Get the Skinny on Fat
WHY WE NEED FAT IN THE DIET: What Type, How Much, and Food Sources
Dietary fat is an essential nutrient found in many forms and food sources. A brief review of terms before we get started may be helpful:
- Dietary fats are a combination of saturated, monounsaturated and polyunsaturated fatty acids, and trans fats. These terms reference the chemical structure of the fat. (Hang with me here, this boring biochemistry stuff is important!). Trans fats are synthetically altered fats that should be avoided.
- Fats consist of chains of 3-36 Carbon molecules in length.
- They are classified by chain length:
- Short-chain consists of less than 6 Carbons
- Medium-chain is 6-12 Carbons
- Long-chain is 13-21 Carbons
- Very long-chain is 22-36 Carbons
The longer the chain, the more difficult the digestive process becomes, requiring a breaking down (emulsification) of the fat by substances released from the gallbladder.
An exception to this process occurs when the medium chains are refined from certain foods, such as coconut oil. These medium chains do not require action from the gallbladder; instead they go straight to the portal system for immediate metabolization. Referred to as MCT oil, this supplement has been used for years in clinical situations involving premature babies and those without a gallbladder.
- Examples of foods that are more than 50% saturated fat are cream, butter, cheese, coconut oil, palm kernel oil, cottonseed oil and some fatty animal meat.
- Examples of monounsaturated fat (omega-9) are avocados, olives and olive oil, macadamia nuts, almonds, pecans, cashews, peanuts, sunflower oil, peanut oil, and canola oil.
- Examples of polyunsaturated fat (omega-6 & omega-3) are safflower oil, flaxseed oil, corn oil, grape seed oil, canola oil, wheat germ oil, and all nuts. Also, some fish and shellfish are rich sources.
The medical community and nutritionists generally advocate a diet that contains primarily polyunsaturated and monounsaturated fats, with saturated fat intake below 10% of total fat intake. An exception to this rule would allow coconut oil to be used, which is high in medium chain triglycerides.
The rest of the dietary fat intake should emphasize, in descending order, omega-3, omega-9, and omega-6 classified fats. The typical Western diet is high in omega-6, and low in omega-9 and omega-3 fats, as well as too high in saturated fat.
The class of fats referred to as the essential fats are represented by alpha-linolenic acid, DHA and EPA, collectively called the omega-3 group. These are a subset of the polyunsaturated fats, and must be obtained in the diet by humans for normal metabolic function and optimal health.
DHA and EPA are considered the most beneficial, and are only available from animal sources. Alpha-linolenic acid is the plant form, with some linoleic acid (omega-6) being converted to omega-3.
- Examples of DHA and EPA are salmon, sardines, herring, mackerel, trout, tuna, cod, swordfish, halibut, tilefish, flounder, red snapper, mussels, and shark.
- Examples of alpha-linolenic acid are walnuts, almonds, pecans, hazelnuts, flaxseed, and butternuts.
The cultures and populations of the world that consume omega-3 and omega-9 as their primary sources of fat have a lower rate of cardiovascular disease.
Consult with a nutritionist to help incorporate more of these heart-healthy fats into your diet.