Ascorbic acid (vitamin C) is a vital nutrient that participates in numerous physiological activities, including functioning as a principal antioxidant, facilitating collagen formation, acting as a cofactor for critical enzymes, regulating neurotransmitter activity, and offering organ protection. This review examines and synthesizes current knowledge on the physiological roles, organ-specific protective effects, dose-dependent mechanisms, and potential toxicity of ascorbic acid in human health. A thorough literature review was conducted, evaluating experimental, clinical, and epidemiological studies concerning the biochemical roles of ascorbic acid, its effects on organ systems, its reactions to stress, and the associated risks and benefits of varying dosages in both human and animal models. Ascorbic acid inhibits reactive oxygen species, diminishing oxidative stress and inflammation, particularly during periods of bodily stress. It is a crucial enzymatic cofactor in biochemical pathways that synthesize neurotransmitters and other metabolic byproducts. It is crucial for collagen synthesis. A recent study indicates that ascorbic acid may modulate stress and the neuroendocrine system by altering neurotransmitter activity, decreasing cortisol levels, and mitigating oxidative damage associated with stress. These effects are thoroughly documented in animals. Principal organs such as the liver, gastrointestinal tract, and cardiovascular system exhibit dose-dependent protective benefits. Nephrotoxicity and hepatotoxicity may manifest at high doses or under specific medical conditions. Ascorbic acid exerts broad-spectrum protective actions on many organs, contingent on the dosage administered. These benefits are attributable to its antioxidant and enzymatic activity. Despite its well-documented physiological benefits, especially at recommended intake levels, caution is warranted regarding potential toxicity at high doses, and further research is needed to define acceptable therapeutic ranges for different clinical situations.
Tiwari et al. (Sun,) studied this question.