2. 考研
  3. [A]No miracle diets for heart disease or cancer [B]How the study was conducted? [C]The outcome of the study on heart disease [D]

[A]No miracle diets for heart disease or cancer [B]How the study was conducted? [C]The outcome of the study on heart disease [D]

admin2019-08-01  20
问题 [A]No miracle diets for heart disease or cancer
[B]How the study was conducted?
[C]The outcome of the study on heart disease
[D]Low colorectal cancer rate: chance or the low-fat diet?
[E]The significance of the study on breast cancer
[F]How fat and heart disease are related?
    Starting a low-fat diet in mid-life does not, by itself, decrease a woman’s risk of heart disease or stroke or dramatically reduce her risk of breast cancer or colorectal cancer, according to three studies published today of almost 50, 000 healthy, post-menopausal women. But the findings still support the general idea that you need to pay attention to how much fat—and particularly what kinds of fat—you eat.
【R1】______
    Researchers randomly divided the participants into two groups, worked hard to get one group to cut its fat intake and then compared the results for each of them for the next several years. Through focus groups and sessions with nutritionists, the so-called intervention group was given a lot of help and information on how to cut the amount of fat in their diet. As a group they weren’t able to get all the way down to 20% fat intake, but they did manage to reduce it to 24% in the first year, though it slid back up to 29% by the sixth year. The other, so-called control group received printed material on dietary guidelines but no other help on healthy eating. The fat content of their diets was 35% after one year and crept up to 37% after six years—and they gained a little weight to boot.(The intervention group lost weight or stayed the same.)
【R2】______
    All told, the women in the two groups showed no overall difference in the number of heart attacks or strokes they suffered over the eight years of the study. Part of the reason may be that the level of LDL or" bad" cholesterol dropped in the intervention group by a tiny 2. 4%—too small a reduction for the study to be able to detect a difference in outcome.
【R3】______
    It’s also possible that if you want to prevent heart disease, it’s not enough to focus just on the total amount of fat in the diet; you also have to look at the types of fat as well as exercise and physical activity levels. Why didn’t the study focus more intently on these variables? Researchers were not as aware of how important they were back in the late 1980s, when they were designing the trial.
【R4】______
    Women in the low-fat group suffered 9 % fewer breast cancers than those in the control group. Although that difference was not statistically significant, it is very suggestive. Given how long it takes for most tumors to grow, it may simply be that the study has not lasted long enough to show a significant effect. In addition, there was a clear benefit for one sub-group of women—those who began the study with the highest total fat consumption and who were able to make and maintain the greatest reduction in the number of fat calories in their diet. This group benefited from al5% to 20% drop in the incidence of breast cancer.
【R5】______
    Women in the low-fat group did not see a significant drop in their rates of colorectal cancer. Given how long it takes colorectal cancer to develop, a 9% difference is significant. Welcome to the wild and complex world of statistics. After looking at the variation in the data with various mathematical tools, research statisticians determined that they couldn’t rule out the possibility that the 9% difference in breast cancer results was due to chance alone. On the other hand, after applying those same mathematical tools to the data in the colorectal cancer study, they determined that the 9% difference in the number of polyps was unlikely to be due to chance alone.
    So, in many ways these studies raised more questions than they answered. Strictly speaking, the results do not apply to men, who tend to get heart disease earlier than women do and for whom a low-fat diet might be particularly beneficial. But this study has set the gold standard for diet studies in the future.
【R2】
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答案C
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