Tea improves memory
food formulations as science builds a picture of the possible
health benefits, most recently that they could improve memory.
Researchers at the University of Newcastle upon Tyne in the UK found that green and black tea inhibit the activity of certain enzymes in the brain which are associated with memory.
They suggest their findings could lead to the development of a new treatment for a form of dementia which affects an estimated 10 million people worldwide, Alzheimer's disease.
"Although there is no cure for Alzheimer's, tea could potentially be another weapon in the armoury which is used to treat this disease and slow down its development," said the lead researcher, Dr Ed Okello.
But although the European black tea market is still strong tea makers have seen a shift in sales in recent years as consumers move away from black tea, instead opting for flavoursome or healthy alternatives, such as fruit and herbal teas. Consumption of these teas has increased by almost 50 per cent between 1997 and 2002, according to market analysts Datamonitor. Green tea consumption in 2002 was more than 20 times the 1997 figure, growing on the back of mounting research of its health-promoting properties.
And this has clearly had an impact on tea bag sales, with British consumers buying 114 million kilograms of 'normal' teabags in 2002, a drop from 127 million in 1997.
For the experiment, the research team from Newcastle University's medicinal plant research centre investigated the properties of coffee and green and black tea in a series of scientific experiments. Black tea - traditional English breakfast tea - is derived from the same plant as green tea, Camellia sinensis, but has a different taste and appearance because it is fermented.
They found that both green and black tea inhibited the activity of enzymes associated with the development of Alzheimer's Disease, but coffee had no significant effect.
Both teas inhibited the activity of the enzyme acetylcholinesterase (AChE), which breaks down the chemical messenger or neurotransmitter, acetylcholine. Alzheimer's is characterised by a drop in acetylcholine, report the scientists.
Green tea and black tea were also found to hinder the activity of the enzyme butyrylcholinesterase (BuChE), discovered in protein deposits found on the brain of patients with Alzheimer's.
The UK researchers claim that green tea went one step further in that it obstructed the activity of beta-secretase, which plays a role in the production of protein deposits in the brain and associated with Alzheimer's disease. Scientists also found that it continued to have its inhibitive effect for a week, whereas black tea's enzyme-inhibiting properties lasted for just one day.
The Newcastle University researchers are now seeking funding to carry out further tests on green tea, which they hope will include clinical trials.
"Our findings are particularly exciting as tea is already a very popular drink, it is inexpensive, and there do not seem to be any adverse side effects when it is consumed. Still, we expect it will be several years until we are able to produce anything marketable," commented Dr Okello.
The growing popularity of flavoured teas is partly down to skilful marketing, claims Datamonitor, as fruit teas, for example, were once looked down on as a drink for new age puritans but have gradually acquired mainstream credibility as a healthier alternative to tea or coffee. But it remains unclear whether health concerns alone have a large impact on hot drinks consumption - after all, sales of decaffeinated coffee are declining in the UK and the US.
"It's more about image," commented Datamonitor consumer analyst John Band."A stereotypical decaf drinker is a recovering caffeine addict, while a stereotypical fruit tea drinker is perceived as 'stable', 'modern' and 'with it'."
Tea leaders moving into this new market include the ABF-owned Twinings brand, which launched new 'Green Tea & Apple' flavoured tea bags in Sweden this month. Available in a pack of 25, they claim to provide "refreshment and hydration and are naturally rich in antioxidants". They are formulated from green tea, 8 per cent natural flavouring and 1 per cent apple pieces.
Full findings of the study, 'In vitro Anti-beta-secretase and dual anti-cholinesterase activities of Camellia sinensis L. (tea) relevant to treatment of dementia', Edward J Okello et al are published in Phytotherapy Research, 18 624-627 (2004).
