Commenting on the studies, Dr Bond from the Tea Advisory Panel notes: “The first, a Dutch study, evaluated the effects of two key ingredients in black tea – L-theanine and caffeine - on cognitive performance. The researchers gave a combination of 97 mg L-theanine and 40 mg caffeine (i.e., moderate levels) as compared to placebo treatment and looked at the effects on cognitive performance, alertness, blood pressure, and heart rate in a sample of 44 young adults. Cognitive performance, self-reported mood, blood pressure, and heart rate were measured before L-theanine and caffeine administration (i.e. at baseline) and 20 minutes and 70 minutes later. This combination of moderate levels of L-theanine and caffeine significantly improved accuracy during task switching and self-reported alertness and reduced self-reported tiredness. These findings are in agreement with those of another recent study in human subjects which showed that consumption of two servings of black tea improves the ability to react to stimuli and to focus attention on the task in hand.
“Taken together, these two studies provide evidence that consumption of black tea improves cognitive function, in particular helping to focus attention during the challenge of a demanding mental task.
“Turning to the second study, this data revealed that black tea polyphenols prevented weight gain following a high fat diet. In this study, Japanese scientists looked at the effects of a fat emulsion containing a black tea polyphenol extract. Levels of fat in the blood as well as one of the enzymes responsible for fat absorption (pancreatic lipase) were measured and reviewed. The findings revealed that the black tea polyphenol extract inhibited pancreatic lipase (i.e., fat absorption) and also the levels of triglycerides (a type of fat) in the blood.
“In a separate study researchers supplemented the high-fat diets with either 1 or 5 per cent of the tea extract for eight weeks. Administration of the 5 per cent black tea extract suppressed increases in body weight, adipose tissue mass, and liver lipid content in those subjects fed a high-fat diet.”
In summary, Dr Bond concludes: “Overall, these results are great news for tea drinkers and suggests that black tea polyphenols support healthy weight loss and reduce body fat thanks to their ability to reduce fat absorption. In addition, other study data is also adding to the growing evidence that black tea consumption can help improve our cognitive performances. As a result, all this new data adds to the growing science that drinking tea, preferably four cups of tea a day, is good for our health and well being.”
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