A review of 41 double-blind, placebo-controlled caffeine trials has highlighted the stimulant's benefits, including improved alertness, short-term recall and reaction time, better mood and reduced levels of fatigue.
The review, published by the British Nutrition Foundation, analysed trials conducted over the past 15 years and found caffeine-associated health benefits even at low dosage levels. It is thought caffeine impacts mood and performance by acting on neurotransmitters in the brain.
"This study provides further evidence that moderate caffeine sources, such as tea, offer cognitive and performance-related benefits," said UK-based nutritionist Carrie Ruxton. "Most of the studies supported the idea that taking in modest levels of caffeine every day makes us more alert, boosts short-term memory and improves reaction time. There were also consistent findings that caffeine consumption is linked to a positive mood and less feelings of fatigue."
"This is great news for tea drinkers," said Dr Catherine Hood from the UK Tea Advisory Panel. "We already know that tea contains powerful antioxidants, but this study also shows ongoing cognitive benefits from regular levels of tea consumption."
The research also concluded that caffeine benefits physical performance. One meta-analysis found caffeine improved exercise test performance by 12 per cent, especially in endurance activities. Another analysis found lower ratings of perceived exhaustion due to caffeine accounted for 30 per cent of the improvement in exercise performance.
"There is no evidence that low to moderate intakes of caffeine, even when consumed around extreme exercise, have a negative effect on hydration," commented Ruxton. "The range of caffeine intake that could maximise benefit in relation to mood, cognitive function, performance and hydration would equate to between one and eight cups of tea per day, and any risk of dehydration from this level of intake would be minimal."