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We all keep getting colds. In sports, they often mean that your ideal training is no longer possible for several days. Find out more about the relationship between diet-specific measures and the immune function. 

Presented by Swiss Sports Nutrition Society

Doing sports on a regular basis certainly benefits your general health and immune system in particular. However, tough endurance loads and extremely intensive training can suppress the immune function for several hours. A drop in blood sugar levels and carbohydrate reserves in the muscles leads to an increase in stress hormones (such as cortisol) and the inflammation parameters. As a result, the function of the immune system becomes suppressed. This is called the «open window», during which you are more susceptible to pathogens. During a long or particularly intensive training unit, however, you can counteract this suppression of the immune system. 

When doing intensive loads, it is recommended that you consume a carbohydrate-rich (sports) drink after a duration of around one hour, primarily to delay the onset of fatigue and achieve a somewhat better performance. This also supports the immune system during the load by counteracting the drop in blood sugar levels and also conserving the glycogen stores. This leads to a smaller increase in the physical stress response. 

A sufficient energy and carbohydrate intake after the sport can also have a positive impact on the immune function. The body can recover better and the carbohydrate reserves in the muscles are thus replenished by the next unit. 

Regular or SPORADIC intake of vitamins? 

Although various nutrients were examined for their alleged effect in supporting the immune system during and immediately after an intensive load (including zinc, Omega-3 fatty acids, plant sterols, antioxidants or glutamine), the results are not really overwhelming. However, a sufficient carbohydrate intake is helpful during and after the sport as are probiotics, vitamin D supplements if you have a low vitamin D level, and possibly vitamin C supplements before an ultra-endurance event as well as zinc lozenges. 

Even if taking vitamin C supplements for a short time after the load reduces the risk of colds, the potentially adverse effects of vitamin or multi-vitamin and mineral supplements should not be forgotten. It was repeatedly observed that high dosages of antioxidant supplements such as vitamin C and E reduce the otherwise existing training effects. The regular, daily intake of such supplements is therefore not recommended. A balanced diet with 5 servings of fruit and vegetables per day seems to provide the body with enough micronutrients to sustain the immune function. In the case of a deficiency, it is recommended that you consult a doctor about taking any supplements (e.g. vitamin D in winter). 

Conclusion 

Probably the most important aspect for a well-functioning immune system in sports is a sufficient energy supply. This is also the reason why there is an increased risk of infection during phases of targeted weight loss. A sufficient intake of proteins, carbohydrates, fats, minerals and vitamins via a balanced diet seems to be the best recipe for maintaining the immune function. 

10 tips to maintain the immune function 

1. Avoid contact with sick people, crowds of people, and shaking hands. 
2. Wash your hands regularly or use hand disinfectant, especially before each meal, and get vaccinated against the flu in winter.  
3. Don’t touch your eyes or nose – this is one of the most common ways to infect yourself. 
4. Avoid stress in general.
5. Avoid over-training and training for too long.
6. Get enough sleep (at least 7 hours a night). 
7. Avoid rapid weight loss and a generally too low energy supply. 
8. Schedule relaxation or adaptation weeks every 2 or 3 weeks. 
9. Do not share any drinking bottles, crockery, etc. 
10. Ensure that the mucous membranes in the nasal cavity do not dry out.

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