New research suggests that regular tea intake could lower the risk of cognitive decline in later life.
Tea is one of the most popular beverages in the United States; in 2015, more than 3.6 billion gallons of tea were consumed in the country, with black tea being the favorite.
The possible health benefits of tea consumption have been well documented. A recent study published in The American Journal of Public Health, for example, associated moderate tea intake with a reduced risk of cardiovascular events.
For this latest study, lead investigator Feng Lei, from the Department of Psychological Medicine at National University of Singapore's (NUS) Yong Loo Lin School of Medicine, and colleagues sought to determine whether there might be a link between tea intake and cognitive decline.
The researchers came to their findings - published in The Journal of Nutrition, Health & Aging - by collecting data from 957 Chinese adults aged 55 and older.
Between 2003 and 2005, the team collected information on the participants' tea consumption, including how much tea they drink, frequency of tea consumption, and what types of tea they consume.
Every 2 years until 2010, the participants underwent standardized assessments that evaluated their cognitive function.
The researchers identified 72 new cases of neurocognitive disorders among participants between 2006 and 2010.
Up to 86 percent lower risk of cognitive decline for tea drinkers
Compared with adults who rarely drank tea, those who consumed tea regularly were found to have a 50 percent lower risk of cognitive decline.
Furthermore, among adults who possessed the APOE e4 gene - which is associated with an increased risk of Alzheimer's disease - those who drank tea regularly were found to be at 86 percent lower risk of cognitive decline.
These findings remained after accounting for numerous confounding factors, including the presence of other medical conditions, social activity, physical activity, and other lifestyle factors.
The researchers note that the cognitive benefits were seen with consumption of tea that was brewed from tea leaves, such as green tea, black tea, and oolong tea.
The study was not designed to pinpoint the mechanisms behind tea's potential brain benefits, but Lei says that it could be down to the beneficial compounds the beverage contains, such as theaflavins, catechins, thearubigins, and L-theanine.
"These compounds exhibit anti-inflammatory and antioxidant potential and other bioactive properties that may protect the brain from vascular damage and neurodegeneration," Lei explains. "Our understanding of the detailed biological mechanisms is still very limited so we do need more research to find out definitive answers."
A 'simple, inexpensive lifestyle measure' could prevent dementia
By 2050, it is estimated that the number of people living with dementia will have risen to 135.5 million.
Although the study from Lei and team was conducted in Chinese adults, the researchers say that their findings are likely to apply to other populations, and they could have important implications for the prevention of dementia.
"Despite high-quality drug trials, effective pharmacological therapy for neurocognitive disorders such as dementia remains elusive and current prevention strategies are far from satisfactory.
Tea is one of the most widely consumed beverages in the world. The data from our study suggests that a simple and inexpensive lifestyle measure such as daily tea drinking can reduce a person's risk of developing neurocognitive disorders in late life."
The researchers plan to conduct further studies on the link between tea and cognitive function. In particular, they want to carry out randomized controlled trials to rigorously test the health effects of tea's bioactive compounds.