Vitamin C, or ascorbic acid, is an essential nutrient that humans cannot synthesize.
It acts as a cofactor for enzymes and is an effective antioxidant due to its high electron-donating ability.
The body regulates vitamin C levels through absorption, transport, and excretion, and the amount needed to prevent scurvy is small and easily obtained in most diets.
There is interest in vitamin C's role in preventing diseases like heart disease and cancer, as it may reduce oxidative damage.
Some population studies show a lower risk of chronic diseases with high vitamin C intake, but controlled trials have not confirmed that higher intakes alone prevent these diseases.
The Recommended Dietary Allowance (RDA) had been increased to 75 mg for women and 90 mg for men, based on its antioxidant role. While more than the RDA is usually not helpful for healthy people, it may be important for those with certain conditions.
High intakes are generally well-tolerated, but a Tolerable Upper Level of 2 grams has been set to avoid gastrointestinal upset at one sitting.
Jacob, Robert A, and Gity Sotoudeh. “Vitamin C function and status in chronic disease.” Nutrition in clinical care : an official publication of Tufts University vol. 5,2 (2002): 66-74. doi:10.1046/j.1523-5408.2002.00005.x