Effects of green tea consumption on cognitive dysfunction in an elderly population: a randomized placebo-controlled study. Issue 1 (December 2015)

• Record Type: Journal Article
• Authors: Ide, Kazuki; Yamada, Hiroshi; Takuma, Norikata; Kawasaki, Yohei; Harada, Shohei; Nakase, Junpei; Ukawa, Yuuichi; Sagesaka, Yuko
• Is Part Of: Nutrition journal. Volume 15:Issue 1(2016)
• Page Start: 1
• Page End: 9
• Publication Date: 2015-12
• Subjects: Green tea -- Oral administration -- Cognitive function -- Elderly -- Randomized-controlled trial; Nutrition -- Periodicals; 612.305
• DOI: 10.1186/s12937-016-0168-7
• Languages: English
• ISSNs: 1475-2891

Abstract

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