Fats Overview, also known as lipids, have been demonized by the popular media but in reality are very important for human nutrition. Triglycerides, phospholipids and sterols all fall under the classification of fats with triglycerides predominating in foods and the body.
Triglycerides consist of three fatty acid chains bound to a central glycerol molecule. The characteristics of these fatty acids chains determine the type of triglyceride. Saturated fat consists of triglycerides whose fatty acids do not contain any double bonds in their chains. Monounsaturated fats have triglycerides with fatty acids containing one double bond. Polyunsaturated fats have multiple double bonds in their fatty acid chains. Saturated fats, like butter, tend to be solid in consistency while unsaturated fats tend to be liquids, like corn oil. In order to make these unsaturated fats solid at room temperature, as is the case with margarine, the double bonds are hydrogenated. During this hydrogenation process, trans-fat can be formed. Trans-fat has gotten a lot of press lately because it can be more harmful for your heart than the saturated fats they are meant to replace.
Triglycerides provide the body with energy as their primary function and contain nine calories per gram. Stored fat insulates the body, providing warmth in cool weather. Lipids are also a structural component, forming the membranes of cells. Some fats are considered to be essential in the diet. These consist of the omega-3 and omega-6 unsaturated fats. They perform important functions in the body and may even act as hormones.
Since triglycerides are insoluble in water, they need to be transported in the blood (which is a water based environment). Fats are absorbed in the intestines into the lymph system where they are packaged in lipoproteins such as VLDL (very low density lipoprotein), LDL (low density lipoprotein) and HDL (high density lipoprotein). Cholesterol is also packed into these molecules along with triglycerides. VLDL and LDL are considered to be “bad cholesterol” while HDL is considered to be “good cholesterol”. If one eats a lot of saturated fat, then their VLDL and LDL levels increase, which can be detrimental to the cardiovascular system.