Trans-Fats: Out of the Frying Pan and Into the Fire
By Greg Post
Summary: In an attempt to get away from saturated fats nutritional science created a whole new product: trans-fats. Trans-fats have been accused of contributing to the heart disease epidemic of the 1990s.
There is a lot of buzz these days about trans-fats. Most of us are aware that they present a health risk. Some researchers have even hypothesized that the pervasive nature of trans-fats is to be blamed for the heart disease epidemic of the 1990's. That is to suggest that much of our current problem with heart disease can, at least in part, be traced back to the fact that trans-fats are almost everywhere in our foods. It would also seem to suggest that reducing trans-fat intake might reduce the incidence of heat disease.
This article does not deal per se with how to avoid trans-fats in your diet. That, indeed, is a worthy topic but must be reserved for another time. Our present concern is one that is a bit more basic in nature. It is this: What is the source of trans-fats and why do we find them in so many of our foods? To theorize that trans-fats may bear some responsibility for the escalation of heart disease in the 1990's is to propose that trans-fats were not so prevalent before that time. It further suggests that the change is due to something we have done to ourselves.
Around the middle of the previous century we became increasingly aware that saturated fat consumption poses a risk to heart health. Conventional wisdom today agrees with that earlier assessment. It was further believed, as it is today, that mono- and polyunsaturated fats are much better for us. For the most part they do not promote atherosclerosis (hardening of the arteries). In addition many unsaturated fats actually reverse the damage caused by their saturated counterparts.
So why not simply have a whole culture switch to using polyunsaturated oils instead of what we were used to using? The question almost answers itself. It is the same as asking, "Why don't people stop smoking? Nobody believes it is a healthy practice. But as long as we have choices to make we will make bad ones. And as long as there is money to be made products will be sold.
Perhaps it is more helpful for us to look at the particular dilemmas facing the scientists of the 1950's. They knew, as we do, that people should eat less saturated fats and more unsaturated fats. However folks were very accustomed to lard and butter, just to mention two common products. Not only do these products have a particular taste, they are also in semi-solid form at room temperature. Unsaturated oils are usually in liquid form at room temperature. So the first problem facing scientists was how to convert unsaturated fats into substances that taste and act like the semi-solid products the populous already appreciated.
But there was a second obstacle. Unsaturated fats tend to spoil more quickly producing a rancid odor and taste. Therefore they cannot be stored for long periods of time. Limited shelf-life can be a hindrance for food producers and marketers. Any product that could be widely sold must be able to stand the test of time in relation to the whole food manufacturing cycle.
Fortunately a solution was found that could simultaneously overcome both obstructions. That solution? Hydrogenation.
All of us are somewhat familiar with the term. We see a variant of it almost every time we read the label from one of the products in the pantry. It has become commonplace. Neatly tucked away between the various unpronounceable ingredients we find the words "partially hydrogenated". This two word combination will be coupled with some oil that we might recognize as good for us. The list of partially hydrogenated oils is impressive and misleading. When we read the labels we should place an emphasis in our minds on the first part of the phrase. Instead of reading the label like this: "partially hydrogenated cottonseed oil", we should read it thus: "partially hydrogenated cottonseed oil". The end of the phrase is somewhat insignificant. The beginning of the phrase means everything.
Hydrogenation is simply a process whereby an unsaturated oil (fat) is saturated with hydrogen. Fats are composed of carbon (C), hydrogen (H) and oxygen (O) atoms along a carbon chain or skeleton. At one end of the chain there is a carboxyl group consisting of bonds between one carbon atom, one hydrogen and two oxygens, or (COOH). Simply put, fats are composed of a chain of carbon atoms. A carbon atom has four bonds. Typically two of the bonds are connected to other carbon atoms in the chain. The other two bonds will be connected to hydrogen. A saturated fat has all of its (free) bonds tied up with hydrogen. In an unsaturated fat some of the carbon bonds are not connected to hydrogen. Instead the carbon atoms form double bonds with each other. The problem with these double bonds, from a manufacturing point of view, is that they make the fat liquid at room temperature and reduce shelf life.
The solution, however, is rather simple. By heating the fat in the presence of hydrogen some of the double carbon bonds are broken and they form an attachment with a new hydrogen partner. It all sounds so romantic. Of course you can see where this is going. Now the fat is approaching saturation again. Not to worry, however. The process is usually stopped prior to the saturation point. The fat is then said to be "partially hydrogenated". Technically it remains unsaturated. It seems as if we can have our cake and eat it too. Now we can have unsaturated fats that act and taste like saturated fats. The consumer has the best of both worlds. The seller has a product which is inexpensive to make, has a long shelf-life and has mass appeal. Who said utopia is not possible?
As is true with most relationships breaking up to form new attachments usually causes a backlash. The carbon atoms that share a double bond are each also bound to one hydrogen atom. The hydrogen atoms are both on the same side of the molecule chain. This configuration is known as a "Cis bond and occurs naturally in unsaturated fats. The hydrogenation process weakens these "Cis bonds. As mentioned earlier they are not all broken. However their weakening causes some of the hydrogen atoms to move to the other side of the carbon chain. The hydrogen atoms are now across (or trans) from each other. The "Cis bond has now become a "Trans bond. Essentially the molecular shape of the chain is altered. We now have the birth (to keep the relationship metaphor going) of a new fat named for its altered "Trans bonds. We know them as trans-fats or trans-fatty acids.
Though the hydrogen process is difficult to picture its end result is clear to all of us. Hydrogenation creates trans-fats. If a high percentage of our manufactured foods contain partially hydrogenated products, they of course contain trans-fats. And anyone who has been paying attention lately knows that trans-fats are bad for us, very bad for us.
There is one more bit of bad news. As noted above, hydrogenation involves exposing unsaturated oils to high heat. Frying with oil does the same thing. Granted only a small number of "Cis bonds are converted to "Trans bonds during the process of frying. It might be argued that we should avoid any exposure to trans-fats. However there is a bigger picture here. I always appreciate those fast food restaurants that make an attempt to produce healthier foods. One way they do this is to use healthy oils in their frying process. But I wonder how many times they use those healthy oils. If a small number of "Cis bonds are converted to "Trans bonds during the first frying phase, how many "Trans bonds exist before the oil is changed? It is like playing trans-fat Russian roulette. "May I have my French fries fried in a new batch of oil, please? It puts a new twist on special orders.
About The Author
Greg Post has degrees in science, divinity and philosophy and is currently an I.T. developer.