Unit 5
Lipids: Fats, Oils, Phospholipids, and Sterols

Dietary lipids have gained much attention over the years because of growing evidence of their association with chronic lifestyle diseases, such as heart disease, cancer, and obesity. However, dietary lipids do have an essential role. They provide the most concentrated form of energy (nine kilocalories per gram of fat), and are the source of essential fatty acids. As is the case with all other nutrients, their over-consumption will result in adverse health effects. In our affluent society, people consume too much fat—especially processed and saturated fats that may contribute to chronic diseases.

In this unit, we examine the chemical and physical characteristics of various types of lipid, and discuss their sources. We study the processes of digestion, absorption and transport of lipids. We review the functions of lipids and the effects of diet on blood cholesterol. Finally, we look at the present trends in fat consumption by Canadians, the current recommendations for fat intake, and the effects of food processing on dietary lipids.

This unit consists of the four sections listed below.

• Section 5.1  Chemistry and Classification
• Section 5.2  Digestion, Absorption, and Transport
• Section 5.3  Functions and Health Effects
• Section 5.4  Lipids in the Diet