Evidence Level
Vitamin C's role in skin health is supported by biochemical necessity and extensive epidemiological data. Pullar et al. (2017) published a comprehensive review in Nutrients concluding that vitamin C is essential for collagen synthesis, provides photoprotection, and improves multiple markers of skin aging. Cosgrove et al. (2007) analyzed data from 4,025 women in the first National Health and Nutrition Examination Survey and found that higher vitamin C intake was significantly associated with lower odds of wrinkled appearance and skin dryness, independent of age, race, and sun exposure. While topical vitamin C (10-20% L-ascorbic acid) has the most direct evidence for skin improvements, oral supplementation maintains the systemic antioxidant pool necessary for ongoing collagen production and UV defense.