Green tea intake and risk of dementia and cognitive decline
What it found
Six of eight studies in people found some link between drinking green tea and lower risk of dementia, Alzheimer's disease, mild cognitive impairment or cognitive impairment.
The studies were mostly low quality, so the evidence is not solid.
What they found
Studies in people
Overall results
Six of the eight studies reported some kind of protective effect of green tea. The other two found no significant link.
High-quality cohort study
One high-quality study that followed people over time found that those who drank green tea more often had a lower chance of developing dementia.
Medium-quality cohort studies
Two medium-quality studies that followed people over time gave mixed results. One found no difference in Alzheimer's disease risk between green tea drinkers and non-drinkers. The other found a lower chance of mild cognitive impairment or dementia combined, but no change for dementia alone.
Cross-sectional studies
The five snapshot studies mostly supported a positive effect. Three found that more green tea was linked to lower chances of cognitive impairment or dementia. One found a lower chance of mild cognitive impairment only in men aged 55 to 69, but not in other groups. One found no significant link.
Other findings
Study quality
Only one of the eight studies was rated high quality. The other two that followed people over time were medium quality, and all five snapshot studies were low quality.
What the authors conclude
“In conclusion, green tea intake might reduce the risk of dementia, AD, MCI, or cognitive impairment.”
Also in their conclusions
- They conclude that green tea intake might reduce the risk of dementia, Alzheimer's disease, mild cognitive impairment, or cognitive impairment.
- They say that easily modified lifestyle habits like green tea intake may be considered to reduce the risk of these diseases.
- They advise that further results from well-designed and well-conducted cohort studies are required to draw a solid conclusion.
How it was done
Dementia is a major global problem, with around 50 million people affected worldwide and 10 million new cases each year. The authors wanted to see whether green tea, a common drink, might help prevent it.
They searched PubMed and reference lists up to 23 August 2018 for studies that looked at green tea intake and dementia, Alzheimer's disease, mild cognitive impairment or cognitive impairment. They found eight studies: three that followed people over time and five that took a snapshot at one point. Seven of the eight used questionnaires to ask about green tea intake.
What it can’t tell you
- Most of the studies were low quality, so the link between green tea and dementia risk is not firmly established.
- The studies used different ways to measure green tea intake and different definitions of dementia and cognitive impairment, which may explain why results were inconsistent.
- These studies can show a link between green tea and dementia risk, but they cannot prove that green tea causes the lower risk.
Who paid
- Conflicts
- S.K., H.W., and N.M. are employees of Suntory Global Innovation Center Limited.
- Authors work at
- Research Institute, Japan
The paper
- Title
- Green Tea Intake and Risks for Dementia, Alzheimer's Disease, Mild Cognitive Impairment, and Cognitive Impairment: A Systematic Review
- Type
- Systematic review
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Kakutani S, Watanabe H, Murayama N (2019). Green Tea Intake and Risks for Dementia, Alzheimer's Disease, Mild Cognitive Impairment, and Cognitive Impairment: A Systematic Review. Nutrients. doi:10.3390/nu11051165Free full textPubMed 31137655DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error