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Vitamin C

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Alternative Names

  • Ascorbic Acid
  • L-Ascorbic Acid
  • Ascorbate
  • Vitamin C Supplement
  • Buffered Vitamin C
  • Liposomal Vitamin C
  • Sodium Ascorbate
  • Calcium Ascorbate
  • Ester-C
  • Ascorbyl Palmitate

Background

  • This page refers to the supplement vitamin C

History

  • Early recognition of Scurvy in sailors during the 18th century led to the identification of citrus fruits as a preventative measure[1]
  • In the early 20th century, Albert Szent-Györgyi isolated ascorbic acid (Vitamin C)[2]
  • By the 1970s–1980s, research began exploring Vitamin C supplementation in athletes for immune support and recovery[3]

Introduction

Vitamin C Supplement

Schematic overview of the vitamin C biosynthetic pathway from glucose-6-phosphate to ascorbic acid[4]

General

  • Water-soluble vitamin essential for collagen synthesis, tendon/ligament integrity, and wound healing[5]
  • Potent antioxidant that helps mitigate exercise-induced oxidative stress and muscle damage
  • Supports immune function, particularly during periods of heavy training or competition[6]
  • May aid in iron absorption, important for endurance athletes at risk for deficiency[7]

Terminology / Formulations

  • Ascorbic Acid: pure, most common supplemental form
  • Buffered Vitamin C: mineral ascorbates (e.g., sodium ascorbate, calcium ascorbate) designed to reduce GI irritation
  • Liposomal Vitamin C: encapsulated form aimed at improving absorption and bioavailability
  • Ester-C: calcium ascorbate with metabolites, marketed for prolonged retention
  • Ascorbyl Palmitate: fat-soluble derivative often used in combination antioxidant formulations

Mechanism

  • Cofactor in collagen synthesis → supports tendon, ligament, and cartilage repair[5]
  • Scavenges reactive oxygen species generated during intense exercise
  • Contributes to carnitine synthesis → may support energy metabolism and endurance[6]
  • Enhances immune cell function → may reduce incidence or duration of upper respiratory infections [8]

Controversy

  • High-dose antioxidant supplementation may blunt mitochondrial and muscle adaptation to endurance training [9]
  • Inconsistent evidence regarding reduction in muscle soreness or performance enhancement[5]
  • Routine high-dose supplementation is not universally recommended for well-nourished athletes[7]
  • Emphasis is shifting toward dietary sources rather than chronic high-dose supplementation[6]

Athletic Performance Benefits

Foods rich in vitamin C

Immune Function / Illness Prevention

  • May reduce incidence of upper respiratory tract infections (URTI) in athletes undergoing heavy training loads [10]
  • Can shorten duration and severity of URTI symptoms, helping maintain training consistency [11]
  • Supports neutrophil and lymphocyte function during physiologic stress[6]
  • May be particularly beneficial in athletes exposed to cold environments or prolonged endurance events [12]

Recovery / Muscle Damage

  • Reduces exercise-induced oxidative stress following high-intensity or prolonged exercise[5]
  • May attenuate secondary muscle damage related to free radical formation
  • Mixed evidence for reduction in delayed onset muscle soreness (DOMS)
  • May support faster return to baseline function following intense training sessions[7]

Tendon / Ligament / Connective Tissue Health

  • Essential cofactor for collagen synthesis, supporting tendon and ligament structure[5]
  • May enhance healing following tendon or ligament injury when nutritional status is adequate[6]
  • Supports cartilage health and joint integrity under repetitive load [13]
  • May be useful adjunct in rehabilitation phases requiring tissue remodeling[7]

Endurance / Energy Metabolism

  • Required for carnitine synthesis, facilitating fatty acid transport and aerobic metabolism[6]
  • May reduce fatigue in individuals with subclinical deficiency[7]
  • Limited evidence for direct improvements in VO₂ max or endurance performance in well-nourished athletes
  • May support performance indirectly through improved recovery and reduced illness burden

Iron Absorption / Hematologic Support

  • Enhances absorption of non-heme iron, supporting hemoglobin and oxygen delivery[7]
  • May help prevent iron deficiency anemia in endurance athletes [14]
  • Particularly relevant for female athletes and those with dietary restrictions

Antioxidant Protection

  • Neutralizes reactive oxygen species generated during high-intensity exercise[5]
  • Helps maintain cellular membrane integrity during physiologic stress[6]
  • May reduce oxidative biomarkers following endurance exercise
  • Excessive supplementation may blunt adaptive signaling pathways in muscle [15]

Other Health Benefits

Vitamin C Supplement

Vitamin C metabolism and activities. Vitamin C, in humans, must be introduced by daily intake through diet. It plays crucial roles both for the proper function of healthy organs and tissues and for tissue repair and regeneration. VitC may act as a scavenger against reactive oxygen species (ROS) and as a chelator, for example, iron metabolism. Both VitC and its catabolic product, dehydroascorbate (DHA), are excreted through urine.[16]

Skin Health / Wound Healing

  • Essential for collagen synthesis, supporting skin integrity and accelerated wound healing[6]
  • May improve dermal repair and reduce healing time following injury or surgery [17]

Cardiovascular Health

  • Supports endothelial function and nitric oxide availability, contributing to vascular health [18]
  • May modestly reduce blood pressure, particularly in individuals with hypertension [19]

Cognitive Function / Neurologic Health

  • Acts as an antioxidant in the central nervous system, protecting against oxidative stress [20]
  • May support neurotransmitter synthesis, including dopamine and norepinephrine [21]

Eye Health

  • Contributes to antioxidant protection in the lens, potentially reducing risk of cataract formation [22]
  • Included in combination formulations (e.g., AREDS) for slowing progression of age-related macular degeneration [23]

Cancer / Antioxidant Defense

  • Functions as an antioxidant that may help reduce oxidative DNA damage [24]
  • Epidemiologic studies suggest diets high in vitamin C–rich foods are associated with lower cancer risk, though supplementation data are inconsistent[25]

Iron Metabolism / Anemia Prevention

  • Enhances absorption of non-heme iron in the gastrointestinal tract
  • May reduce risk of iron deficiency anemia in at-risk populations [26]

Respiratory Health

  • May reduce severity and duration of respiratory infections, particularly under physical stress [27]
  • Some evidence suggests benefit in exercise-induced bronchoconstriction [28]

Metabolic / Endocrine Health

  • May improve markers of oxidative stress and inflammation in metabolic conditions [29]
  • Potential role in improving insulin sensitivity, though evidence remains mixed [30]

Gout / Uric Acid Regulation

  • May lower serum uric acid levels through increased renal excretion [31]
  • Associated with reduced risk of gout in some longitudinal studies [32]

Dosing

  • The adult RDA for vitamin C is 90 mg/day for men and 75 mg/day for women; people who smoke need an additional 35 mg/day. For most athletes, routine daily needs are generally met through diet unless there is deficiency, poor intake, or a specific clinical reason to supplement.[25]
  • Oral absorption is most efficient at moderate intakes; at 30–180 mg/day, about 70%–90% is absorbed, but absorption falls substantially at higher doses.
  • In sport-specific guidance, the Australian Institute of Sport notes that 500–1000 mg/day acutely during illness may be considered for some athletes under supervision, but routine unsupervised use is not generally advocated[33]

Safety Profile

  • Vitamin C is generally well tolerated because it is water soluble and excess absorbed vitamin C is excreted in the urine[25]
  • The tolerable upper intake level for adults is 2,000 mg/day from food plus supplements
  • In athletes, short-term moderate supplementation is usually safe, but chronic high-dose antioxidant use should be approached carefully because it may not add benefit and may affect training adaptation[33]

Adverse Effects

  • The most common adverse effects of high oral intakes are diarrhea, nausea, and abdominal cramps[25]
  • High vitamin C intake can increase urinary oxalate and has been associated with a higher risk of kidney stones in susceptible individuals
  • Other reported effects, such as reduced vitamin B12 or copper levels, dental enamel erosion, and allergic responses, have been described, though some earlier concerns were not consistently confirmed

Pharmacokinetics

  • Vitamin C absorption is dose dependent and uses active intestinal transport; tissue and plasma levels are tightly regulated by the body[25]
  • At intakes above 1 g/day, absorption falls to less than 50%, and unmetabolized ascorbic acid is excreted in the urine.
  • Oral dosing shows a ceiling effect: 1.25 g/day produces mean peak plasma concentrations around 135 micromoles/L, and even very large oral doses do not approach the concentrations achievable with IV vitamin C.

Interactions

  • Vitamin C supplements may interact with chemotherapy and radiation therapy; because the effect of antioxidants during cancer treatment remains controversial, high-dose use should be discussed with the treating oncologist[25]
  • In combination with other antioxidants, vitamin C may blunt the HDL rise seen with niacin/simvastatin therapy, so clinicians may want to monitor lipids in patients taking both
  • For athletes, the most practical “interaction” concern is with other antioxidant supplements, since stacking high-dose antioxidants may increase the chance of GI effects and may theoretically dampen desired training adaptations. [34]

WADA Considerations

  • Vitamin C itself is not listed on the 2026 WADA Prohibited List. [35]
  • However, dietary supplements remain a contamination risk for tested athletes, even when the intended ingredient is not prohibited. [36]
  • Global DRO specifically states that its database does not contain information on dietary supplements, so athletes should not use a vitamin C supplement label alone as anti-doping assurance. [37]
  • If an athlete chooses to use a vitamin C supplement, USADA recommends using products that are NSF Certified for Sport to reduce, though not eliminate, the risk of a positive test from contamination. [38]

See Also

References

  1. ↑ Carpenter, Kenneth J. The History of Scurvy and Vitamin C. Cambridge University Press, 1986.
  2. ↑ Szent-Györgyi, Albert. Studies on Biological Oxidation and Vitamin C. Nobel Lecture, 1937.
  3. ↑ Hemilä, Harri. "Vitamin C and Exercise-Induced Stress." Sports Medicine, vol. 19, no. 2, 1995, pp. 129–142.
  4. ↑ Xu, Yichen, et al. "Vitamin C in cardiovascular disease: From molecular mechanisms to clinical evidence and therapeutic applications." Antioxidants 14.5 (2025): 506.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Peake, Jonathan M., et al. “Antioxidants, Exercise, and Oxidative Stress: An Update.” Sports Medicine, vol. 37, no. 4–5, 2007, pp. 361–379.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 Carr, Anitra C., and Silvia Maggini. “Vitamin C and Immune Function.” Nutrients, vol. 9, no. 11, 2017, p. 1211.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 Maughan, Ronald J., et al. “Dietary Supplements.” Journal of Sports Sciences, vol. 36, no. 1, 2018, pp. 1–2.
  8. ↑ Hemilä, Harri, and Elizabeth Chalker. “Vitamin C for Preventing and Treating the Common Cold.” Cochrane Database of Systematic Reviews, 2013, Issue 1.
  9. ↑ Paulsen, Gøran, et al. “Vitamin C and E Supplementation Hampers Cellular Adaptation to Endurance Training in Humans.” The Journal of Physiology, vol. 592, no. 8, 2014, pp. 1887–1901.
  10. ↑ Hemilä, Harri, and Elizabeth Chalker. “Vitamin C for Preventing and Treating the Common Cold.” Cochrane Database of Systematic Reviews, 2013, Issue 1.
  11. ↑ Hemilä, Harri, and Elizabeth Chalker. “Vitamin C for Preventing and Treating the Common Cold.” Cochrane Database of Systematic Reviews, 2013, Issue 1.
  12. ↑ Hemilä, Harri. “Vitamin C and Infections.” Nutrients, vol. 9, no. 4, 2017, p. 339.
  13. ↑ Pullar, Juliet M., et al. “The Roles of Vitamin C in Skin Health.” Nutrients, vol. 9, no. 8, 2017, p. 866.
  14. ↑ Lane, David J. R., and Des R. Richardson. “The Active Role of Vitamin C in Mammalian Iron Metabolism.” Free Radical Biology and Medicine, vol. 75, 2014, pp. 69–83.
  15. ↑ Paulsen, Gøran, et al. “Vitamin C and E Supplementation Hampers Cellular Adaptation to Endurance Training in Humans.” The Journal of Physiology, vol. 592, no. 8, 2014, pp. 1887–1901.
  16. ↑ D′ Aniello, Cristina, et al. "Vitamin C in stem cell biology: impact on extracellular matrix homeostasis and epigenetics." Stem cells international 2017.1 (2017): 8936156.
  17. ↑ Pullar, Juliet M., et al. “The Roles of Vitamin C in Skin Health.” Nutrients, vol. 9, no. 8, 2017, p. 866.
  18. ↑ Frei, Balz, et al. “Cardiovascular Disease and Antioxidant Vitamins.” Circulation, vol. 97, no. 16, 1998, pp. 1420–1425.
  19. ↑ Juraschek, Stephen P., et al. “Effects of Vitamin C Supplementation on Blood Pressure.” The American Journal of Clinical Nutrition, vol. 95, no. 5, 2012, pp. 1079–1088.
  20. ↑ Harrison, Fiona E., and Joseph M. May. “Vitamin C Function in the Brain.” Antioxidants & Redox Signaling, vol. 19, no. 17, 2013, pp. 2066–2085.
  21. ↑ Harrison, Fiona E., and Joseph M. May. “Vitamin C Function in the Brain.” Antioxidants & Redox Signaling, vol. 19, no. 17, 2013, pp. 2066–2085.
  22. ↑ Jacques, Paul F., et al. “Long-Term Nutrient Intake and Early Age-Related Nuclear Lens Opacities.” Archives of Ophthalmology, vol. 119, no. 7, 2001, pp. 1009–1019.
  23. ↑ Age-Related Eye Disease Study Research Group. “A Randomized, Placebo-Controlled, Clinical Trial of High-Dose Supplementation.” Archives of Ophthalmology, vol. 119, no. 10, 2001, pp. 1417–1436.
  24. ↑ Frei, Balz, et al. “Cardiovascular Disease and Antioxidant Vitamins.” Circulation, vol. 97, no. 16, 1998, pp. 1420–1425.
  25. ↑ 25.0 25.1 25.2 25.3 25.4 25.5 National Institutes of Health Office of Dietary Supplements. “Vitamin C Fact Sheet for Health Professionals.” 2023.
  26. ↑ Lane, David J. R., and Des R. Richardson. “The Active Role of Vitamin C in Mammalian Iron Metabolism.” Free Radical Biology and Medicine, vol. 75, 2014, pp. 69–83.
  27. ↑ Hemilä, Harri. “Vitamin C and Infections.” Nutrients, vol. 9, no. 4, 2017, p. 339.
  28. ↑ Hemilä, Harri. “Vitamin C May Alleviate Exercise-Induced Bronchoconstriction.” BMJ Open, vol. 3, no. 6, 2013.
  29. ↑ Ellulu, Mohammed S., et al. “Effect of Vitamin C on Inflammation and Metabolic Markers.” International Journal of Preventive Medicine, vol. 6, 2015.
  30. ↑ Afkhami-Ardekani, Mahmood, and Mojgan Shojaoddiny-Ardekani. “Effect of Vitamin C on Blood Glucose.” Diabetes, Obesity and Metabolism, vol. 9, no. 5, 2007, pp. 755–758.
  31. ↑ Juraschek, Stephen P., et al. “Effects of Vitamin C Supplementation on Serum Uric Acid.” Arthritis Care & Research, vol. 63, no. 9, 2011, pp. 1295–1306.
  32. ↑ Choi, Hyon K., et al. “Vitamin C Intake and the Risk of Gout in Men.” Archives of Internal Medicine, vol. 169, no. 5, 2009, pp. 502–507.
  33. ↑ 33.0 33.1 Australian Institute of Sport. “Vitamin C.” Australian Sports Commission, accessed 15 Apr. 2026, www.ausport.gov.au/ais/nutrition/supplements/group_b/antioxidants/vitamin-c
  34. ↑ Maughan, Ronald J., et al. “IOC Consensus Statement: Dietary Supplements and the High-Performance Athlete.” British Journal of Sports Medicine, vol. 52, no. 7, 2018, pp. 439-455.
  35. ↑ World Anti-Doping Agency. “Prohibited List.” WADA, effective 1 Jan. 2026, www.wada-ama.org/en/resources/world-anti-doping-code-and-international-standards/prohibited-list
  36. ↑ U.S. Anti-Doping Agency. “There are Risks Associated with Using Supplements.” USADA, accessed 15 Apr. 2026, www.usada.org/substances/supplement-connect/realize-safety-issues-exist/
  37. ↑ Global Drug Reference Online. “Home.” Global DRO, accessed 15 Apr. 2026, www.globaldro.com/Home
  38. ↑ U.S. Anti-Doping Agency. “Reduce Your Risk of Testing Positive or Experiencing Adverse Health Effects.” USADA, accessed 15 Apr. 2026, www.usada.org/substances/supplement-connect/reduce-risk-testing-positive-experiencing-adverse-health-effects/
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