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Nutr J. 2016 May 4;15(1):49. doi: 10.1186/s12937-016-0168-7.

Effects of green tea consumption on cognitive dysfunction in an elderly population: a randomized placebo-controlled study.

Author information

1
Department of Drug Evaluation & Informatics, Graduate school of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
2
Department of Drug Evaluation & Informatics, Graduate school of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan. hyamada@u-shizuoka-ken.ac.jp.
3
White Cross Nursing Home, 2-26-1 Suwa-cho, Higashimurayama, Tokyo, 189-0021, Japan.
4
Central Research Institute, ITO EN, Ltd., 21 Mekami, Makinohara, Shizuoka, 421-0516, Japan.

Abstract

BACKGROUND:

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.

METHODS:

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.

RESULTS:

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).

CONCLUSIONS:

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.

TRIAL REGISTRATION:

UMIN000011668.

KEYWORDS:

Cognitive function; Elderly; Green tea; Oral administration; Randomized-controlled trial

PMID:
27142448
PMCID:
PMC4855797
DOI:
10.1186/s12937-016-0168-7
[Indexed for MEDLINE]
Free PMC Article

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