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Green Tea and Brain Health: Reading the MRI Study
“Three cups protect the brain” is an appealing headline, but it is stronger than the evidence behind it. A 2025 study in npj Science of Food examined green tea consumption and brain MRI measurements in older Japanese adults. It found an association worth studying, not a tested tea prescription for preventing dementia.
What the researchers measured
The analysis included 8,766 community-dwelling participants aged 65 or older without dementia. A food-frequency questionnaire estimated tea consumption, while MRI assessed white matter lesions and brain volumes. Higher reported green tea intake was associated with smaller white matter lesion volumes after statistical adjustment. There was no corresponding significant association with hippocampal or total brain volume.
An MRI association is not a prevention trial
This was an observational analysis of baseline data, not random assignment to drink three cups daily. Diet, activity, health status and other habits can differ between tea drinkers and non-drinkers; adjustment cannot remove every possible influence. An imaging marker is also different from demonstrating fewer future dementia diagnoses. The result cannot show that increasing tea shrank a participant’s lesions.
Why “three cups” is not a universal dose
Cup size, leaf dose, brewing and caffeine exposure vary. The source’s serving comparisons describe an estimated relationship in one population, not a threshold below which tea is useless or above which protection is guaranteed. Nor can this study identify a particular catechin as the cause. Laboratory mechanisms can suggest explanations but do not complete the causal chain in humans.
Enjoy tea without turning it into treatment
A comfortable cup can be part of daily life. This study gives a reason for further research, not for replacing assessment of memory concerns or increasing intake despite sleep problems or caffeine sensitivity. The careful headline is that green tea intake and an MRI marker were associated in older adults; whether changing intake changes clinical outcomes remains open.
Sources and further reading
- Shibata et al., 2025: Green tea intake and MRI findings in older adults
- NIH NCCIH: Green tea research and safety