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 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.
The vitamin 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. Almost everyone over age 70 has at least one or
two of them.
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, but effective treatments exist
for those diseases. This is the one disease for which there was nothing
prior to this. At best, laser surgery can slow down the growth of abnormal
blood vessels in the most severe cases.
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.
The daily dosages of the antioxidants used in the
study were 500 milligrams of vitamin C, 400 IU 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.