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纽约时报:动物油背黑锅多年,植物油反式脂肪才是心脏病元凶!

2015年03月22日 厨艺, 生活常识 暂无评论 阅读 1 次

来源|纽约时报|

中国人祖祖辈辈都吃猪油,心脏病一直都很罕见,也生育力旺盛。现在猪油被妖魔化,用多链不饱和脂肪酸的植物油代替后,心脏病居高不下,不孕症比比皆是,人工受孕中心赚翻了天。

1957年,初出茅庐的库默罗医生请求当地一家医院给他一些心脏病人的血管样本做研究。不出意料,他发现这些心脏病人的血管充满了脂肪堆积,但这不是一般的脂肪,而是一种特别的脂肪,也就是我们今天所熟知的反式脂肪(trans fat)。

 

库默罗医生因此深入研究,得出结论,证明了反式脂肪和心脏病的直接关联。但是,他的研究结论并没有得到广泛接受——这过程经历了30年。而直到50年后,美国的FDA才正式决定在食物中去除反式脂肪。

真相总是难以接受的。

库默罗医生今年99岁,至今仍然继续为伊利诺亚大学工作。过去两年,他连续发表了几篇研究,矛头直指造成今天广泛的心脏病的元凶:多链不饱和脂肪酸的植物油,例如,大豆油,玉米油,和葵花子油。

库默罗医生指出,问题不在于胆固醇,甚至不在于坏胆固醇(LDL),胆固醇和心脏病毫无关系。问题只在于胆固醇的被氧化。而那些高温油炸的烹饪过程是最容易把植物油氧化的。

库默罗医生的研究很好的解释了为什么半数的心脏病病人他们的体内的胆固醇是正常的,甚至是低的。

库默罗医生自己的饮食也证明了这点,除了吃新鲜的蔬菜水果外,他还每周吃几次红肉,饮用全脂牛奶。

他已经不记得最后一次吃油炸的东西是什么时候了,也从未吃过人造奶油,但是他会用黄油(Butter)来炒蛋。

库默罗医生说,鸡蛋是大自然赐给人类的最好的食物,包含了所有的9种氨基酸,还有多种维他命和矿物质。吃鸡蛋只吃蛋白不吃蛋黄真的是疯了。

库默罗医生的研究因为太过超前,所以他早期曾受到很大困难,甚至连研究经费都很难拿到。科学界一直都认为如猪油牛油之类的饱和脂肪才是心脏病的元凶。

所幸历史是人民写的。科学家们总是会出错的。传统总是正确的。

虽然今年已经99岁,但是库默罗医生的饱和脂肪饮食(黄油/猪油)令他仍然拥有完美的如同百科全书般的记忆力。他仍然清楚记得所有的人,时间,地点,更令人惊叹的是,是那些复杂的科学概念。

 

 

反式脂肪才是心脏病的真凶

  喷香的猪油、奶油能不能吃?豆油菜、籽油、调和油能不能吃?美国科学家库默罗教授(Fred Kummerow)答案是,只要不是反式脂肪(trans fat)都可以吃。但必须避免高温煎炸导致的植物油氧化危害。原因很简单天然油脂会很快在体内降解。反式脂肪(trans fat)熬得住岁月,“顽强地”在我们的心血管内存留。堆积在心脏上,最终将人们杀死。所以建议仔细阅读一下手里食品的营养标签,看看是否含有反式脂肪及比例。它将决定你的明天。

--------------------

1957年,初出茅庐的库默罗医生请求当地一家医院给他一些心脏病人的血管样本做研究。不出意料,他发现这些心脏病人的血管充满了脂肪堆积,但这不是一般的脂肪,而是一种特别的脂肪,也就是我们今天所熟知的反式脂肪(trans fat)。

库默罗医生因此深入研究,得出结论,证明了反式脂肪和心脏病的直接关联。但是,他的研究结论并没有得到广泛接受--这过程经历了30年。而直到50年后,美国的FDA才正式决定在食物中去除反式脂肪。

真相总是难以接受的。

库默罗医生今年99岁,至今仍然继续为伊利诺亚大学工作。过去两年,他连续发表了几篇研究,矛头直指造成今天广泛的心脏病的元凶:多链不饱和脂肪酸的植物油,例如,大豆油,玉米油,和葵花子油。

库默罗医生指出,问题不在于胆固醇,甚至不在于坏胆固醇(LDL),胆固醇和心脏病毫无关系。问题只在于胆固醇的被氧化。而那些高温油炸的烹饪过程是最容易把植物油氧化的。

库默罗医生的研究很好的解释了为什么半数的心脏病病人他们的体内的胆固醇是正常的,甚至是低的。

库默罗医生自己的饮食也证明了这点,除了吃新鲜的蔬菜水果外,他还每周吃几次红肉,饮用全脂牛奶。

他已经不记得最后一次吃油炸的东西是什么时候了,也从未吃过人造奶油,但是他会用黄油(Butter)来炒蛋。

库默罗医生说,鸡蛋是大自然赐给人类的最好的食物,包含了所有的9种氨基酸,还有多种维他命和矿物质。吃鸡蛋只吃蛋白不吃蛋黄真的是疯了。

库默罗医生的研究因为太过超前,所以他早期曾受到很大困难,甚至连研究经费都很难拿到。科学界一直都认为如猪油牛油之类的饱和脂肪才是心脏病的元凶。

所幸历史是人民写的。科学家们总是会出错的。传统总是正确的。

虽然今年已经99岁,但是库默罗医生的饱和脂肪饮食(黄油/猪油)令他仍然拥有完美的如同百科全书般的记忆力。他仍然清楚记得所有的人,时间,地点,更令人惊叹的是,是那些复杂的科学概念。

背景:人工反式脂肪是指通过氢化处理,把液态植物油转为固态或半固体的氢化油。其优点是改善味道、耐高温、不易变质、保存期长,而且比饱和动物脂肪便宜。以前人们一度以为氢化油较动物脂肪健康,但研究证明,吸取氢化油会增加坏胆固醇,同时减少好胆固醇,增加患心脏病的风险。美国食品及药物管理局相信一旦禁用人工反式脂肪后,每年可减少两万宗心脏病病发个案,也会减少七千人死亡。

反式脂肪酸常添加在哪类食品中?

日常生活中,含有反式脂肪酸的食品很多,诸如蛋糕、糕点、饼干、面包、沙拉酱、薯片、爆米花、巧克力、冰淇淋……凡是松软香甜,口味独特的含油(植物奶油、人造黄油等)食品,都含有反式脂肪酸。原因是,用植物油催化加氢制取脂肪时,反式脂肪酸也同时生成了。

一般来说,口感很香、脆、滑的多油食物就可能使用了部分氢化植物油,富含氢化植物油的食品就可能有反式脂肪酸。还有速食店和西式快餐店的食物也常常使用氢化油脂。现制现售的奶茶尤其要注意,因为它“乳化”“滑润”的状态特性需要氢化植物油。

氢化植物油就是反式脂肪酸吗?

植物油不完全氢化才会产生反式脂肪,完全氢化的部分就不是反式脂肪而是饱和脂肪,因此氢化植物油不能等同于反式脂肪。比如某些产品的加工需要完全氢化的植物油,因此这类食品中反式脂肪酸的含量其实很低,当然完全氢化会使饱和脂肪含量大幅上升,也不宜过多食用。

附件1:

文章来源:纽约时报

http://www.nytimes.com/2013/12/17/health/a-lifelong-fight-against-trans-fat.html?_r=0

Health

A Lifelong Fight Against Trans Fats

By MELANIE WARNERDEC. 16, 2013

Photo

Fred Kummerow, 99, in his lab at the University of Illinois where he still directs research. Credit Sally Ryan for The New York Times

In 1957, a fledgling nutrition scientist at the University of Illinois persuaded a hospital to give him samples of arteries from patients who had died of heart attacks.

When he analyzed them, he made a startling discovery. Not surprisingly, the diseased arteries were filled with fat — but it was a specific kind of fat. The artificial fatty acids called trans fats, which come from the hydrogen-treated oils used in processed foods like margarine, had crowded out other types of fatty acids.

The scientist, Fred Kummerow, followed up with a study that found troubling amounts of artery-clogging plaque in pigs given a diet heavy in artificial fats. He became a pioneer of trans-fat research, one of the first scientists to assert a link between heart disease and processed foods.

It would be more than three decades before those findings were widely accepted — and five decades before the Food and Drug Administration decided that trans fats should be eliminated from the food supply, as it proposed in a rule issued last month.

Photo

Fred Kummerow in 1953.

Now, Dr. Kummerow (KOO-mer-ow) is still active at age 99, living a few blocks from the university, where he runs a small laboratory. And he continues to come to contrarian conclusions about fat and heart disease.

In the past two years, he has published four papers in peer-reviewed scientific journals, two of them devoted to another major culprit he has singled out as responsible for atherosclerosis, or the hardening of the arteries: an excess of polyunsaturated vegetable oils like soybean, corn and sunflower — exactly the types of fats Americans have been urged to consume for the past several decades.

The problem, he says, is not LDL, the “bad cholesterol” widely considered to be the major cause of heart disease. What matters is whether the cholesterol and fat residing in those LDL particles have been oxidized. (Technically, LDL is not cholesterol, but particles containing cholesterol, along with fatty acids and protein.)

“Cholesterol has nothing to do with heart disease, except if it’s oxidized,” Dr. Kummerow said. Oxidation is a chemical process that happens widely in the body, contributing to aging and the development of degenerative and chronic diseases. Dr. Kummerow contends that the high temperatures used in commercial frying cause inherently unstable polyunsaturated oils to oxidize, and that these oxidized fatty acids become a destructive part of LDL particles. Even when not oxidized by frying, soybean and corn oils can oxidize inside the body.

If true, the hypothesis might explain why studies have found that half of all heart disease patients have normal or low levels of LDL.

“You can have fine levels of LDL and still be in trouble if a lot of that LDL is oxidized,” Dr. Kummerow said.

This leads him to a controversial conclusion: that the saturated fat in butter, cheese and meats does not contribute to the clogging of arteries — and in fact is beneficial in moderate amounts in the context of a healthy diet (lots of fruits, vegetables, whole grains and other fresh, unprocessed foods).

Continue reading the main story

His own diet attests to that. Along with fruits, vegetables and whole grains, he eats red meat several times a week and drinks whole milk daily.

He cannot remember the last time he ate anything deep-fried. He has never used margarine, and instead scrambles eggs in butter every morning. He calls eggs one of nature’s most perfect foods, something he has been preaching since the 1970s, when the consumption of cholesterol-laden eggs was thought to be a one-way ticket to heart disease.

“Eggs have all of the nine amino acids you need to build cells, plus important vitamins and minerals,” he said. “It’s crazy to just eat egg whites. Not a good practice at all.”

Dr. Robert H. Eckel, an endocrinologist and former president of the American Heart Association, agreed that oxidized LDL was far worse than nonoxidized LDL in terms of creating plaque.

But he disputed Dr. Kummerow’s contention that saturated fats are benign and that polyunsaturated vegetable oils promote heart disease. “There are studies that clearly show a substitution of saturated fats with polyunsaturated fats leads to a reduction in cardiovascular disease,” said Dr. Eckel, a professor at the University of Colorado.

Robert L. Collette, the president of the Institute of Shortening and Edible Oils, a trade association, says oil manufacturers work with their customers to take precautions against oxidation.

“Oxidation is something that consumers can detect,” he said. “Therefore, it is in everyone’s best interest to control it.”

The long arc of Fred Kummerow’s life and career illustrates the frustratingly slow pace of science and the ways in which scientific conformity can hinder the search for answers. Born in Germany just after World War I broke out, he moved to Milwaukee with his family when he was 9. His father, who worked at a cement block factory, did not have the money to send him to college, so Dr. Kummerow worked full time at a drug distribution company while attending the University of Wisconsin in the evenings. After he earned a Ph.D. in biochemistry, his first job was at Clemson University in South Carolina, where he helped prevent thousands of deaths in the South from pellagra, a disease resulting from a deficiency of vitamin B3.

His early research on trans fats was “resoundingly criticized and dismissed,” said Dr. Walter Willett, the chairman of the nutrition department at the Harvard School of Public Health, who credited Dr. Kummerow with prompting his desire to include trans fats in the Nurses’ Health Study. A 1993 finding from that study, which showed a direct link between the consumption of foods containing trans fats and heart disease in women, was a turning point in scientific and medical thinking about trans fats.

“He had great difficulty getting funding because the heart disease prevention world strongly resisted the idea that trans fats were the problem,” Dr. Willett continued. “In their view, saturated fats were the big culprit in heart disease. Anything else was a distraction from that.”

At an age when life itself is an accomplishment, Dr. Kummerow said he had no intention of stepping away from the work that has consumed him for six decades. He continues to work from home and talks daily to the two scientists who work in his lab, which receives funding from the Weston A. Price Foundation.

His wife of 70 years, Amy, died last year at age 94 from Parkinson’s disease; he has three children, three grandchildren and a great-grandchild.

He takes no medications, and his mind shows no sign of aging: He has an encyclopedic recall for names, dates and, more impressive, complex scientific concepts. After his muscles became inflamed from a blood pressure drug that he has since stopped taking, he started using a wheelchair combined with a walker.

His most significant health problem, appropriately enough, was an artery blockage at age 89 — probably a result of the inevitable effects of aging, not diet.

Bypass surgery took care of the blockage, and the fact that he now has an artery from his arm running into his heart has made him even more determined to keep working. Heart disease remains the leading cause of death for Americans, and he would like to stick around to continue funding research that will help change that.

“What I really want is to see trans fats gone finally,” he said, “and for people to eat better and have a more accurate understanding of what really causes heart disease.”

A version of this article appears in print on December 17, 2013, on page D2 of the New York edition with the headline: A Lifelong Fight Against Trans Fats.

附件2:FDA发布的新闻

http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm373939.htm

FDA NEWS RELEASE

For Immediate Release:?Nov. 7, 2013?

Media Inquiries:??Shelly Burgess,?shelly.burgess@fda.hhs.gov, 301-796-4651

Consumer Inquiries:?1-888-INFO-FD

FDA takes step to further reduce?trans?fats in processed foods

Reducing trans fat intake could prevent thousands of heart attacks and deaths?

?

The U.S. Food and Drug Administration announced its preliminary determination that?partially hydrogenated oils (PHOs), the primary dietary source of artificial?trans?fat in processed foods, are not “generally recognized as safe” for use in food. The FDA’s preliminary determination is based on available scientific evidence and the findings of expert scientific panels.?

?

The agency has opened a 60-day comment period on this preliminary determination to collect additional data and to gain input on the time potentially needed for food manufacturers to reformulate products that currently contain artificial?trans?fat should this determination be finalized.

“While consumption of potentially harmful artificial?trans?fat has declined over the last two decades in the United States, current intake remains a significant public health concern,” said FDA Commissioner Margaret A. Hamburg, M.D. “The FDA’s action today is an important step toward protecting more Americans from the potential dangers of?trans?fat. Further reduction in the amount of?trans?fat in the American diet could prevent an additional 20,000 heart attacks and 7,000 deaths from heart disease each year – a critical step in the protection of Americans’ health.”

?

Consumption of?trans?fat raises low-density lipoprotein (LDL), or “bad” cholesterol, increasing the risk of coronary heart disease. The independent Institute of Medicine (IOM)?has concluded that?trans?fat provides no known health benefit and that there is no safe level of consumption of artificial?trans?fat. Additionally, the IOM recommends that consumption of?trans?fat should be as low as possible while consuming a nutritionally adequate diet.

In recent years, many food manufacturers and retailers have voluntarily decreased?trans?fat levels in many foods and products they sell.?Trans?fat can be found in some processed foods, such as certain desserts, microwave popcorn products, frozen pizzas, margarines and coffee creamers.?Numerous retailers and manufacturers have already demonstrated that many of these products can be made without?trans?fat. ?

?

Thanks to these efforts, along with public education, the consumption of?trans?fat in American diets has been significantly reduced. Since?trans?fat content information began appearing in the Nutrition Facts label of foods in 2006,?trans?fat intake among American consumers has declined from 4.6 grams per day in 2003 to about 1 gram per day in 2012.

“One of the FDA’s core regulatory functions is ensuring that food, including all substances added to food, is safe,” said Michael Taylor, the FDA’s deputy commissioner for foods and veterinary medicine. “Food manufacturers have voluntarily decreased?trans?fat levels in many foods in recent years, but a substantial number of products still contain partially hydrogenated oils, which are the major source of?trans?fat in processed food.”

Following?a review of the submitted comments, if the?FDA finalizes its preliminary determination, PHOs would be considered “food additives” and could not be used in food unless authorized by regulation. If such a?determination were made, the agency would provide adequate time for producers to reformulate products in order to minimize market disruption.?The FDA’s preliminary determination is only with regard to PHOs and does not affect?trans?fat that naturally occurs in small amounts in certain meat and dairy products.

More information about?trans?fat and information the FDA is seeking is available through a Federal Register?notice. Thedocket?will be open for comment for 60 days.

To submit comments by mail, send to the FDA at:

Division of Dockets Management (HFA-305)

Food and Drug Administration

5630 Fishers Lane, Rm. 1061

Rockville, MD 20852

?

All submissions must include the agency name and docket number.

For more information:

* Federal Register Notice:?Tentative Determination of Food Additive Status of Partially Hydrogenated Oils:?Request for Comments and Scientific Data and Information?

* National Academies of Science, Institute of Medicine Report:?Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids???

* HHS Million Hearts Initiative

* USDA Dietary Guidelines for Americans, 2010??

* FDA Consumer Update: FDA Targets?Trans?Fat in Processed Foods

* FDA Voice:?Trans?Fat: Taking the Next Important Step?

* Talking about?Trans?Fat – What You Need to Know

?

The FDA, an agency within the U.S. Department of Health and Human Services, protects the public health by assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices. The agency also is responsible for the safety and security of our nation’s food supply, cosmetics, dietary supplements, products that give off electronic radiation, and for regulating tobacco products.

附件3:伊利诺大学发布新闻

http://illinois.edu/lb/article/5510/79081

Professor Fred Kummerow, 99, led the effort to ban trans fats

11/7/2013

The U.S. Food and Drug Administration has announced that it will take on the thorny subject of trans fats in food, a decades-old controversy that has set public health advocates against the food industry. The FDA has all but declared that partially hydrogenated oils can no longer be “generally recognized as safe.”

This turn of events is a decades-old dream of Fred Kummerow, 99, a professor of comparative biosciences at Illinois. Kummerow was the?sole author?of a?petition to the FDA?in 2009 to ban trans fats, a petition the agency had not responded to in any substantive way until this month. His petition outlined the many ways that artificial trans fats are harmful to health, relying on data from decades of research from his lab and others to bolster his case that people should not be eating anything with hydrogenated or partially hydrogenated oils as an ingredient.

This summer Kummerow filed a?lawsuit against the FDA?for its lack of response to his petition. Now the agency has at last addressed the dangers of trans fats in food. It is proposing to ban artificial trans fats from the food supply unless they are proven safe.

“This is a victory!” Kummerow said. “When is it going to start?”

On Nov. 7, the FDA opened a 60-day comment period on their “preliminary determination” that partially hydrogenated oils were not “generally recognized as safe” for use in food. This will allow the agency to hear from those in industry “on the time potentially needed for food manufacturers to reformulate products that currently contain artificial trans fat should this determination be finalized,” the FDA said in a?report on the matter.

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