Although vision loss is an issue facing the aging population, proper nutrition can help prevent and possibly reverse the most common visual disorders, namely cataracts and macular degeneration.
Cataracts are the leading cause of decreased vision in adults older than 65 and the leading cause of blindness in the world. Cataract surgery is the most common surgical procedure for elderly Americans, costing Medicare about $3.5 billion per year.
Cataract formation is associated with several biochemical changes in the eye's lens: decreased levels of the key antioxidants glutathione and vitamin C; increased lipid, amino acid, and protein oxidation; loss of amino acids; and decreased lens metabolism.
Long-term intake of over 1,000 mg vitamin C per day has been linked with a substantially reduced risk of cataracts. The U.S. Recommended Dietary Allowance for vitamin C is 60 mg, but that measurement is only the minimal amount needed to stave off deficiency conditions. To get enough vitamin C into the lens of the eye, one must have more than survival amounts of vitamin C in the blood.
Other helpful antioxidants include vitamin E, selenium, glutathione, bioflavonoids, and carotenoids. One study found men who ate the greatest amounts of the carotenoids lutein and zeaxanthin were 18% less likely to develop cataracts.
Supplementing with bilberry (Vaccinium myrtillus) and vitamin E halted cataract formation in 49 of 50 patients in one study. Beta-carotene helps protect the lens of the eye from excessive oxidation.
In another study, 38 people took a nutritional supplement containing beta carotene, vitamins C and E, copper, manganese, riboflavin, selenium, and zinc. The supplement improved vision in 40% of 38 regular users, compared to 16% who improved in the intermittent-use control group. After six months, vision and contrast sensitivity improved in 88% of those who supplemented regularly.