Vitamin C (ascorbic acid) is an antioxidant found in fruits and vegetables. Scientific evidence suggests vitamin C lowers the risk of developing cataracts. Risk factors for cataracts include smoking, diabetes and steroid use, which deplete the eye's lens of vitamin C.
Also, when taken with other essential nutrients, vitamin C can slow the progression of age-related macular degeneration (AMD) and visual acuity loss. AMD is the leading cause of blindness in people over age 55 in the Western world. The number of people with AMD is expected to triple by 2025.
Benefits to Eye Health
Vitamin C helps promote healthy capillaries, gums, teeth, cartilage and the absorption of iron. Almost all cells of the body depend on it, including those of the eye, where it is concentrated in all tissues. Vitamin C also supports the health of blood vessels in the eye.
Our bodies do not create all of the vitamin C we need. This is why daily intake of vitamin C through diet, nutritional supplements, or fortified foods and beverages is important for maintaining good eye health.
Vitamin C and Cataracts
Numerous studies have linked vitamin C intake and decreased risk of cataracts. In one study, women taking vitamin C for 10 years or more experienced a 64 percent reduction in the risk of developing nuclear cataracts. Researchers estimate that by delaying the onset of cataracts for 10 years, half of cataract-related surgeries could be averted.
Other research showed that women taking a daily supplement with a dosage of 364 mg experienced a 57 percent reduction in their risk of certain types of cataracts.
Taking a supplement with at least 300 mg/day of vitamin C appears to help prevent cataract development.
Vitamin C and Age-Related Macular Degeneration (AMD)
The landmark Age-Related Eye Disease Study (AREDS), sponsored by the National Eye Institute, linked AMD and nutrition. The study showed that people at high risk for the disease who took 500 mg/day of vitamin C, along with beta-carotene, vitamin E and zinc supplementation, slowed the progression of advanced AMD by about 25 percent and visual acuity loss by 19 percent. Other studies have confirmed these results.
The U.S. Food and Drug Administration (FDA) recommends that men get 90 mg/day of vitamin C and women get 75 mg/day.
However, people under stress need more vitamin C than the recommended daily allowance. These groups include smokers, alcoholics, diabetics, pregnant or breast-feeding women, older adults, athletes, and people with chronic diseases who experience environmental stress from heat, cold or radiation. There is little scientifically documented risk in taking higher doses of vitamin C, except for diarrhea.
Vitamin C is found almost exclusively in fruits and vegetables, including citrus fruits such as oranges, lemons, grapefruit and limes. The table above lists foods known to be high in vitamin C. Also, the USDA Nutrient Database offers comprehensive nutritional information on more than 8,000 raw and prepared foods.
If you are not getting enough vitamin C through diet alone, consider adding a vitamin C supplement to your daily routine. However, always consult with a health care professional before taking supplements.
*At this time, the AOA is unaware of any studies that have examined interactions between medications and vitamin C. The AOA also is not aware of any adverse health reports from interactions between medications and vitamin C. However, the AOA recommends consulting with a health care professional before taking any supplement.