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 every day may help reduce white matter lesions in the brain.

Green tea and coffee are known to have benefits on the brain due to neuroprotective ingredients. Earlier studies have also shown their cognitive benefits, but in a recent large-scale research conducted in Japan, researchers examined how consumption of these popular beverages among older adults directly affect the brain's structural changes.

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

Researchers evaluated dietary data, conducted MRI scans, and performed cognitive tests on over 8,000 participants aged 65 and older. The MRI scans revealed information regarding brain health including the volume of white matter lesions, hippocampal volume, and total brain volume. Based on their green tea and coffee intake, participants were categorized into four groups: 0–200 ml, 201–400 ml, 401–600 ml, and ≥601 ml.

Analysis showed that higher green tea consumption was significantly linked to lower volumes of white matter lesions (WML). However, there was no significant association with other measures including hippocampal and total brain volume.

Those who drank 600 ml of green tea daily had WML volumes 3% lower than those consuming 200 ml or less, while those who drank 1,500 ml daily had WML volumes 6% lower than the reference group. However, coffee consumption did not significantly affect any of the brain volume measures.

"In conclusion, this study revealed that increased green tea consumption was associated with reduced cerebral white matter lesions. Given that cerebral white matter lesions are closely related to vascular dementia and AD (Alzheimer's disease) our findings indicate that drinking green tea, especially three or more glasses per day, may help prevent dementia," the researchers wrote.

However, the study has several limitations. The researchers focused only on green tea and coffee intake as beverages, excluding amounts in snacks, and did not account for variations in brewing methods that could affect bioactive substance content. Also, due to a limited sample size of black tea consumers, the association between black tea and brain volume changes could not be investigated. As the study was cross-sectional, it could not establish a causal relationship between green tea consumption and white matter lesions.

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