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An antioxidant in green tea may help combat an underlying cause of Alzheimer's disease but only when it is used in its purified form, suggests a study cited in The Journal of Neuroscience.
Accumulation of beta-amyloid — a very small protein fragment of a larger protein in brain cells — is one of the possible causes of Alzheimer's disease.
In the study, researchers developed mice that contained overproducing beta-amyloid proteins. The researchers tested the effects of high dosages of the green tea antioxidant — epigallocatechin-3-gallate (EGCG) — on the rats.
After several months of injecting the mice with EGCG daily, the nerve cells of treated mice were found to generate as much as 54 per cent less beta-amyloid proteins than those of non-treated mice.
The researchers also found that other antioxidants in green tea inhibited the ability of EGCG to reduce beta-amyloid proteins, suggesting that EGCG in its purified form was more effective.
One of the researchers, Dr Jun Tan, director of the Neuroimmunology Laboratory at the University of South Florida, was quoted as saying that if the nature of beta-amyloid in the Alzheimer's mouse model is representative of that in humans, EGCG dietary supplementation may be effective in preventing and treating Alzheimer's disease.
Alzheimer's disease accounts for 50 to 60 per cent of all dementia cases, making it the most common cause of dementia.
Contrary to common perception, dementia is not part of normal ageing. It is an illness that causes brain cells to die faster than normal. The disorder is characterised by memory loss, personality and mood changes and difficulty in performing routine tasks.
Alzheimer's Disease International (ADI) — an umbrella organisation of Alzheimer associations worldwide — says on its website that most people with dementia live in developing countries, with China and its neighbouring countries leading in numbers.
ADI was citing a report published in The Lancet, a medical journal.
In Singapore, based on the National Mental Health Survey in 2003, 6 per cent of Singaporeans aged 65 and above have dementia. In absolute figures, this translates to about 14,000 people with dementia today, said Dr Philip Yap Ling Kiat, consultant, department of geriatric medicine at the Alexandra Hospital.
"With an ageing population and if prevalence remains at 6 per cent, we can expect 48,000 people with dementia in 2030, a very large number, given our small country," he said.
For years, green tea has been studied for its cancer-fighting and heart-protecting properties. Generally, tea contains chemicals called polyphenols, which provide the antioxidant properties. EGCG, the antioxidant used in the study, is the main polyphenolic component in green tea, said the study.
Tea also contains caffeine and traces of minerals, amino acids and enzymes.
To prepare an antioxidant-rich brew of tea, nutritionist Anna Jacobs recommends using more tea leaves per cup or less water. Brew it longer and stir the tea leaves when you let the tea leaves brew.
Each cup of tea, which provides plenty of fluid, can count towards the recommended eight glasses of fluid daily. But do keep a watch on the total caffeine intake, she advised.
Both Dr Yap and Ms Jacobs find the results of the study promising, but agreed that more needs to be done to obtain conclusive evidence for humans.
Meanwhile, some ways to keep dementia at bay, said Dr Yap, include preventing diseases such as diabetes, hypertension, high cholesterol and coronary artery diseases.
Also, engage in mental activities such as learning new things, piecing puzzles and reading the papers.
A bridge game, for instance, not only stimulates your mind but also brings about laughter and cheer and helps to maintain good relationships and an active social network — all of which can keep your mind sharp and sound. — TODAY/az
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