Effect of vitamin C supplements on physical performance

Area of Science:

• Exercise Physiology
• Nutritional Biochemistry
• Sports Science

Background:

• Vitamin C (ascorbic acid) is vital for diet, potentially mitigating exercise-induced oxidative stress.
• Oxidative stress from exercise may play a role in beneficial training adaptations.
• High-dose vitamin C supplementation might interfere with these adaptations.

Purpose of the Study:

• To investigate the impact of vitamin C supplementation on exercise-induced oxidative stress and athletic performance.
• To differentiate the effects of high-dose versus low-dose vitamin C intake on training adaptations.

Main Methods:

• Systematic review and analysis of 12 studies examining vitamin C supplementation and exercise.
• Comparison of outcomes based on varying vitamin C dosages (e.g., >1 g/day vs. ~0.2 g/day).

Main Results:

• High-dose vitamin C (>1 g/day) substantially impaired athletic performance in 4 out of 4 studies reviewed.
• Potential mechanisms include reduced mitochondrial biogenesis.
• Lower doses (~0.2 g/day) from dietary sources did not show significant performance impairment.

Conclusions:

• High-dose vitamin C supplementation may be detrimental to athletic training adaptations and performance.
• Moderate vitamin C intake through fruits and vegetables is likely sufficient for health benefits without compromising training.