Trans Fats: The Science and the Risks
This man-made fat was developed to protect us against butter. Turns out, it acts like butter inside our bodies.
What exactly are trans fats? How are they made? How bad are they,
really? And just how solid is the science that the FDA consulted when
they voted to list trans fats on nutrition labels? To get to the bottom of
these and other questions about trans fats, WebMD spoke to leading
What Exactly Are Trans Fats?
Trans fatty acids or trans fats are formed when manufacturers
turn liquid oils into solid fats. Think shortening and hard margarine.
Manufacturers create trans fats via a process called hydrogenation. Hydro-what?
In a nutshell, hydrogenation is a process by which vegetable oils are converted
to solid fats simply by adding hydrogen atoms.
Why hydrogenate? Hydrogenation increases
the shelf life and flavor stability of foods. Indeed, trans fats can be found
in a laundry list of foods including vegetable shortening, margarine, crackers
(even healthy sounding ones like Nabisco Wheat Thins), cereals, candies, baked
goods, cookies, granola bars, chips, snack foods, salad dressings, fats, fried
foods, and many other processed foods.
Trans fatty acids are found naturally in
small quantities in some foods including beef, pork, lamb, butter, and milk,
but most trans fatty acids in the diet come from hydrogenated foods. So there
is good news: When the new nutrition labels go into effect Jan. 1, 2006, it
will be easier to screen these fats out of your diet. Until then, look at the
package's list of ingredients. Products that contain partially hydrogenated
oils or vegetable shortening may contain trans fats.
Where Did Trans Fats Come From?
Trans fats were developed during the
backlash against saturated fat -- the artery-clogging animal fats found in
butter, cream, and meats. Then food manufacturers realized that trans fats
lasted longer than butter without going rancid. The result: Today trans fats
are found in 40% of the products on your supermarket shelves.
"We used to use animal fats, and people
said, 'saturated fats are bad,' so we switched to trans fats," says Ruth
Kava, PhD, RD, director of nutrition at the New York City-based American
Council on Science and Health. "This kind of gives us an unfortunate focus
on ingredients rather than the whole diet when the problem isn't this fat or
that fat, it's too many calories."
"Anything was good if it decreased
saturated fat consumption in the 1950s through the 1980s," agrees Alice H.
Lichtenstein, Dsc, professor of nutrition at Tufts University in Boston.
"But then studies began to question trans fats," too. Finally, in the
1990s, the evidence became clear: When vegetable oil is turned into a solid,
like butter, it acts like butter inside the body.
Next, learn about the risks.
What Do Trans Fats Do Inside the Body?
Like saturated or animal fats, trans fats
contribute to clogged arteries. Clogged arteries are a sign of heart disease;
they increase your risk of both heart attack and stroke. Here's how it works:
Trans fats raise low-density lipoprotein (LDL) or "bad" cholesterol
levels. This contributes to the buildup of fatty plaque in arteries.