Vitamin C is essential, but the smartest strategy is right-sizing—not megadosing. Hit your RDA with everyday foods, keep a modest supplement on standby for off days or illness, and steer clear of routine high intakes above the UL, especially for children. If you have medical conditions or questions about dosing, check with your healthcare provider. With a food-first plate and sensible supplementation, you’ll get the immune support you want—without the tummy troubles you don’t.