When we think about healthy habits for the brain, exercise and puzzles often come to mind. But what about the drinks we enjoy every day? Researchers in Japan and around the world have studied whether green tea, coffee, or black tea might reduce the risk of dementia. The results are fascinating—and green tea seems to stand out.
What the studies say
A large Japanese study followed older adults for several years and looked at their daily drink habits. People who drank green tea regularly (two or more cups per day) were much less likely to show signs of memory decline compared to people who rarely drank it. Interestingly, coffee drinkers did not show the same clear benefit.
(Shirai et al., Public Health Nutrition, 2020)
Another Japanese project, called the Nakajima Study, tracked nearly 1,000 older adults for five years. It found that people who drank green tea every day had about one-third the risk of developing dementia or mild memory problems compared to those who did not. Again, coffee and black tea showed no significant protective effect.
(Noguchi-Shinohara et al., PLOS ONE, 2014)
A more recent global review of over 750,000 people confirmed this pattern. The authors found that higher tea consumption overall was linked to a modestly lower risk of dementia. Coffee showed a more complicated picture: one to three cups a day might help, but drinking much more offered no extra benefit.
(Wu et al., Food & Function, 2024)
Finally, a 2025 brain imaging study in Japan found that people who drank more green tea had fewer “white matter lesions” in their brains—these lesions are linked to a higher risk of dementia. Coffee did not show this benefit.
(Kuroda et al., npj Science of Food, 2025)
Why might green tea help?
Green tea is rich in special plant compounds called catechins, especially EGCG. These have strong antioxidant and anti-inflammatory effects, which may protect brain cells from damage. Tea also contains a small amount of caffeine, which may help with alertness and blood flow to the brain. Scientists believe it is the combination of these natural chemicals that makes green tea unique.
What this means for you
Of course, no single food or drink can prevent dementia. Genetics, exercise, diet, sleep, and social activity all play a role. But adding green tea to your daily routine is a simple, natural step that may support long-term brain health. If you already enjoy coffee or black tea, moderate amounts are fine, but the strongest scientific evidence points to green tea as the most protective choice.
So next time you brew a cup, remember: you may not just be refreshing your body—you could also be giving your brain a little extra support for the years ahead.
References
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Shirai, Y., et al. Green tea and coffee intake and risk of cognitive decline in older adults: the NILS-LSA study. Public Health Nutrition, 2020.
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Noguchi-Shinohara, M., et al. Consumption of green tea, but not black tea or coffee, is associated with reduced risk of cognitive decline. PLOS ONE, 2014.
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Wu, C., et al. Tea consumption and risk of dementia: a systematic review and dose–response meta-analysis. Food & Function, 2024.
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Kuroda, Y., et al. Green tea consumption and cerebral white matter lesions in older Japanese adults. npj Science of Food, 2025.