Vitamin C is an essential nutrient that your body needs to stay healthy. It is found in a variety of fruits and vegetables, as well as in oral supplements. Citrus fruits, such as oranges, kiwi, lemon, and grapefruit, are some of the best sources of vitamin C. Other sources include bell peppers, strawberries, tomatoes, cruciferous vegetables (broccoli, Brussels sprouts, cabbage, cauliflower), and white potatoes.
Vitamin C is also added to some fortified breakfast cereals. Experts agree that vitamin C is one of the safest and most effective nutrients. It may not be the cure for the common cold, but it can provide protection against immune system deficiencies, cardiovascular disease, prenatal health problems, eye diseases, and even skin wrinkles. The maximum tolerable intake level for adults is 2000 mg per day. Smokers may need 35 mg more than non-smokers. Vitamin C functions as a cofactor in many enzymatic reactions in animals (including humans) that mediate a variety of essential biological functions.
It acts as an enzyme substrate or cofactor and electron donor. Steaming or microwaving foods can help retain most of the vitamin C content. The recommended daily amount for adult men is 90 milligrams and 75 milligrams for adult women. Until the late 18th century, many sailors who ventured on long sea voyages with little or no intake of vitamin C contracted or died from scurvy. This is because humans cannot synthesize vitamin C endogenously and must get it from their diet.
In a trial, daily supplements of vitamin C (120 mg) plus molybdenum (30 mcg) for 5 to 6 years significantly reduced the risk of cerebrovascular death by 8% for 10 years of follow-up after the end of the active intervention. Vitamin C is one of many antioxidants that can protect against damage caused by free radicals, toxic chemicals, and pollutants like cigarette smoke. However, clinical trial data on vitamin C are limited by the fact that plasma and tissue concentrations of vitamin C are strictly controlled in humans. The results of most clinical trials suggest that moderate vitamin C supplementation alone or with other nutrients offers no benefit in preventing cancer.