Green tea reduces the risk of dementia: what this study says

Green tea is full of benefits. It is not surprising that science is therefore looking into it. A Japanese study published on January 7, 2025 makes a surprising link: green tea helps reduce the risk of dementia in the long term, if consumed regularly.

The study in question is large-scale: these are data collected from 8,766 participants aged 65 or over, over 2 years, between 2016 and 2018. The data concerns both green tea and coffee, in order to to be able to compare the two very popular drinks.

Benefits of green tea

The investigation was based on brain examinations by MRI (magnetic resonance imaging), in order to study the different cerebral regions of the brain, and in particular the white matter. Aging inexorably induces lesions in this white matter; but in cases of dementia, they are more numerous and more acute. Their increased presence in the temporal part, in particular, would be an important marker.

Result: the researchers believe they have highlighted “ a significant association between less severe cerebral white matter damage and higher green tea consumption », in adults over 65 years old without dementia. The reduction in risks also seems proportional to the number of cups drunk each day (within reason). This same association does not exist for coffee.

How to explain it? This is not the first time that this type of link has been demonstrated. Green tea is associated with reduced risks of cognitive decline in other studies, such as a meta-analysis published in 2014.

This showed that regular consumption of tea, over a prolonged period, significantly lowered blood pressure. Green tea also has a greater anti-hypertensive effect than black tea. Improved arterial pressure is therefore one of the possible explanations for the reduction in white matter lesions. This also explains the difference with coffee, which of course contains more caffeine, which has a negative effect on blood pressure.

The authors of the 2025 study mention some limitations to their work. For example, they were unable to study the issue of black tea. The way the tea was brewed was also not observed, ” which could lead to variations in the content of bioactive substances », nuance the authors. Furthermore, the study focuses exclusively on the Japanese population: habits and genetics are all elements that can influence the results, which do not necessarily have to be extended everywhere in the world. However, the strengths of the study, such as the breadth of its data, make it possible to add a new stone to the edifice of work dedicated to the benefits of green tea.