Sunday, August 30, 2009

What Is Trans Fat?

I know we aren't supposed to eat trans fats because they aren't good for us, and many companies now advertise their foods do not contain any. But what are they exactly?? Marissa N.

Dear Marissa,

Trans fats are those that have been chemically modified in order to become more solid.
This mimics the structure of oils that are naturally solid at room temperature, such as lard.

Simply put, fatty acids contain long strands of carbon chains. Each carbon atom is linked to another on each side, and then there are two more free bonds: these are either available to double-bond to the carbon atom on each side, or to be saturated with Hydrogen atoms on both the top and the bottom. When an oil has more hydrogen atoms saturating it, it becomes more solid.

Several decades ago when we knew foods like butter and animal fat contributed to high cholesterol, it was mistakenly assumed this was because of the cholesterol present.
So food scientists got the bright idea of making corn oil margarine: we would take a 'healthy' oil (because it was so liquid) and saturate it with hydrogen atoms. Then we could have a butter substitute that was not going to contribute to heart disease!

Several years later, however, research showed that the saturation of the fats was what contributed to elevating serum cholesterol levels, even moreso than eating foods with cholesterol.
An example of a high-cholesterol/low-saturated-fat food is shrimp. It is not unhealthy to eat a food such as this when on a cholesterol-lowering diet.

Margarine, on the other hand, was found to contribute to elevating cholesterol even though it was made with a cholesterol-free product: the process of saturating it turned it into an unhealthy fat.

Some time ago most food products stopped using lard in their ingredients, and a few years later they stopped using "tropical oils" (coconut and palm oil) which--while they do not contain cholesterol--contain a high percentage of saturated fats. The time has now come to find other ways of making the texture and taste suitable without using trans fats in order to keep our diets heart healthy.

1 comment:

  1. Wow, I had no idea that's what trans fats were... good grief, talk about dangerous. Based on the struggle so many have with food it almost seems like that activity should be criminal. Thanks for sharing this info Laurie!