For some time, experts have been reading tea leaves, green tea leaves. Over the years, science has looked into whether green tea helps prevent heart disease, even cancer. Many of these studies have been served tepid, full of caveats and the tea has often been tested on small animals. Well now from Japan comes this news. Drinking green tea may lower the risk of death, especially from heart disease and that is in people, not in hamsters. NPR's Patricia Neighmond reports on the study in this week's journal of the American Medical Association.
The study took place in northeastern Japan where 80% of the population drinks green tea. Researchers looked at over 40,000 adults, comparing those who drank less than one cup of tea a day to those who drank three to five cups a day. Over eleven years, those who drank more tea were less likely to die of heart disease. Epidemiologist Shinichi Kuriyama from Tohoki University School of Medicine headed the study.
Our findings might explain differences in mortality profile between Japan and the US. Now Japanese has the longest longevity in the world.
In the study, women saw a greater decrease in heart disease than men. For women who drank 5 or more cups of green tea daily, there was a 31% lower risk of death from heart disease. For men, the risk was reduced by 22%. For both men and women, the biggest decrease was in death due to stroke. Doctor Kuriyama.
We don't know the mechanism of the green tea in those study, but the recent evidence shows that hypertension, or cholesterol, or atherosclerosis itself could be improved by drinking green tea.
Although Kuriyama's study did not specifically look at hypertension, cholesterol or atherosclerosis, Kuriyama speculates that certain antioxidants in green tea help keep arteries healthy. Green tea is made by a more simple process than black tea. With green tea, leaves are steamed immediately after picking them. With black tea, moistures are removed, tea leaves are fermented in a humidity-controlled room and then dried, a longer process that may remove some antioxidants. Joe Vinson is a biochemist at the University of Scranton in Pennsylvania who studies antioxidants in food. Vinson says the results of the study are important, but not at all conclusive.
To me, it's not cause and effect, it's, it's a hint that green tea is good for the heart.
To solidly establish cause and effect, Vinson says a rigorous long-term clinical trial would be needed. And in any case, Vinson says all tea, both black and green, may help arterial health by increasing the body's natural production of nitric oxide, which makes arteries more flexible.
It makes your arteries be able to constrict and open up again more easily, with less changes in your blood pressure, less stress on your heart.
So, bottom line, it can't hurt, says Vinson, to drink more tea, both black and green, both hot and cold. Americans traditionally are not tea drinkers, although that's changing somewhat with the increasing cold bottled green tea beverages. And interestingly Japanese researcher Kuriyama recommends cold tea because he says some studies have implicated hot beverages in oesophageal cancer. In his study, Kuriyama found no link between drinking green tea and reduced death due to cancer as other studies have suggested.
Patricia Neighmond, NPR News.
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atherosclerosis
[7AWErEuskliE5rEusis]
n.
[医]动脉硬化症
antioxidant
[5Anti5CksidEnt]
n.
[化]抗氧化剂, 硬化防止剂
oesophageal
[i:7sCfE5dVi(:)El]
adj.
[解]食管的
tepid
1
a feeling, reaction etc that is tepid shows a lack of excitement or interest
synonym lukewarma tepid response from the audience
2
tepid liquid is slightly warm, especially in a way that seems unpleasant
synonym lukewarmtepid coffee
hamster
[5hAmstE®]
n.
东欧或亚洲产的大颊的鼠类
|