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     The high-protein, low-carbohydrate (碳水化合物) diets many people turn to for weight loss might have

potentially harmful long-term effects on the colon, a small study indicates.

     In the study, UK researchers found that a protein-heavy, low-carb diet created certain changes in the colon

that could contribute to colon cancer risk The study itself does not show whether high-protein 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 weight loss 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 short-term diets: a one-week menu plan

to keep their weight; a four-week high-protein diet with reasonable amounts of carbohydrates; and a four-week

high-protein diet low in carbs.

     On average, the study found when the men were on the high-protein diets, they had higher levels of

substances known as N-nitroso 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 high-protein, low-carb diet, they had lowered amounts of fiber-

originated 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 get about 28 grams of fiber per day-though it's not known whether

that's enough for someone on a high-protein weight-loss diet.

1. What is the best title of the text?

A Plan a Healthy Diet

B. Take Care of Your Colon

C. How to Lose Weight

D. How to Protect against Cancer

2. The underlined word "colon" in Paragraph 1 probably refers to "_____".

A. an organ

B. intelligence

C. a habit

D. behaviour

3. The study shows that high-protein, low-carb diets may _____.

A. affect your mood

B. lower cancer risks

C. harm your body

D. keep your figure

4. It can be inferred from the text that _____.

A. we shouldn't take the study seriously

B. weight problems are hard to solve

C. it is better to follow a low-carb diet

D. people should be cautious to lose weight

5. The author is intended to _____.

A. advise how to lose weight

B. introduce a scientific finding

C. describe a research process

D. talk about healthy diets