Essential And Nonessntial Fatty Acids
If a fatty acid can only be obtained from the diet (for humans) then the fatty acid is an essential fatty acid. Two fatty acids cannot be synthesized in the human body and are therefore essential. These are linoleic and linolenic fatty acids, which are both unsaturated. Nonessential fatty acids can be made by the human body and so do not need to be obtained from diet alone. These are made from carbohydrates and proteins or from other fatty acids. Fatty acids are an important source of energy. While carbohydrates or proteins only provide 4 kcal/g of energy, fatty acids provide more than twice the energy per unit weight of 9 kcal mg. This is one reason why a high-fat diet can lead to obesity.