Vitamin C

Vitamin C, also known as L-ascorbic acid, is an essential water-soluble micronutrient that the human body cannot synthesize endogenously. It is naturally present in various fruits and vegetables, such as citrus fruits, bell peppers, strawberries, and broccoli. As a potent antioxidant, it protects cells from oxidative stress and is a critical component for the growth, development, and repair of all body tissues. Because it is water-soluble, the body does not store it in large amounts, making regular dietary intake or supplementation necessary for maintaining health.

Vitamin C functions primarily as an electron donor, making it a powerful antioxidant that neutralizes harmful free radicals and regenerates other antioxidants like Vitamin E. It acts as a mandatory cofactor for several enzymes, most notably those responsible for the biosynthesis of collagen, which is essential for the structural integrity of skin, tendons, and bones. Additionally, it facilitates the production of carnitine (for energy metabolism) and catecholamines (like norepinephrine). In the digestive tract, Vitamin C significantly enhances the absorption of non-heme iron from plant-based foods, and within the immune system, it supports various cellular functions of both the innate and adaptive immune responses.

Based on current guidelines from the NIH and the Linus Pauling Institute, the Recommended Dietary Allowance (RDA) is 90 mg for men and 75 mg for women daily. Individuals who smoke require an additional 35 mg per day to offset oxidative damage from tobacco. For optimal health and immune support, research suggests an intake of 200–500 mg per day, as doses above 1,000 mg show significantly decreased absorption efficiency. It is vital to stay below the Tolerable Upper Intake Level (UL) of 2,000 mg to prevent adverse effects. Individuals with chronic kidney disease should limit intake to 100 mg daily to avoid oxalate accumulation, and those with G6PD deficiency or hemochromatosis should consult a physician before high-dose use.