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A Closer Look at Essential Fats
Lately, there has been much talk about omega 3 and omega 6 fatty acids, along with their potential benefits. There has also been a great deal of attention given to the fact that trans-fatty acids are harmful. However, the discussion of fats is a complex subject and there is still much that is not understood by science. Lipids can exist in the human body in the form of sterols, phospholipids, and triglycerides. However, this article will only focus on the fatty acids that help to make up triglycerides and phospholipids. It is an attempt to explain the overall differences between saturated and unsaturated fats, as well as the differences between the essential and the harmful fatty acids.
Structure of Fatty Acids
The molecular structure is the main factor which determines the nature and type of fatty acid. A fatty acid consists of a hydrocarbon chain with a carboxyl (COOH) group at one end. The factors which determine the molecular structure of the fatty acid include the number of carbons in the chain, the presence and number of missing hydrogen pairs, the relative positions of these missing pairs, and the orientations of the hydrogen atoms. These factors in turn determine characteristics such as the melting point, the shape, and the level of polarization of the fat molecule. For example, a saturated fat is defined as having no missing hydrogen pairs which means that the molecule is saturated with hydrogen. Although many saturated fats are solid at room temperature, this is not the defining characteristic. A fatty acid with one missing hydrogen pair is a mono-unsaturated fat, while a fatty acid with 2 or more missing hydrogen pairs is a poly-unsaturated fat. The convention for labeling the natural fatty acids is such that the first number represents the number of carbon atoms, the second number represents the number of missing pairs, and the third number tells the position of the first missing pair. For example:
18:3 omega 3 means that there are 18 carbon atoms and 3 missing hydrogen pairs starting at the 3rd carbon from the hydrocarbon end. This is a poly-unsaturated fat.
4:0 means that there are 4 carbon atoms and no missing hydrogen pairs. This is a saturated fat.
18:1 omega 9 means that there are 18 carbon atoms and 1 missing hydrogen pair which is at the 9th position. This is a mono-unsaturated fat.
Functions of Essential Fats and What Makes Them Essential
The natural unsaturated fats have the hydrogen atoms near the missing pairs on the same side of the molecule (cis configuration). Because the hydrogen atoms are sharing their electrons with the carbon atoms, they have a slight positive charge and therefore repel each other. This bends the cis configured fatty acid into a distinct shape and polarizes the molecule, which alters its electrical property. Incidentally, the body has the capability to remove hydrogen pairs from the fatty acids but cannot remove the hydrogen pairs from the 3rd or the 6th positions. As a result, omega 3 and omega 6 fatty acids are essential because we need fats with the hydrogen pairs already removed from these positions. These fatty acids, along with the highly unsaturated fatty acids that are made from them, have many functions in the body which include but not limited to the following:
1. Transporting oxygen from the lungs to the red blood cells
2. Regulating cell division and gene expression
3. Development of the central nervous system
4. Manufacture of prostaglandins which have many functions in the body
5. Structural components of cell membranes
Effects of distorted fats and what causes them
Unsaturated fatty acids can be distorted if they are subjected to harsh conditions. These conditions can cause the fatty acid molecules to twist around so that the hydrogen atoms surrounding the missing hydrogen pairs are across from each other. This configuration is known as the trans (Latin for across) configuration and will alter the shape, the melting point, the polarization of the molecule, and will adversely affect its function. The body will often try to use trans-fatty acids for functions which are best fulfilled by the cis-fatty acids. This often leads to disastrous results that can cause long term health problems. Although production of trans-fatty acids is the most well known result of distorting fatty acids, there are other potentially harmful results such as bond shifting, abnormal conjugations, and other effects which are yet to be studied. The distortion of unsaturated fats can result from rancidity as well as from excessive heating and processing. This is especially true for partial hydrogenation where hydrogen is forced into the fat molecules under extreme heat and pressure.
Putting it all together
Although many of the effects of essential fatty acids are yet to be understood, it is clear that they are necessary in the diet. It is equally clear that getting adequate amounts of essential fatty acids means eating the right type of foods as opposed to just eating larger quantities of greasy junk. It is equally necessary to avoid many of the distorted fats including trans-fatty acids which are present in deep fried foods, processed cooking oils, and partially hydrogenated oils such as margarines.
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