Vitamin C

Vitamin C is a potent reducing agent/antioxidant in animal species and land plants. Humans rely on vitamin C for the activity of enzymes involved in collagen, carnitine, and norepinephrine synthesis, and vitamin C status may impact physiological health, including risk for infections, cardiovascular disease, and cancer. The recommended daily intake for vitamin C is 90 mg/day for adult men and 75 mg/day for adult women, and the tolerable upper limit is 2000 mg/day. Supplemental vitamin C should not replace high intakes of fruits and vegetables, but may offer health benefits under certain circumstances for some individuals. Low intakes of fresh fruits and vegetables, either by choice or due to scarcity, increase the risk for scurvy, a concern for isolated populations, refugees, cancer patients, the critically ill, and the elderly. Smokers, individuals with diabetes, and adult men living alone are also at risk for suboptimal vitamin C status; in developed countries, current vitamin C deficiency rates range from 8% to 19%. Individuals with a history of renal stone formation or conditions associated with iron overload should use caution when supplementing vitamin C.