Probiotics Benefit Distance Runners
A probiotic called Lactobacillus substantially cuts the rate and length of respiratory illness in professional long distance runners, according to a small study in the British Journal of Sports Medicine. Intensive exercise can subdue the normal immune response, and as a result some athletes are vulnerable to respiratory viruses, such as colds and flu.
During four months of intensive winter training, 20 elite endurance athletes were given either three freeze-dried capsules twice daily of the probiotic Lactobacillus fermentum or a placebo. The treatments lasted 28 days each, interspersed by a month of nothing (washout period) so that by the end of the period, all the athletes had each had the probiotic and placebo.
The researchers assessed treadmill performance, immune response, and the length and severity of respiratory tract infections. There was no difference in running performance between those taking the probiotic and those taking the placebo. But athletes taking the probiotic had less than half the number of days of symptoms of their colleagues taking the placebo. Respiratory symptoms while taking Lactobacillus lasted 30 days compared with 72 days while taking the placebo. Symptoms also tended to be less severe.
The authors say that probiotics seem to increase systemic immunity, possibly by boosting the activity of T cells.