A combination of 97 milligrams of L-theanine and 40 milligrams of caffeine was associated with improvements in attention,
Publication of the study comes a year after EFSA turned down Unilever-submitted health claims linking black tea consumption and improved mental focus. The European scientific assessor said in January 2009 that the dossier failed to demonstrate causality.
While no one was available for comment from Unilever prior to publication, global media relations director, Trevor Gorin, told NutraIngredients.com in 2009 following EFSA’s opinion that his company stood by the claims.
The new study supports the association between tea and attention, although it did not report any benefits for alertness. The findings of the randomized, placebo controlled, double-blind, cross-over study in the journal Appetite.
The study, led by Suzanne Einöther from sensation, perception and behaviour at Unilever R&D Vlaardingen, recruited 29 healthy regular tea and/or coffee drinkers to take part in the study. The average age was 30.6, 11 were men, and the body mass index was between 20 and 30 kg/m2.
People were randomized to consume a drink containing L-theanine (Suntheanine, Taiyo) and caffeine mixed with iced tea powder in water, or a placebo (water with iced tea powder) separated by between 6 and 14 days, and subsequently completed a cognitive test at baseline, and then 10 and 60 minutes after drinking.
“This study provided further evidence that the L-theanine/caffeine combination improves attention on the switch task,” wrote the researchers. “The improvement in accuracy in combination with unaltered response speed is in line with previous studies.
“Tentative evidence was [also] found that the effect of the L-theanine/caffeine combination on attention is not specific to the visual modality, as we found faster responses in both the visual and auditory modality on the intersensory task after the combination as compared to placebo,” they added.
“Taken together with the previous studies, we conclude that a high dose of L-theanine combined with caffeine, at the level of a single cup of tea, can help to improve attention,” they concluded.
Published online ahead of print, doi:10.1016/j.appet.2010.01.003
“L-theanine and caffeine improve task switching but not intersensory attention or subjective alertness”
Authors: S.J.L. Einother, V.E.G. Martens, J.A. Rycroft, E.A. De Bruin