Zinc is an essential trace mineral all living organisms require for cell metabolism. Your abilities to taste, smell and see in the dark depend on zinc. Because zinc is needed for cell division and to synthesize protein, it also plays a role in wound healing and immune function. Bone and vascular health require another mineral, calcium. People need calcium for growth and development when young and to prevent bone loss in the aging. A high calcium intake reduces zinc absorption in animals, and this interaction between zinc and calcium may also occur in humans, according to the Linus Pauling Institute.
Basic Functions
According to a review published in the "Journal of Laboratory and Clinical Medicine,” zinc regulates gene expression, hormone release, neurotransmission and how cells communicate with each other. Zinc also protects cells from oxidative damage and is used as a catalyst to promote chemical reactions in nearly 200 different enzymes. Calcium also affects hormone production, cell signaling and nerve transmission as well as muscle and vascular function, but only 1 percent of stored reserves are used for these purposes. The other 99 percent, says the Office of Dietary Supplements of the National Institutes of Health, is deposited in teeth and bone and withdrawn when needed to make new bone. In contrast, zinc is not stored in the body.
Dietary Sources and Supplements
Zinc is found in many foods, including beef, chicken, dairy products, legumes, nuts and whole grains. This mineral is particularly abundant in certain shellfish, including oysters, lobsters and crabs. In supplemental form, zinc is available as zinc sulfate, zinc acetate and zinc gluconate. Over-the-counter cold remedies, nasal sprays and throat lozenges also contain zinc. Dairy products like milk, cheese and yogurt are the most significant dietary sources of calcium. Certain vegetables also provide calcium, such as broccoli and kale. As a supplement, calcium is available as calcium carbonate and calcium citrate.
Deficiencies in Humans
Zinc deficiency is associated with poor immune function, delayed growth and development, impaired neurological function, night blindness and the loss of taste. Infants, children, women who are pregnant or nursing, people with chronic disorders or over the age of 65 are most at risk for zinc deficiency. Calcium deficiency in humans is not as obvious until osteoporosis appears, and the risk for this condition increases with age because calcium absorption in humans decreases from up to 60 percent in childhood to only 15 to 20 percent in adulthood, according to the Office of Dietary Supplements.
Zinc and Calcium Interactions
Foods that are high in phytic acid and oxalic acid prevent calcium absorption in humans. Phytic acid, a natural component of high-fiber foods such as nuts, seeds, beans and soy, also inhibits the absorption of zinc when combined with calcium. Oxalic acid is also found in beans and in certain vegetables, including sweet potatoes, rhubarb, collard greens and spinach. According to a study published in the “American Journal of Clinical Nutrition,” increasing calcium intake to 1,360 milligrams per day decreases zinc absorption in postmenopausal women.
References
- Office of Dietary Supplements: Zinc
- Linus Pauling Institute; Zinc; Jane Higdon, Ph.D.; December 2003
- "Journal of Laboratory and Clinical Medicine"; Understanding Zinc: Recent Observations and Interpretations; H.H. Sandstead; September 1994
- ODS: Calcium
- “American Journal of Clinical Nutrition"; High Dietary Calcium Intakes Reduce Zinc Absorption and Balance in Humans; R.J. Woods, et al.; June 1997
Member Comments