Effect of glutamine and protein supplementation on exercise-induced decreases in salivary IgA

Postexercise immune impairment has been linked to exercise-induced decrease in plasma glutamine concentration. This study examined the possibility of abolishing the exercise-induced decrease in salivary IgA through glutamine supplementation during and after intense exercise. Eleven athletes performe d cycle ergometer exercise for 2 h at 75% of maximal oxygen uptake on 3 sep arate days. Glutamine (a total of 17.5 g), protein (a total of 68.5 g/6.2 g protein-bound glutamine), and placebo supplements were given during and up to 2 h after exercise. Unstimulated, timed saliva samples were obtained be fore exercise and 20 min, 140 min, 4 h, and 22 h postexercise. The exercise protocol induced a decrease in salivary IgA (IgA concentration, IgA output , and IgA relative to total protein). The plasma concentration of glutamine was decreased by 15% 2 h postexercise in the placebo group, whereas this d ecline was abolished by both glutamine and protein supplements. None of the supplements, however, was able to abolish the decline in salivary IgA. Thi s study does not support that postexercise decrease in salivary IgA is rela ted to plasma glutamine concentrations.