L-Glutamine Hydrochloride vs. L-Alanyl-L-Glutamine (dipeptide)
Among 231 on-market l-glutamine products with an identifiable primary form, 35.9% use L-Glutamine Hydrochloride (83 products) and 28.6% use L-Alanyl-L-Glutamine (dipeptide) (66).
| L-Glutamine Hydrochloride | L-Alanyl-L-Glutamine (dipeptide) | |
|---|---|---|
| Quality tier | Unrated | Unrated |
| L-Glutamine by weight | 80.0% | 67.3% |
| Share of market | 35.9% | 28.6% |
| On-market products | 83 | 66 |
| Median declared dose | 160 mg middle half: 160–400 | 269.2 mg middle half: 67.3–336.5 |
| Most common brands | Universal, GNC AMP Advanced Muscle Performance, MMUSA | Gaspari Nutrition, Metabolic Nutrition, VPX |
Doses are declared per serving in mg. “By weight” is the share of the ingredient that is the nutrient itself (e.g. elemental magnesium in a magnesium salt).
Why L-Glutamine Hydrochloride is unrated
Same amino acid delivered as a salt; no human study comparing glutamine HCl with free glutamine was located.
Why L-Alanyl-L-Glutamine (dipeptide) is unrated
Marketed for solubility and stability; the cited trial tested acute dipeptide ingestion during hydration stress in endurance exercise but not against free glutamine. No head-to-head human bioavailability or efficacy comparison of this form was located in PubMed searches.
Source: Hoffman JR et al. 2010, J Int Soc Sports Nutr 7:8, PMID 20181080