Understanding Hydrogenated Oils and Trans Fats

Over the last decade, there has been a lot of press about the negative effects of hydrogenated oils and trans-fats, which recently led to New York City passing the first law to ban the use of hydrogenated oils in restaurants. Yet even with all the negative publicity about hydrogenated oils, few people actively avoid consuming them and only a very small percentage of people really understand what they are and why they are harmful.
This article is designed to explain the major differences between good and bad fats and take the mystery out hydrogenated oils and trans-fats. It also explains how eliminating hydrogenated oils from your nutritional program will improve your long-term health and fat loss. However, before getting to hydrogenated oils, I will cover some basic scientific information about fats that is necessary to fully understand why some fats are good and hydrogenated oils are bad.
The structure of fats: The main part of a fat molecule is made up of carbon atoms chained together with hydrogen atoms attached to their sides. When all of the carbon atoms have hydrogen atoms attached to both sides, they form a saturated fat. If one hydrogen atom is missing, the fat is monounsaturated and fats with multiple hydrogen atoms missing are called polyunsaturated.
This by itself is not too important, but whenever a hydrogen atom is missing (unsaturated), there will be a double bond between the carbon atoms instead of the usual single bond. You may be wondering why this is significant, but understanding the double bonds is the key to understanding hydrogenated fats and fats in general.
The double bond between carbon atoms along with the missing hydrogen atom allows the fat molecule to be more versatile and becomes useable for various physiological reactions throughout the body. Fats with double bonds have many beneficial effects, such as improving your immune system, heart health, mood, skin, energy, nutrient absorption, and much more.
Some fats are more beneficial than others and generally the more double bonds the fat contains, the more positively it will affect your body. Probably the most well known beneficial fats are the Omega-3 oils found in fatty fish, which have either 5 or 6 double bonds. On the down side, fats with more double bonds are also more fragile and susceptible to physical manipulations. The importance of this will become apparent when you read about hydrogenation.
Saturated fats (no double bonds) on the other hand can only be used as energy for the body and cannot be used in the cellular reactions that create the beneficial effects listed above. In addition any extra saturated not needed for energy will be stored as fat. There is however one benefit to saturated fats: they are very durable and are highly resistant to physical alterations.
Hydrogenation is a manufacturing process used to alter unsaturated fats, generally to increase the shelf life of packaged products. This change is achieved by altering unsaturated fats at the point of their double bond(s). Unsaturated oils can either be completely hydrogenated or partially hydrogenated and each process affects fats differently. It is also important to note that saturated fats cannot be hydrogenated, because they have no double bonds or missing hydrogen atoms.
When an unsaturated fat is completely hydrogenated, it essentially becomes a saturated fat. Unfortunately there are also some additional unnatural compounds created during the process that are not found in natural saturated fats. After this process, the fat will have almost an indefinite shelf life, although it loses all any health benefits associated with the original fat.
Completely hydrogenated fats are generally only used with fats that are almost completely saturated to begin with and they are less common than partially hydrogenated fats. This is unfortunate, because contrary to how the name sounds completely hydrogenated fats are actually less unhealthy than partially hydrogenated ones.
As the name implies, partially hydrogenated fats do not undergo the full hydrogenation process. This means the fat does not end up resembling a saturated fat and there are even more unnatural compounds produced during this process than full hydrogenation. In addition, permanent damage is done to the double bonds that change their properties from healthy to unhealthy.
Bear with me for just a little bit more science, because this is what the previous information has been leading up to. When double bonds are in their natural occurring state, they are in a "cis" configuration. You don't have to remember this, but you do need to know that during hydrogenation the "cis" configuration gets altered into a "trans" configuration. In other words, hydrogenation turns healthy unsaturated fats into unhealthy trans-fats.
In the past it was believed that saturated fats were the unhealthiest fats, but in recent years trans-fats have taken over that title. It is important to note that since trans-fats are created by altering unsaturated fats, you will never find trans-fats in saturated fats or completely hydrogenated fats. Also, healthier fats with many double bonds are easier to corrupt during the hydrogenation process.
I hope you feel somewhat comfortable with the science behind fats, because it helps explain why trans-fats are so unhealthy. As previously discussed, unsaturated fats are used in many beneficial chemical reactions throughout the body and the double bonds are key to these reactions. Trans-fats maintain the appearance of a healthy unsaturated fat and the body can't tell the difference between them. Unfortunately, there is a big difference in the way they function.
When your body tries to use the trans-fats in necessary physiological reactions, they will not be effective. Trans-fats essentially stop the beneficial reactions from taking place, which can affect virtually every important system within your body. Some of the many negative effects include: impairing heart performance, weakening your immune system, weakening the protective barrier around cells, and disrupting the function of essential fats.
Now that you have read the science, here is some additional practical information to help you limit your consumption of trans-fats. While it is true that partially hydrogenated oil is a major source of trans-fat, it is not the only one. Simply exposing unsaturated oils to high temperatures, such as when frying food, will alter double bonds and create trans-fats. Since fats with many double bonds are quite fragile, they can be turned into trans-fats at much lower temperatures than fats with only 1 double bond (monounsaturated).