What it's actually good for
Vitamin A is essential for vision (particularly night vision), immune defense, and the maintenance of epithelial tissues throughout the body. Deficiency is the leading cause of preventable childhood blindness globally and significantly increases susceptibility to infections. In well-nourished populations, most people get sufficient vitamin A from diet (liver, dairy, eggs, and beta-carotene from colorful vegetables). Supplementation is most justified for those with restricted diets, fat malabsorption conditions, or documented deficiency. The narrow therapeutic window of preformed vitamin A means more is not better — excess is genuinely toxic, making this a supplement where dosing precision matters.