Home > Nutrition > Sport > Supplements > Vitamin C

Vitamin C, also known as ascorbic acid, is an essential water-soluble nutrient found in lots of fruits and vegetables. It plays an important role in immunity mainly due to its antioxidant capacity, antimicrobial and antiviral actions. Vitamin C occurs in high concentrations in leucocytes but during a common cold, the levels fall dramatically when oxidative stress increases. Vitamin C is a scavenger of these reactive oxidative species and hence can reduce excessive tissue damage during an infection. 

---

---

Deficiency is uncommon, but boosted levels can bolster immune function, and decrease infection risk. Research has shown that regular supplementation with Vitamin C helps reduce the duration of the common cold as well as the severity of its symptoms. Up to ~50% reduction of the incidence of URTI’s has been seen in those who exercise heavily, when oxidative stress increases, while supplementing with Vitamin C.  

The best dietary sources of Vitamin C include, but are not limited to, citrus fruits, tomatoes, potatoes, red and green peppers, kiwifruit, broccoli, strawberries, brussels sprouts, and cantaloupe/rockmelon. The recommended daily intake (RDI in Australia) is 45mg daily for the general population.

Vitamin C in foods and in supplementation form is safe at intakes up to 1,800 mg/day for children, depending on age, and up to 2,000 mg/day for adults. Chronic megadoses (<1g) can have a cellular blunting effect on training adaptations that athletes strive to gain for performance improvements.

The potential benefit of Vitamin C supplementation on reducing the incidence of upper respiratory track infections during heavy training periods, or travel, needs to be weighed against the facts around regular intakes of megadoses (<1g) that can have negative performance effects.

---

---

Related Pages

• Guide to Athletic Supplements
• Supplements and the Athlete's Immune System — some supplements are thought to prevent exercise-induced immune suppression and provide protection from infection.
• Vitamin Supplementation — the good and the bad.
• Antioxidants — all about antioxidant supplementation and performance