Zinc plays a key role in better aging

Courtesy of the LA Times

Two studies published this year addressed the role of zinc in maintaining health in older people. One, a yearlong study of 50 nursing home residents 65 or older found that people with low levels of zinc in the bloodstream -- defined as 70 micrograms per deciliter or less -- had twice the incidence of pneumonia and nearly 50% more antibiotic prescriptions over the year than those with normal zinc status.

The study, conducted by scientists at Tufts University and Boston University and published last month in the American Journal of Clinical Nutrition, also found that those who began the study with normal zinc levels had a 39% lower mortality rate -- from any cause -- than those who were deficient.

In a second small study, led by Dr. Ananda Prasad at the Wayne State University School of Medicine, 50 free-living, healthy elderly subjects were recruited from a senior center to receive either a daily zinc supplement or placebo for a year to determine if zinc supplementation offered protection against colds and flu.

By the end of the yearlong study, zinc-takers had significantly higher zinc levels in the bloodstream and had suffered significantly fewer infections -- seven cases versus 35 cases in those taking a placebo.

The study also found lower serum levels of a chemical called malondialdehyde and other signs of oxidative stress (the production of cell-damaging free radicals) in the group taking supplements, confirming earlier evidence that zinc can function as an antioxidant.

The study was published in the American Journal of Clinical Nutrition in March.

Adequate zinc is critical for the production of lymphocytes -- the army of specialized white cells in the immune system that help defend against foreign invaders.

Zinc deficiency leads to impaired immunity and thus decreased resistance to a host of bacterial, viral, fungal and parasitic invaders. Recovery from illness takes longer when zinc levels are low than when zinc status is normal.

Multiple vitamin and mineral supplements can help meet needs. A recent analysis of food and supplement use from a large survey of Americans taken by the U.S. Department of Agriculture (known as the USDA's Continuing Survey of Food Intakes by Individuals) found that supplement users had better dietary intake of zinc than nonusers.

Among people age 71 and older, 43% of those who shunned supplements consumed inadequate intake of zinc from foods compared with 29% of supplement users. And when the amount of zinc supplied from supplements was factored in, only 5% of supplement users failed to meet the estimated average requirement.

Poor zinc intake is not just a problem among the elderly. Data from another large government food intake survey known as NHANES III indicated that after seniors, teenage females had the lowest zinc intake, with 61% failing to meet recommendations. Fewer than half of women at any age took in an adequate amount.