L-theanine Must be Pure for Proper Absorption, Study Finds
A new study finds that
L-theanine must be administered
in its pure form rather than as the mixture of D-theanine and L-theanine
found in many nutritional supplements in order to be absorbed by
the body.
Researchers from Iowa State University orally administered to
rats pure L-theanine, pure D-theanine, and an ingredient
commercially marketed as ?L-theanine? that actually was a
racemic mixture (a 50:50 split between D- and L-theanine). They
then measured blood concentrations, urinary excretion, and a
marker of theanine metabolism in the blood.
The results show that the animals? bodies had a preference for
pure L-theanine and that the pure form is better absorbed in the
gut. The concentration of L-theanine seen in the blood was
greater with the pure L-theanine than it was with the racemic
mixture. There was also a trend toward greater urinary excretion
of L-theanine when consumed as the racemic form.
The majority of clinical and animal studies determining the
bioavailability of L-theanine have used Suntheanine, a form of
pure L-theanine.
Simple HPLC analysis cannot discriminate between D- and L-theanine
yet a number of companies are relying upon this method to assert
that they have the pure L-isomer, declared Scott Smith, Vice
President of Taiyo Kagaku, the manufacturer of Suntheanine in
Minneapolis. The patented enzymatic synthesis method locks in
the L-isomer and thus gives us pure L-theanine every batch.
Suntheanine is an elegant example of where chemistry dictates
biology.?
For the benefits of
L-theanine
and technical information click here
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Reference:
Desai MJ, Gill MS, Hsu WH, Armstrong DW. Pharmacokinetics of
theanine enantiomers in rats. Chirality. 2005 Mar;17(3):154-62.
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