Can green tea protect the brain? Here’s how much to drink a day to get the beneficial effects

Green tea is widely praised for boosting metabolism and aiding weight loss, but can it also protect brain health? New research suggests that drinking green tea daily may help reduce white matter damage in the brain.

Green tea and coffee are known to benefit the brain due to their neuroprotective ingredients. Previous research has also shown their cognitive benefits, but in a recent large-scale study in Japan, researchers examined how consumption of these popular drinks by older adults directly affects structural changes in the brain.

Results published in the journal Nature suggest that drinking three or more glasses of green tea a day may help protect brain health. However, coffee consumption showed no significant effect.

The researchers assessed dietary data, performed MRI scans and cognitive tests on more than 8,000 participants aged 65 and older. MRI scans revealed information about brain health, including the volume of white matter lesions, hippocampal volume, and total brain volume. Based on green tea and coffee consumption, participants were divided into four groups: 0–200 ml, 201–400 ml, 401–600 ml, and ≥601 ml.

The analysis showed that higher green tea intake was significantly associated with smaller white matter lesion (WML) volume. However, there was no significant association with other measures, including hippocampus and total brain volume.

In people drinking 600 ml of green tea per day, the volume of WML was 3% lower than in those drinking 200 ml or less, while in those drinking 1,500 ml per day, the volume of WML was 6% lower than in the reference group. However, coffee consumption did not significantly affect any of the brain volume measures.

“In summary, this study revealed that increased green tea consumption was associated with reduced brain white matter damage. “Given that changes in the white matter of the brain are closely associated with vascular dementia and atopic dermatitis (Alzheimer’s disease), our findings indicate that drinking green tea, especially for three or more glasses per day, may help prevent dementia,” the researchers wrote.

However, the study has several limitations. The researchers focused only on consumption of green tea and coffee as beverages, excluding the amounts contained in snacks, and did not take into account differences in brewing methods that could affect the content of bioactive substances. Additionally, due to the limited sample size of black tea consumers, the association between black tea and changes in brain volume could not be examined. Because the study was cross-sectional, it was not possible to establish a causal relationship between green tea consumption and changes in white matter.