It could be one of the most popular medicines to be prescribed. Research shows that the 196 million cups of tea which Britons consume every day could form a potent weapon in fighting Alzheimer's disease.

Tea is already thought to protect the body against heart disease and cancers, but research shows black and green tea inhibit the activity of enzymes associated with the development of Alzheimer's, a form of dementia that affects about 10 million people around the world.

The findings come in the wake of much research that suggest flavanoids contained in tea, particularly green tea, protect against strokes, heart attacks and many different types of cancers, as well as more prosaic conditions such as tooth decay and dehydration. One study shows that drinking three cups a day is the equivalent of eating six apples.

Green and black tea derive from the same plant, Camellia sinensis, which is grown throughout the tropics but also in places such as Turkey. Black tea consists of fermented leaves, comes mainly from India and forms the basis of traditional types drunk in Britain such as Assam or Ceylon. Green tea is less processed and is popular in China and Japan, where it has been linked to longevity and low rates of heart disease and cancer.

Scientists at Newcastle University's Medicinal Plant Research Centre found both teas inhibited the activity of the enzyme acetylcholinesterase (AChE), which breaks down the chemical messenger, or neurotransmitter, acetylcholine. Alzheimer's is characterized by reduced acetylcholine. Both teas also hinder the activity of the enzyme butyrylcholinesterase (BuChE), which has been found in protein deposits on the brains of patients with Alzheimer's.

Green tea went one step further in obstructing the activity of beta-secretase, which helps produce protein deposits in the brain linked to Alzheimer's. The findings, published in Phytotherapy Research, could help in developing treatments for Alzheimer's. The researchers are seeking funds to further investigate green tea in the hope of creating a medicinal tea.

Dr. Ed Okello, the lead researcher and a green tea drinker himself, said, "Our findings are particularly exciting, as tea is already a popular drink, it is inexpensive, and there do not seem to be any adverse side-effects."