STiR coffee and tea magazine

Volume 5, Number 4

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The EFSA report states: "Scientific substantiation of the claimed effect: The references provided included a re- port from an authoritative body on the effects of isolated L-theanine given at pharmacological doses, narrative reviews and monographs on the characterization of the Camellia si- nensis (L.) Kuntze plant and its byproducts, and a number of narrative reviews about the health effects of L-theanine. These publications did not contain original data which could be used for the scientific substantiation of the claims. A number of the references provided reported either on the ef- fects of food constituents (e.g. caffeine and catechins) other than L-theanine, on the effects of L-theanine in combination with other food constituents (e.g. caffeine), or on health out- comes (e.g. anxiety, mood, brain chemistry, brain ischaemia, theanine bioavailability, theanine toxicity, hydration and car- diovascular health) other than the claimed effects. The Panel considers that no conclusions can be drawn from these refer- ences for the scientific substantiation of the claims." However, studies carried out in Japan at the University of Shiga Prefecture, Human Culture Department, found that "the properties of L-theanine can be summed up as being a relaxing agent without sedation and is also implicated in reducing the perception of stress and slightly improving at- tention." And Tim Bond, commenting on a Dutch study into the effects of L-theanine, explained that the 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 re- duced self-reported tiredness. These findings are in agree- ment 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." There is more work to be carried out in this field before claims about the benefits of L-theanine can be made. How- ever, the results of other research work being carried out by AVT, by the Tea Advisory Panel, and other similar bodies around the world into other aspects of tea and health are increasingly positive. And so Tim Bond's words of advice to the consuming public are: "Drinking black, green and oolong tea all tick a lot of boxes when it comes to our health - from reducing diabetes, cardiovascular disease, stroke, arthritis, and obesity risks to possessing protective properties against cancer, as well as oral health and hydration benefits. With the strong body of positive scientific evidence around its health benefits, tea should be enjoyed on a daily basis."

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