Green Tea Drinkers May Experience Less Dementia-Related Brain Damage: Study Reveals

Green tea has been touted as having several health advantages for millennia. These might include lowering the risk of dementia, boosting weight reduction, preserving skin health, and lowering the risk of cardiovascular disease. More proof that green tea may help prevent cognitive decline and hence lower the risk of dementia comes from a recent Japanese study. The study found that older adults who frequently consumed green tea had fewer dementia-related brain lesions than those who did not.

Studies Support the Health Benefits of Green Tea

Studies have supported many of the long-held assertions that drinking green tea has several health advantages. More proof that green tea may benefit both your body and brain has now come from Japanese studies.

According to the study, which was published in npj Science of Food, older adults who regularly drank green tea had fewer white matter lesions in their brains, which may indicate that green tea can help prevent dementia.

Green Tea’s Health Benefits

Green tea has one of the highest levels of antioxidants of any tea, as well as polyphenols, which could bring various health benefits, including:

• Helping combat some cancers, including those of the breast, gastrointestinal tract, lung, prostate, and liver
• Encouraging weight loss in people with obesity
• Anti-inflammatory effects on the skin and cardiovascular system
• Cognitive benefits

This study investigated almost 9,000 community-dwelling adults recruited from the Japan Prospective Studies Collaboration for Aging and Dementia between 2016 and 2018, to determine whether green tea or coffee had any effect on brain health.

All participants filled in a Food Frequency Questionnaire to record their consumption of green tea and coffee. Their daily intake of green tea and coffee was classified into four groups: 0–200, 201–400, 401–600, and at least 601 milliliters (ml). One cup of tea was equivalent to approximately 200 ml.

They also underwent magnetic resonance imaging (MRI) scans to assess cerebral white matter lesions, hippocampal volume, and total brain volume.

The Connection Between Green Tea and Fewer Brain Lesions

The researchers discovered a substantial correlation between consuming more green tea and having fewer white matter lesions in the brain after controlling for confounding variables. They found no connection between coffee drinking and anything. Additionally, they discovered no correlation with either total brain volume or hippocampus.

Allder clarified the possible causes of these effects: “Unlike green tea,” he added, “coffee did not show similar benefits, possibly because green tea’s unique composition, such as catechins, might be more effective against white matter lesions than coffee’s compounds, which are mainly chlorogenic acid and caffeine.”

The effects of green tea did not, however, extend to participants with the APOE e4 allele or those with depression. In these people, the researchers found no association between green tea and fewer brain lesions. They suggest that, as both are strong risk factors for dementia, green tea may not be effective in reducing white matter lesions in these individuals.

Allder agreed, noting that “the absence of benefits in individuals with depression might be due to the interaction between chronic inflammation and oxidative stress associated with depression, which could counteract the neuroprotective effects of green tea.”

“Similarly, the lack of effect in APOE e4 carriers suggests a genetic predisposition that could diminish green tea’s impact, potentially due to APOE e4‘s strong association with amyloid pathology and vascular contributions to cognitive impairment,” he explained.

Is There Anything Negative About Drinking Green Tea?

Unlike black tea, green tea is not fermented, so it retains polyphenols, such as flavanols, of which catechins are particularly important. Catechins are antioxidants that neutralize free nitrogen and oxygen radicals.

Studies have shown that they reduce the inflammation that may lead to many chronic and age-associated conditions, such as some cancers, cardiovascular diseases, and neurodegenerative diseases.

The researchers warn that there were limitations to the study. It was a cross-sectional study, so they could not determine a causal relationship between green tea consumption and reduced white matter lesions.

Also, they could not account for how the tea was brewed or whether participants were also consuming it in snacks. And, because there were few black tea drinkers in their Japanese cohort, they could not compare the effects of green and black teas.

Allder called for further studies on diverse populations, different ethnic groups, and different regions, to determine whether genetic and lifestyle factors influence the benefits of green tea, adding that “research should also focus on targeted subgroups, such as individuals with depression or the APOE e4 allele, to explore the mechanisms that might limit green tea’s effectiveness in these populations.”

“Long-term investigations are necessary to evaluate the impact of green tea consumption on the progression of dementia and cognitive decline. Additionally, comparative analyses should be carried out to assess how green tea compares with other beverages or dietary interventions in preventing white matter lesions,” he told MNT.

He also cautioned people to be careful not to drink too much green tea.

“While green tea is generally safe, excessive consumption (over 3-4 cups per day) may cause side effects like insomnia, gastrointestinal distress, or liver damage due to high caffeine or catechin levels,” Allder advised.

But, as the researchers conclude, their findings could point to another way to help reduce dementia risk.

“Given that cerebral white matter lesions are closely related to vascular dementia and Alzheimer’s disease, our findings indicate that drinking green tea, especially three or more glasses per day, may help prevent dementia,” they write.