Most of us are bombarded with information about fats (much of it conflicting or confusing) and the healthiest way to eat. The terms “saturated fats,” “omega-3 fats,” and “trans fats” are familiar parts of our collective vocabularies. But, what do these terms really mean and how are they significant in terms of eating healthy and in a Paleo-appropriate way? If you take a little time to read this primer on fats and fatty acids, you will soon become familiar with these essential nutrients, their nomenclature and how they affect your health and well-being.
Fats vs. Fatty Acids
The terms “fats” and “fatty acids” are often used interchangeably in lay literature and by news media. In fact, fatty acids are sub-units of fats. Most of the common fats that we eat and the fat we store in our body are technically called acylglycerols, which are fatty acids (acyl group) linked to an alcohol (glycerol) via an ester bond (connects acid + alcohol by eliminating a water molecule). Acylglycerols (fats) can have:
One fatty acid (acyl) group + glycerol: and are called monoacylglycerol or monoglycerides
Two fatty acid (acyl) groups + glycerol: and are called diacylglycerol or diglycerides
Three fatty acid (acyl) groups + glycerol: and are called triacylglycerol or triglycerides
Monoglycerides and diglycerides are metabolic intermediates and don’t appear in large concentrations in food or in our body. Hence, triglycerides are the major acylglycerol (FAT) in our foods and in our bodies. Although almost all of the fatty acids we eat and which we store in our bodies are triglycerides, fatty acids are also incorporated in all cell membranes as compounds called phospholipids. Further, when fats are broken down (the ester bond cleaved) and taken out of your fat cells and transported in the bloodstream, they are called free fatty acids. In order for a fatty acid to travel (be soluble) in a liquid (your bloodstream), it must be bound to a protein. Free fatty acids are bound to albumin, the major plasma protein in blood.
Fatty acids fall into one of three major categories:
Much of the confusion about fatty acids stems from multiple systems of naming these molecules. Fatty acids can have common names, systematic names and numerical names. Most commonly fatty acids are referred to by their common names and numerical names.