Nutritional aspects of fats and oils

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Abstract

Fats and oils (collectively called lipids) constitute a substantial portion of our diets. About 35–40% of dietary energy (Europe, North America) comes from fat. Fat, at about 9 cal/g, is calorically dense compared to both protein and carbohydrate at about 4 cal/g. About 95% of dietary fat is composed of triglycerides. The remaining portion of fat in our diets is made up of other lipids such as cholesterol and phospholipid. Fatty acids are the building blocks of the majority of these lipids. Recently, much interest has been focused on the types of fatty acids in our diets, including saturated, mono-unsaturated, and polyunsaturated fatty acids (including both the ω-6 and ω-3 types). Nutritionally, the only essential lipids in our diets are the so-called essential fatty acids, linoleic acid (ω-6) and some ω-3 (linolenic acid and/or docosahexaenoic acid). The advent of hydrogenation to produce such products as margarines has introduced the unnatural trans fatty acids. Due to the concern over fat consumption, the development of fat substitutes for foods is an active area of research. Medium-chain triglycerides have been used as an alternative source of fat energy for those individuals unable to digest normal fats in the diet. These topics are discussed in detail in this chapter.