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Health Benefits Of Tea: Milking It Or Not

September 27, 2012 - MELISSA BLOCK, HOST:

Lots of studies suggest that drinking tea is good for you. Researchers have demonstrated證明 beneficial effects益處 on your heart and blood pressure血壓. Compounds in tea might even help you keep the pounds off保持身材(減肥). But, and this is bad news for me, some scientists now believe that adding milk to your tea may diminish減少/縮小 those benefits. NPR's Allison Aubrey reports.

ALLISON AUBREY, BYLINE: Tea connoisseur鑑賞家/行家, Robert Rex-Waller, has a few strong opinions about what makes for a perfect cup of tea.

ROBERT REX-WALLER: I have just a small electric kettle插電的水壺.

AUBREY: As steam rises up蒸氣緩緩上升 in the tea room here at the Park Hyatt Hotel in D.C. where Rex-Waller oversees tea service茶道服務, he waits for the moment when just a few bubbles start to form.

REX-WALLER: I believe in not boiling it over水不要滾過頭.

AUBREY: So really you don't want it to reach a full boil不要等水滾起來?

REX-WALLER: I don't want it to reach a full boil.

AUBREY: Where are we? Temperature-wise那(溫度)到底幾度才是最理想的?

REX-WALLER: We're probably at about 130, 140.

AUBREY: Anything hotter may be too harsh, he says, for the classic Chinese green tea正統的中式茶道 he's serving up. It's called Dragon Well龍井, and after he scoops挖起一勺(當名詞則是一勺的意思) some tea leaves茶葉 into an infuser濾茶器 and adds water, he's ready to taste what he's come to appreciate as a very distinctive獨特的 flavor.

REX-WALLER: I mean this has a, for me, a very spinachy菠菜flavor. And you can really see that the, this great, bright green chlorophylls葉綠素 all still there, I mean it's got this, I don't know if you can smell it?

AUBREY: Oh, I can definitely smell that. You get the sort of spinachy-seaweed菠菜-海帶 essence精華.

REX-WALLER: Right, exactly.

AUBREY: This is the taste of pure, unadulterated純粹/沒有添加雜質的 green tea, Rex-Waller says. And you certainly don't need to add milk or sugar to it.

REX-WALLER: There are some teas where I would cringe(因為害怕而)畏縮 a little bit if someone poured milk into them.

AUBREY: After studying in China, Rex-Waller says he adopted the tea customs茶道 he learned there.

REX-WALLER: A Chinese person would not add any milk to that tea. I think it would be considered sacrilegious褻瀆神明的(會遭受天譴的) to a point.

AUBREY: Sacrilegious.

REX-WALLER: Well, someone who's making these teas - they're really pouring their soul into it, so to take away from that I think would just be, would dishonor the tea.

AUBREY: The case for pure tea, unadulterated by milk, may be a struggle in a society that has a communal sweet tooth一個普遍熱愛甜食的國家 and maybe a penchant for cream喜好奶精. Even Starbucks serves up a sweetened green tea latte加了糖的綠茶拿鐵 with steamed milk熱牛奶. But researchers who study the potential health benefits of tea, say the Chinese way may be the best way to go. Dutch researcher Rick Hursel of Maastricht University is convinced.

RICK HURSEL: We always recommend two to three cups a day in between間 meals. No milk. That's my recommendation.

AUBREY: Hursel and his colleagues study compounds in tea called flavonols黃酮醇(, which are thought to be beneficial. One type of flavonol in green tea, called catechins兒茶素, are the focus of a lot of research these days. Black tea has similar compounds. What Hursel has demonstrated in small short term studies, is that these catechins may have a positive influence on body weight regulation. Meaning they may slightly modify修飾/修改 a person's metabolic set point新陳代謝模式.

黃酮醇是什麼?

黃酮類物質（Flavonoid）是一群來自於水果、蔬菜、茶、葡萄酒、種子或是植物根的一群化合物。雖然他們不被認為是維生素，但是在生物體內的反應裡，被認為有營養功能：例如像是抗氧化等或是具有一些抗發炎反應功效。也被認為有抵抗或是減緩腫瘤的形成。

兒茶素是什麼?

兒茶素（Catechin），又稱茶單寧，兒茶酚，是茶葉中黃烷醇類物質的總稱，兒茶素是茶多酚中最重要的一種，約佔茶多酚含量的75%到80%，也是茶的苦澀味的來源之一。

HURSEL: We've shown that green tea is able to increase your energy expenditure加強身體消耗的熱量, so the amount of calories you burn, and also to increase the amount of fat you are burning.

AUBREY: Now, before you get too excited, it's important to point out here that the effects are very small and perhaps only fleeting短暫的. More research is needed to determine whether this holds up 說不說得通 in a significant way. But Hursel says the interesting thing is that when they add milk to the tea, the metabolic effects 新陳代謝的效力seem diminished減少.

HURSEL: Something happens which we don't want to happen.

AUBREY: Hursel says it's not exactly clear what. The theory is that the proteins蛋白質 in the milk bind 黏合or stick to the beneficial catechins, making it tough for the body to absorb them efficiently. And this has also been observed among scientists who study tea's effect on blood vessel血管 health. Flavonols in tea seem to play a role in helping regulate blood pressure穩定血壓, at least in preliminary初步的 studies. But the effect may be diminished when milk proteins or other types of protein are eaten with it. Now, not all scientists are convinced that the effect of milk is strong enough to cancel out兩相抵消 potential health benefits.

ALAN CROZIER: There is no convincing evidence that milk's a problem.

AUBREY: That's researcher Alan Crozier of Glasgow University. He says, given the very high levels of flavonols in tea, and the very small amount of milk added to a typical cup of tea, the effect is likely minimal極小.

CROZIER: The amount of milk is not going to greatly interfere干擾 with the way they're absorbed. The fats in the milk might slow down the absorption, but there's no evidence that they cause irreversible不可逆的 binding and stopping the bioactive compounds生物活性物質 being absorbed.

AUBREY: Whether it's dictated by規定/支配 tradition or potential潛在的/可能的 health benefits, Robert Rex-Waller of the Park Hyatt Hotel says, really, people should enjoy tea the way they like it.

REX-WALLER: I used to scoop sugar onto everything there was. And so everyone has their own preference喜好.

AUBREY: He says if you prefer black tea with milk and sugar, one idea is to have that with breakfast. Then later in the day, try to add in a cup of green tea sans少/不加(法文) milk and sugar. Allison Aubrey, NPR News.