Herb Garden

Immune Modulation and Pathogen Defense
Ascorbic acid plays a critical role in both the innate and adaptive immune systems. It accumulates in phagocytic cells, such as neutrophils, and can enhance chemotaxis and phagocytosis, effectively generating reactive oxygen species (ROS) to ultimately destroy microbes. [1,2] Clinical reviews suggest that while regular supplementation may not prevent the general population from acquiring the common cold, it consistently reduces the duration and severity of symptoms. [3] Furthermore, ascorbic acid contributes to the maintenance of cellular integrity by protecting the host's cells from the oxidative burst associated with the immune response to pathogens. [2]

Collagen Synthesis and Tissue Repair
Beyond immunity, ascorbic acid is an obligate cofactor for the enzymes prolyl and lysyl hydroxylase, which are responsible for stabilizing the tertiary structure of collagen. [4] This function makes it indispensable for connective tissue health, wound healing, and the maintenance of blood vessel integrity. Because of its potent antioxidant capacity, it also serves as a primary defense against environmental oxidative stress (such as UV radiation) in the skin. [5] Studies indicate that optimal intake is associated with better skin appearance and a reduction in tissue damage markers. [4]

Toxicity
Ascorbic acid has low toxicity and is widely tolerated because it is water-soluble; excess amounts are efficiently excreted by the kidneys. [6] The primary adverse effects of high-dose ingestion (>2000 mg/day) are gastrointestinal disturbances, such as osmotic diarrhea and abdominal cramping, caused by the unabsorbed vitamin in the gastrointestinal tract. [7] While generally safe, there is a theoretical concern regarding hyperoxaluria and kidney stones in individuals with a history of renal disorders, as oxalate is a metabolic end-product of vitamin C. [6,7]