科学家的数据和言论有多可信？

蒋继平

2013年11月9日

今天美国新闻联播网（CNN)在首页登出了一位特约专栏作家的文章。http://www.cnn.com/2013/11/08/opinion/carroll-fda-trans-fat/index.html?hpt=hp_t4这位专栏作家是美国印第安那大学医学院的教授，同时也是健康政策和职业化研究中心的主任。 他的题目是：再见和好好的清除植物油（反式脂肪）。

在文章中，他的主要论点可以简述为：

1. 食品药品管理局在消除食品加工中添加人工植物油方面走出了第一步。

2. 食品药品管理局的做法是正确的。这是因为植物油对人体非常不好。

3. 他说数据证明植物油增加坏的胆固醇和心脏病。

4. 他说食品制造商很可能会采取合作，尽管消除植物油会增加成本。

他在文章中提及了在食品加工过程中添加植物油的历史，说这种做法已经有一百多年的历史记录。到1990年，科学证据已经显示植物油对人体的健康不利，尤其是会增加胆固醇和引发心血管方面的病。

他说从2006年起，食品药品管理局就要求食品制造商必须标明植物油在食品加工中的比例。从2007年起，麦当劳已经停止使用植物油。其他一些食品连锁店也尽量减少使用植物油。因而，从那时开始， 美国人对植物油的消费大幅地下降。

他还提到，原先科学家认为植物脂肪（不饱和脂肪）比动物脂肪（饱和脂肪）对人体较为安全。现在看来却却相反。所以，食品药品管理局的决定将使我们不得不改正我们的错误，这是早晚要做的事，只是一个时间问题。

读了AaronE. Carroll教授的这篇文章，我觉得科学家的数据和解释根本经不起历史的检验，有的根本就是政治的工具。一会儿A比B安全，一会儿反过来。当某些有决定权的人要推销一种产品时，就说它是好的。

食品药品管理局的行动和这篇文章使我联想到最近有关转基因食品的安全之争。因为， 目前的植物油大多数是转基因作物的产品，所以， 食品药品管理局的做法从一个侧面反应出对转基因食品的清除。难道你不会这么认为吗？

中国的一些科学家总是喜欢引用美国农业部的一些数据，来根据他们自己的意图加以解释，这样的话，这些数据的可信度有多高？

我非常严肃认真地向中国的政府和科学家们提出一个建议，希望你们认真地观察和研究一下美国在转基因食品上采取的措施，在社会上的反应，和转基因食品的生产销售以及在转基因作物研发方面的最新动态。千万不能把20年前的信息当成今日的理据来推销。

我担心中国的读者很难打开CNN的网址，所以， 将原文付后。供有兴趣的人自己查看。需要进一步说明的是， 我的文章不是直接的翻译，而是列出大意，希望大家明鉴。

Goodbyeand good riddance, trans fats

AaronE. Carroll is a professor of pediatrics at the Indiana UniversitySchool of Medicine and the director of its Center for Health Policyand Professionalism Research.

The FDAtook a first step toward eliminating artificial trans fats in foodsupply 。

Aaron Carroll:FDA made the right move, since trans fats are very bad for people 。

He saysevidence shows trans fats increase bad cholesterol and heart disease。

Carroll: It'slikely food suppliers will comply despite the costs of removing transfats。

The Food and Drug Administration on Thursday took astep toward essentially a total banon artificial trans fats in America's food supply.

This is not a trivial change. Not that long ago,trans fats were a part of all kinds of processed foods. Partiallyhydrogenated oils, as they are otherwise known, tend to improve boththe shelf life and flavor of many foods. Trans fats have been aroundfor more than a hundred years. They're used in a wide range of foods,from frozen pizza to microwave popcorn to packaged cookies.

But trans fats are amazingly bad for you. By the1990s, evidence was building that trans fats carried a significantrisk for increasing coronary heart disease. Specifically, they werefound not only to increase your level of low-density lipoprotein(LDL, or bad cholesterol) but to decrease your level of high-densitylipoprotein (HDL, or good cholesterol). Because of this, the negativeeffects of trans fats are about double those of saturated fat (whichisn't that good for you, either).

It gets worse. Trans fats also increase your level oflipoprotein(a) and triglycerides, both of which are thought to beassociated with cardiovascular disease.

These laboratory findings bear out in all kinds ofepidemiologic studies showing that a diet containing higher levels oftrans fats carried greater health risk than a diet similarly high insaturated fat

There has been a longstanding argument that we shouldstop using trans fats. The American Heart Association recommends thatpeople's diets contain 2 grams or less of trans fats a day. Thatamount is what you might normally get in dairy products and meat. Butif you eat processed foods, you'll end up consuming more trans fats.

In 2006, the FDAstarted mandating that food labels list the amount of trans fatsin foods in order to make consumers aware of their hazard.

Some companies have made an effort to stay away fromtrans fats. McDonalds stopped using them 7years ago. Burger King has a minimal amount in its foods, andthat's from small amounts that are present naturally in meat andcheese. New York banned trans fats in restaurants in 2007. It was acontroversial decision at the time, but consumption of trans fats inthe city has droppeddramatically because of the ban.

The Centers for Disease Control and Prevention saysthat removing trans fats from the U.S. food supply couldprevent about 20,000 heart attacks a year and 7,000 deaths fromcardiovascular disease.

Finally, the FDA issued a Federal Register noticeannouncing that trans fats are not "generally recognized assafe." Such a notice allows a period of time for people andbusinesses to comment and offer opinions and evidence if they believethat trans fats should not be banned.

Of course, there are costs to such a move. The FDAestimates that it will cost about $8 billion initially to removetrans fats from the food supply. It believes the 20-year costs to bebetween $12 billion and $14 billion.

I think it's likely that processed food producerswill comply. There's almost no good evidence -- or argument -- tosupport the continued use of trans fats. In fact, it's been reported that some manufacturers have voluntarily lowered the use of trans fats by almost 75% in the past eight years. Given these moves, it'snot hard to imagine them going the rest of the distance.

There is some irony inthis, of course. Trans fats first became more common in our diet because they were believed to be safer than animal fats (think margarine instead of butter).Turns out the opposite is true. The FDA's actions are putting us onthe road to correcting that mistake, hopefully sooner rather than later.