The combined effects of L-theanine and caffeine on cognitive performance and mood

Abstract

The aim of this study was to compare 50 mg caffeine, with and without 100 mg L-theanine, on cognition and mood in healthy volunteers. The effects of these treatments on word recognition, rapid visual information processing, critical flicker fusion threshold, attention switching and mood were compared to placebo in 27 participants. Performance was measured at baseline and again 60 min and 90 min after each treatment (separated by a 7-day washout). Caffeine improved subjective alertness at 60 min and accuracy on the attention-switching task at 90 min. The L-theanine and caffeine combination improved both speed and accuracy of performance of the attention-switching task at 60 min, and reduced susceptibility to distracting information in the memory task at both 60 min and 90 min. These results replicate previous evidence which suggests that L-theanine and caffeine in combination are beneficial for improving performance on cognitively demanding tasks.

Caffeine and theanine exert opposite effects on attention under emotional arousal

“…Such results are in line with previous research showing that tea containing caffeine (40-90 mg) and theanine (36-97 mg) enhanced alertness and reduced calmness relative to a placebo tea (De Bruin et al 2011;Giesbrecht et al 2010). Similarly, studies that differentiated between the influence of caffeine (50-150 mg) and theanine (100-250 mg) found that, when consumed together, caffeine and theanine enhanced alertness and reduced fatigue (Haskell et al 2008;Owen et al 2008). However, we found no evidence that theanine ameliorated the effects of caffeine on other mood dimensions, including tension, anger, and confusion.…”

“…This research has demonstrated that caffeine reliably enhances vigilance and psychomotor performance (Smith 2011) and may enhance processes that require executive control, including response inhibition (Barry et al 2007), selective visual attention (Brunyé et al 2010a(Brunyé et al , 2010b, and working memory (Addicott and Laurienti 2009). Caffeine and theanine, consumed together, exert similar effects to that of caffeine alone, in that 35-50 mg caffeine and 90-100 mg theanine enhanced mental alertness, task-switching attention, and recognition memory relative to placebo (Einöther et al 2010;Giesbrecht et al 2010;Kelly et al 2008;Owen et al 2008). Opposite doses, i.e., 90-100 mg caffeine and 36-46 mg theanine exerted similar effects (De Bruin et al 2011).…”

“…Notably, such effects appeared to be additive in that visual response time and N2-P300 amplitudes were similar between caffeine with theanine together and the sum of caffeine and theanine alone (Kahathuduwa et al 2016). Thus, some work suggests that the cognitive benefits of caffeine are similar with and without theanine (Kelly et al 2008;Owen et al 2008), indicating that the cognitive effects of tea may be driven by caffeine, whereas other work suggests that theanine has independent or additive effects when consumed with caffeine (Haskell et al 2008;Kahathuduwa et al 2016).…”

“…Other studies suggest that caffeine is primarily responsible for any beneficial influence on attention, as 50 mg caffeine, with and without 100 mg theanine, improved sensitivity on an attention task, whereas theanine alone had no effects (Kelly et al 2008). Similarly, 50 mg caffeine and 100 mg theanine together improved attention switching 60 min after intake, but only caffeine showed the effect 90 min after intake (Owen et al 2008). It is possible that while theanine may provide some benefit to regulating emotion, decreasing arousal in a stressful situation actually leads to less efficiency in controlling behavior and a reduced ability to produce an appropriate response.…”

Green and Black Tea Consumption and Risk of Stroke

“…Theanine is readily bioavailable from both green and black tea, crosses the blood-brain barrier, and has demonstrated effects on brain function. 41 The chemical structure of theanine, which contains the glutamate molecule, suggests that it might reduce glutamate-related endothelial damage. Studies of middle cerebral artery occlusion in mice have demonstrated a neuroprotective effect of ␥-glutamylethylamide (theanine) and at dosages of 05 and 1.0 mg/kg, it reduces the size of the cerebral infarct in the gerbil.…”