Research indicates that levels of glutamine fall after
exhaustive exercise. One theory is that a shortage of glutamine
is at least partially responsible for the increased frequency of
illness observed in athletes during periods of heavy training
and after endurance competitions. If feeding the body more
glutamine to meet the needs in times of heavy endurance training
and competition would strengthen the immune system, frequency of
illness could be decreased. In a study by Dr. Castell and co-
workers, the consumption of glutamine immediately and 2 hours
after a marathon and ultramarathon reduced the incidence of
infections during the week after competition by 32% when
compared with a placebo. However, in a follow-up study, the
researchers were unable to show a positive effect of glutamine
supplementation on immune function in a group of marathon
runners. In another study, competitive swimmers taking a
glutamine supplement during a season reported fewer symptoms of
chest congestion and frequency of coughing. On