Câu hỏi:

Read the following extract from Jess McElhinney's article on health issues and choose the correct answer to each of the questions.

In a study of aspirin's effect on blood clotting in which abstinence from chocolate was required, a large proportion of participants broke the rules. Their "offence" led to what is believed to be the first biochemical evidence that a few squares of chocolate a day can almost halve the risk of heart attack death by decreasing the tendency of tiny particles (or platelets) to clot in narrow blood vessels. "What these chocolate offenders taught us is that the chemical in cocoa beans has a biochemical effect similar to aspirin in reducing platelet clumping, which can be fatal if a clot forms and blocks a blood vessel, causing a heart attack," said Diane Becker from Johns Hopkins University in Maryland, USA, who led the study. Becker cautions that this discovery should not become an excuse to indulge in large amounts of chocolate frequently, since chocolate also contains high amounts of sugar, butter and cream. However just a few squares of dark chocolate the purest form may be just what the doctor ordered. For almost 20 years researchers have known that chemicals, called flavonoids, most common in dark chocolate, help blood flow and lower blood pressure. This new finding, presented at the American Heart Association's annual scientific sessions in Chicago this week, identifies the effect of everyday doses of chocolate found in regular foods such as hot chocolate or chocolate bars. This differs from previous studies which have examined the effects of eating unrealistic doses of flavonoids, equivalent to several pounds of chocolate a day. "Eating a little bit of chocolate or having a drink of hot cocoa as part of a regular diet is probably good for personal health, so long as people don't eat too much of it, and too much of the kind with lots of butter and sugar," said Becker. In the study, 139 chocolate offenders were disqualified from a larger experiment which aimed to examine the effects of aspirin on blood clotting. Before the study began, all participants were instructed to follow a strict exercise and diet regimen and to refrain from smoking or using foods and drinks known to affect blood-clotting activity, like caffeinated drinks, wine, grapefruit juice and, of course, chocolate. Platelet samples from both groups (offenders and non-offenders) were run through a mechanical blood vessel system designed to time how long it takes for platelets to clump together. Chocolate lovers' samples were found to clot more slowly, on average taking 130 seconds to block the system. Platelets from those who stayed away from chocolate clotted faster, taking an average of 123 seconds. 

 

According to the findings, what helps lower blood pressure?