How green tea may protect brain health, reduce dementia risk

For centuries, green tea has been celebrated for its health benefits. Emerging research now strengthens its reputation as a brain-boosting beverage. A new study from Japan links regular green tea consumption with fewer brain lesions associated with cognitive decline, offering hope for reducing dementia risk.

The Science Behind the Study

The research, published in npj Science of Food, analyzed data from nearly 9,000 adults aged 60 and above as part of the Japan Prospective Studies Collaboration for Aging and Dementia. Between 2016 and 2018, participants completed a Food Frequency Questionnaire tracking their green tea and coffee intake. They were divided into four categories based on daily consumption, ranging from less than 200 ml to more than 600 ml per day.

Participants also underwent MRI scans to measure cerebral white matter lesions—areas linked to dementia—along with hippocampal and total brain volumes. Researchers adjusted for factors such as age, education, blood pressure, diabetes, and lifestyle habits.

Key Findings

The study revealed a significant association between higher green tea consumption and fewer white matter lesions. However, no similar association was found with coffee intake. According to Dr. Steven Allder, a consultant neurologist at Re:Cognition Health, catechins like EGCG in green tea may offer neuroprotective effects by combating oxidative stress and reducing inflammation. Unlike green tea’s polyphenols, coffee's primary compounds—chlorogenic acid and caffeine—may be less effective against white matter lesions.

Interestingly, the protective effects of green tea were not observed in individuals carrying the APOE e4 allele, a known genetic risk factor for dementia, or in those with depression. Dr. Allder suggests that chronic inflammation and oxidative stress linked to depression may neutralize green tea’s benefits, while the strong amyloid pathology associated with APOE e4 may diminish its impact.

Why Green Tea Matters for Brain Health

Green tea is rich in antioxidants and polyphenols, particularly catechins, which neutralize harmful free radicals. Studies indicate that these compounds reduce inflammation associated with age-related conditions, including cardiovascular diseases and neurodegenerative disorders.

Potential Benefits of Green Tea

• Reduced risk of some cancers (breast, gastrointestinal, lung, prostate, and liver)
• Weight management support
• Anti-inflammatory effects on the cardiovascular system and skin
• Cognitive protection against dementia

Limitations and Next Steps

While the findings are promising, this cross-sectional study does not establish a causal relationship between green tea and reduced white matter lesions. Variables such as how the tea was brewed or consumed in snacks were not controlled. Additionally, the lack of black tea drinkers in the cohort limited comparisons between different types of tea.

Dr. Allder advocates for broader research encompassing diverse populations to explore the genetic and lifestyle factors that influence green tea’s benefits. Long-term studies are needed to assess its role in slowing cognitive decline and preventing dementia progression. Comparative research with other beverages and dietary strategies may also shed more light on effective preventive measures.

Green Tea and Safe Consumption

While green tea is generally safe, moderation is key. Dr. Allder warns that excessive consumption—over 3-4 cups a day—may cause side effects like insomnia, gastrointestinal discomfort, or liver strain due to its caffeine and catechin content.

In conclusion, green tea’s link to fewer white matter lesions suggests it may offer a simple, accessible way to promote brain health and reduce dementia risk. Consuming at least three cups daily could be a beneficial habit to adopt.