Effect of magnesium on granulocyte function and on the exercise induced inflammatory response

Magnesium status is a well-known modulator of the immune system. In the present study we investigated the effect of magnesium on granulocyte signalling and function. Furthermore, we performed a double-blinded randomised study investigating the effect of a two-month magnesium supplementation period on the exercise-associated alterations in immune function. In vitro incubation of granulocytes in media of different magnesium composition resulted in significant changes in chemotactic peptide-induced calcium transients while basal calcium levels were not affected. Likewise, the stimulus-induced formation of free radicals was affected by extracellular magnesium while phagocytosis of granulocytes was not affected. In the second part of the study we investigated whether a two-month period of magnesium supplementation was able to diminish alterations in immune cell counts and functions after an exercise test until exhaustion. The magnesium status was similar in both human and placebo groups and did not change significantly after the supplementation period. Exhaustive exercise induced an activation of the immune system as indicated by an increase in granulocyte count and a post-exercise lymphopenia. In addition, chemotactic peptide-induced cellular calcium transients were enhanced post-exercise while oxidative burst and phagocytosis were decreased. These results suggest that magnesium is an important modulator of immune cell function under in vitro conditions. However, a magnesium supplementation seems to be unable to prevent any exercise-associated alterations in immune cell function in athletes with balanced magnesium status.