People with low levels of vitamins A and E are nearly twice as likely to need cataract surgery as those with high levels, a Finnish study says.
The investigation supports mounting evidence that "free radicals," highly charged substances formed naturally in the body, cause the growth of cataracts, which cloud the eye lens. Vitamins A and E mop up free radicals.
Unlike previous studies that relied on diet surveys, the Finnish study, published in the current issue of The British Medical Journal, measured levels of nutrients in the blood.
Dr. Paul Knekt, the leading investigator at the Social Insurance Institution in Helsinki, said the findings showed a "strong link" between low nutrient levels and the likelihood of needing cataract surgery. But he said further studies were needed to prove that diet could decrease the risk of getting cataracts. Survey From 1966 to 1972
Dr. Graham Colditz, an associate professor of medicine at Harvard University, said, "It is looking promising that supplementation or modification of diet may prove to be major approaches to the prevention of cataract."
Dr. Colditz was a co-investigator of a 50,000-woman study that found a 40 percent lower rate of needing cataract surgery among women whose diets were rich in vitamin A compared with those whose diets lacked the vitamin. The study was published in the Aug. 8 issue of The British Medical Journal.
The latest findings were based on a Finnish health survey that collected blood samples from 1,419 people from 1966 to 1972. Between January 1970 and December 1984, 47 people aged 40 to 83 had cataract surgery, which removes the thickened portion of the lens.
Investigators compared the levels of several nutrients in samples of blood stored from these patients to samples from 94 healthy volunteers. Those in the bottom 30 percent for alpha-tocopherol, the key ingredient of vitamin E, were 1.9 times as likely to need cataract surgery compared with those in the top third.
Likewise, those who ranked in the lowest third for beta-carotene, an ingredient that makes carrots orange and is a precursor to vitamin A, were 1.7 times as likely to need cataract surgery compared with people who ranked in the top 30 percent for levels of the nutrient.