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Supplements Work to Treat Vision Loss in ElderlyBy: Kenneth Chang High doses of certain
dietary supplements provide the first effective treatment for the leading
cause of vision loss among the elderly, a new nationwide clinical study
has concluded. The disease, macular
degeneration, destroys the central portion of the retina, the
light-gathering cells at the back of the eye. Among people who already
have significant yellowish deposits accumulating at the back of their eyes
— the hallmark of the disease — the supplements cut their risk of
vision loss by one-fifth. "This is keeping them with good vision,"
said Dr. Frederick Ferris, director of clinical research at the National
Eye Institute, which sponsored the study. "We were surprised at how
effective it is, given it is just supplements." The supplements — a
combination of zinc and the antioxidants vitamin C, vitamin E and
beta-carotene — did not appear to slow the early stages of the disease,
when the yellowish deposits develop, but that is a normal part of aging
and is not necessarily of concern, Dr. Ferris said. "Almost everyone
over age 70 has at least one or two of them," he said. The supplements also did
not protect against the formation of cataracts, despite hopeful signs from
earlier studies. "We were surprised by that," Dr. Ferris said. About 1.7 million
Americans, mostly over 60, have lost part of their vision from macular
degeneration. As the disease progresses,
the center of the field of view begins to blur, making it difficult to
read, drive and recognize faces. Victims must rely on their peripheral
vision, looking out of the corners of their eyes and missing much of the
color and detail. Glaucoma and cataracts
strike more people than macular degeneration, but effective treatments
exist for those diseases. "This is the one disease for which we had
nothing prior to this," Dr. Ferris said. At best, laser surgery can
slow down the growth of abnormal blood vessels in the most severe cases of
macular degeneration. Earlier studies had
indicated that people who eat large amounts of fruits and vegetables,
which contain vitamins and beta-carotene, are at lower risk of developing
macular degeneration. An earlier, smaller clinical study had suggested
zinc might be helpful. The 4,757 participants in
the study ranged in age from 55 to 80. Among those whose disease
had progressed to the intermediate stage, the zinc supplements reduced by
11 percent the risk of the disease progressing to the advanced stage, and
the antioxidants reduced the risk by 10 percent. When the two were
combined, the risk dropped by 19 percent. The study followed the
participants for 6.5 years on average. Researchers do not know
whether the supplements merely delay vision loss or whether they can
postpone it indefinitely. "At this point, I don't have any reason to
believe this 25 percent reduction wouldn't continue out to seven, eight,
nine years," Dr. Ferris said. The findings are published
in the October issue of the journal Archives of Ophthalmology. The
researchers are also presenting the results at a news conference today at
the National Institutes of Health in Bethesda, Md. The daily dosages of the
antioxidants used in the study were 500 milligrams of vitamin C, 400
milligrams of vitamin E and 15 milligrams of beta-carotene, a molecule
that provides the color of carrots and sweet potatoes. The body converts
the beta-carotene into vitamin A. The daily dosage of zinc was 80
milligrams with 2 milligrams of copper. High levels of zinc can cause a
deficiency of copper in the body, which can lead to anemia. Those amounts are well
above the usual levels recommended by the Food and Drug Administration:
three times as much vitamin A, eight times as much vitamin C, 13 times as
much vitamin E and five times as much zinc. Although all the
supplements are readily available without prescription, "People ought
to discuss this with their doctor," Dr. Ferris said. Beta-carotene
raises the risk of lung cancer among smokers. "For that group, we
probably recommend they take a formulation without the beta-
carotene," Dr. Ferris said. People who took zinc
supplements in the study suffered a slightly higher rate of problems like
urinary tract infections and kidney stones. |
