A steaming cup of tea, the relaxing drink of choice for millions in countries such as Britain and China, could help ward off the effects of Alzheimer's disease, scientists said.
Laboratory tests found that regular cups of green and black tea inhibit the activity of certain enzymes in the brain which bring on Alzheimer's, a form of generative dementia that affects an estimated 10 million people worldwide.
The research by the Medicinal Plant Research Centre at Newcastle University, northeast England, is published in academic journal Phytotherapy Research.
Scientists tested coffee as well as green and black tea, the latter of which -- the variety enjoyed by most Britons -- is derived from the same plant as the green variety but has a different taste and appearance as it is fermented.
The results found that while coffee had no significant effect, both green and black tea inhibited the activity of enzymes associated with the development of Alzheimer's.
According to the journal, tea 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.
Green tea and black tea also hinder the activity of the enzyme butyrylcholinesterase (BuChE), seen in protein deposits found on the brains of patients with Alzheimer's.
However green tea alone had a further effect, obstructing the activity of beta-secretase, which has a role in the production of protein deposits in the brain associated with Alzheimer's.
The effects of green tea also last for a week, scientists found, as against only a day for black tea.
"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 head researcher Dr Ed Okello.
"It would be wonderful if our work could help improve the quality of life for millions of sufferers and their carers.
"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."