Zinc must be linked to gustin in order for your sense of taste to function properly. Because of this relationship between zinc and taste, and because taste and smell are so closely linked in human physiology, impaired senses of taste and smell are common symptoms of zinc deficiency.
• Support immune function: Many types of immune cells seem to depend upon zinc for optimal function. Particularly in children, zinc deficiency compromises white blood cell numbers and immune response, while zinc supplementation can restore conditions to normal. Many viral infections can be treated and prevented with zinc.
• Support cell production: Zinc plays an important role in cell production, including creating new skin cells, allowing healthy collagen production, and wound healing. It plays a vital role in the health of the skin, scalp, and hair, and promotes healthy cell division and proper formation of tissues.
• Transport and mobilize vitamin A: Without zinc, your body cannot effectively transport vitamin A around your body, and you cannot efficiently mobilize vitamin A when it is needed. Zinc facilitates moving the supply of vitamin A from the liver to the skin to repair damaged skin. It is helpful in the treatment of acne, diaper rash, cold sores, and burns.
• Prevent vision loss: Zinc works with antioxidants, including vitamins C ad E and beta-carotene, to prevent vision loss in people with age-related macular degeneration (AMD).
• Prevent osteoporosis: Zinc influences your skeletal system through its regulation of insulin-like growth factor (IGF-I). IGF-I is a hormone-like agent that is primarily produced in your liver and carried to your body tissues via your bloodstream. IGF-I is a critical factor in the regulation of bone formation, re-absorption, and calcium balance within bones (homeostasis). Low intakes of zinc are associated with less production and secretion of IGF-I. Consequently, lower circulating IGF-I translates into more rapid loss of calcium from bone with aging and subsequent development of osteoporosis.
• Preventing depression: Zinc can keep you happy. It is essential to maintaining and developing neurological networks, it is also necessary for the effective neural communication within those networks. Like some antidepressant drugs, zinc stimulates the production of brain derived neurotrophic factor (BDNF), a growth factor that helps to support the survival and differentiation of neurons in your brain and peripheral nervous system. Communication between neurons in the hippocampus—the area of the brain responsible for learning, memory and emotional regulation—relies upon the presence of zinc. Low levels of zinc increase the incidence and intensity of depression.

In addition to dietary deficiency, problems in your digestive tract can contribute to zinc deficiency. These problems include irritable and inflammatory bowel disorders, as well as insufficient output by the pancreas that prevents proper digestion. Protein deficiency, and deficiency of one particular amino acid, cysteine, can also contribute to zinc deficiency by preventing synthesis of molecules that your body uses to transport and store zinc. Loss of zinc through chronic diarrhea or profuse sweating can also contribute to deficiency.

Because of the link between zinc and the taste-related protein called gustin, an impaired sense of taste or smell are common symptoms of zinc deficiency. Depression, lack of appetite, mental lethargy, hair loss, weight loss, delayed wound healing, chronic infection, rough skin or rashes, growth failure in children, and frequent colds and infections can also be symptomatic of insufficient dietary zinc. Deficiency in zinc can decrease the activities of one or more phase I detoxification enzymes.

A metallic, bitter taste in your mouth can indicate zinc toxicity, as can stomach pain, nausea, vomiting, cramps, and diarrhea mixed with blood. In 2000, the National Academy of Sciences set a tolerable upper limit (UI) of 40 milligrams for daily intake of zinc for adults age 19 and over.  The establishment of this limit was largely related to the ability of zinc, especially supplemental zinc, to impair the status of other nutrients.

The most important of these nutrients are copper and calcium. Even at moderate doses of 18-20 milligrams that you can easily ingest from eating things like oysters or calf liver, zinc can compromise your body’s supply of copper. When few foods high in calcium are included in your diet, high levels of zinc intake (usually obtained from supplements) can also decrease absorption of calcium from your intestines into your body. If you routinely eat more than 1500 mg of calcium per day, you may need to increase your daily zinc intake accordingly. High doses of manganese may inhibit the absorption of zinc. Alternatively, high intakes zinc may inhibit the absorption of manganese. Zinc is not fully available in your body without adequate supplies of riboflavin. Beta-carotene can also improve the availability zinc from grains. Eating one medium-sized carrot (about 50 grams) along with each cup of cooked rice increases the availability of zinc by about 35-40%.

Like most minerals, zinc is present in many different forms in food, and can vary greatly in its response to cooking and processing. In some foods, where a greater percent of zinc is found in water-soluble form and contact with water is great, high losses of zinc can occur. For example, when navy beans are cooked, 50% of the original zinc is lost. Processed grains have almost 75% less zinc than whole grains.

Adzuki beans and wheat germ are excellent sources of zinc. Sesame seeds, natto, lentils, chickpeas, pumpkin seeds, spelt, oats, wild rice, black-eyed peas, wheat bran, black beans, cashews, green peas, rye, spinach, sunflower seeds, mandarin oranges, palm hearts, tofu, crimini mushrooms, peanuts, shiitake mushrooms, almonds, and blackberries are very good sources of zinc. Good sources include asparagus, summer squash, okra, chard, maple syrup, tomatoes, and miso.