While studies have shown that drinking tea can protect the brain and nerve cells in animals, no such studies have been conducted on humans previously. In this study, tea intake was studied in elderly participants and the associated changes in memory and other cognitive abilities were assessed. Results showed that higher tea intake decreased the incidence of decline of cognitive abilities and memory. The best benefits were observed with the consumption of fermented or black tea compared to semi-fermented or oolong tea. It was also found that coffee intake did not provide similar benefits.
Drinking tea is an old Chinese custom that dates back to nearly 5000 years ago. As the drink made from the leaves of Camellia sinensis has achieved popularity worldwide, its health implications have also been studied in detail. Tea is available in three forms – fermented or black, semi-fermented or oolong and non-fermented or green tea. Tea is believed to contain many compounds and chemicals that help in the prevention of heart diseases and cancers and to even reduce death rates. Animal studies have shown that tea helps in the protection of the nerve cells and brain. However, no concrete studies have been conducted that show the same benefits of tea intake in humans. This study was conducted to analyze cross-sectional and longitudinal data of a population cohort of older Chinese adults in the Singapore Longitudinal Aging Studies (SLAS) to assess the association between intake of tea levels and cognitive impairment and cognitive decline.
* The study included 2,501 Chinese participants who were aged 55 years and above.
* All the participants were assessed more than one to two years and the total amount of tea consumption was recorded.
* Before the start of the study and at conclusion, the mental abilities and cognitive skills were assessed for all the participants using a standard test. Based on this test, any score equal to or below 23 was considered as a decrease in cognitive skills. Any drop of one or more point was considered to be a decline in the cognitive skills.
* Initial assessment showed that nearly 50 percent of the participants took oolong tea, around 40 percent of the participants took black tea and 24 percent of the participants took green tea.
* Results showed that high regular intake of tea was linked to decreased incidence of cognitive skill. However, moderate consumption of tea was linked to lesser benefits.
* The benefits were clearest for black tea or fermented tea while oolong or semi-fermented tea was found to offer fewer benefits.
* It was also seen that consumption of coffee did not provide similar benefits as did the consumption of tea.
Authors agree that this study was conducted over a short term and may not reflect the actual long-term cognitive skill decrease in participants. They also agree that there may be other factors in the participants’ day-to-day life that may affect the cognitive decline. The authors suggest further longer term, larger studies to see if tea consumption could prevent other brain and memory diseases such as Alzheimer’s disease.
Tea is relatively inexpensive and nontoxic and is consumed in large amounts. While animal studies have shown that tea protects the brain from age-related decline of memory and other risk factors, this study particularly shows similar benefits of tea intake in humans. Authors conclude that tea “has a huge potential effect in promoting cognitive health and perhaps delaying the onset of dementia.” Dementia is age-related memory loss and cognitive skill damage that is common and this study reveals that tea, particularly black tea can reduce the risk of such a cognitive decline. The authors suggest future studies to evaluate the definitive protective effects of tea in the prevention of dementia and other memory disorders such as Alzheimer’s disease.
For More Information:
Tea Consumption and Cognitive Impairment and Decline in Older Chinese Adults
The American Journal of Clinical Nutrition, 2008
By Tze-Pin Ng; Lei Feng
From the University of Singapore, Singapore
*FYI Living Lab Reports Are Summaries of the Original Research.