VOA标准英语2010年-Eating More 'Good' Fats Lowers Risk of

Reducing saturated¹ fat in diet alone isn't enough, study says

Art Chimes | Washington, DC 25 March 2010
 

People who eat more polyunsaturated fats have been found to have a lower risk of heart disease.

Related Links-PLoS Medicine article

"If you're taking out the saturated fat, what are you replacing it with?" — Dariush Mozaffarian

For years, doctors have been telling patients to cut down on saturated fats — the kinds of fats in meats and milk, for example. Reducing fat in the diet, especially saturated fat, was believed to be an important strategy to reduce heart disease.

Now, a new study says reducing fats isn't enough. We have to focus on the kinds of fats we eat. 

Previous studies found that people who ate a lot of saturated fats were more likely to have a lot of the kinds of cholesterol² that can clog³ arteries⁴ and lead to heart attacks. But there was little direct evidence to show that cutting saturated fats actually lowered the risk of heart disease.

"And we wanted to look at whether replacing saturated fat with polyunsaturated fat, with a healthy fat rather than, for example, with carbohydrates⁵ or protein or other things, was beneficial," says Dr. Dariush Mozaffarian of the Harvard School of Public Health. He thought the answer might lie in the numerous studies over the years that looked at diet and heart disease.

"And so, we wanted to do a systematic⁶ review of all the literature, find all of the appropriate studies and pool them to see if together, there's a benefit for replacing saturated fat specifically with polyunsaturated fat."

So Mozaffarian and his colleagues studied the studies, eight of them, in which some participants ate less saturated fat and more polyunsaturated fats, the kind of fats that are in fish, nuts, and vegetable oils. They were compared with a control group that had more saturated fat in their diets.

This kind of research is called a meta-analysis. Often combining the results of several similar studies can produce conclusions that the individual studies don't support. Sometimes that's partly because combining studies increases the number of people participating in the research. In this case, the combined studies included more than 13,000 people.

Reducing saturated fats may reduce cholesterol, but low fat diets alone don't seem to do much to actually reduce clogged⁷ arteries and heart attacks.

"There's actually, in the last several years, been convincing evidence that replacing saturated fat in one's diet with carbohydrates has very little effect on heart disease. And so if that's not going to produce benefit, what sorts of replacements⁸ [for saturated fats] might?"

Mozaffarian's study found that people who replaced saturated fat with polyunsaturated fat had about a 20 percent lower risk of heart attack or other heart disease.

It's still not exactly clear how the polyunsaturated fats confer this benefit. But the researcher says their effect on cholesterol may be part of the answer.

"So for example, dietary fats also actually, in many cases, improve HDL cholesterol, the good cholesterol, compared to carbohydrates, and they actually lower triglycerides, a type of blood lipid which is associated with harm."

But Mozaffarian said dietary fats may also affect blood pressure and inflammation of the blood vessels⁹; they may even have an impact on the heart's electrical function.

Whatever the mechanism¹⁰, the study does suggest some guidance for people who want to lower their risk of heart disease.

"They can't just look at a product that says 'low grams of saturated fat' or 'low saturated fat' and assume that it's healthy," he said. "If you're taking out the saturated fat, what are you replacing it with?"

And it doesn't mean we have to spend a lot of time parsing¹¹ the nutritional¹² labeling that is now on packaged foods in many countries.

"If someone says I should eat fruits, vegetables, whole grains, fish, nuts, and avoid processed foods, sugary beverages¹³, and foods with trans fats or high in salt, that's actually much simpler, I think, than chasing all of these numbers."

Professor Dariush Mozaffarian of Harvard School of Public Health. His study was published this week in the journal PLoS Medicine.
 

1 saturated   

a.饱和的，充满的

参考例句：

• The continuous rain had saturated the soil. 连绵不断的雨把土地淋了个透。
• a saturated solution of sodium chloride 氯化钠饱和溶液

2 cholesterol   

n.（U）胆固醇

参考例句：

• There is cholesterol in the cell of body.人体细胞里有胆固醇。
• They are determining the serum-protein and cholesterol levels.他们正在测定血清蛋白和胆固醇的浓度。

3 clog   

vt.塞满，阻塞；n.[常pl.]木屐

参考例句：

• In cotton and wool processing,short length fibers may clog sewers.在棉毛生产中，短纤维可能堵塞下水管道。
• These streets often clog during the rush hour.这几条大街在交通高峰时间常常发生交通堵塞。

4 arteries   

n.动脉( artery的名词复数 )；干线，要道

参考例句：

• Even grafting new blood vessels in place of the diseased coronary arteries has been tried. 甚至移植新血管代替不健康的冠状动脉的方法都已经试过。 来自《简明英汉词典》
• This is the place where the three main arteries of West London traffic met. 这就是伦敦西部三条主要交通干线的交汇处。 来自《简明英汉词典》

5 carbohydrates   

n.碳水化合物，糖类( carbohydrate的名词复数 )；淀粉质或糖类食物

参考例句：

• The plant uses the carbohydrates to make cellulose. 植物用碳水化合物制造纤维素。 来自《简明英汉词典》
• All carbohydrates originate from plants. 所有的碳水化合物均来自植物。 来自辞典例句

6 systematic   

adj.有系统的，有计划的，有方法的

参考例句：

• The way he works isn't very systematic.他的工作不是很有条理。
• The teacher made a systematic work of teaching.这个教师进行系统的教学工作。

7 clogged   

（使）阻碍( clog的过去式和过去分词 )； 淤滞

参考例句：

• The narrow streets were clogged with traffic. 狭窄的街道上交通堵塞。
• The intake of gasoline was stopped by a clogged fuel line. 汽油的注入由于管道阻塞而停止了。

8 replacements   

n.代替( replacement的名词复数 )；替换的人[物]；替代品；归还

参考例句：

• They infiltrated behind the lines so as to annoy the emery replacements. 他们渗透敌后以便骚扰敌军的调度。 来自辞典例句
• For oil replacements, cheap suddenly looks less of a problem. 对于石油的替代品来说，价格变得无足轻重了。 来自互联网

9 vessels   

n.血管( vessel的名词复数 )；船；容器；（具有特殊品质或接受特殊品质的）人

参考例句：

• The river is navigable by vessels of up to 90 tons. 90 吨以下的船只可以从这条河通过。 来自《简明英汉词典》
• All modern vessels of any size are fitted with radar installations. 所有现代化船只都有雷达装置。 来自《现代汉英综合大词典》

10 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

11 parsing   

n.分[剖]析，分解v.从语法上描述或分析（词句等）( parse的现在分词 )

参考例句：

• A parsing program, or parser, is also called a recognizer. 分析过程又称作识别程序。 来自辞典例句
• This chapter describes a technique for parsing using the bottom-up method. 本章介绍一种使用自底向上方法的分析技术。 来自辞典例句

12 nutritional   

adj.营养的，滋养的

参考例句：

• A diet lacking in nutritional value will not keep a person healthy.缺乏营养价值的饮食不能维持人的健康。
• The labels on food products give a lot of information about their nutritional content.食品上的标签提供很多关于营养成分的信息。

13 beverages   

n.饮料( beverage的名词复数 )

参考例句：

• laws governing the sale of alcoholic beverages 控制酒类销售的法规
• regulations governing the sale of alcoholic beverages 含酒精饮料的销售管理条例