2014年7月24日訊 /生物谷BIOON/--與健康相關的頭條新聞中，經常出現類似含咖啡因的咖啡是患疾病的「詛咒」或可包治百病的新聞，比如每天×杯咖啡，可降低或提高你患Y病的風險。但一項針對各種歐洲咖啡的咖啡因和咖啡醯奎寧酸（CQA）開展新的研究，再次提出了從化學性質上來說，單單「一杯咖啡」意味著什麼。
在這項非資助的研究項目，也即「好奇心驅動的研究」中，來自英國格拉斯哥大學的Alan Crozier描述了，團隊測得了100多個特濃咖中咖啡因-CQA的比例。結果表明，咖啡因-CQA之比在濃咖啡中從0.7-11不等，而這取決於製備條件。因此一杯咖啡其實是一個變量研究單位，同時研究指出評估使用咖啡的健康益處可能是非常困難的，以及對此開展流行病學研究是不可取的。
但什麼是CQAs？豆類含有各種（聚）酚類，包括3 -，4-和5-O-咖啡醯奎寧酸，這寫成分是咖啡中的主要酚類化合物。流行病學的研究表明習慣性喝咖啡的消費者2型糖尿病，心血管疾病，以及子宮內膜癌和肝癌的低風險可能是由於咖啡中CQAs的存在。
雖然CQAs的生物效應是不確定的，但有一點我們知道，它們比咖啡因對烘焙更為敏感。咖啡豆類型也會影響咖啡因-CQA比例，Arabica和Robusta是最常見的咖啡豆類型，後者比前者含有兩倍的咖啡因。
英國研究者Tim Bond認為，在不同地方採取的製備方法可以顯著影響咖啡成分，因此需在咖啡銷售點提供更多的信息，讓消費者做出明智的決策。
西澳大利亞大學營養學和新陳代謝專家Kevin Croft表示贊同：未來的研究將提供咖啡攝入量更準確的評估，將更加可靠的評估關鍵咖啡成分攝入量與疾病風險之間的聯繫。（生物谷Bioon.com）
英文原文報導：
Coffee Cup Size Leads To Caffeine Confusion
Health-related headlines often cite coffee as either a caffeinated curse or cure-all, with lines such as 『x cups of coffee a day could lower or raise your risk of disease y』. But a new study into the caffeine and caffeoylquinic acid (CQA) content of various European coffees has again shown the huge variety in what 『a cup of coffee』 means chemically, and how easy it can be for pregnant women to exceed the recommended 200mg of caffeine a day.
In a non-funded project – 『curiosity driven research,』 is how group leader, Alan Crozier from the University of Glasgow, UK, describes it – the team measured the caffeine-to-CQA ratio in over 100 espressos. This expanded their previous study on coffees in Scotland. Crozier says a co-worker’s home town in Italy yielded the most consistent cups of coffee of the project. What with this, and research group member Iziar Ludwig’s trips back to Spain, there was no shortage of brews to analyse.
Results showed that the caffeine-to-CQA ratio in espressos ranged from 0.7–11, depending on the preparation conditions. With serving volumes from 13–104ml, it’s no wonder that Crozier says 『cup of coffee is an exceedingly variable unit. To estimate health benefits using cups may be very difficult,』 – and inadvisable in epidemiological studies.
But what are CQAs? Beans contain various (poly)phenols, including 3-, 4- and 5-O-caffeoylquinic acids, the main phenolic compounds in coffee. Epidemiological studies have suggested the link between the lower risk of type 2 diabetes, cardiovascular diseases, and endometrial and hepatocellular cancer in habitual coffee consumers might be due to the presence of CQAs in coffee. They sound like super-compounds, but that’s a big 『might』, and research continues.
Whilst the biological effects of CQAs are uncertain, one thing we do know about them is they are more sensitive to roasting than caffeine. The bean or blend also affects the caffeine-to-CQA ratio. Arabica and Robusta are the most common bean types and the latter contains twice as much caffeine as the former.
Tim Bond of the UK Tea Advisory panel suggests that 『where preparation method can significantly impact composition, more information could be provided at the point of sale to allow consumers to make informed decisions.』
Nutrition and metabolism expert Kevin Croft of the University of Western Australia agrees: 『Future research to provide more accurate estimates of coffee intake and biomarkers of key coffee constituents will provide more reliable assessment of links between coffee intake and disease risk.』