Shining a light on stealth fats

Content provided by the Faculty of the Harvard Medical School

Shining a light on stealth fats

No more hunting for evidence of trans fats in your food. Now you can find it right on the label.

Behold the food label, the simple listing of ingredients printed on packages of prepared food. Who knew that the addition of a single line, for trans fats, could be sparking a huge and healthy makeover of the American diet?

Until recently, trans fats could be found in nearly half of all items on grocery store shelves. They're also in French fries, doughnuts, and other restaurant fried foods. But only savvy shoppers who knew the code phrases for trans fats — "partially hydrogenated vegetable oil" and "vegetable shortening" — could tell what products contained these artery-clogging fats.

As of January 1, 2006, though, the codes will be broken. Food labels must clearly list trans fat along with saturated and unsaturated fats, cholesterol, carbohydrates, protein, and the like.

The change has food companies scrambling to remove trans fat from their products. Frito-Lay has switched to trans-free oils for making Doritos, Tostitos, Cheetos, and other snacks. The J.M. Smucker Company has created a Crisco with zero trans fat. Nabisco has spent millions of dollars on a trans-free Oreo that tastes like the original, but so far hasn't been successful. McDonald's, which pledged in 2003 to switch to non-hydrogenated oils, hasn't done so as of late 2005, at least not here. But in Denmark, where trans fats are banned, McDonald's has managed to go trans-free.

Healthier vegetable oils can sometimes be used to replace partially hydrogenated oils. For foods that require a creamier, harder, or more durable fat, companies are trying coconut and palm oil, oils from specially bred soybeans and other oily seeds, and chemical processes that create fats that mimic partially hydrogenated oils but without creating trans fats.

Why the ruckus?

Trans fats are in the same family as unsaturated fat. Think of them as the evil cousins of the healthy omega-3 fats in fish, flaxseeds, and walnuts.

Once upon a time, the only sources of trans fat were bacteria living in the forestomach of ruminants. As a result, beef, lamb, buffalo, deer, and dairy products have small amounts of trans fat. Today, trans fat is everywhere, thanks to the ingenuity of early 20th-century chemists who discovered that they could turn a liquid vegetable oil into a solid or semi-solid by bubbling hydrogen gas through it. Partially hydrogenated oils don't spoil or turn rancid as readily as non-hydrogenated fats and can withstand repeated heating without breaking down.

These characteristics made trans fat a workhorse of the food industry. The FDA has estimated that until recently, 95% of prepared cookies, 100% of crackers, and 80% of frozen breakfast products contained trans fat.

There's just one problem — unlike other unsaturated fats, trans fat isn't at all kind to your heart. Eating trans fat boosts LDL (bad) cholesterol, especially the small, dense LDL particles that are most damaging to arteries. It depresses protective HDL, which trucks LDL to the liver for disposal. Trans fat has unhealthy effects on triglycerides; makes blood platelets stickier than usual and so more likely to form artery-blocking clots in the heart, brain, and elsewhere; and feeds inflammation, which plays key roles in the development of heart disease, stroke, and diabetes.

This arterial assault translates into higher rates of heart disease. Dr. Walter Willett, a member of the Harvard Heart Letter editorial board, and his colleagues at the Harvard School of Public Health have estimated that replacing trans fat with healthier unsaturated fats could save 30,000 or more lives a year.

Avoiding trans fats

The Institute of Medicine, the organization that sets recommended intakes of nutrients, identified trans fats as something to minimize. It doesn't advocate becoming a vegetarian or giving up dairy products, but instead staying away from foods with man-made trans fat.

"If you are trying to improve your diet, avoiding added trans fat is an important and healthy step," says Dr. Willett. Just because a food is trans fat–free doesn't make it healthy, he cautions. You still need to keep an eye on sugar, refined starch, and saturated fat.

The new food labels make it easier to spot foods containing trans fat, at least in the grocery store. No more squinting at the tiny print in the ingredients list. Instead, you can read trans fat content in the bold print near the top. Restaurants aren't required to provide nutrition information about the food they serve, so getting trans fat information when dining out is still tricky. Avoiding deep-fried foods is one strategy, since many restaurants still use hydrogenated vegetable oils in their fryers. You can also ask a server how a particular item is prepared. The more servers and chefs hear this question, especially in regard to trans fat, the more likely restaurants will switch to healthier oils.

As trans fats get elbowed aside, hearts across the country will beat a little easier.

Last updated:	September 05, 2008