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BOSTON, MASSACHUSETTS. Cataract removal is the most commonly performed surgery among older
people. It is estimated that about 45 per cent of all people over the age of 75 years have cataracts that
impair their vision. Several studies have shown a protective effect of certain antioxidant vitamins specifically
vitamin C, vitamin E and carotenoids. Researchers at Tufts University have just released the results of a
large study designed to evaluate the effect of vitamins on the incidence of two specific types of cataracts,
cortical cataracts and posterior subcapsular (PSC) cataracts. Because the two types occur in different part
of the eye's lens the researchers reasoned that the vitamins required for protection might be different.
The study involved 492 non-diabetic women aged 53 to 73 years who were part of the large Nurses' Health
Study begun in 1976. All participants had completed food frequency and supplement usage questionnaires
every second year for 13 to 15 years. The researchers found lens opacities in 55 per cent of the participants
with 37 per cent being cortical opacities and 6.3 per cent being PSC opacities. They also observed that
women under the age of 60 years whose daily vitamin C intake exceeded 360 mg/day had a 57 per cent
lower risk of developing a cortical cataract than did women whose intake was below 140 mg/day. Women
under the age of 60 years who had supplemented with vitamin C for 10 years or more had a 60 per cent
lower risk of cortical cataracts than did women who had not supplemented. Vitamin C did not appear to
protect against the much less common PSC opacities, but carotenoids and, to a lesser extent, folic acid did
seem to confer some protection amongst women who had never smoked. NOTE: The current
Recommended Daily Allowance (RDA) for vitamin C is 75 mg/day for women – clearly totally inadequate for
providing any meaningful protection against cataracts. |
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