Trans Fatty Acids and the Heart

Recent studies have suggested that trans fatty acids have a deleterious effect on cholesterol levels and the risk of heart disease, and point out that we're eating far more of these evil fats than we should, and far more than we used to.

What are trans fatty acids, and where do they come from?

We're used to hearing about saturated and unsaturated fatty acids. Saturated fatty acids - which come from animal fats (meat, lard, dairy products) as well as tropical oils such as coconut and palm oils - raise the levels of LDL cholesterol. Unsaturated fats - which come from vegetable oils - in general, do not increase cholesterol levels, and may reduce them.

Because saturated fatty acids were found to be bad for you a couple decades ago, the food industry wanted to switch to using unsaturated fatty acids. Unfortunately, unsaturated fatty acids become rancid relatively quickly. To combat the instability of unsaturated fatty acids, manufacturers began to "hydrogenate" them, a process that makes them more stable. The result was a more solid and longer lasting form of vegetable oil, called "partially hydrogenated" oil.

Unfortunately, when unsaturated vegetable fats are subjected to the process of hydrogenation, a new type of fatty acid is formed. This new type of fatty acid is called trans fatty acid. So when manufacturers began substituting partially hydrogenated vegetable oils for saturated fats in processed foods, they began adding - for the first time - relatively large amounts of trans fatty acids to the typical diet.

So what's the problem with trans fatty acids?

Trans fatty acids turn out to increase total cholesterol levels and LDL cholesterol levels, and to reduce HDL cholesterol levels. In other words, trans fatty acids are detrimental to cardiac health.

Which is worse - saturated fatty acids or trans unsaturated fatty acids?

Both saturated fats and trans fatty acids are bad for you. Saturated fats are almost always found in foods that also contain cholesterol, so saturated fats offer a "one-two" punch to heart health. On the other hand, trans fatty acids not only increase LDL cholesterol, they also decrease HDL cholesterol. So while nobody can say yet definitively which is worse, it does appear that both are bad.

Which foods contain trans fatty acids?

Fortunately, it is relatively easy to identify foods that contain relatively large amounts of trans fatty acids: margarines (the more solid the margarine, the more the trans fatty acids; stick margarines contain the most, tub margarines contain less, and semi-liquid margarines contain the least;) high-fat baked goods (especially doughnuts, cookies and cakes;) and any product for which the label says "partially hydrogenated vegetable oils" (which, it sadly appears, includes virtually all processed foods.) DrRich is particularly distressed to point out that trans fatty acids absolutely lace his two favorite food groups: french fries and potato chips. (This tragic warning also includes corn chips and many crackers.)

Well, darn it, what are the good fats?

Unsaturated vegetable oils from canola, peanuts, olive, flax, corn, safflower and sunflower (as long as they have not been subjected to the process of hydrogenation) are heart healthy. These oils contain monounsaturated or polyunsaturated fatty acids that can reduce total cholesterol and increase HDL cholesterol levels. These oils also contain the essential fatty acids - specific fatty acids necessary for life but which the body cannot make itself. (These include omega-3 and omega-6 fatty acids.)

So what is the health-conscious consumer to do?There are three basic steps to reducing the amount of "bad" fat in the diet and substituting "good" fat. First, avoid the saturated fatty acids found in meat and dairy products, as well as the tropical oils (palm and coconut.) Second, avoid trans fatty acids by steering clear of commercially fried foods, high-fat baked goods, and stick margarines. Third, whenever possible substitute one of the natural unsaturated vegetable oils, listed above, in recipes calling for stick margarine, butter, or lard.

Nobody ever said life was going to be easy.