《考研英語(yǔ)閱讀理解100篇 高分版》 Unit 25 - TEXT THREE

Everyone is interested in whether different foods or nutrients affect our odds of getting diseases like cancer or of developing risk factors for those diseases, such as too much weight or high blood pressure. But there are many barriers to studying dietary change, which is why we still have no easy answers to the question of what, exactly, we should eat to be at our healthiest. It's also why you can be forgiven for often feeling whipsawed by headlines: Is coffee good or bad? What about alcohol, garlic, or chocolate?
This week researchers reported in the Journal of the American Medical Association that breast cancer survivors who cram their diets with fruits and vegetables are no more likely to escape a recurrence than women who stick to the usual five-a-day recommendation. Does that mean fruits and vegetables don't protect against cancer? No—just that in this specific group of women with breast cancer, the extra greens and additional apples didn't seem to help.
We asked researchers to explain why studies involving dietary changes are so hard to do—and what consumers should keep in mind when they read about them. Here's what the experts said:
Most diet studies take place in the real world. That means study subjects are keeping diaries of what they eat as they go rather than having their intake strictly controlled by someone else. You can give them meal advice, counseling, and how-to books up to their ears, but at the end of the day, they are on their own when it comes to what they put in their mouths. It's easier to get people to add something—like garlic, in the form of tasty sandwich spreads, or dark chocolate—than to take something away; no wonder a recent study comparing low-fat and low-carb diet plans found that almost no one was sticking to them by the end.
In studies focusing on diet, including the recent study on breast cancer recurrence, the amount of calories subjects reported eating would have caused them to lose far more weight than they actually did lose. The misreporting isn't necessarily vicious, but the inaccuracies add up. Say you're phoned about your daily intake on a day when it was someone's birthday at work and you had a slice of cake. You may not report it, thinking that a typical day wouldn't include the cake... forgetting yesterday's “special occasion” piece of pizza, and the Big Gulp of the day before. Or, despite the portion size guides you get, you characterize your bagel from the deli as a 4-ounce standard serving when a 4-ounce bagel hasn't been sighted in any major city for a decade.
“You can't put a camera in everyone's belly and see exactly what they ate,” says Christopher Gardner, a nutrition scientist at the Stanford Prevention Research Center who has recently published research on garlic and diet plans. You can get around this in some studies by taking objective measurements. Weight, for example, or if you're assessing intake of fruits and veggies, you can measure the level of pigments called carotenoids in the blood. In the breast cancer study, blood tests showed that the study subjects actually did eat more fruits and veggies (carotenoid concentration was 73 percent higher in those women after one year and 43 percent higher after four years). But objective measures can't definitively nail down whether someone is eating nutrients in certain proportions.
1. One can be forgiven for feeling whipsawed by those headlines because _____.
[A] there is no solid and convincing scientific hypothesis on these subjects
[B] the question about what the healthiest food is has no answers
[C] opinions on these subjects are quite contradictory
[D] there is no authoritative answer to these questions
2. Which one of the following statements is TRUE of the conclusion of the study on breast cancer recurrence?
[A] Women who stick to the five-a-day recommendation are less likely to have a recurrence.
[B] Women who eat extra greens and vegetables are less likely to escape a recurrence.
[C] Women could depend on fruit diet to avoid the breast cancer recurrence.
[D] Fruits and vegetables are no good to women with breast cancer.
3. From the results of the studies focusing on diet, it can be inferred that _____.
[A] the amount of calories set in diet could not help people to lose weight
[B] people are reluctant to take part in such studies
[C] it is difficult to get valuable conclusion from these studies
[D] this kind of studies is not objective enough
4. The fact that a 4-ounce bagel hasn't been sighted in any major city for a decade implies that _____.
[A] you should re-examine the standard size of the food you intake
[B] you tend to give an inaccurate report of your actual diet
[C] you fail to cooperate with the doctor by false record of your daily food
[D] you make a mistake in noting down the size of standard serving
5. The limitation of the objective measurements mentioned in the last paragraph is that _____.
[A] they could only assess the proportion of fruits and veggies study subjects have taken
[B] they could not have the subjects follow exactly the food proportion of their diet
[C] they could not identify the levels of all the nutrients in patients' blood
[D] they could not tell the exact proportions of nutrients study subjects have eaten