title: Effects of green tea consumption on cognitive dysfunction in an elderly population: a randomized placebo-controlled study.
abstract: 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.
  
  
  
  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.
  
  
  
  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).
  
  
  
  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.
  
  
  
  UMIN000011668.
authors.affiliation: Department of Drug Evaluation & Informatics, Graduate school of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Ide
authors.affiliation: 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.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamada
authors.affiliation: White Cross Nursing Home, 2-26-1 Suwa-cho, Higashimurayama, Tokyo, 189-0021, Japan.
authors.forename: Norikata
authors.initials: N
authors.lastname: Takuma
authors.affiliation: Department of Drug Evaluation & Informatics, Graduate school of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Kawasaki
authors.affiliation: Department of Drug Evaluation & Informatics, Graduate school of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Harada
authors.affiliation: Central Research Institute, ITO EN, Ltd., 21 Mekami, Makinohara, Shizuoka, 421-0516, Japan.
authors.forename: Junpei
authors.initials: J
authors.lastname: Nakase
authors.affiliation: Central Research Institute, ITO EN, Ltd., 21 Mekami, Makinohara, Shizuoka, 421-0516, Japan.
authors.forename: Yuuichi
authors.initials: Y
authors.lastname: Ukawa
authors.affiliation: Central Research Institute, ITO EN, Ltd., 21 Mekami, Makinohara, Shizuoka, 421-0516, Japan.
authors.forename: Yuko M
authors.initials: YM
authors.lastname: Sagesaka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002392:Catechin / Q000008:administration & dosage; D003071:Cognition / Q000187:drug effects; D060825:Cognitive Dysfunction / Q000188:drug therapy / Q000453:epidemiology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D009735:Nursing Homes; D018384:Oxidative Stress; D010919:Placebos; D010936:Plant Extracts / Q000008:administration & dosage; D011795:Surveys and Questionnaires; D013662:Tea / Q000737:chemistry
chemical_list: D010919:Placebos; D010936:Plant Extracts; D013662:Tea; D002392:Catechin
keywords: Cognitive function; Elderly; Green tea; Oral administration; Randomized-controlled trial