Taiyo International's Suntheanine product may be the only 'pure' L-theanine ingredient on the US market, claim its researchers who report that the amino acid, which is found in green tea and associated with relaxing effects, may sometimes have a different composition in bulk commercial products.
The findings of Dr Daniel Armstrong, the Caldwell Professor of Chemistry at Iowa State University, are from a series of chemical analyses performed on several commercially available raw materials claiming to be pure L-theanine.
Armstrong said that his team's analysis of several ingredients being sold and marketed as 'L-theanine' had revealed that they contain more than just the L-form.
"We found all of those tested that are made through chemical synthesis or claiming to be extracted from green tea actually have about 50 per cent present as D-theanine," he said, adding that "the only material that proved to be pure L-theanine was the Suntheanine brand, produced via biofermentation, which had more than 99.95 per cent L-theanine, our current detection limit".
Armstrong said the method used was very selective at separating out the D- and L-forms. "As amino acids go, in the body the D-form may have a very different action, like putting your left shoe on your right foot. There have been no studies on the biological effects of D-theanine or D-theanine-rich 'L-theanine'," he added.
The purity of amino acids, which is related to their 'stereochemistry' - the spatial arrangement of atoms and groups in a compound and its relation to the properties of the compound - can have a dramatic influence on their metabolism and biological activity.
"Chemical synthesis of L-theanine, or its purported extraction from green tea, is fraught with the problem of forming much greater amounts of D-theanine than found in tea," explained Scott Smith, vice president of Minneapolis, Minnesota-based Taiyo International, the North American sales office for Japan's Taiyo Kagaku Company.
"Our proprietary biological fermentation process assures dietary supplement manufacturers, and consumers, that they are getting only pure L-theanine. We know the biological effects of our Suntheanine brand L-theanine. I'm not sure that the biological effects of other theanine ingredients are known," he concluded.
The study findings are being submitted for presentation at a national scientific research conference and for publication in a peer reviewed journal.