The path to healthy aging has plenty of signposts -- eat more fruits and
vegetables for their antioxidants, get enough calcium for strong bones, have a
few fish meals a week to protect the heart.
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.
Men require 11 milligrams of zinc a day, and women require 8 milligrams.
For the most part, this amount can usually be obtained from the diet through
eating foods such as protein-rich meats, fish and poultry.
But the authors of the two recent reports suggest that dietary intake of zinc in
the elderly may be marginal because some older people may find these foods too
expensive or difficult to chew.
Still, even with these restrictions, it's still possible to get adequate zinc.
Dairy products, beans and nuts provide zinc, as do some fortified, ready-to-eat
cereals. Multiple vitamin and mineral supplements can help meet needs,
particularly if the quality of the diet is good to start with.
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.
Men, who tend to consume more protein foods, fared better.
If you decide to use supplements, note that zinc and copper compete with one
another for absorption in the digestive tract, so it's wise to take in about 2
to 3 milligrams of copper per day along with the recommended 8 or 11 milligrams
of zinc.
Rather than fussing with individual nutrients, you can take a balanced vitamin
and mineral supplement, which should contain the proper ratio of zinc to copper.
