Edele Mancini1, Christoph Beglinger2, Jürgen Drewe2, Davide Zanchi1, Undine E Lang1, Stefan Borgwardt3. 1. University of Basel, Department of Psychiatry, Wilhelm Klein Str. 27, 4012 Basel, Switzerland. 2. University Hospital Basel, Department of Gastroenterology, 4031 Basel, Switzerland. 3. University of Basel, Department of Psychiatry, Wilhelm Klein Str. 27, 4012 Basel, Switzerland; King's College London, Institute of Psychiatry, Department of Psychosis Studies, London, United Kingdom. Electronic address: stefan.borgwardt@upkbs.ch.
Abstract
BACKGROUND: Green tea (Camellia sinensis) is a beverage consumed for thousands of years. Numerous claims about the benefits of its consumption were stated and investigated. As green tea is experiencing a surge in popularity in Western culture and as millions of people all over the world drink it every day, it is relevant to understand its effects on the human brain. PURPOSE: To assess the current state of knowledge in the literature regarding the effects of green tea or green tea extracts, l-theanine and epigallocatechin gallate both components of green tea-on general neuropsychology, on the sub-category cognition and on brain functions in humans. METHODS: We systematically searched on PubMed database and selected studies by predefined eligibility criteria. We then assessed their quality and extracted data. We structured our effort according to the PRISMA statement. OUTCOME: We reviewed and assessed 21 studies, 4 of which were randomised controlled trials, 12 cross-over studies (both assessed with an adapted version of the DELPHI-list), 4 were cross-sectional studies and one was a cohort study (both assessed with an adapted version of the Newcastle-Ottawa assessment scale). The average study quality as appraised by means of the DELPHI-list was good (8.06/9); the studies evaluated with the Newcastle-Ottawa-scale were also good (6.7/9). CONCLUSIONS: The reviewed studies presented evidence that green tea influences psychopathological symptoms (e.g. reduction of anxiety), cognition (e.g. benefits in memory and attention) and brain function (e.g. activation of working memory seen in functional MRI). The effects of green tea cannot be attributed to a single constituent of the beverage. This is exemplified in the finding that beneficial green tea effects on cognition are observed under the combined influence of both caffeine and l-theanine, whereas separate administration of either substance was found to have a lesser impact.
BACKGROUND: Green tea (Camellia sinensis) is a beverage consumed for thousands of years. Numerous claims about the benefits of its consumption were stated and investigated. As green tea is experiencing a surge in popularity in Western culture and as millions of people all over the world drink it every day, it is relevant to understand its effects on the human brain. PURPOSE: To assess the current state of knowledge in the literature regarding the effects of green tea or green tea extracts, l-theanine and epigallocatechin gallate both components of green tea-on general neuropsychology, on the sub-category cognition and on brain functions in humans. METHODS: We systematically searched on PubMed database and selected studies by predefined eligibility criteria. We then assessed their quality and extracted data. We structured our effort according to the PRISMA statement. OUTCOME: We reviewed and assessed 21 studies, 4 of which were randomised controlled trials, 12 cross-over studies (both assessed with an adapted version of the DELPHI-list), 4 were cross-sectional studies and one was a cohort study (both assessed with an adapted version of the Newcastle-Ottawa assessment scale). The average study quality as appraised by means of the DELPHI-list was good (8.06/9); the studies evaluated with the Newcastle-Ottawa-scale were also good (6.7/9). CONCLUSIONS: The reviewed studies presented evidence that green tea influences psychopathological symptoms (e.g. reduction of anxiety), cognition (e.g. benefits in memory and attention) and brain function (e.g. activation of working memory seen in functional MRI). The effects of green tea cannot be attributed to a single constituent of the beverage. This is exemplified in the finding that beneficial green tea effects on cognition are observed under the combined influence of both caffeine and l-theanine, whereas separate administration of either substance was found to have a lesser impact.
Authors: Janett Barbaresko; Arno Werner Lellmann; Annemarie Schmidt; Andreas Lehmann; Anna Maria Amini; Sarah Egert; Sabrina Schlesinger; Ute Nöthlings Journal: Adv Nutr Date: 2020-09-01 Impact factor: 8.701
Authors: James A Hendrix; Angelika Amon; Leonard Abbeduto; Stamatis Agiovlasitis; Tarek Alsaied; Heather A Anderson; Lisa J Bain; Nicole Baumer; Anita Bhattacharyya; Dusan Bogunovic; Kelly N Botteron; George Capone; Priya Chandan; Isabelle Chase; Brian Chicoine; Cécile Cieuta-Walti; Lara R DeRuisseau; Sophie Durand; Anna Esbensen; Juan Fortea; Sandra Giménez; Ann-Charlotte Granholm; Laura J Hahn; Elizabeth Head; Hampus Hillerstrom; Lisa M Jacola; Matthew P Janicki; Joan M Jasien; Angela R Kamer; Raymond D Kent; Bernard Khor; Jeanne B Lawrence; Catherine Lemonnier; Amy Feldman Lewanda; William Mobley; Paul E Moore; Linda Pollak Nelson; Nicolas M Oreskovic; Ricardo S Osorio; David Patterson; Sonja A Rasmussen; Roger H Reeves; Nancy Roizen; Stephanie Santoro; Stephanie L Sherman; Nasreen Talib; Ignacio E Tapia; Kyle M Walsh; Steven F Warren; A Nicole White; Guang William Wong; John S Yi Journal: Transl Sci Rare Dis Date: 2021-04-15