Tea May Help Immune Response

Tea May Help Immune Response

BOSTON--Harvard researchers reported that L-theanine, an aminoacid found in tea, may provide natural resistance to microbial infections andperhaps even tumors. In an online early edition of the Proceedings of theNational Academy of Sciences (www.pnas.org),researchers led by Arati B. Kamath, Ph.D., studied blood cells given by non-teadrinkers who had consumed approximately 600 mL/d of black tea for either two orfour weeks and by non-tea, non-coffee drinkers who drank five to six cups perday of instant coffee. The tea group consumed approximately 1.3 mmol/d of L-theanine.

Cell samples from people on the tea regimen indicated that the brief exposureto the tea's L-theanine, which is turned into ethylamine in the liver, initiatedimmunological memory. When researchers introduced bacteria to theethylamine-exposed cells, these cells multiplied 10-fold, producing largeramounts of a chemical that fought the bacteria. Those cells that had not beenexposed to tea did not attack the invading antigens.

According to Kamath et al, human gamma delta T cells mediate innate immunityto microbes via T-cell receptor-dependent recognition of unprocessed antigens,which usually make up tumor cells, bacteria, parasites and fungi, as well asedible plant products such as tea, apples, mushrooms and wine.