Women who take high doses of vitamin C are at increased risk of developing age-related cataracts, according to a study in Sweden. Among some 24,600 women studied over eight years, who consumed a dose of 1,000 milligrams of vitamin C regularly or occasionally were 25 percent more likely than those who did not use the supplement to cataract were excised.
The risk was even greater in users of extra vitamin C for 10 or older or aged 65 or over, or taking hormone replacement therapy or corticosteroids. But in the American Journal of Clinical Nutrition, the team Alicja Wolk of the Karolinska Institute in Stockholm, warns that the apparent relationship between vitamin C and risk of cataract excludes vitamin C from fruits and vegetables.
Instead, the study assessed the risk of cataract associated with high doses of vitamin C supplements common in Sweden. According to the authors, the results support previous findings.
59 percent of women 49 to 83 years in good general health reported using a dietary supplement. 5 percent of them said to take only vitamin C and 9 per cent multivitamin with 60 milligrams of vitamin C.
Of the 1225 women who took only vitamin C, 143 (almost 13 per cent) were removed cataracts during the study. However, cataracts were removed in 878 of 9974 women not using supplements (9 percent) and 252 of 2259 users of multivitamins (11 percent).
The increased risk of cataracts in the supplement users versus nonusers, remained evident in the analysis that considered age intervals of five years, waist size, education, smoking, alcohol consumption and use drugs, such as hormone replacement therapy.
The researchers say more studies are needed to confirm the results, especially in older women treated with hormone replacement therapy or steroids, as well as studies on the mechanisms that would promote the association.
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