Recent research from the Kanazawa University Graduate School of Medical Sciences has found an intriguing relationship between the consumption of green tea and a reduction in cerebral white matter lesions (WML) in older adults who do not have dementia. The study suggests that drinking three or more cups of green tea daily may offer a neuroprotective effect, potentially preserving brain health, while no significant impact was observed from coffee consumption on brain structure.
Green tea and coffee, both of which are rich in neuroprotective compounds such as antioxidants and anti-inflammatory agents, are among the most commonly consumed beverages worldwide, trailing only water. These beverages have long been associated with cognitive benefits, and previous studies have hinted at their role in protecting against age-related cognitive decline. However, there has been a lack of focused research on how these drinks might directly impact structural changes in the brain, particularly in the older population.
The most recent study, titled “Green tea consumption and cerebral white matter lesions in community-dwelling older adults without dementia,” was published in npj Science of Food. It is part of the Japan Prospective Studies Collaboration for Aging and Dementia, a large-scale, multi-center observational study that involved eight research centers across Japan. The aim of this study was to assess the effect of green tea and coffee on white matter lesion (WML) volume, hippocampal volume (HV), and total brain volume (TBV) in a cohort of elderly adults. These brain structures are critical markers of cognitive health and are often linked to neurological diseases such as Alzheimer’s Disease (AD) and vascular dementia.
Understanding White Matter Lesions
White matter lesions, which are small regions of damage within the brain’s white matter, often indicate the presence of small vessel disease. These lesions have been correlated with cognitive impairments, and their presence is a key feature of several neurodegenerative diseases, including Alzheimer’s and other forms of dementia. Brain imaging technologies like magnetic resonance imaging (MRI) allow researchers to study these lesions and better understand the relationship between lifestyle factors, brain structure, and cognitive health.
In this study, the researchers used MRI scans to track the volume of white matter lesions as well as hippocampal and total brain volumes. These measurements can provide insights into how factors like diet, exercise, and beverage consumption can influence brain health over time.
Research Methodology
From 2016 to 2018, data were collected from 8,766 participants aged 65 years and older, who were part of the Japan Prospective Studies Collaboration for Aging and Dementia. Researchers collected detailed dietary information through a Food Frequency Questionnaire, which categorized participants’ daily consumption of green tea and coffee into four groups: 0-200 ml, 201-400 ml, 401-600 ml, and ≥601 ml per day.
MRI scans provided quantitative data on WML volume, hippocampal volume, and total brain volume. In addition, the team accounted for several potential confounding factors, including demographic characteristics (age, sex), underlying health conditions (hypertension, diabetes), lifestyle habits (smoking, exercise), and genetic risk factors such as the presence of the ApoE ε4 allele, which is commonly linked to an increased risk of Alzheimer’s disease.
For clarity and accuracy, the analysis excluded individuals who had mild cognitive impairment (MCI) or dementia, as well as those with incomplete data, resulting in a final cohort of 8,766 participants.
Findings: Green Tea and Brain Health
The results revealed that increased green tea consumption was significantly associated with smaller white matter lesion volumes. Specifically, participants who consumed 600 ml of green tea daily showed 3% lower WML volumes than those consuming 200 ml or less per day. Interestingly, those who consumed 1,500 ml of green tea per day had WML volumes that were 6% lower than those who drank less than 200 ml daily. These findings suggest that even modest amounts of green tea may be protective against white matter damage that could lead to cognitive decline.
While the results for WML volume were compelling, green tea intake was not found to significantly affect hippocampal volume or total brain volume. These two metrics are often regarded as key indicators of neurodegeneration, particularly in diseases like Alzheimer’s. Therefore, while green tea consumption seemed to help protect against the small vessel damage that leads to white matter lesions, it did not appear to directly alter the overall size of the hippocampus or total brain mass, according to this study.
Coffee’s Impact: A Null Effect
In stark contrast to green tea, the study found no significant association between coffee consumption and the volume of white matter lesions, hippocampal volume, or total brain volume. This suggests that while coffee does contain some neuroprotective compounds like chlorogenic acid and caffeine, it does not appear to have the same impact on the brain’s structural health as green tea.
The researchers hypothesize that the difference in outcomes between coffee and green tea may be due to the distinct biochemical compounds present in these two beverages. Green tea is especially rich in polyphenolic compounds called catechins, with epigallocatechin gallate (EGCG) being the most well-known and studied for its potent antioxidant and anti-inflammatory properties. These catechins could play a role in reducing inflammation and protecting blood vessels, thus potentially mitigating white matter lesions and promoting overall brain health.
Subgroup Analysis: The Role of Depression and ApoE ε4
To deepen the understanding of these effects, the research also looked at subgroups within the study based on depression status and the presence of the ApoE ε4 allele. ApoE ε4 is a variant of the ApoE gene associated with a greater risk of Alzheimer’s disease, and depression is a known risk factor for cognitive decline.
In participants who did not have depression or the ApoE ε4 allele, a more pronounced reduction in white matter lesion volume was observed with increased green tea consumption. This suggests that the brain-protective effects of green tea may be more pronounced in individuals with a lower genetic predisposition to neurodegenerative diseases or those who do not suffer from depression. However, for those who had depression or carried the ApoE ε4 allele, the effects of green tea on white matter lesions were not as pronounced.
Antioxidants and Anti-inflammatory Effects of Green Tea
The neuroprotective effects of green tea are likely attributed to the antioxidant and anti-inflammatory properties of catechins, specifically EGCG. EGCG has been shown in laboratory studies to reduce oxidative stress, which can damage blood vessels in the brain, as well as reduce inflammation that contributes to white matter lesions and other forms of brain damage. Additionally, green tea may improve vascular health by supporting endothelial function, further aiding in the protection against cerebrovascular damage.
While the study demonstrates a significant association between green tea consumption and reduced white matter lesion volumes, it is important to note that the research does not conclusively prove causality. No experimental validation was conducted on individual compounds of green tea, such as catechins, to confirm their specific roles in this effect.
Reference: Shutaro Shibata et al, Green tea consumption and cerebral white matter lesions in community-dwelling older adults without dementia, npj Science of Food (2025). DOI: 10.1038/s41538-024-00364-w