广东省2012届高中英语2轮总复习 专题3 第3课时主旨大意题学案

主旨大意题(2011 汕头金山中学考前适应卷) The highprotein, lowcarbohydrate(碳水化合物) diets many people turn to for weight loss might have potentially harmful longterm effects on the colon, a small study indicates. In the study, UK researchers found that a proteinheavy, lowcarb diet created certain changes in the colon that could contribute to colon cancer risk. The study itself does not show whether highprotein diets really raise the risk of any colon diseases, but the findings raise that possibility. Diets relatively high in protein and lower in carbs have been shown to help heavy people lose weight. “People should not be discouraged from losing weight，” Dr Flint said. However, he added, they should make sure that any weightloss plan includes adequate amounts of fiber and a high protein intake over months to years might have ill effects on the colon. The findings are based on 17 overweight men who followed three shortterm diets: a oneweek menu plan to keep their weight; a fourweek highprotein diet with reasonable amounts of carbohydrates; and a fourweek highprotein diet low in carbs. On average, the study found when the men were on the highprotein diets, they had higher levels of substances known as Nnitroso compounds(亚硝基化合物) and other metabolites(代谢物) that have been linked to cancer. And when they were on the highprotein, lowcarb diet, they had lowered amounts of fiberoriginated compounds thought to be protective against cancer. Exactly what those changes might mean for a person's health is not clear. But Flint said that the findings suggest that people should be cautious about consuming too much protein and too little fiber over a long period. In general, experts recommend that adults...