Format

Send to

Choose Destination
Nutr Neurosci. 2017 Jul;20(6):369-377. doi: 10.1080/1028415X.2016.1144845. Epub 2016 Feb 12.

Acute effects of theanine, caffeine and theanine-caffeine combination on attention.

Author information

1
a Department of Physiology, Faculty of Medicine , University of Peradeniya , Sri Lanka.
2
b Department of Nutritional Sciences , Texas Tech University , Lubbock , USA.
3
c Department of Chemistry, Faculty of Science , University of Kelaniya , Sri Lanka.

Abstract

OBJECTIVE:

l-theanine is a constituent of tea which is claimed to enhance cognitive functions. We aimed to determine whether theanine and theanine-caffeine combination have acute positive effects on cognitive and neurophysiological measures of attention, compared to caffeine (a positive control) and a placebo in healthy individuals.

DESIGN:

In a placebo-controlled, five-way crossover trial in 20 healthy male volunteers, we compared the effects of l-theanine (200 mg), caffeine (160 mg), their combination, black tea (one cup) and a placebo (distilled water) on cognitive (simple [SVRT] and recognition visual reaction time [RVRT]) and neurophysiological (event-related potentials [ERPs]) measures of attention. We also recorded visual (VEPs) and motor evoked potentials (MEPs) to examine any effects of treatments on peripheral visual and motor conduction, respectively.

RESULTS:

Mean RVRT was significantly improved by theanine (P = 0.019), caffeine (P = 0.043), and theanine-caffeine combination (P = 0.001), but not by tea (P = 0.429) or placebo (P = 0.822). VEP or MEP latencies or SVRT did not show significant inter-treatment differences. Theanine (P = 0.001) and caffeine (P = 0.001) elicited significantly larger mean peak-to-peak N2-P300 ERP amplitudes than the placebo, whereas theanine-caffeine combination elicited a significantly larger mean N2-P300 amplitude than placebo (P < 0.001), theanine (P = 0.029) or caffeine (P = 0.005). No significant theanine × caffeine interaction was observed for RVRT or N2-P300 amplitude.

DISCUSSION:

A dose of theanine equivalent of eight cups of back tea improves cognitive and neurophysiological measures of selective attention, to a degree that is comparable with that of caffeine. Theanine and caffeine seem to have additive effects on attention in high doses.

KEYWORDS:

Attention; Caffeine; Cognitive effects; Event-related potentials; P300; Reaction time; Tea; Theanine

PMID:
26869148
DOI:
10.1080/1028415X.2016.1144845
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Taylor & Francis
Loading ...
Support Center