Green tea may help in Alzheimer’s disease: Study

By Dr. Ananya Mandal, MDJan 9 2011

A new study finds that a cup of green tea may protect against Alzheimer’s disease and other forms of dementia. The researchers looked at the effects of a concentrated green tea extract that had been treated in the laboratory to mimic the effects of normal digestion. They found over 30 major compounds, called polyphenols that remained active after being “digested”. The extract was then tested to see whether it protected rat nerve cells from the toxic effects of certain chemicals and a protein linked to Alzheimer’s disease. It was seen to protect the cells against death caused by beta-amyloid. However, higher concentrations reduced the number of cells compared to the untreated cells.

The study was carried out by researchers from the Medicinal Plant Research Group at the School of Agriculture in Newcastle University in collaboration with the Scottish Crop Research Institute and the GGS Indraprastha University in India. It was published in the peer-reviewed journal Phytomedicine.

The authors write that there is evidence supporting the theory that green tea polyphenols might improve thinking (cognition) in animals and humans. Particularly a type of polyphenol called a flavonol, found in tea and thought to have anti-cancer, cholesterol-lowering and nerve-protection properties. They conclude that green tea metabolites (the contents of the green tea extract) can reduce cell death caused by hydrogen peroxide and beta-amyloid protein in the laboratory. Two compounds are known to play a significant role in the development of Alzheimer's disease - hydrogen peroxide and a protein known as beta-amyloid. The say this provides the basis for further study of flavanols as a potential way of alleviating some of the effects of Alzheimer’s disease.

According to Dr. Ed Okello of Newcastle University, the executive director of the university’s Medicinal Plant Research Group team and based in the School of Agriculture, Food and Rural Development who led the study, “What was really exciting about this study was that we found when green tea is digested by enzymes in the gut, the resulting chemicals are actually more effective against key triggers of Alzheimer's development than the undigested form of the tea. In addition to this, we also found the digested compounds had anti-cancer properties, significantly slowing down the growth of the tumor cells which we were using in our experiments.”