Athlete health: harnessing the power of microbes!

When it comes to health and immunity, exercise is something of a double-edged sword. Regular exercise over months and years is now believed to help keep illness and infection at bay by preventing or even reversing the age-related decline in immunity observed in the population at large⁽¹⁾. In the short term however, heavy or prolonged bouts of exercise – eg running a marathon - generates a temporary dip in immunity following the strenuous effort, often referred to as post-exercise immune depression⁽²⁾. Although this dip in immune function is transitory, it nevertheless creates favorable conditions for viruses and bacterial infections after the effort, especially in the upper respiratory tract⁽³⁾. This can lead to an increase in the incidence of upper respiratory tract infections (URTIs – coughs, colds, sore throats etc) in the days following the event^(3,4).

Nutritional defenses

The good news is that excellent nutrition can mitigate the stress in the immune system generated by exercise. This includes the use of such nutrients such as protein, carbohydrate, amino acids and vitamins/minerals during and after exercise (for a more in-depth discussion, readers are advised to see this article)^(5,6). In more recent years however, there’s been an increasing interest in the use of probiotic supplements for enhancing athlete immunity. As we have discussed in previous SPB articles, a growing body of research has demonstrated that the use of probiotic supplementation produces immune and gastrointestinal system benefits. These include:

·        An increase in circulating leucocytes (key cellular components of the immune system)⁽⁷⁾.

·        Stimulation of the maturation of immune cells present in the gut, such as lymphocytes, macrophages, and dendritic cells⁽⁸⁾.

·        With certain strains of probiotics (eg Lactobacillus casei and Lactobacillus fermentium), a reduced risk of URTIs and flu-like symptoms, and an increase in the concentration of a key immune antibody known as ‘sIgA’ (the body’s first line of defence against pathogens) in gut mucosal tissues⁽⁹⁾.

As we also explained in a previous SPB article, these immune effects translate to real-world benefits in those undertaking long or strenuous bouts of exercise. For example, a study published in the journal ‘Nutrients’ investigated the effects of probiotic supplementation on the production of key immune cells and subsequent URTIs after running a marathon⁽¹⁰⁾. It found that marathoners who supplemented with a blend of Lactobacillus acidophilus, Lactobacillus paracasei, Lactococcus lactis, Bifidobacterium animalis, and Bifidobacterium bifidum for 30 days before a marathon mounted a stronger and more targeted immune response after their marathon efforts than those who didn’t. Importantly, this resulted in a lower incidence of URTI symptoms and severity in the probiotic-supplemented runners in the following week (see figures 1a and 1b).

Figures 1a (top) and 1b (bottom): Symptom incidence and severity in probiotic vs. placebo athletes