Trans Fats: The Science and the Risks

[Guest guest]

Thought this might be of interest to anyone who needs to lower cholesterol.

Moe

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 U.S. Food and Drug Administration

consulted when they voted to list trans fats on nutrition labels? To get to the

bottom of these and other pressing questions about trans fats, WebMD spoke to

leading nutritionists and gathered the answers that you need -- now.

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. All fatty acids are chains of carbon atoms with

hydrogen atoms attached. With trans fats, hydrogen atoms are on opposite sides

of the chain of carbon atoms at the carbon-carbon double bond. Trans means

across in Latin, thus trans fats.

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 'Oh my god 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 build up

of fatty plaque in arteries.

" The science that shows that trans fats increase LDL cholesterol levels is

outstanding and very strong. All evidence is pointing in the same direction, "

Lichtenstein tells WebMD.

In the Nurse's Health Study, women who consumed the greatest amounts of trans

fats in their diet had a 50% higher risk of heart attack compared to women who

consumed the least amount of trans fatty acids.

Some researchers suspect that trans fats also increase blood levels of two other

artery-clogging compounds -- a fat-protein particle called lipoprotein(a) and

blood fats called triglycerides.

Equally worrisome, population studies indicate that trans fats may up the risk

of diabetes. Researchers at the Harvard School of Public Health in Boston

suggest that replacing trans fats in the diet with polyunsaturated fats (such as

vegetable oils, salmon, etc.) can reduce diabetes risk by as much as 40%.

How much trans fat is safe? No one really knows. Kava says that the prestigious

Institute of Medicine reported that there isn't enough research yet to recommend

a safe amount of trans fats. " We know that like saturated fats, trans fats can

raise bad cholesterol but there is conflicting data about what it does to good

cholesterol, " she says. " I wish the data were stronger. "

The FDA, while requiring manufacturers to put the amount of trans fats on

nutrition labels, will not require a % daily value (DV) for trans fat because

there is not enough information at this time to establish a such a value, she

says. Food labels do offer such information about saturated fats.

How Do Trans Fats Compare to Saturated Fats?

" Trans fats raise (bad) LDL cholesterol levels slightly less than do saturated

fats, " says Lichtenstein. " But saturated fats also raise levels of high density

lipoprotein (HDL) or " good " cholesterol, and trans fatty acids don't. " Thus,

some researchers say trans fats are worse. Lichtenstein, however, figures the

two fats probably cause equal harm in our diets because we eat far more

saturated fat than trans fats.

The FDA estimates that Americans aged 20 and older consume 5.8 grams of trans

fats per day -- that's about 2.6% of our daily calories. By comparison, we

consume 4 to 5 times more saturated fat per day. About 40% of our trans fat

intake comes from cakes, cookies, cracker, pies and bread, while 17% comes from

margarine.

Who Should Be Concerned About Trans Fats?

Of course, everyone should try to limit their consumption of trans fats and

saturated fats. However, " individuals who are told by their physicians that they

have elevated LDL cholesterol should be most concerned, " Lichtenstein says.

" They should minimize their intake of both trans fats and saturated fats. "

Kava adds: " The most important thing is looking at the number of calories and

then serving size. Then check out saturated fat and trans fat on the label. It

might help some people make smarter decisions. "

Are All Fats Bad?

Not at all. Polyunsaturated and monounsaturated fats -- found mainly in canola,

olive and peanut oils -- can result in less LDL and more HDL production in the

body, says Boston-based community nutritionist Dana Greene, MS.

" That's a good thing, " Greene says. But we should still limit our daily fat

intake to 30% or less of our daily calories, she stresses. Her advice? " Choose

heart healthy fats including nuts, avocado, peanut butter and trans fat free

margarines such as Promise and Smart Beat. "

Originally published July 17, 2003.

Medically updated May 26, 2004.

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SOURCES: Ruth Kava, Ph.D., R.D., director of nutrition at the New York

City-based American Council on Science and Health. Alice H. Lichtenstein, Dsc,

professor of nutrition at the Friedman School of Nutrition Science and Policy at

Tufts University in Boston. Dana Greene, MS, a Boston-based community

nutritionist.