Vitamin C May Reduce Cataracts Risk
Women younger than 60 years old may lower their risk of developing cataracts later in life by increasing their intake of vitamin C, according to a new study in the American Journal of Clinical Nutrition.1 A cataract is a clouding of the eye lens that leads to blurred or obstructed vision. It occurs most often in the elderly, although it is occasionally seen in younger individuals. This new study suggests that nutritional intervention with vitamin C may reduce the need for corrective eye surgery.
In 1980, 492 women between ages 53 and 73 who were participants in the Nurses Health Study and had no prior diagnosis of cataract, completed a questionnaire regarding diet and use of nutritional supplements. The women filled out a new questionnaire every few years until 1993 to 1995, and the average intake of various nutrients was calculated for each participant. Thorough eye exams were performed on each woman between 1993 and 1995.
In the group as a whole, no significant association was found between the intake of any specific nutrient and the risk of developing a cataract. However, among women less than sixty years old, vitamin C intake (from food and supplements) greater than 362 mg per day lowered the risk of developing cataracts in the middle part of the lens (cortical opacity) by 57%, compared with intake of less than 140 mg per day. Taking supplemental vitamin C for ten or more years also reduced the risk of cataracts by 60% in these women, relative to those who never took vitamin C supplements. There was no significant association with nutrient intake and risk of cataracts in women older than sixty.
The association between nutrient intake and risk of cataracts may also be related to whether a woman has ever smoked cigarettes. Non-smoking women with the highest intakes of folic acid, beta-carotene and total carotenoids lowered their risk of developing cataracts in the outer part of the lens (posterior subcapsular opacity) by 74%, 72%, and 81%, respectively, compared with women with the lowest intakes of these nutrients. However, among current and past smokers, there was no significant association between intake of these nutrients and cataract risk. This may be due to the fact that smoking depletes carotenoids and antioxidants in the lens, which is believed to be a predisposing factor in developing cataracts. The authors suggest that smokers may not be able to achieve high enough concentrations of these nutrients to adequately protect the lens.
In addition to vitamin C and beta-carotene, intake of other nutrients and nutritional supplements may help protect against the development of cataracts.2 3 Research has shown that vitamin E is low in individuals with cataracts and that supplementation with vitamin E may reduce the risk of developing cataracts. For this reason, physicians often recommend 400 IU per day of supplemental vitamin E. One author suggests that taking 240 to 480 mg per day of a standardized bilberry extract, containing 25% anthocyanosides, may reduce the risk of cataracts.4 Eating a diet high in spinach and kale may also prevent cataracts.5 These particular foods are high in two carotenoids (lutein and zeaxanthin) that are found in large concentrations in the lens of the eye. Other foods that contain these compounds include leeks, collard greens, peas, and romaine lettuce.
1. Taylor A, Jacques PF, Chylack LT, et al. Long-term intake of vitamins and carotenoids and odds of early age-related cortical and posterior subcapsular lens opacities. Am J Clin Nutr 2002;75:540–9.
2. Rouhiainen P, Rouhiainen H, Salonen JT. Association between low plasma vitamin E concentration and progression of early cortical lens opacities. Am J Epidemiol 1996;144:496–500.
3. Leske MC, Chylack LT Jr, He Q, et al. Antioxidant vitamins and nuclear opacities. The Longitudinal Study of Cataract. Ophthalmology 1998;105:831–6.
4. Bravetti G. Preventive medical treatment of senile cataract with vitamin E and anthocyanosides: clinical evaluation. Ann Ottamol Clin Ocul 1989;115:109.
5. Chasan-Taber L, Wilett WC, Seddon JM, et al. A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in US women. Am J Clin Nutr 1999;70:509–16.
Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of Garlic and Cholesterol: Everything You Need to Know (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice in Westport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.
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