Vitamin C
Vitamin C (Ascorbic Acid)
Essential antioxidant vitamin that supports immune function, collagen synthesis, and recovery from intense exercise.
Vitamin C is a water-soluble vitamin that humans cannot produce, making dietary or supplemental intake essential. It's a powerful antioxidant, crucial for immune function, and necessary for collagen production. While deficiency is rare in developed countries, supplementation may benefit those under physical stress, athletes, and smokers.
Mechanisms of Action
Antioxidant Defense
Neutralizes harmful free radicals throughout the body
Immune Cell Function
Supports the production and function of immune cells
Collagen Synthesis
Essential cofactor for building connective tissue
Recommended Dose
500-1000mg
Optimal Timing
- With meals
- Split doses if taking >500mg
Take with food
Best Form
Ascorbic acid or buffered vitamin C
Alternatives: Liposomal vitamin C, Ester-C, Sodium ascorbate
Standard ascorbic acid is well-absorbed and cost-effective. Buffered forms may be gentler on the stomach.
Duration
Minimum: 2 weeks
Optimal: weeks
Cycling: Not required
Note: Splitting doses improves absorption. Taking with food reduces GI upset. Body can only absorb ~200mg at once efficiently.
Immune Support
May reduce cold duration and severity
Reduced Oxidative Stress
Especially beneficial after intense exercise
Skin Health
Supports collagen production for healthier skin
GI Upset
Stomach discomfort at high doses
Safe at recommended doses; upper limit 2000mg/day
Consult doctor; may need to limit intake
May benefit from higher intake (additional 35mg/day recommended)
Who Should NOT Take This
- History of kidney stones (use caution with high doses)
- Hemochromatosis (iron overload disorder)
Drug Interactions
High doses may affect warfarin metabolism
May interfere with some treatments; consult oncologist
May reduce effectiveness when combined with niacin
Possible Side Effects
Tip: Reduce dose; stay under 2000mg/day
Tip: Take with food
Tip: Keep dose under 1000mg if history of stones
Warnings
- Very high doses may increase kidney stone risk
- Megadoses don't provide additional benefit
- May interfere with certain lab tests
Hemilä H, Chalker E • Cochrane Database of Systematic Reviews (2013)
“Regular supplementation had a modest but consistent effect in reducing the duration of common cold symptoms.”
Key Findings:
- Reduces cold duration by 8% in adults
- More effective in those under physical stress
- Doesn't prevent colds in general population
Carr AC, Maggini S • Nutrients (2017)
“Vitamin C supports various cellular functions of both the innate and adaptive immune system.”
Key Findings:
- Supports epithelial barrier function
- Enhances phagocyte function
- Supports lymphocyte function
Braakhuis AJ • International Journal of Sport Nutrition and Exercise Metabolism (2012)
“Vitamin C supplementation attenuates exercise-induced oxidative stress.”
Key Findings:
- Reduces oxidative stress markers after exercise
- May support recovery in athletes
- Benefits most clear in those with inadequate intake
Rawat D et al. • Nutrients (2022)
“High-dose vitamin C may reduce mortality and ICU length of stay in critically ill patients.”
Key Findings:
- Potential benefits in severe infections
- High doses may reduce ICU stay
- Supports immune function during acute illness
Hemilä H, Chalker E • BMC Public Health (2023)
“Vitamin C consistently reduces the severity of the common cold across multiple trials.”
Key Findings:
- Reduces cold severity by ~8%
- Effects consistent across age groups
- Benefits from regular supplementation
AI-discovered studies. Verify citations before citing.
High-dose vitamin C supplementation accelerates recovery from exercise-induced muscle damage: a meta-analysis
Carr AC et al. • Sports Medicine (2024)
This meta-analysis strengthens evidence for vitamin C's role in exercise recovery and muscle damage prevention.
- Vitamin C supplementation reduced muscle soreness by 23% compared to placebo
- Faster recovery of muscle function observed with doses above 1000mg
- Greatest benefits seen in endurance rather than resistance exercise
Vitamin C reduces the severity of common colds: a meta-analysis
Hemilä H, Chalker E • BMC Public Health (2023)
Vitamin C consistently reduces the severity of the common cold across multiple trials.
- Reduces cold severity by ~8%
- Effects consistent across age groups
- Benefits from regular supplementation
Vitamin C Supplementation for the Treatment of COVID-19: A Systematic Review and Meta-Analysis
DOIRawat D et al. • Nutrients (2022)
High-dose vitamin C may reduce mortality and ICU length of stay in critically ill patients.
- Potential benefits in severe infections
- High doses may reduce ICU stay
- Supports immune function during acute illness