2019-01-10 15:35:57 来源：网络专四专八资料下载
Excessive calories from sugar can contribute to weight problems,
and sugar is also well known for its ability to promote teeth __1__
Too many calories from fat have also taken their toll from the __2__
public's health. In 1988, the U.S surgeon general issued a report
linking high level of fat intake to an increased risk for obesity.
Obesity is a risk factor for high bloody pressure, stroke, and __3__
diabetes. Research has also shown a relationship between high
levels of fat in the diet and cancer. In addition, scientists
have linked some types of fat to high blood cholesterol level,
which must lead to heart disease. Such reports have prompted __4__
health experts and nutritionists to recommend that adults and
children over age 2 not only watch their sugar intake but
also to limit their fat intake to a maximum of 30% of their __5__
complete calories. This has encouraged many people to turn __6__
to products made with fat and sugar substitutes.
Low-calorie sugar substitutes have been around for decades,
but the recent trend in eating "light" has created a boom in this
branch of food-technology research. Today, food chemists are
seeking for better substitutes by modifying existing foods, __7__
searching for new compounds in nature, and concoct entirely __8__
new substances. But the research process is complicated by our
incomplete understanding of how the human body interacts with
the chemicals we eat.
For example, scientists do not already know exactly why some __9__
substances taste sweet. Other questions involve the safe and __10__
usefulness of artificial fats and sweeteners.