Lipids have a broader spectrum of structures and compositions, which is why they are defined based on their physical properties. They are commonly referred to as organic molecules that do not dissolve in water but dissolve in non-polar solvents. Lipids are categorized into three types including triglycerides, phospholipids, and sterols (Murphy 326). Lipids play three important roles in the body including; they function as the structural components for cell membranes, serve as energy storehouses, and work as key signaling molecules. This discussion analyzes each of the three types of lipids, their structures, their role in the body, and their overall health effects.
Types and structure of Lipids
Triglycerides make up over 95% of the lipids in foods and the body. They are common in fried foods, butter, cheese, vegetable oil, whole milk, and cream, and fatty meats. Naturally occurring triglycerides are obtained in foods like olives, nuts, corn, and avocados (Feingold and Peter 281). Fats and oils are the common names for triglycerides, where fats are lipids in the form of solid whereas oils are lipids in the form of liquid. The structure of a triglyceride comprises glycerol and three fatty acids. The glycerol is the backbone comprising of three carbon, while fatty acids are the longer chains of carbon molecules linked to the glycerol backbone. Fatty acids exist in different types, but triglycerides might contain a mixture of some or all of them. They are categorized depending on the length of carbon chains and the extent of saturation. Different foods contain different amounts of fatty acids, which determines health risks.
Phospholipids make up around 2% of the dietary lipids. They play the important role of building the protective barrier for cell membranes. Essentially, phospholipids are synthesized to form organelle and cell membranes. Phospholipids also form structures within the blood and body fluids where fat is enclosed and transported across the bloodstream. Phospholipids contain a glycerol backbone like the triglycerides but only comprise two fatty acid molecules linked to the glycerol backbone (Feingold and Peter 285). The structural difference between a phospholipid and a triglyceride is the position of the third carbon. Instead of fatty acid, the phospholipid contains a phosphate group. For this reason, phospholipids are water-soluble and fat-soluble.
Sterols are the least popular types of lipids commonly referred to as steroids. Sterols have chemical structures that are completely different from those of triglycerides and phospholipids. Most sterols comprise multi-ring structures that look like chicken wire. They are considered complex in terms of structure, containing interlinking carbon rings, some side chains of carbon, attached oxygen, and hydrogen. Cholesterol is the commonly known form of sterol which is further classified as high-density lipoprotein (HDL) and low-density lipoprotein (LDL). Primarily, HDL is considered good cholesterol since it takes cholesterol to the liver where it can be eliminated from the bloodstream before it can build up to the arteries (Gurr and Harwood 202). LDL, on the other hand, is considered bad cholesterol since it takes cholesterol directly to the arteries leading to atherosclerosis that can cause stroke or heart disorders.
Functions of Lipids
Lipids primarily serve as energy reserves proving the body with energy as and when it is required. Compared to other body cells that only store a limited supply of fats, specialized fat cells are capable of expanding to store huge supplies of fats. For example, glucose is stored in the body as glycogen and serves as a ready source of energy. The human body requires energy to empower the muscles for all kinds of physical activities (Murphy 352). Even children require energy to play and engage in all sorts of physical exercise. Without energy reserves, athletes wouldn’t be able to go down the track while dances wouldn’t be able to showcase their moves or keep their legs moving throughout the performance.
In addition to being energy storehouses, lipids function as regulating and signaling agents. For example, triglycerides control and maintain constant body temperature. For this reason, those with an insufficient amount of fats in the body feel colder, are always fatigued, and suffer from pressure sores on the skin due to fatty acid deficiency (Murphy 371). Fats also play a crucial role in maintaining tissue structure, sustaining memory storage, and facilitating nerve impulse transmission. In the brain, lipids help in the formation of nerve cell membranes that insulates the neurons and provide for the signaling of electrical impulses across the brain.
General body insulation and protection is another key function of lipids. Vital body organs such as the skin, liver, kidney, brain, and heart are surrounded and insulated by visceral fats. Surprisingly, 60% of the brain comprises fats, which shows the main structural role that fats play in the body (Murphy 418). The fat layer underneath the skin protects the body against extreme temperatures and maintains the internal body temperature. In the buttocks and hands, the fat layer prevents friction when these parts get into contact with hard surfaces frequently. When engaging in strenuous physical activities, the fat layer provides the body with extra padding. Other functions of lipids include hormones production, helping in digestion, and facilitating bioavailability.
Health Effects
Although lipids are important for healthy living and in supporting various body processes, excessive fats in the blood put individuals at risk of developing heart and liver diseases. Heart diseases have been found to be among the top ten causes of death in the US and other parts of the world (Gurr and Harwood 170). A buildup of LDL, for example, causes clogging of arteries that leads to stroke and other cardiovascular diseases. Excessive fat levels are associated with a high intake of foods such as cheese, fatty meat, cream, fried foods, butter, milk, and processed foods. To avoid excessive fats going directly to the bloodstream, HDL-promoting foods are recommended including olive oil, fish, legumes, vegetables, nuts, and fruits rich in fiber.
Works Cited
Feingold, Kenneth R., and Peter M. Elias. “Role of lipids in the formation and maintenance of the cutaneous permeability barrier.” Biochimica et Biophysica Acta (BBA)-Molecular and Cell Biology of Lipids 1841.3 (2014): 280-294.
Gurr, M. I., and J. L. Harwood. “Dietary lipids: implications for health and disease.” Lipid biochemistry. Springer, Boston, MA, 1991. 162-243.
Murphy, Denis J. “The biogenesis and functions of lipid bodies in animals, plants and microorganisms.” Progress in lipid research 40.5 (2001): 325-438.
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