Dietary fat is one of the three macronutrients that we need for survival. The other two macronutrients are proteins and carbohydrates. There are four types of dietary fats and, with the exception of trans fats, we need to regularly include them in our diet for good health. This article will provide you with an overview of each one of the different types of fats.
Fat (and its liquid form oil) is a common name for triglycerides that are in our food and body. In the introduction to fats, I mentioned that fats are made up of one molecule of glycerol and three molecules of fatty acids, which can be variable in size.
Types Of Dietary Fats
The backbone of a fatty acid is a chain of carbon and hydrogen atoms linked together. At the end of the chain there is an acid group (COOH) and a methyl group (CH3), (marked as pink and blue, respectively in the images below). Based on this carbon/hydrogen chain and the types of links within the chain, the fats can be separated into three naturally occurring types and one “altered” or artificial type. They are:
- trans (altered – hydrogenated)
The difference between the four types of dietary fats lies in the degree of saturation of the carbon chain with the hydrogen atoms.
A single fat can consist of different types of fatty acids but it is classified (or categorized) on the basis of which type of fatty acid predominates. For example, olive oil (liquid form of a fat) is classified an monounsaturated but it’s makeup consist of 77% monounsaturated fatty acids and 9% of saturated and 9% of polyunsaturated fatty acids (Source).
Saturated fats predominantly consist of fatty acid chains that are fully loaded with hydrogen. As you can see in the image below, with the exception of the end carbons, each carbon atom is linked to a hydrogen atom. Also notice that between each carbon (ignore the acid group at the end) there is only a single bond (exemplified by a single line).
Saturation of a fatty acid affects its stability and firmness. For this reason saturated fats are solid and more stable (all fats eventually become rancid when exposed to air).
For many years saturated fats have been vilified and we were discouraged to include them in our diet. New scientific studies are slowly but surely vindicating this fat and in fact the research suggests that we need to include these fats as part of our healthy diets.
According to Dr. Mike Hart, good sources of healthy saturated fats are:
- coconut oil
- grass-fed beef
- pastured butter
- free range eggs
The reason Dr. Hart favors these saturated fats is that
…these foods contain fats that are beneficial to our health as well as containing the various fats in ratios that are conducive to achieving optimal health…
Fatty acids that are missing one hydrogen in their carbon chain are called monounsaturated fatty acids (MUFAs). Notice, in the image below, the red arrow points to an area where a hydrogen is missing. When this atom is missing the carbon atoms join together in a double bond (=).
The most common monounsaturated fatty acids are palmitoleic acid and oleic acid. Olive oil a monounsaturated oil. It contains 71% of oleic acid.
Monounsaturated fats are considered healthy fats and they are the typical fats of the healthy Mediterranean diet. It is believed that including MUFAs in your diet may lower your risk of many diseases and conditions including:
- heart disease
- lowering you low-density lipoprotein (LDL) levels
- increasing blood levels of high-density lipoprotien (HDL)
- protect you against inflammation
- improve blood glucose regulation
- protect you against cancer
- help you burn fat and lose weight
Excellent sources of monosaturated fats are:
- olive oil
- nuts (almonds, cashews, pecans, macadamias
- peanut oil
Fatty acids that lack more than one hydrogen atoms in their carbon chain are called polyunsaturated fatty acids (PUFAs). The fatty acid below is missing 2 hydrogens and has two double carbon bonds instead. At room temperature they are liquid and they are referred to as oils.
Polyunsaturated fats contain essential fatty acids, meaning that we cannot produce them and therefore we must include them in our diets. There are two distinct families of essential fatty acids:
- omega-3 fatty acids: the first double bond is three carbon atoms away from the methyl end (blue color in the image)
- omega-6 fatty acids: the first double bond is six carbon atoms away from the methyl end
Omega-3 fatty acids are quite limited in our diets and you need to ensure that you consume them regularly. These fats can be found in
- walnuts and walnut oil
- flaxseed and flaxseed oil
- fatty fish
- krill oil
- canola oil
- dark green vegetables (for example, spinach)
Omega-6 fatty acids are the main fatty acids in vegetable oils such as corn, soybean, sunflower, sesame. It is plentiful in our diets. As a matter of fact there is a debate going on currently that maybe we are consuming too much of this fat to the detriment of our health.
Polyunsaturated fats are considered “good fats” but it not necessarily true. They must be in a proper balance for the body to stay healthy. Because of the overabundance of omega-6 in our diets the proportion of these two essential fatty acids is completely out of whack. Our diets are high in omega-6 and low in omega-3. This imbalance leads to chronic inflammation, autoimmune diseases, blood clots and certain types of cancer (Reference).
Trans fats are not occurring naturally. They are artificially produced fats. These fats are not required by our bodies and in fact they can cause a significant damage to our cells.
These fats are produced when polyunsaturated fats such as vegetable oils are hydrogenated. In other words, hydrogens are added to the “empty” spots in the carbon chain of a polyunsaturated fatty acid.
The reason why this method became commonly used was to increase the shelf life of some of the fats and to alter the texture of foods. For example, a partially hydrogenated vegetable becomes margarine and some foods become creamier, flakier and tastier.
The problem is that because they so closely resemble natural fats our body does not recognize them as impostors and does not get rid of them. These trans fatty acids may incorporate into our cell membranes and interfere with normal metabolism.
Trans fats pose serious health risks including heart disease, raising LDL cholesterol levels, inflammation, diabetes, stroke and other chronic conditions.
I hope that this article helped you learn more about the four types of dietary fats and oils. Make sure to increase your intake of omega-3 fatty acids and reduce the consumption of omega-6 fatty acids to even out the balance between them. As well, do not eat trans fats. Many products contain partially hydrogenated fats, ditch those as well. Lastly, as much as possible eliminate processed foods that are labeled as “fat-free or low-fat” from your diet. These types of processed foods are not helping us lose weight. On the contrary, they may be contributing to the current obesity epidemic in America.