Vitamin C for Exercise-Induced Immune Suppression
B Good Evidence At least one randomized trial supports this, with mostly consistent results.Research suggests regular vitamin C supplementation may reduce post-exercise URTI incidence in athletes, military personnel, and individuals under extreme physical stress. Benefits appear more pronounced in those exposed to severe physical stress.
The Bottom Line
Research suggests regular vitamin C supplementation may reduce post-exercise URTI incidence in athletes, military personnel, and individuals under extreme physical stress. Benefits appear more pronounced in those exposed to severe physical stress.
Key Study Findings
Population: General population
Population: Athletes
Key Statistics
5
Studies
600
Participants
Positive
Grade
Referenced Papers
Dosage & Usage
mg = milligrams · mcg = micrograms (1,000× smaller) · IU = International Units
Commonly Used Dosages
- general:
- 75-90 mg/day
- acuteillness:
- 1,000-2,000 mg/day
- immunesupport:
- 200-1,000 mg/day
Upper limit: 2,000 mg/day
Dosages Studied in Research
| Dosage | Duration | Effect | N |
|---|---|---|---|
| 45% | 988 weeks | Positive | 26282 |
| Probiotics, prebiotics, fatty acids, vitamins | -- | Positive | -- |
| Vitamin C, E, glutamine, zinc | -- | Positive | -- |
Best taken: With meals; divide doses >500 mg for better absorption
Safety & Side Effects
Reported Side Effects
- ⚠ Gastrointestinal distress (nausea, diarrhea, cramps) at high doses
- ⚠ Increased risk of kidney stones in susceptible individuals
- ⚠ Interference with certain lab tests (glucose, occult blood)
- ⚠ Iron overload risk in hemochromatosis patients
Known Interactions
- ● Enhances non-heme iron absorption (beneficial or harmful depending on iron status)
- ● High doses may reduce effectiveness of certain chemotherapy agents
- ● May interfere with anticoagulant therapy (warfarin) at high doses
- ● Aluminum-containing antacids (increased aluminum absorption)
Tolerable upper intake: 2,000 mg/day
Always consult your healthcare provider before starting any supplement.
Frequently Asked Questions
Does Vitamin C help with Exercise-Induced Immune Suppression?
How much Vitamin C should I take for Exercise-Induced Immune Suppression?
Are there side effects of Vitamin C?
How strong is the evidence for Vitamin C and Exercise-Induced Immune Suppression?
Related Evidence
Other ingredients for Exercise-Induced Immune Suppression
Vitamin C for other conditions
References
- [1] Tiziana Galeazzi et al.. Nutrients. 2025. Micronutrient Deficiencies in Pediatric IBD: How Often, Why, and What to Do? doi:10.3390/nu17091425 PubMed
- [2] Ahmed Gouda et al.. Biol Trace Elem Res. 2022. Zinc and L-Ascorbic Acid Dietary Supplementation Affected Antioxidant Status, Heat Shock Protein 70, and Some Immunoglobulins in Japanese Quail Under … doi:10.1007/s12011-021-02884-y PubMed
- [3] Carroll A Reider et al.. Nutrients. 2020. Inadequacy of Immune Health Nutrients: Intakes in US Adults, the 2005-2016 NHANES. doi:10.3390/nu12061735 PubMed
- [4] Omar A Masri et al.. World J Gastroenterol. 2015. Role of vitamins in gastrointestinal diseases. doi:10.3748/wjg.v21.i17.5191 PubMed
- [5] Nils Hovdenak et al.. Eur J Obstet Gynecol Reprod Biol. 2012. Influence of mineral and vitamin supplements on pregnancy outcome. doi:10.1016/j.ejogrb.2012.06.020 PubMed
- [6] Philip C Calder et al.. Br J Nutr. 2002. The immune system: a target for functional foods? doi:10.1079/BJN2002682 PubMed
- [7] D C Nieman. Can J Appl Physiol. 2001. Exercise immunology: nutritional countermeasures. doi:10.1139/h2001-041 PubMed
- [8] D C Nieman. Med Sci Sports Exerc. 2000. Is infection risk linked to exercise workload? doi:10.1097/00005768-200007001-00005 PubMed
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