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- Title
Effects of green tea consumption on cognitive dysfunction in an elderly population: a randomized placebo-controlled study.
- Authors
Kazuki Ide; Hiroshi Yamada; Norikata Takuma; Yohei Kawasaki; Shohei Harada; Junpei Nakase; Yuuichi Ukawa; Sagesaka, Yuko M.; Ide, Kazuki; Yamada, Hiroshi; Takuma, Norikata; Kawasaki, Yohei; Harada, Shohei; Nakase, Junpei; Ukawa, Yuuichi
- Abstract
<bold>Background: </bold>Green tea is a beverage with potential effects on cognitive dysfunction, as indicated by results of experimental studies. However, its effects in humans, especially at real-world (typical) consumption levels, are unclear.<bold>Methods: </bold>A double-blind, randomized controlled study was conducted to assess the effects of green tea consumption on cognitive dysfunction (Mini-Mental State Examination Japanese version (MMSE-J) score <28) in Japan. Participants were randomly allocated to the green tea or placebo group, and consumed either 2 g/day of green tea powder (containing 220.2 mg of catechins) or placebo powder (containing 0.0 mg of catechins), respectively, for 12 months. Cognitive function assessments were performed every 3 months using the MMSE-J and laboratory tests.<bold>Results: </bold>Thirty-three nursing home residents with cognitive dysfunction were enrolled (four men, 29 women; mean age ± SD, 84.8 ± 9.3; mean MMSE-J score ± SD, 15.8 ± 5.4), of whom 27 completed the study. Changes of MMSE-J score after 1 year of green tea consumption were not significantly different compared with that of the placebo group (-0.61 [-2.97, 1.74], least square mean (LSM) difference [95 % CI]; P = 0.59). However, levels of malondialdehyde-modified low-density lipoprotein (U/L), a marker of oxidative stress, was significantly lower in the green tea group (-22.93 [-44.13, -1.73], LSM difference [95 % CI]; P = 0.04).<bold>Conclusions: </bold>Our results suggest that 12 months green tea consumption may not significantly affect cognitive function assessed by MMSE-J, but prevent an increase of oxidative stress in the elderly population. Additional long-term controlled studies are needed to clarify the effects.<bold>Trial Registration: </bold>UMIN000011668.
- Subjects
JAPAN; GREEN tea; RANDOMIZED controlled trials; COGNITIVE ability; LOW density lipoproteins; TREATMENT of dementia; COGNITION; COMPARATIVE studies; FLAVONOIDS; RESEARCH methodology; MEDICAL cooperation; NURSING care facilities; PLACEBOS; RESEARCH; TEA; PLANT extracts; OXIDATIVE stress; EVALUATION research; BLIND experiment
- Publication
Nutrition Journal, 2016, p1
- ISSN
1475-2891
- Publication type
journal article
- DOI
10.1186/s12937-016-0168-7