Trans Fat Blues

Eating just seems to get dangerouser and dangerouser, as Lewis Carroll’s Alice might have put it.

It was bad enough having to worry about our intake of artery-clogging saturated fats. But now we’ve learned there’s another kind of fat to watch out for, one that’s not listed on the nutrition labels. And, of course, it’s in many of the foods we love the most--in cookies, crackers and French fries and in yummy pastries with light, flaky crusts.

It’s the bad fat du jour: trans fat. And, gram for gram, it’s as bad for our hearts--or worse--than lard.

Experts who study the link between food and the coronary heart disease that claims the lives of about 500,000 Americans each year have been warning about the dangers of trans fat for years. Now, the Food and Drug Administration agrees. On Nov. 12, citing mounting evidence for a connection between these mostly man-made fats and heightened blood cholesterol levels and coronary heart disease, the FDA proposed changes to the nutrition labels on foods.

Today, labels tell us how much fat is in a food, and how much of that total is saturated fat. Tomorrow’s labels--if the proposal is implemented--will tell us more. Amounts of trans fats will be added to the total for saturated fat, so that the full tally of heart-unfriendly fats is clearly listed. Elsewhere on the label, the number of trans fats would be indicated.

In addition, foods won’t be able to carry claims such as “low saturated fat” unless they also are low in trans fats.

Experts in heart disease and nutrition say the proposal would give consumers a truer picture of the relative healthfulness of particular foods.

But they also caution us not to get overly fixated on trans fats in our efforts to stay healthier. We still need to guard against obesity, they say, no matter what form those extra calories come in: Obesity raises our risk for serious illnesses such as heart disease and diabetes.

And just because the evils of trans fats have been uncloaked doesn’t mean that saturated fats are suddenly innocent little angels.

“The bottom line is it’s a good proposed ruling, and the American Heart Assn. certainly supports it,” says Alice Lichtenstein, a professor of nutrition at Tufts University in Boston and a member of the heart association’s nutrition committee. But, she adds, Americans get more grams of saturated fats than trans fats in their diet--and need to cut down on both. “We don’t want to overemphasize trans fats and take the focus away from saturated fats,” she says.

Food industry responses to the FDA proposal are less enthusiastic.

“We’re still reading the fine print of it,” says Robert Reeves, president of the Institute of Shortening and Edible Oils, a Washington-based trade association. “There’s a good chance of confusion to the consumer in adding one more element to the food label,” he adds. The Snack Food Assn. and the National Food Processors Assn. also emphasized the need to not confuse consumers.

Getting to Know Trans Fats

What are trans fats anyway? How do scientists know they’re bad for us? And what can we do now--since the labeling proposal, even if it’s approved, won’t likely be implemented for several years--to lower our intake?

The things that we call “fats”--butter, margarine and oils--are really a hodgepodge of different molecules containing long chains of carbon atoms studded with hydrogen atoms. These molecules come in various forms: saturated, polyunsaturated and monounsaturated.

Saturated fats (found in large amounts in meat and dairy products) are completely filled with hydrogen atoms--no room to add any more. Monounsaturated fats (plentiful in olive and canola oil) and polyunsaturated fats (abundant in soybean, safflower and corn oil) both have places where extra hydrogens can link on.

Fats rich in saturates are semi-solid at room temperature because they stack together (or “crystallize,” as fat chemists say) nice and tightly. They tend to have a palate-pleasing, creamy consistency that produces pastry to make grandma proud.

Polyunsaturated and monounsaturated fats--liquid at room temperature--make for less appetizing pastry, and cookies and crackers that lack snap. And polyunsaturated fats also go rancid over time. That’s because oxygen in the air reacts with them, creating an unpleasant taste.

Ironically, the reason trans fats are so widespread in our diets today has partly to do with the emerging discovery, roughly 40 years ago, that a diet high in saturated fats is unhealthful. Economics also drove the change: Vegetable shortening was cheaper than animal fats.

Fat chemists already knew that you could turn polyunsaturated oils into different beasts by chemically attaching hydrogen atoms.

The Creation of Margarine

This solved the problem of rancidity. It also created trans-fatty acids--which melt at higher temperatures, allowing liquid oil to be turned into solids. Margarine and shortening--also great for pastry--came to be.

As the data rolled in about the dangers of saturated fat, more and more trans-fatty acids worked their way into our foods.

Back then, this dietary change was considered very healthful, recalls Ed Emken, a lipid chemist formerly with the U.S. Department of Agriculture, in Peoria, Ill. “Everyone was encouraged to eat margarine instead of butter,” he says, “because it was ‘better for you.’ ”

True, there were folks who wondered if such “unnatural” chemicals might pose some threat if our bodies didn’t know how to metabolize them. But Emken and colleagues showed that we metabolize trans fats just fine--similarly, in fact, to the way we metabolize saturated fats.

So it’s no big surprise, says Emken, that trans fats do similar things to human blood cholesterol.

Two different lines of scientific inquiry--”metabolic” studies and “epidemiological” studies--point accusing fingers at trans fats.

In the eight or nine metabolic studies conducted in the last decade, scientists fed people diets with different types and amounts of fats. They found, consistently, that trans fats raise levels of bad (or LDL) cholesterol, much as saturated fats do.

Trans fats--unlike saturated fats--also appear to lower levels of good (or HDL) cholesterol. But there’s disagreement about the significance of this, says Lichtenstein, who conducted some of this research: The effect on good cholesterol tends to be seen at higher trans fat levels than are in the average American diet.

But metabolic studies, while significant, have their limitations. They don’t measure the bottom line we’re interested in--heart disease. They’re conducted just for weeks or months and can’t enroll large numbers of people.

That’s where epidemiology comes in--studies, for instance, in which scientists track many thousands of people, taking detailed descriptions of the diets people say they eat and following what happens to their health. The downside: You have to rely on what people tell you they’re eating. And it’s always possible that something else the people are doing or eating (not the fat, or whatever you happen to be studying) is causing a disease. Scientists do what they can to factor out that possibility.

Several epidemiological studies, including ones at Harvard involving tens of thousands of nurses and male health care providers, suggest that eating trans fats is linked to heart disease.

In fact, the Harvard scientists estimate that trans fats are responsible for between 30,000 to 100,000 premature coronary heart disease deaths every year. Gram for gram, they say, trans fats are twice as bad for us as saturated fats. Other scientists think the two fat types are roughly equivalent.

Thus, labeling products with amounts of trans fats is important, says Dr. Alberto Ascherio, professor of nutrition and epidemiology at the Harvard School of Public Health in Cambridge, Mass., and a coauthor of the Harvard research. As things stand, he says, manufacturers have an incentive to put trans fats in foods.

“Currently, saturated fat has to be on the label--and people know it is bad,” he says. “Trans fats don’t have to be on the label, and so one way to sell your product as a health product is to take out the saturated fat and put in some trans. That way, you can advertise your product as low in saturated fat with the implicit suggestion that it may be healthy.”

Although there’s usually no way to know how much trans fat a food contains, we can still do much to cut down, experts say. One strategy is simply to lower our overall fat intake. (Remember: Too many saturateds are also bad; we eat more of them than trans fats.)

For cooking, we can use monounsaturated oils, such as olive and canola, and choose tub margarine spreads--which tend to contain lower amounts of trans fats than stick margarine. Some spreads lack trans fats altogether and are labeled as such. Companies are working hard to come up with more trans-free alternatives.

We can also limit our intake of baked goods containing partially hydrogenated vegetable oil, such as many pies, cookies, snack cakes, doughnuts and crackers. Other foods loaded with trans fat as well as saturated fats include foods like French fries and fried chicken.

As for the labels, between now and Feb. 15, the FDA is soliciting comments from the public. Next, it will review the comments and decide whether to forge ahead with, drop or modify the ruling. This could easily take a year. There may also be a grace period before manufacturers have to comply.

But whatever the time frame, the FDA labeling proposal is only one part of the answer, says Margo Wootan, senior scientist for the Center for Science in the Public Interest, a Washington-based nonprofit health advocacy group that petitioned the FDA in 1994 to require trans fat labeling. Americans eat out frequently, often at fast-food outlets, and such meals don’t require any labeling.

“We’ve been calling on restaurants to switch to liquid vegetable oils,” she says. “A simple oil change could make a real difference in reducing the nation’s rate of heart disease.”

Times health writer Jane E. Allen contributed to this article.

(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)

Fat Facts

All fats are not created equal: Slight molecular differences make big differences to their physical properties--and big health differences too.

Unsaturated fats (found in vegetable oils) are bendy molecules that are liquids at room temperature.

Saturated fats (found in meat and dairy foods) are semisolid at room temperature and, when eaten to excess, raise cholesterol levels and increase our risk for heart disease.

Trans fats have an intermediate melting temperature, and are found in margarine, many fried foods and baked goods made with vegetable shortening. Trans fats also raise our heart disease risk when eaten to excess.