What is zinc?
The importance of zinc in human health was first described in 1961; zinc is an essential trace mineral for all life forms and present in every cell of human body. It involves in numerous aspects of cellular metabolism and supports normal growth and development during pregnancy and childhood.
Over 300 different enzymes require zinc for their catalytic activity and it plays a role in immune system, protein and cell membranes synthesis, wound healing, DNA synthesis, and cell signaling. In addition, zinc also plays a critical structural role for the antioxidant enzyme copper-zinc superoxide dismutase (CuZnSOD). A daily intake of zinc is required to maintain overall well-being, because the body has no specialized zinc storage system.
Deficiency of zinc is now known to be an important malnutrition problem world-wide. The World Health Organization (WHO) estimates that 800,000 people die annually due to zinc deficiency, with 450,000 of these being children under the age of five.
The symptoms of zinc deficiency include change in appetite, impaired taste sensation, night blindness, diarrhea, delayed healing of wounds, and hair loss. Severe deficiency could lead to slowing of growth and development, delayed sexual maturation, and immune system deficiencies.
People at risk of zinc deficiency are usually due to inadequate zinc intake or absorption. There are other circumstances could cause zinc deficiency:
People with inflammatory bowel disease and malabsorption syndromes – Gastrointestinal surgery and digestive disorders (celiac disease, ulcerative colitis, Crohn’s disease, and short bowel syndrome) can decrease zinc absorption and increase zinc losses from gastrointestinal tract.
Strict vegetarians – High levels of phytic acid in these foods reduce zinc absorption.
Pregnant and lactating women – High fetal requirements for zinc, and lactation can deplete maternal zinc stores.
Alcoholics – Ethanol consumption decreases intestinal absorption of zinc and increases urinary zinc excretion.
Older infants with exclusive breast-fed – Inadequate intake of zinc-rich complementary foods
Zinc health benefits:
1. Improves immune function
Adequate zinc intake is important to maintain the integrity of the immune system. The body requires zinc to activate T-lymphocytes which is a subtype of white blood cell that plays a central role in immunity. A study in men and women over 65 years old found that a zinc supplementation for three months increased levels of some immune cells. Severe zinc deficiency depresses immune function and makes people in developing countries who have low levels of zinc have a higher risk of getting infections.
2. Antioxidant ability
Zinc plays a structural role in the cell membranes and antioxidant enzyme copper-zinc superoxide dismutase (CuZnSOD) as mentioned above. It is an effective anti-inflammatory and antioxidant agent, helping fight off free radicals and decrease the chance of chronic disease development such as cancer, heart disease and Parkinson’s disease. In addition, loss of zinc from cell membranes could increase susceptibility to oxidative damage and impairs their function.
3. Treats common cold
The use of zinc lozenges has been advocated for reducing the duration of the common cold. Many controlled trials of zinc lozenges for the treatment of common colds in adults have done and more than half of the trials found that it reduced the duration of cold symptoms. Zinc can reduce the number of pro-inflammatory cytokines, which aggravate the body during cold. Also, zinc’s ability to stimulate white blood cell to fight off infections and reduce cold.
4. Supports growth and development
Zinc is essential for rapid growth of cells, and repair and functioning of DNA. The enormous enzymatic activity that take place during pregnancy make it one of the most important nutrients for mothers and infants. Significant delays in linear growth, weight gain, neurological and behavioral development, are common symptoms of zinc deficiency in children. Zinc availability affects cell-signaling systems that coordinate the response to the growth-regulating hormone and other growth factors.
The optimum intake of zinc is 25mg daily for average adults to achieve maximum health benefits. Zinc could be toxic if intake amount reaches over 40mg per day. Our body absorbs 20 – 40% of the zinc present in food. Zinc from animal foods like red meat, fish, and poultry is more readily absorbed by the body than zinc from plant foods. Zinc is best absorbed when taken with a meal that contains protein.
Zinc is found in most multi-vitamin and mineral supplements, and its available in several forms including zinc gluconate, zinc sulfate, and zinc acetate. Research suggests that all forms work in similar ways as in absorption, bioavailability, or tolerability.
Food sources high in zinc: Oysters, beef, chicken, pork, crab, shrimp, salmon, cheese, yogurt, milk, beans, cashews, almonds, peanuts, chickpeas, oatmeal