Before going further in a discussion about dietary fat, it would be helpful to explain the 3 different types of fat and implications for our health. Fats are simply chains of carbon atoms strung together in different lengths and are called short, medium or long chain based on that length. The carbon atoms then have available bonding sites which are most commonly filled by hydrogen atoms. When every available bonding site is filled with a hydrogen the fat is said to be saturated.
Saturated fats are found in meats, dairy (cheese, milk and cream) and eggs as well as Palm oil, coconut oil and cocoa butter. Saturated fats, because of their structure, pack together tightly and are solid at room temperature. They are very stable and are useful for cooking being less likely to go rancid and form dangerous free radicals at higher temperatures. Saturated fats provide flavor to our food and promote satiety and for many other reasons are an important part of a healthy diet.
Monounsaturated fats have one hydrogen atom missing and the empty spot will bond weakly with a neighboring carbon. This double bond causes a kink in the chain causing these chains to pack together less efficiently and be liquid at room temperature.
The monounsaturated fat found most commonly in our food is oleic acid. Foods high in this kind of fatare olive oil, avocados and tree nuts like almonds and walnuts and also peanuts and cashews. These fats are relatively stable and do not go rancid easily and can be used for cooking. Monounsaturated fats, especially olive oil, are what distinguish the “Mediterranean diet” from other lower carb and relatively high fat diets. I’ll write more about that in a future post.
Finally, polyunsaturated fats (PUFA’s) have two or more double bonds.
They remain liquid even when refrigerated and are very unstable, oxidizing easily and becoming rancid. When subjected to heat or oxygen, free radicals are formed. Polyunsaturated oils such as soybean, safflower, sunflower and corn oil are often rancid even before being purchased and should be avoided. Omega 3 and omega 6 PUFA’s are “essential” fatty acids. This means that we need them to survive yet they are not made in our body so they must be consumed in the diet. These fats are naturally found in plant based foods such as flax seeds or, in a more useable form for humans, in animals that eat these plants such as fish, grass fed beef or wild game. I will write more about these important fatty acids later. Each of these fats are important for our health and will be naturally balanced if we are consuming a diet of mostly whole foods.