Vitamin C (calcium ascorbate) has scientific support for its use during convalescence, though the evidence is moderate rather than robust. Convalescence refers to the period of recovery after illness, surgery, or trauma, during which the body repairs tissues and restores immune function. Vitamin C is well-known for its roles in immune support, collagen synthesis, and as an antioxidant. Several studies have demonstrated that vitamin C deficiency can impair wound healing, increase susceptibility to infections, and slow recovery. Supplementation with vitamin C can help correct deficiencies and may support faster tissue repair and improved immune response during recovery.

Clinical trials and reviews indicate that vitamin C supplementation can reduce the duration and severity of respiratory infections and may shorten hospital stays for certain patient populations, such as those recovering from surgery or critical illness. For example, a 2019 meta-analysis in Nutrients found that vitamin C reduced the length of ICU stays and duration of mechanical ventilation in critically ill patients. While these benefits are not universally observed in all studies, and high-quality randomized controlled trials are limited, the biological plausibility and moderate clinical evidence justify its use for supporting recovery in convalescence, especially in those at risk of deficiency. Calcium ascorbate is simply a less acidic, well-tolerated form of vitamin C.