An American study has found that the daily intake of vitamin C has an important role in preventing cataracts. Cataracts are present in 45 per cent of people older than 75 years, and their removal is the most commonly performed surgical procedure among older people. The research backs growing evidence that nutrition is fundamental to eye health.
The study, published in the American Journal of Clinical Nutrition, examined the prevention of one type of cataract in women younger than 60 years old.
The researchers examined long-term vitamin consumption in a group of women aged 53 to 73, and found that daily vitamin C intake from diet and supplements during the previous 13 to 15 years had a significant role in the prevention of one type of cataract in women younger than 60 years of age.
The 492 non-diabetic subjects were chosen from a group of women nurses in the Boston area whose diet and health information has been followed up biennially since 1976. The participants received detailed eye examinations for the detection of several different forms of cataracts, and information on their long-term vitamin intake and supplement use was collected from food frequency questionnaires from 1980 through 1993 to 1995.
Of all eyes examined, 34 per cent had cortical opacities, a common form of cataracts involving intermediate fibre cells of the cortex. Almost 40 per cent of the eyes had other forms of cataracts, with one-third having lens clouding in more than one location. Most of the women had very early opacities and so had not experienced visual symptoms.
A significant interaction was observed between age, vitamin C intake and the prevalence of cataracts. For women younger than 60 years, the consumption of vitamin C less than 362 mg each day was associated with a 57 per cent lower risk of developing cortical opacities, and the use of vitamin C supplements for at least 10 years was associated with a 60 per cent reduction in the risk of cataracts, when compared to no supplement use.
Additionally, the incidence of posterior subcapsulary cataracts was considerably lower in women who had never smoked and who had high intakes of folate and carotenoids. These results add to a growing body of evidence that certain nutrients can be used to reduce the rates of development of this major age-related complaint.