Introduction
University of Hawai‘i at Mānoa Food Science and Human Nutrition Program and Human Nutrition Program
E hinu auaneʻi na nuku, he pōmaikaʻi ko laila
Where the mouths are shiny with fat food, prosperity is there
Learning Objectives
By the end of this chapter, you will be able to:
- Describe the function and role of lipids in the body
- Describe the process of lipid digestion and absorption
- Describe tools and approaches for balancing your diet with lipids
The coconut is considered to be the ‘Tree of Life’ in the Pacific. The coconut provided wood for shelter and craftsmanship along with being a source of hydration, animal feed and income through copra. It also serves many ecological functions such as a source for shade, protection from the wind, and coastal erosion control.[1] A thriving coconut tree provided Pacific Island families with great prosperity.
For many Pacific communities the coconut provided a valuable source of fat to a diet that was generally low in fat as the major nutrient found in the mature coconut is fat. As you read further, you will learn the different types of fats, their essential roles in the body, and the potential health consequences and benefits of diets rich in particular . You will be better equipped to decide the best way to get your nutritional punch from various fats in your diet.
Lipids are important molecules that serve different roles in the human body. A common misconception is that fat is simply fattening. However, fat is probably the reason we are all here. Throughout history, there have been many instances when food was scarce. Our ability to store excess caloric energy as fat for future usage allowed us to continue as a species during these times of famine. So, normal fat reserves are a signal that metabolic processes are efficient and a person is healthy.
Lipids are a family of organic compounds that are mostly insoluble in water. Composed of fats and oils, lipids are molecules that yield high energy and have a chemical composition mainly of carbon, hydrogen, and oxygen. Lipids perform three primary biological functions within the body: they serve as structural components of cell membranes, function as energy storehouses, and function as important signaling molecules.
The three main types of lipids are triglycerides, phospholipids, and sterols. Triglycerides make up more than 95 percent of lipids in the diet and are commonly found in fried foods, vegetable oil, butter, whole milk, cheese, cream cheese, and some meats. Naturally occurring triglycerides are found in many foods, including avocados, olives, corn, and nuts. We commonly call the triglycerides in our food “fats” and “oils.” Fats are lipids that are solid at room temperature, whereas oils are liquid. As with most fats, triglycerides do not dissolve in water. The terms fats, oils, and triglycerides are discretionary and can be used interchangeably. In this chapter when we use the word fat, we are referring to triglycerides.
Phospholipids make up only about 2 percent of dietary lipids. They are water-soluble and are found in both plants and animals. Phospholipids are crucial for building the protective barrier, or membrane, around your body’s cells. In fact, phospholipids are synthesized in the body to form cell and organelle membranes. In blood and body fluids, phospholipids form structures in which fat is enclosed and transported throughout the bloodstream.
Sterols are the least common type of lipid. Cholesterol is perhaps the best well-known sterol. Though cholesterol has a notorious reputation, the body gets only a small amount of its cholesterol through food—the body produces most of it. Cholesterol is an important component of the cell membrane and is required for the synthesis of sex , and bile salts.
Later in this chapter, we will examine each of these lipids in more detail and discover how their different structures function to keep your body working.
Figure 5.1 Types of Lipids
Learning Activities
Technology Note: The second edition of the Human Nutrition Open Educational Resource (OER) textbook features interactive learning activities. These activities are available in the web-based textbook and not available in the downloadable versions (EPUB, Digital PDF, Print_PDF, or Open Document).
Learning activities may be used across various mobile devices, however, for the best user experience it is strongly recommended that users complete these activities using a desktop or laptop computer and in Google Chrome.
- Snowdon W, Osborn T. (2003). Coconut: It’s role in health. Secretariat of the Pacific. ↵
A class of nutrients containing carbon, hydrogen, a little oxygen, and some other atoms. Commonly known as fats that include fatty acids, triglycerides, phospholipids, and sterols.
A chemical messenger in the body that is released into the blood from one specific location in the body and travels to another location, where it elicits a specific response.