Vitamin C (also known as ascorbic acid) is a water-soluble vitamin and a powerful antioxidant. Abundant in fruits and vegetables, vitamin C helps the body form and maintain connective tissue, including collagen found in the cornea of the eye.
Vitamin C also promotes healthy bones, skin and blood vessels, including the delicate capillaries in the retina. Studies suggest long-term consumption of vitamin C also may reduce the risk of forming a cataract and vision loss from macular degeneration.
Unlike most animals, humans are unable to produce vitamin C in the body. So we must get our daily dose of ascorbic acid from our diet. A diet deficient in vitamin C can lead to scurvy — a serious disease characterized by muscle weakness, swollen and bleeding gums, loss of teeth, bleeding under the skin, soreness and stiffness of the joints, anemia, fatigue and depression.
So how much vitamin C do you need? According to the National Institutes of Health, the Recommended Dietary Allowance (RDA) of vitamin C is 90 milligrams (mg) per day for men and 75 mg for women. Research suggests smokers need more vitamin C than nonsmokers.
Many researchers, however, feel you should consume significantly more vitamin C than the RDA. For example, 500 mg was the daily dose of vitamin C used in studies that showed a reduced risk of cataracts. And long-term studies have found that people who take more than 700 mg of supplemental vitamin C per day have a 25 percent lower risk of coronary heart disease than those who don't take vitamin C supplements.
Because it is water-soluble, vitamin C is generally considered safe at high doses. Excess vitamin C is excreted in urine. However, doses greater than 2,000 mg per day may cause nausea and diarrhea, as well as increase the risk of kidney stones.
Excellent natural sources of vitamin C include peppers, citrus fruits, berries, tropical fruits, potatoes, tomatoes and green leafy vegetables. Foods with the highest content of vitamin C are:
Sweet red peppers
Sweet green peppers
The above values are for fresh, raw foods. Cooking and canning foods can decrease their vitamin C content. Light also destroys vitamin C.
This post originally appeared on All About Vision.