Triglycerides vs Phospholipids
Lipids are carbon-containing organic compounds and are considered as a macronutrient in the food. These compounds do not dissolve in water (hydrophobic), but dissolve in fats (lipophilic). Hence, lipids are digested, transported and absorbed in a different manner when compared to other macronutrients like carbohydrates and proteins. Also, lipids yield more calories, compared to other energy sources. Usually lipids are obtained through both animal and plant foods. In addition, non-lipid molecules like carbohydrates and proteins can also be converted into lipids in the body. These converted lipids usually stored in adipose tissue for later use as energy. Based on the molecular structure, lipids can be classified into three types; triglycerides, phospholipids, and sterols. Each type plays a different role in the body. Triglycerides and phospholipids make the majority while sterols exist in very small quantities in the body.
What are Triglycerides?
Triglycerides are the simple fats and make up the majority of lipids found in the body and in foods. Usually, 98% of the dietary fats are triglycerides; hence they provide much of the flavor and texture in foods. They are considered as a major energy reserve and are stored in adipocyte cells located in the adipose tissue.
Triglyceride molecule is composed of glycerol; which makes the ‘glycerol backbone’, and three fatty acids. The ‘glycerol backbone’ of triglyceride molecule is always constant, but fatty acids attached to the ‘backbone’ may differ. During digestion of triglycerides, fatty acids are cleaved from the glycerol backbone, resulting free fatty acids, which are then available for use by the body. When the three fatty acids have been separated, the remaining glycerol backbone is available for the production of energy.
The main functions of triglycerides are serving as an energy source and abundant energy reserve, providing protection to vital organs, and acting as a thermal and electric insulator in the body.
What are Phospholipids?
Unlike the triglycerides, phospholipids are present in small number of specific foods like egg yolks, liver, soybeans, and peanuts. Phospholipids are not essential dietary need because the body can synthesize them when needed. They have the same glycerol backbone as triglycerides but contain only two fatty acids rather than three. Hence the vacant site on the glycerol is attached to a phosphate group, which makes the hydrophilic, polar head. This unique structure allows phospholipids to dissolve in both water and fat. Here, the non-polar hydrophobic tail (fatty acids) can attach fat- soluble substances while the polar hydrophilic head can attach water-soluble substances or polar molecules. Phospholipids are a major component of the cell membrane. In addition, they act as emulsifier (bile), and also provide transport functions in the body (as lipid particle carriers).
What is the difference between Triglycerides and Phospholipids?
• Triglycerides are more abundant than phospholipids.
• Triglycerides are soluble only in fat, whereas phospholipids are soluble in both water and fat.
• Triglyceride molecule contains three fatty acid chains, whereas phospholipid molecule contains two fatty acids plus one phosphate group.