Black tea reduces risk of Parkinson's Disease

Findings from a collaboration between the National Neuroscience Institute (NNI) and NUS have revealed for the first time, that drinking black tea (but not green tea) reduces the risk of developing Parkinson's Disease among the Chinese population in Singapore.

The findings, which are published in the on-line issue of American Journal of Epidemiology (Dec 2007) suggest that black tea may exhibit neuroprotective effects on Parkinson's Disease. The findings, presented at the 1st Asian and Oceanian Parkinson's Disease and Movement Disorders Congress (Oct 2007) won the second prize for Best Research Presentation Award.

There has always been a lack of data from Asian populations on dietary and lifestyle factors associated with Parkinson's Disease, said co-Principal Investigator for the research project, Asst Prof Koh Woon Puay, Department of Community, Occupational and Family Medicine. To fill this gap, the researchers examined these factors in relation to Parkinson's Disease in the Singapore Chinese Health Study with a cohort of 63,257 Chinese men and women. This is a first community-based study of the disease's risk factors in an Asian population.

Between 1992 and 2005, data was collected through in-person interviews using structured questionnaires. Results from the study showed that individuals who had a higher dietary intake of caffeine were less likely to develop Parkinson's disease. This result tallies with what several large population-based studies in USA and Europe have shown.

However, a novel finding by the NNI-NUS team is that black tea intake also reduces the risk for developing the disease -- and it is not just the caffeine content in black tea that is responsible. Green tea, in contrast, did not show any significant protective effects on the disease.

Black tea magic

Black tea has a history of 5,000 years in China. For the Chinese, black tea refers to post-fermented teas such as Pu-erh, dubbed the national treasure of China.While green tea usually loses its flavour within a year, black tea retains its flavour for several years. Since the Tang Dynasty, black tea steeped in hot water has been known to serve as a cheap cloth dye. Besides its use as a dye, it is of course, a popular beverage. Some examples of Chinese black teas are Lapsang souchong, originally from Mt Wuyi, Fujian Province; Keemun from Anhui Province; Dian Hong from Yunnan Province and Ying De Hong from Guangdong Province.

Black tea comes from the leaves of Camellia sinensia -- a perennial evergreen shrub that is native to Southeast Asia. The leaves are oxidised under controlled temperature and humidity. Then the leaves are dried to arrest the oxidation process. They are then sorted into grades according to their sizes.

According to a study in 2006 by University College London, black tea also has an effect on stress hormone levels in the body. In the study, 75 young male regular tea drinkers were split into two groups and monitored for six weeks. One group, the control group was given a caffeinated placebo devoid of the active tea ingredients. The other group was given fruit-flavoured caffeinated tea mixture made up of the constituents of an average cup of black tea. When both groups were subjected to challenging tasks which induced stress, the group taking the tea mixture was found to be able to reduce their cortisol levels by an average of 47 per cent.

"We had observed an inverse association between consumption of black tea and the risk of Parkinson's Disease in the Chinese population residing in Singapore. Our research is a very promising first step to identify dietary and lifestyle factors related to Parkinson's disease in an Asian context. More studies will be needed before we can firmly establish the protective effect of black tea on the disease and understand its underlying mechanism. Such research will enable us to develop strategies to prevent or reduce the progression of this debilitating neurodegenerative condition," said Dr Louis Tan, senior consultant neurologist at NNI-TTSH who is leading the study with Dr Koh of NUS.

The NNI-NUS study is unique. "To our knowledge, this is the first prospective cohort study of Parkinson's Disease risk factors in a non-white population living in Asia. Singapore Chinese are well suited for the study of coffee, green tea and black tea consumption and health outcomes since all three types of beverages possess divergent intake profiles in this population. Other strengths of the study are its population-based design and the collection of data on tea-drinking prior to disease diagnosis," said Dr Koh.

Next, the team intends to dentify other factors that may affect an individual's risk of developing Parkinson's Disease as well as understand the mechanism of black tea's protective effect on the disease. Experimental scientists have shown that black tea extracts (oxidised polyphenols such as thearubigins and theaflavins ) possess neuro-protective and neuro-rescue properties in an animal model of Parkinson’s Disease, said Dr Koh. But at the moment, it is too early for the team to identify what the possible protective content may be.

forwarded to us by Ramesh