Tea drinking and dementia risk Original paper

In this meta-analysis of prospective cohort studies, tea drinking was associated with a reduced risk of dementia.

The association between tea drinking and dementia risk.

A total of 410,951 participants (baseline age range of 38 to 75+), of whom 7,382 developed dementia during the study period.

A meta-analysis of 7 prospective cohort studies was performed. Three studies were conducted in Japan, and 1 study each was conducted in the United Kingdom, China, Finland, and Germany. The follow-up period ranged from 5 to 21 years.

Compared to not drinking tea, tea drinking was associated with a 29% lower risk of dementia, including a 12% and 25% lower risk of Alzheimer’s disease and vascular dementia, respectively.

In 3 studies in which more than 80% of tea drinkers consumed tea every day, tea drinking was associated with a 21% lower risk of dementia. In the 4 studies in which fewer than 80% of tea drinkers consumed tea every day, tea drinking was associated with a 40% lower risk of dementia.

A limitation of this study is that the researchers were unable to conduct subgroup analyses according to the dose or type of tea (e.g., black tea vs. green tea).

In all studies participants were either asked if they drank tea or if they drank a specific type of Camellia Sinensis tea (e..g, green tea, black tea). No studies specifically asked participants about their herbal tea consumption.

Five of the 7 studies were considered high quality, and the other 2 were considered moderate quality. Additionally, each of the included studies adjusted their analyses for several important cofounders, which increases confidence in the results.