Green Tea Consumption and Dementia Risk

As I am drinking my morning tea, I’m reading this new study on green tea.  Green tea contains about 4 times more catechins than other teas such as black tea.  However, most of the studies on the association between tea and dementia have used black tea.  Of the 10 publications that evaluated the relationship between tea consumption and dementia between 2001 and 2023, only three examined green tea.

The purpose of the current study is to determine the association of green tea consumption with and interaction of green tea and coffee consumption on dementia risk among middle aged and older Japanese people through a 12 year follow-up of an earlier study called the Murakami cohort study. (Nakamura K, Takachi R, Kitamura K, et al.  The Murakami Cohort Stud of vitamin D for the prevention of musculoskeletal and other age related disease: a Study Protocol.  Environ Health Prev Med 2018;23:28).

In this 12 year follow-up of the Murakami cohort study.  Participants were 13,660 individuals (48.1% men and 51.9% women), aged 40-74 years. A self-administered questionnaire was conducted between 2011 and2013.  Green tea consumption was quantitatively determined with a validated questionnaire.

Higher green tea consumption was associated with lower hazard ratios for dementia, with the highest quartile of intake having the best results compared to the lowest quartile of intake in this Japanese population.   There was a corresponding 4.8% reduction in dementia risk per 1 cup increase.  However, there was not an associated reduced risk of dementia in both green tea and coffee consumption.

Commentary: Previous research sheds further light on this topic.  A meta-analysis by Li et al. (Li F, Liu X, Jiang B, et al.  Tea, coffee, and caffeine intake and risk of dementia and Alzheimer’s disease: a systematic review and meta0analysis of cohort studies., Food Funct 2024; 15:8330-44), showed that there is a linear association between tea consumption and risk of dementia with a 4% decreased risk of dementia per 1 cup increase.  This meta-analysis study included black and green tea.  The current study, which examined the effect of only green tea, suggests that the effect may be greater than black tea.  Another research group, Uchida et al (Uchida K, Meno K, Korenaga T, et al.  Effect of matcha green tea on cognitive functions and sleep quality in older adults with cognitive decline: a randomized controlled study over 12 months.  Plos One 2024;19) conducted a randomized controlled trial in which 1 cup of green tea per day was consumed (2 gm green tea powder) but did not find a significant change in cognition after one year.  Another cohort study of over 31,00 adults followed for about six years found that the risk of dementia development decreased with more frequent daily green tea consumption with the greatest effect for the group if 5 or more cups vs. less than one cup per day.  (Tomata Y, Sugiyama K, Kaiho Y, et al.  Green tea consumption and the risk of incident dementia in elderly Japanese: the Ohsaki Cohort 2006 Study.  Am J Geriatr Psychiatry 2016;24;881-9).  I found it interesting that one study (Nanjo F, Goto K, Seto R, et al.  Scavenging effects of tea catechins and their derivatives  on 1,1-diphenyl-02-picrylhydrazyl radical.  Free Radic Biol Med 1996;21:895-902) observed that the effect of tea consumption on cognitive function was greater in Asians than in Caucasians.   One explanation for this was the usual intake by Asians was green tea, vs. black tea in Caucasians.

The catechins in the green tea seem to be the magic. The amount of catechins in green tea was 67.0 mg/g dry tea leaves, about 4 times that of black tea (15.4mg/g).  While I love my organic fair trade black tea each morning and after lunch, I think I will renew my greater intake of green tea.  Here’s to optimal brain aging.

Reference:  Kaise R, Kitamura K, Watanabe Y, et al.  Green tea consumption and dementia risk in community-dwelling Japanese people aged 40-74 years: A 12 year cohort study. J Nutrition, Health and Aging.  2025;August 29.