Vitamin C
Vitamin C, or ascorbic acid, is an essential water-soluble vitamin. It acts as an antioxidant and enzyme cofactor and is required for collagen synthesis, carnitine production, and several signaling compounds. It also improves absorption of non-heme iron from plant foods.
The DGE vitamin C recommendations are 110 milligrams per day for adult men and 95 milligrams for adult women; the values are higher for smokers and during lactation. These recommendations cover total dietary intake, not a supplement serving. Bell peppers, citrus fruit, berries, kiwifruit, cabbage, broccoli, potatoes, and many other fruits and vegetables contribute. Storage, prolonged heating, and water used in cooking can reduce the amount because vitamin C is sensitive and water-soluble.
Severe deficiency impairs collagen formation and can eventually cause scurvy, with symptoms such as bleeding, poor wound healing, and fatigue. In industrialized countries, severe deficiency is uncommon, but highly restricted intake, malabsorption, or other clinical circumstances can raise risk. Those symptoms are not specific enough for self-diagnosis.
Vitamin C supports normal immune function; it does not create an impenetrable immune "boost." Likewise, collagen synthesis is a biological role, not proof that a large dose builds muscle, repairs every tendon problem, or accelerates recovery. Adequate total nutrition, progressive training, sleep, and appropriate medical care remain separate factors.
Food can readily cover the reference value for many people. High supplemental intakes commonly cause diarrhea, nausea, or abdominal cramps. They may increase urinary oxalate and deserve particular caution in people prone to certain kidney stones or with iron-overload disorders, because vitamin C enhances iron absorption. The NIH vitamin C fact sheet summarizes these safety issues and medication considerations.
Vitamin supplements can address a documented gap or a situation in which food intake is insufficient, but megadosing is not a general strength-training strategy. Count vitamin C from multivitamins, powders, fortified drinks, and standalone products together rather than evaluating each label in isolation.