Nutrition and Athlete Immune Health: What Current Research Suggests

Key Takeaways

• Studies found staying healthy may help athletes maintain more consistent training.   

• Research indicates that illness can result in missed or restricted training among elite athletes.   

• Current evidence suggests sleep, stress, travel, exposure to illness, low energy availability, and recent illness may influence illness risk.   

• Researchers describe immune resistance and immune tolerance as complementary strategies involved in the body's response to infection.   

• According to research, adequate nutrition can help supports normal immune function, while researchers continue to explore whether certain nutritional strategies may also help reduce the burden of illness.   

• Evidence reviewed indicates that probiotics, vitamin C, vitamin D, and zinc may have potential benefits in specific situations, although findings and applications vary.   

• Research suggests nutrition, adequate sleep, stress management, good hygiene, and appropriate recovery may all contribute to supporting athlete immune health.  

This article summarizes findings from published scientific research, including research conducted, reviewed, or compiled by GSSI scientists. The information presented reflects the findings, observations, and interpretations of the studies discussed and is provided for general educational and informational purposes only. Individual responses, outcomes, and needs may vary. This content should not be interpreted as medical, health, safety, or training advice.

Missing a workout because you're tired is frustrating. Missing weeks of training because you're sick may completely derail a season.  

For elite athletes, illness can be much more than an inconvenience. Every missed session may reduce training consistency, interrupt adaptation, and compromise performance. Research reviewed suggests that staying healthy may therefore be just as important to consistent training as building strength, endurance, or speed.  

This Sports Science Exchange review introduces a different way of thinking about athlete immune health. Instead of focusing only on making the immune system stronger, researchers propose that nutrition may also help support immune tolerance - the body's ability to control infection while limiting unnecessary inflammation and tissue damage.  

Historically, much of the focus has been on strengthening immune defenses. Current research is also exploring the potential role of nutrition in supporting immune tolerance and reducing the overall burden of illness.  

Understanding this balance may change how athletes think about nutrition, recovery, and staying healthy throughout the year.  

Why Athlete Immune Health Matters for Performance  

Elite performance may depend, in part, on consistent training.  

Researchers report that illness is the second most common reason athletes seek medical care during training and major competitions. In a three-year surveillance study of Olympic athletes, approximately 70% of illnesses resulted in complete time away from training or competition, while the remaining illnesses restricted performance by reducing training intensity or volume.  

Research reviewed also found that medal winners at Olympic Games and World Championships experienced fewer and shorter upper respiratory infections than less successful athletes.  

The takeaway is straightforward: athletes who experience fewer or shorter illnesses may be better able to maintain consistent training, which can help support their performance goals.  

How Illness May Reduce Training and Competition Performance  

The impact of illness can extend beyond a few missed workouts.  

Evidence reviewed indicates that upper respiratory infections may account for a significant proportion of lost training days, while more severe infections can prevent athletes from competing altogether.  

Researchers also note that exercising with illnesses involving symptoms below the neck may prolong recovery and, in rare cases, may contribute to serious medical complications such as myocarditis, rhabdomyolysis, or exertional heat illness.  

For athletes, reducing the impact of illness may therefore be an important part of maintaining training availability throughout a season.  

What Research Suggests About Illness Risk in Athletes  

For many years, exercise scientists believed heavy training temporarily suppressed immunity, creating an "open window" during which viruses could more easily cause infection.  

More recent research challenges that long-standing assumption.  

Current evidence suggests that many of the biggest infection risk factors for athletes may be similar to those affecting the general population. These include:  

• Winter cold and flu season   

• Exposure to sick individuals   

• Poor sleep   

• Psychological stress   

• Anxiety and depression   

• Air travel   

• Low energy availability   

• Recent illness   

Increases in training load may also contribute to illness risk, although current evidence suggests its impact may be smaller than previously thought.  

How the Immune System May Protect Athletes  

Researchers describe the body's defense against bacteria, viruses, and other pathogens through two complementary strategies: immune resistance and immune tolerance.  

Immune resistance works to destroy invading pathogens. Immune tolerance helps control infection while limiting excessive inflammation and tissue damage.  

Research suggests both strategies may be important to athlete immune health. Too little immune resistance may allow pathogens to spread, while an overly aggressive response may damage healthy tissue, increase recovery time, and divert valuable energy away from training and performance.  

Rather than simply aiming for the strongest possible immune response, researchers propose that athlete immune health may depend on maintaining an appropriate balance between fighting infection and limiting unnecessary damage.  

Immune Resistance vs. Immune Tolerance: A Different View of Athlete Immunity 

One of the key ideas explored in this review is that improving athlete immune health may not always be about making the immune system more aggressive.  

Researchers propose that most healthy athletes already possess normal immune resistance. If so, trying to further "boost" immune defenses may provide limited additional benefit.  

Instead, researchers suggest that nutritional strategies supporting immune tolerance may help reduce the overall burden of illness, potentially contributing to milder symptoms, faster recovery, or fewer lost training days.  

This shifts the question from simply, "Can this supplement stop athletes from getting sick?" to another question researchers believe may be important: "Can this supplement reduce how sick athletes become?"  

That distinction offers athletes and coaches a different way to think about nutrition and immune health.  

How Nutrition May Support Athlete Immune Health  

Research highlights adequate nutrition as an important part of supporting normal immune function.  

Macronutrients - carbohydrates, protein, and fat - provide the energy and amino acids needed for immune cell metabolism, antibody production, and protein synthesis.  

Micronutrients, including vitamins and minerals, support antioxidant defenses, DNA synthesis, cellular communication, and regulation of immune activity.  

Researchers emphasize the importance of correcting nutrient deficiencies because inadequate nutrition can impair immune function.  

However, once nutritional requirements are met, additional supplementation intended solely to increase immune resistance has generally shown limited benefits in healthy athletes.  

This may help explain why many products marketed as immune boosters have produced inconsistent results in sports research.  

Instead, several nutritional interventions discussed in the review may have potential roles in supporting immune tolerance or reducing the burden of illness in certain situations.  

Can Probiotics Support Athlete Immune Health?  

Probiotics are live microorganisms that may help maintain a healthy gut microbiome and influence immune function.  

Studies reviewed reported fewer upper respiratory infections, fewer illness days, reduced symptom severity, and improved maintenance of salivary immune markers among athletes receiving probiotic supplementation.  

Although findings remain promising rather than definitive, some probiotic supplements may merit consideration during periods of increased illness risk, particularly before international travel or winter competition.  

Because probiotic products are not all the same, athletes should discuss supplementation options with their physician or sports dietitian before choosing a product.  

May Vitamin C Help Athletes During Heavy Training?  

Vitamin C can function as an important antioxidant that helps limit tissue damage during immune responses.  

Evidence highlighted in the review found that vitamin C supplementation ranging from 250 mg to 1 g per day reduced upper respiratory illness symptoms among athletes exposed to heavy physical stress, including marathon runners and endurance athletes.  

Based on these findings, researchers have suggested vitamin C may have potential utility  during periods of heightened infection risk, such as heavy training blocks or travel.  

What Does Research Say About Vitamin D and Immune Function?  

Vitamin D can play a role in both innate and adaptive immunity.  

Research reviewed notes that vitamin D insufficiency is common among athletes during winter months when sunlight exposure is limited.  

Research evidence supports maintaining adequate vitamin D status, with supplementation appearing to be most beneficial for athletes who are deficient. Research reviewed also indicates that daily or weekly supplementation appears more effective than infrequent high-dose boluses.  

These findings may highlight the importance of maintaining adequate vitamin D status rather than assuming additional supplementation will provide the same benefit for every athlete.  

May Zinc Help Shorten Common Cold Symptoms?  

Unlike many supplements promoted for illness prevention, evidence reviewed for zinc points to a potential role after symptoms have already begun.  

A meta-analysis cited in the review found that approximately 75 mg of elemental zinc per day, started within 24 hours of symptom onset, shortened common cold duration by roughly three days.  

These findings suggest zinc lozenges may have a potential role in reducing the duration of common cold symptoms rather than preventing illness altogether.  

What Strategies May Help Athletes Reduce Their Risk of Illness?  

Based on the evidence discussed in the review, researchers identify practical strategies athletes can use throughout the year:  

• Avoid close contact with people who are sick whenever possible.   

• Stay up to date with recommended vaccinations.   

• Wash hands regularly and avoid touching the face unnecessarily.   

• Avoid training or competing with symptoms below the neck.   

• Manage both physical and psychological stress.   

• Aim for 7-9 hours of quality sleep each night.   

• Maintain adequate energy intake and consume sufficient dietary protein.   

• Consider zinc lozenges at the first signs of a common cold.   

• Consider vitamin C supplementation during periods of increased illness risk.   

• Consider probiotics during winter training or international travel.   

Together, these strategies may reflect a broader approach to athlete immune health - one that considers nutrition alongside sleep, stress, hygiene, recovery, and exposure to illness.  

Key Takeaways on Nutrition and Athlete Immune Health  

Scientific studies have examined whether athlete immune health may be about more than simply "boosting" immunity.  

Research reviewed proposes that balancing immune resistance with immune tolerance may help explain differences in how the body responds to infection and the burden of illness athletes experience.  

According to science, adequate energy intake, sufficient protein, and key micronutrients may help support normal immune function. Evidence reviewed also indicates that probiotics, vitamin C, vitamin D, and zinc may have potential benefits in specific situations, although findings and applications vary across these nutritional strategies.  

Alongside nutrition, research highlights sleep, stress management, good hygiene, and appropriate recovery as potentially important considerations for athlete immune health. Together, these strategies may help athletes reduce disruptions from illness and maintain more consistent training.  

For athletes training in demanding conditions, maintaining appropriate hydration and carbohydrate intake remains an important component of supporting training and recovery. Athletes may incorporate products such as Gatorade Thirst Quencher to help complement a broader evidence-based hydration and fueling strategy.