There was a big discussion on the Supertraining list about this topic recently:
http://groups.yahoo.com/group/Supertraining/message/26832
>More importantly, there are several studies showing that glutamine
>supplementation doesn't alter exercise-induced suppression of the
>immune system! The bottom line is that blood glutamine levels,
>whether they drop or not following exercise, don't seem to affect
>immunity to any great extent, which precludes the use of glutamine
>for this reason.
The small reductions in plasma glutamine that follow prolonged endurance
exercise likely do not affect immune function. The reduction is small and
short-lived (approx. 2 hours or so), and plasma glutamine rarely drops below
normal concentrations during this time.
http://groups.yahoo.com/group/Supertraining/message/26906
>>So, would there be any reason for someone who is on a regular
>>resistance training program to supliment glutamine. Or is that just
>>a waste of time and money?
Currently there's no good evidence that glutamine supplementation will offer
benefit to resistance trainers.
My thinking is that its placebo effect. Taking a single amino won't do any more than taking a lot at once (ie, a complete protein source). In fact taking more of one than any other can be detrimental. Whey protein is much, much cheaper than glutamine.