I'd agree with odry2015 in suggesting that supplements are not a quick fix towards achieving goals. Granted, they can assist, but the fact remains that they're supplements, not replacements.
With the vast array of protein powders currently available, for example, one truly does have to be astute when it comes to considering which one will best support their goals.
As such, no amount of supplementation can completely replace the benefit of eating a balanced and varied diet, something that allows the body to absorb naturally occurring vitamins and minerals from food sources it digests.
Moreover, a huge number of supplements currently available are synthetically manufactured. Although they may be cheaper to purchase, they don't contain the same nutritional value as those that are extracted from natural sources.
Equally, if one doesn't already possess knowledge of the ingredients contained within a product that they intend to take, conduct thorough research into its benefits/side effects before purchasing.
I certainly do not mean to criticise, but given that l'glutamine is a naturally occurring amino acid (non-essential), one that can also be obtained from consumption of lean cuts of meat, eggs and dairy products, does the OP understand why they are supplementing with l'glutamine?