Green, black tea can reduce stroke risk

February 19, 2009 By Enrique Rivero

(PhysOrg.com) -- Drinking at least three cups of green or black tea a day can significantly reduce the risk of stroke, a new UCLA study has found. And the more you drink, the better your odds of staving off a stroke.

The study results, published in the online edition of Stroke: Journal of the American Heart Association, were presented Feb. 19 at the American Heart Association's annual International Stroke Conference in San Diego, Calif.

The UCLA researchers conducted an evidence-based review of all human observational studies on stroke and tea consumption found in the PubMed and Web of Science archives. They found nine studies describing 4,378 strokes among nearly 195,000 individuals, according to lead author Lenore Arab, a professor of medicine in the division of general internal medicine and health services research at the David Geffen School of Medicine at UCLA.

"What we saw was that there was a consistency of effect of appreciable magnitude," said Arab, who is also a professor of biological chemistry. "By drinking three cups of tea a day, the risk of a stroke was reduced by 21 percent. It didn't matter if it was green or black tea."

And extrapolating from the data, the effect appears to be linear, Arab said. For instance, if one drinks three cups a day, the risk falls by 21 percent; follow that with another three cups and the risk drops another 21 percent.

This effect was found in tea made from the plant Camellia sinensis, not from herbal teas.

There are very few known ways to reduce the risk of stroke, Arab said. And developing medications for stroke victims is particularly challenging, given that the drug has to get to the stroke-damaged site quickly because damage occurs so fast. Arab said that by the time a stroke victim gets medical care, it's nearly too late to impede the damage.

"That's why these findings are so exciting," she said. "If we can find a way to prevent the stroke, or prevent the damage, that is simple and not toxic, that would be a great advance."

Though no one is certain which compounds in tea are responsible for this effect, researchers have speculated that the antioxidant epigallocatechin gallate (EGCG) or the amino acid theanine may be what helps. Antioxidants are believed to help prevent coronary artery disease.

"And we do know that theanine is nearly 100-percent absorbed," Arab said. "It gets across the blood-brain barrier and it looks a lot like a molecule that's very similar to glutamate, and glutamate release is associated with stroke.

"It could be that theanine and glutamate compete for the glutamate receptor in the brain," she added.

Although a randomized clinical trial is needed to confirm this effect, the findings suggest that drinking three cups of green or black tea a day could help prevent an ischemic stroke.

Study co-authors with Arab are Weiqing Liu, a senior statistician in the UCLA Department of Biomathematics, and David Elashoff, associate professor of medicine in the division of general internal medicine and health services search at the David Geffen School of Medicine at UCLA.

The Unilever Lipton Institute of Tea funded this study.

Provided by UCLA

Explore further: A daily cup of tea may soothe your heart

Related Stories

A daily cup of tea may soothe your heart

March 1, 2016
(HealthDay)—Drinking as little as a cup of tea daily may be good for your heart health, new research suggests.

Southern diet could raise your risk of stroke

February 7, 2013
Eating Southern-style foods may be linked to a higher risk of stroke, according to research presented at the American Stroke Association's International Stroke Conference 2013.

Carbonated drinks linked with out-of-hospital cardiac arrest of cardiac origin

September 1, 2015
Carbonated beverages are associated with out-of-hospital cardiac arrests of cardiac origin, according to results from the All-Japan Utstein Registry presented for the first time today at ESC Congress. The study in nearly ...

What science doesn't know about menopause

December 15, 2015
My physio, a young woman called Lucy, was simply making conversation. She wanted to distract me from the serious discomfort she was about to inflict by massaging the nerves around my painful posterior tibial tendon, an ankle ...

Is phosphate the next sodium?

July 6, 2015
Is phosphate the next sodium—a once seemingly benign food additive now linked to heart disease and death? It's nearly as ubiquitous as sodium in processed foods but so under the radar, it's not even listed on food labels.

Recommended for you

Global calcium consumption appears low, especially in Asia

October 18, 2017
Daily calcium intake among adults appears to vary quite widely around the world in distinct regional patterns, according to a new systematic review of research data ahead of World Osteoporosis Day on Friday, Oct. 20.

Experts devise plan to slash unnecessary medical testing

October 17, 2017
Researchers at top hospitals in the U.S. and Canada have developed an ambitious plan to eliminate unnecessary medical testing, with the goal of reducing medical bills while improving patient outcomes, safety and satisfaction.

New study: Nearly half of US medical care comes from emergency rooms

October 17, 2017
Nearly half of all US medical care is delivered by emergency departments, according to a new study by researchers at the University of Maryland School of Medicine (UMSOM). And in recent years, the percentage of care delivered ...

No evidence that widely marketed technique to treat leaky bladder/prolapse works

October 16, 2017
There is no scientific evidence that a workout widely marketed to manage the symptoms of a leaky bladder and/or womb prolapse actually works, conclude experts in an editorial published online in the British Journal of Sports ...

Ten pence restaurant chain levy on sugary drinks linked to fall in sales

October 16, 2017
The introduction of a 10 pence levy on sugar sweetened drinks across the 'Jamie's Italian' chain of restaurants in the UK was associated with a relatively large fall in sales of these beverages of between 9 and 11 per cent, ...

New exercises help athletes manage dangerous breathing disorder

October 16, 2017
A novel set of breathing techniques developed at National Jewish Health help athletes overcome vocal cord dysfunction and improve performance during high-intensity exercise. Vocal cord dysfunction, now also referred to as ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

nilbud
1 / 5 (1) Feb 21, 2009
What a load of scummy advertising if I drink 15 cups of tea a day I can never have a stroke, according to the tea salesmen. Truly unbelievable.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.