How Much Vitamin C Do Runners Need for Peak Performance?

December 13, 2025 •

4 min read

Intense, prolonged exercise like running can temporarily increase oxidative stress and suppress the immune system, making adequate nutrition, particularly vitamin C, vital. Understanding how much vitamin C do runners need is key for optimal performance, faster recovery, and overall health.

Quick Summary

Runners require sufficient vitamin C for immune function, collagen synthesis, and antioxidant protection against exercise-induced oxidative stress. The right dosage depends on training intensity and dietary intake, with a food-first approach recommended over mega-doses.

Key Points

Standard Intake: Most runners can meet their needs (75-90mg daily) through a balanced diet rich in fruits and vegetables.
Higher Needs: Training intensity and stress can increase a runner's requirement for vitamin C to support the immune system and recovery.
Antioxidant Balance: While vitamin C is an important antioxidant, mega-doses may interfere with the body's natural training adaptations. Moderation is key.
Collagen Support: Vitamin C is vital for collagen synthesis, helping to maintain strong connective tissues like tendons and ligaments that endure stress during running.
Enhanced Iron Absorption: Consuming vitamin C with plant-based iron sources can significantly improve absorption, which is critical for preventing iron deficiency in runners.
Food First Approach: Always prioritize whole food sources over supplements for a full range of nutrients and better overall health.
Supplement Strategically: Consider moderate supplementation (e.g., 200-500mg) during periods of high-stress training or illness, but consult a professional.

The Importance of Vitamin C for a Runner's Body

Vitamin C, or ascorbic acid, is a water-soluble vitamin that plays several crucial roles in the human body, with unique significance for runners. Unlike some vitamins, it is not stored by the body in large amounts, meaning a consistent daily intake is necessary. For athletes, especially those engaged in regular, intense training, the demands on the body are higher, increasing the importance of maintaining optimal vitamin C levels for recovery and performance.

Immune System Support

Regular, high-volume running can place considerable stress on the body, leading to a temporary dip in immune function. This 'open window' of immune suppression can increase a runner's susceptibility to upper respiratory tract infections. Vitamin C is well-known for its role in supporting the immune system by bolstering the function of various immune cells, helping to reduce the incidence and duration of colds, particularly in physically stressed individuals like marathon runners.

Antioxidant Protection and Recovery

During intense exercise, the body's metabolic processes create free radicals, which can cause oxidative damage to cells and muscle tissue. Vitamin C is a potent antioxidant that helps neutralize these free radicals, mitigating exercise-induced oxidative stress and inflammation. This action can help reduce post-exercise muscle soreness (DOMS) and accelerate recovery. However, studies suggest that excessive antioxidant supplementation, including high-dose vitamin C, might actually blunt some of the beneficial training adaptations the body makes in response to oxidative stress signals. A balanced approach is therefore critical.

Collagen Synthesis for Joint and Tissue Health

Running is a high-impact sport that places significant stress on connective tissues, including tendons, ligaments, and cartilage. Vitamin C is an essential cofactor for collagen synthesis, the structural protein that maintains the integrity and resilience of these tissues. Adequate vitamin C intake is therefore crucial for repairing and strengthening connective tissues, helping to prevent injuries and supporting faster recovery from tendon or ligament issues. For this reason, supplemental collagen is often paired with vitamin C to enhance absorption and effectiveness.

Enhanced Iron Absorption

Iron is vital for runners as it is a key component of hemoglobin, the protein in red blood cells that transports oxygen to working muscles. Some runners, particularly women and those on plant-based diets, can be at risk of low iron levels. Vitamin C significantly enhances the absorption of non-heme iron, the type found in plant foods. By pairing a vitamin C-rich food with an iron-rich meal, runners can boost their iron intake and support optimal aerobic performance.

Dosage and Sources for Runners

While the standard recommended daily intake for adults is 75mg for women and 90mg for men, runners may have higher needs due to the increased metabolic demand of training. The safe upper intake level is set at 2,000mg/day, with higher doses potentially causing gastrointestinal issues. The best approach is a food-first strategy, supplemented only when necessary during periods of high training load or illness.

Factors Influencing Vitamin C Needs:

Training Volume and Intensity: Higher mileage and intensity increase oxidative stress, raising the demand for antioxidants.
Dietary Habits: Runners with restrictive or limited diets, especially those low in fruits and vegetables, may need to pay closer attention to their intake.
Stress and Environment: Environmental stressors like pollution or high-altitude training can increase oxidative damage and vitamin C requirements.
Injury and Recovery: During rehabilitation from connective tissue injuries, targeted intake may support healing.

High Vitamin C Food Sources for Runners:

Red and Green Bell Peppers: A single cup of chopped red bell pepper contains a very high concentration of vitamin C.
Oranges and Other Citrus Fruits: A large orange can provide the standard daily recommended amount.
Kiwi: One cup of sliced kiwi offers a significant vitamin C boost.
Strawberries: One cup of strawberries provides more than the daily value.
Broccoli: Another powerhouse vegetable rich in this essential vitamin.

Comparison: Food vs. Supplements


Feature	Food-Based Vitamin C	Supplement-Based Vitamin C
Overall Nutrients	Offers a complete nutritional package, including fiber, minerals, and other antioxidants.	Provides a concentrated dose of ascorbic acid, but lacks the benefits of whole foods.
Absorption	Vitamins from food are generally better absorbed by the body than from supplements.	Absorption can vary. Mega-doses can lead to poor absorption and excretion.
Safety	Extremely safe. Difficult to consume excessive amounts solely through diet.	Safe at recommended doses, but megadoses can cause gastrointestinal issues and potentially blunt training adaptations.
When to Use	Daily, as the primary source for meeting baseline needs.	Can be beneficial during specific high-stress periods, intense training cycles, or post-injury rehabilitation.

Conclusion: Fuel Your Performance Wisely

For most runners, a consistent intake of vitamin C can be achieved by prioritizing a diet rich in brightly colored fruits and vegetables. While supplements can offer a targeted boost during specific high-stress periods, such as intense training or injury recovery, they are not a substitute for a balanced diet. High-dose supplementation should be approached with caution, as it carries risks of side effects and may interfere with some of the body's natural adaptive responses to training. By focusing on whole food sources and considering targeted, moderate supplementation when needed, runners can effectively fuel their immune health, recovery, and performance.

For more in-depth information on the interaction between antioxidants and exercise, consult scientific resources such as this review on Antioxidants in Athlete’s Basic Nutrition.

Frequently Asked Questions

Routine vitamin C supplementation does not prevent colds in the general population but has been shown to reduce the risk by about 50% in individuals under heavy physical stress, like marathon runners. It may also slightly reduce the duration and severity of colds.

For most runners, a food-first approach is best because whole foods provide additional beneficial nutrients like fiber and minerals, and the vitamins are often better absorbed. Supplements are most useful for targeted support during intense training or injury recovery.

Yes, excessive vitamin C intake (over 2,000mg/day) can lead to gastrointestinal issues like stomach upset and diarrhea. Furthermore, some research suggests that very high doses of antioxidants can interfere with the beneficial oxidative stress signals that drive adaptation to exercise.

Vitamin C is essential for synthesizing collagen, a key protein in connective tissues like tendons and cartilage. This helps maintain the integrity of these tissues, which are subject to high impact during running, supporting joint health and aiding in injury recovery.

The ideal timing depends on the goal. For general immune support, taking it with breakfast is fine. For enhanced recovery, taking vitamin C after exercise can help combat oxidative stress generated during the run. If supplementing with iron, take them together to improve absorption.

Yes, vitamin C significantly improves the absorption of non-heme iron from plant-based foods, which is particularly beneficial for vegetarian or vegan runners at a higher risk of iron deficiency. Pairing iron-rich foods with a vitamin C source is a smart strategy.

While severe deficiency (scurvy) is rare, suboptimal levels can manifest as slow-healing wounds, dry skin, easy bruising, a depressed immune system (frequent colds), and fatigue. If experiencing these symptoms, it is best to consult a healthcare provider.