题型:阅读理解 题类:常考题 难易度:普通
湖南省衡阳市一中2018-2019年高一上学期英语10月月考试卷
A medical study has shown that excess(过度的)coffee drinking could cause heart attacks in people who do not metabolize(使新陈代谢)caffeine fast enough.
The study, published recently in the Journal of the American Medical Association, says an enzyme(酶)that metabolizes caffeine in the liver works differently in some people, depending on the makeup of the gene(基因). People who have a slow version (版本)of the enzyme are at a greater risk(风险)of a heart attack when they drink more coffee. The risk had something to do with a person's age and how many cups of coffee he drinks.
The team from the University of Toronto in Canada studied 4,024 people living in coffeerich Costa Rica between 1994 and 2004, of whom half suffered nonfatal(非致命的)heart attacks. They found slightly more than half had the slow version of the gene, while the rest had the fast form.
Two to three cups of coffee a day increased the possibilities of a heart attack by 36 percent for those with the slowacting gene and four or more cups a day lifted it by 64 percent.
But those under 50 who had the fast version of the gene had a lower risk of heart disease, even with four or more cups a day.
Those with the fastacting gene who drank two to three cups of coffee a day had 22 percent reduced possibilities of having a heart attack, but drinking four or more cups a day only lessened the risk by 1 percent. Scientists recommend limiting coffee consumption(消耗量)to within four cups a day.
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