| <small>L</small>-Theanine may help the body's immune response to infection by boosting the disease-fighting capacity of gamma delta [[T cells]]. The study, published in 2003, included a four-week trial with 11 coffee drinkers and 10 tea drinkers, who consumed 600 milliliters of coffee or black tea daily. Blood sample analysis found the production of antibacterial proteins was up to five times higher in the tea drinkers, an indicator of a stronger immune response.<ref>{{cite journal |author=Kamath A, Wang L, Das H, Li L, Reinhold V, Bukowski J |title=Antigens in tea-beverage prime human Vgamma 2Vdelta 2 T cells in vitro and in vivo for memory and nonmemory antibacterial cytokine responses |journal=Proc Natl Acad Sci USA |volume=100 |issue=10 |pages=6009–14 |year=2003 |pmid=12719524 |doi=10.1073/pnas.1035603100 |pmc=156317}}</ref> | | <small>L</small>-Theanine may help the body's immune response to infection by boosting the disease-fighting capacity of gamma delta [[T cells]]. The study, published in 2003, included a four-week trial with 11 coffee drinkers and 10 tea drinkers, who consumed 600 milliliters of coffee or black tea daily. Blood sample analysis found the production of antibacterial proteins was up to five times higher in the tea drinkers, an indicator of a stronger immune response.<ref>{{cite journal |author=Kamath A, Wang L, Das H, Li L, Reinhold V, Bukowski J |title=Antigens in tea-beverage prime human Vgamma 2Vdelta 2 T cells in vitro and in vivo for memory and nonmemory antibacterial cytokine responses |journal=Proc Natl Acad Sci USA |volume=100 |issue=10 |pages=6009–14 |year=2003 |pmid=12719524 |doi=10.1073/pnas.1035603100 |pmc=156317}}</ref> |