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Supplement Use Among Elderly Is On the
Rise
Little data on how drugs affect health
By
Earl Lane, Newsday
January 28, 2003
More than half of the
elderly may take dietary supplements regularly, according to recent
surveys, and health professionals say much of that use is based on spotty
evidence about the benefits of particular supplements for seniors.
With a welter of supplements on the market, including a surge in
availability of herbal products such as echinacea and ginkgo biloba,
specialists say there is an urgent need for more data on supplement use
and how it may affect health and longevity in older people.
According to one survey, more than 40 percent of men and 50 percent of
women aged 60 and above reported using at least one vitamin or mineral
supplement.
"It's clear that supplement use by the elderly is increasing
rapidly," said Katherine Tucker, a Tufts University nutritionist. She
spoke at a recent conference on dietary supplements and the elderly at the
National Institutes of Health in Bethesda, Md.
For all ages, some supplements have real benefit in redressing certain
nutritional deficiencies, experts say. Dr. Bess Dawson-Hughes, director of
the metabolic bone diseases clinic at Tufts-New England Medical Center,
said fewer than 10 percent of men and women over 50 have adequate calcium
intake through their diets alone.
"This leaves a substantial calcium gap that needs to be filled by
diet modification, food fortification and supplements," says
Dawson-Hughes.
The nonprofit Institute of Medicine, which provides scientific advice to
the government, has endorsed the need for adequate intake of vitamin B-12,
calcium and vitamin D in the elderly, through diet or supplements if
necessary.
But there is less agreement on the value of other supplements, including
antioxidants such as vitamin E and beta carotene that have been the
subject of several large-scale studies in recent years for their possible
effects against cancer. Susan Mayne, a Yale University epidemiologist,
said the available data show "no clear benefit to the use of
supplemental antioxidant nutrients for cancer prevention." Two
studies found that high doses of beta carotene can actually increase the
risk of lung cancer among smokers.
No single supplement is proving to be a magic bullet to prevent a
particular cancer or retard cellular aging of tissues, experts said. But
some researchers are convinced an imbalance between oxidants and
antioxidants can cause damage to DNA, proteins and fats in the body. Such
"oxidative stress" may trigger numerous chronic diseases, they
argue.
Bruce Ames, a biochemist at the University of California, Berkeley, is
convinced that deficiencies in micronutrients can lead to damaged DNA and
decay in the mitochondria - the powerhouses of cells - as we age. "I
think there's a lot of room to lengthen life span and affect the
degenerative diseases of aging," Ames told the conference.
Dr. Robert Russell, a Tufts University nutritionist, said, "It
probably will not be single nutrients alone but in combination that
eventually prove the most effective in preventing the diseases of
aging."
Joseph Hanlon, a University of Minnesota pharmacologist, said he considers
dietary supplements to be drugs rather than foods. "From an efficacy
and safety standpoint, we have a long way to go" to fully understand
them, Hanlon said. Under a 1994 law, manufacturers are not required to
submit safety information to the FDA prior to marketing a supplement.
Hanlon said he is particularly concerned about possible adverse
interactions between supplements and prescription medications, which older
people often take several at a time. Hanlon said he is most concerned
about 15 to 20 prescription drugs with a narrow range of therapeutic
action, including blood-thinning agents, anti-convulsants and
antidepressants. St. John's wort, an herb, can reduce the anticoagulant
effect of the blood-thinning drug warfarin.
More generally, the effort to assess supplements for the elderly is
hampered by methodological problems. "There is very little high
quality scientific evidence for people over 65," said Dr. Virginia
Stallings, a nutrition specialist at the University of Pennsylvania School
of Medicine. "They don't participate in clinical trials."
Also, physiological changes in aging can affect supplement absorption.
Body fat increases and the heart's pumping capacity tends to decrease,
said Dr. Tamara Harris, chief of geriatric epidemiology for the National
Institute on Aging. Kidneys lose some function. Liver mass is reduced, and
there are gastric changes in the gut.
While many dietary supplements are water-soluble, some may be stored or
metabolized in body fat, Harris said. If the body has more fat as it ages,
such supplements will reside longer in the body.
For those seniors who do use supplements, surveys suggest they are more
apt to eat a healthy diet of fruits and vegetables to begin with, less
likely to smoke or drink to excess and more physically active than those
who do not take supplements. Observational studies on use of dietary
supplements in the elderly must take into account these so-called
"healthy volunteers" who can skew results, specialists said. And
there is no substitute, they said, for randomized clinical trials.
Some elderly choose supplements to make up for poor nutrition, experts
said, or in hopes of maintaining health so they can live at home or as an
alternative to conventional drugs they believe have failed.
Several studies show that some seniors don't tell their doctors what
supplements they are using, because they do not consider them worth
mentioning or fear embarrassment. But with the potential for interaction
with other medications, experts said, patients and physicians alike need
to do better. Jean Lloyd, a nutritionist with the U.S. Administration on
Aging, said a survey of doctors at one hospital found only 18 percent
willing to talk about dietary supplement use with their patients.
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