Vitamin C is an antioxidant. It protects cells from free-radical damage; builds and maintains collagen and connective tissue; improves iron and folate absorption; and helps wounds heal.

How Much: Recommended dietary allowance (RDA) = 90 milligrams (mg) daily for men; 75 mg for women.  Smokers need an additional 35 mg daily.

Too Much: Tolerable upper limit (UL) of vitamin C is 2,000 mg daily.

Too Little: Weight loss, fatigue; inflamed or bleeding gums, slower healing times; repeated infections and colds.

Foods: Citrus and other fruits, including strawberries, kiwifruit, cantaloupe and tomatoes; bell peppers, broccoli, Brussels sprouts and potatoes. Cooking can destroy the vitamin C content of food. 

Interactions: Aspirin; non-steroidal anti-inflammatory drugs (NSAIDS); certain types of cancer treatments and radiation; statins; certain drugs for HIV/AIDS; and blood thinners. 

Research Note: Vitamin C helps prevent gout by lowering uric acid levels. One large study found 1,500 mg of vitamin C per day – the equivalent of 30 oranges – reduced gout risk by half. Research also suggests that getting at least 500 mg of daily vitamin C can lower blood pressure three to five points – enough to reduce the risk of stroke.