Delivering the amino acid L-glutamine in the form of the dipeptide L-Alanyl-L-Glutamine may increase blood levels 224%, compared with L-glutamine only, says a new study.
Findings published in Nutrition Research also indicated that an enzymatically hydrolyzed wheat protein (HWP) could match the dipeptide L-Alanyl-L-Glutamine, when given in equivalent amounts.
The study used two commercially available ingredients: Kyowa Hakko’s Sustamine, the only GRAS dipeptide of L-Alanyl-L-Glutamine and used to help with rehydration and exercise recovery; and HWP from DMV International Nutritionals.
“The results of this study indicate that L-glutamine ingested as a dipeptide (L-Alanyl-L-Glutamine) or possibly oligopeptide (HWP) in fluid increased the amount of L-glutamine tranferred to plasma relative to that provided by the free-form amino acid,” wrote researchers led by Jay Hoffman from University of Central Florida.
Non-essential amino acid
Hoffman and his co-workers explain that L-glutamine is one of 20 amino acids found naturally in the human body, and is considered to be a nonessential amino acid, under most conditions.
However, under certain circumstances, including excessive exercise and training, levels of the amino acid may fall below normal levels, and supplementation may restore levels.
Evidence showing how the form of the amino acid affects blood levels is limited, said the researchers, and so they sought to compare blood levels of glutamine after ingestion of L-glutamine supplied in the free form to a near-equivalent dose of the amino acid supplied as a dipeptide with alanine or as a polypeptide produced from the hydrolysis of wheat protein.
Data from eight men asked to consume one of four drinks on four different occasions (control drink, L-glutamine drink, Sustamine drink, and a HWP drink) showed that peak concentrations of L-glutamine occurred after 30 minutes for both the L-glutamine and Sustamine drinks, and after 45 minutes for the HWP drink.
Sustamine was associated with significantly higher blood levels of L-glutamine, compared with the free-form amino acid. While the blood levels achieved for HWP were significantly lowed than for Suatmine, when the researchers accounted for the lower L-glutamine dose in HWP they found that the increase was “approximately the same as for AlaGln”.
“The results suggest a greater transfer from the gut to plasma of L-Gln when supplied as AlaGln and possibly also as HWP compared with when the same dose was provided as the free amino acid,” they wrote.
“In consideration of the time course of peak concentration of L-glutamine in plasma, the hypothesis that L-Alanyl-L-Glutamine ingestion can increase plasma glutamine concentrations greater that the other methods of ingestion is accepted.”
The study was funded by DMV International.
Source: Nutrition Research
April 2012, Volume 32, Issue 4, Pages 272–277
“l-glutamine absorption is enhanced after ingestion of l-alanylglutamine compared with the free amino acid or wheat protein”
Authors: R.C. Harris, J.R. Hoffman, A. Allsopp, N.B.H. Routledge