Glutamine
What is it? A conditionally-essential amino acid that makes up 60% of your free amino acid pool.
Why is it good? Glutamine is used to repair muscles, strengthen the immune system and raise growth hormone levels. It is very important for muscle repair, as well as the building and maintenance of lean muscle mass. Supplemental glutamine has even been shown to prevent immune system depression resulting from overtraining.
How much should you take? Take approximately 10 grams daily during your first week. Dosage may then be increased to 20 grams -- 10 twice daily -- for three weeks. Cycle off for 10 days, then repeat dosage.
Health warnings: Exceeding the recommended dosage can cause intestinal upset.
took me about 2 seconds to find this in an old post.