Ask the Doctor—Are there any nutritional ways to prevent cataracts?
By Terry Grossman, MDQ Are there any nutritional ways to prevent cataracts?
As light passes through the lens of the eye, proteins in the lens are unavoidably subjected to damage by free radicals. These damaged proteins change from crystal clear to cloudy and over time can create dark regions in the lens known as cataracts.
The body is able to prevent free-radical damage by transforming the toxic free radicals into harmless compounds through the use of three built-in antioxidant enzymes: catalase, superoxide dismutase, and glutathione peroxidase, all of which normally are found within the lens itself. However, a small percentage still escapes neutralization and can lead to lens damage and cataract formation.
In addition to the antioxidant enzymes, the body utilizes dietary vitamins, minerals, and other micronutrients as another line of defense to neutralize free-radical damage. Italian researchers established an association between diet and cataract risk 40 years ago when they found that people who consumed higher amounts of meat, cheese, cruciferous vegetables (like broccoli, kale, and cauliflower), spinach, tomatoes, peppers, citrus fruit, and melon needed cataract surgery less often. Increased risk occurred among people who consumed higher amounts of butter, total fat, and salt. They also found that using olive oil and eating spinach appeared to protect against cataract formation, while eating carrots did not.
Several more recent studies have looked at the relationship between nutritional supplementation and cataract risk.
The most notable are highlighted below.
• The Lens Opacities Case-Control Study in 1991 followed 1,380 patients and found that “regular use of multi-vitamin supplements decreased risk” of cataract formation. Individual nutrients such as vitamins B1, B2, B3, C, and E; carotene; and iron reduced risk individually as did supplemental combinations of vitamins C and E and carotene.
• The Beaver Dam Eye Study from Wisconsin followed 1,354 patients from 1988 to 1995. Antioxidant intake was determined from a food questionnaire. People who consumed the highest amount of the bioflavonoid lutein—found in green, leafy vegetables such as spinach and kale as well as yellow foods such as squash and egg yolks—had 50 percent fewer cataracts compared with people who consumed the least lutein.
• The US Male Health Professionals’ Study followed 36,644 men between 45 and 75 years of age beginning in 1986 and found that men with a higher lutein intake had a 19 percent decreased rate of cataract surgery.
• The Blue Mountain Eye Study from Australia found that “long-term use of multivitamins, B group, and vitamin A supplements was associated with reduced prevalence of either nuclear or cortical cataracts.” Folate and vitamin B12 supplementation was also found to be useful.
• The Nurses’ Health Study from Boston found that vitamin C intake was associated with a 64 percent decreased cataract risk among women who used vitamin C for 10 or more years compared with women who had never taken vitamin C supplements.
After reviewing these and many additional studies that researched other nutrients, it would appear the most useful nutrients for cataract prevention include vitamins A, C, and E; the B vitamins; the carotenoids; the minerals selenium and iron; and the bioflavonoids lutein, zeaxanthin, and lycopene.