Three different lipids, or fats, are found in the foods we eat. Phospholipids (lecithin), sterols (cholesterol), and the largest category—triglycerides. Most of the fat in the body also consists of triglycerides. They are saturated fats. Though they serve important functions in the body, triglycerides, along with cholesterol, contribute to heart disease. With so much research indicating the importance of limiting dietary saturated fats, what is the function of triglycerides and do we need them at all?
The name triglyceride comes from chemical composition. Triglycerides contain three molecules (tri) of fatty acid and one molecule of glycerol. Lipids do not dissolve in water like other food items that enter the body, so they must first be broken down to be absorbed. After they are absorbed into the intestinal lining, lipids are rebuilt, mixed with cholesterol and turned into droplets covered in a layer of protein. These “lipoproteins” are called chylomicrons. The body safely absorbs and stores smaller chylomicrons. Larger ones sometimes accumulate on the walls of the blood vessels, causing that spot to thicken and harden, which is what can lead to heart disease. However, triglycerides serve several positive and necessary functions in the body.
Function 1 – Energy
All dietary fats, including triglycerides, are a highly concentrated source of energy, but they are the body’s second choice because they are more difficult than carbohydrates to convert into energy. When fats are catabolized (broken down to be used for energy), the body only uses half of the fat calories. Any calories that are not immediately used turn into triglycerides to be stored as fat -- also called adipose tissue -- throughout the body until needed for energy.
Function 2 – Insulation and Protection
The layer of fat under the skin insulates the body from extreme temperature changes. Fat around internal organs serves as a protective cushion from mechanical trauma.
Function 3 – Nutrition
Vitamins A, D, E, and K are fat-soluble vitamins, which means the body must have fat to absorb them. These vitamins are transported through the vessels by the chylomicrons. Vitamins E, D, and K are also stored in the fat. If there is too little dietary fat, or if a medical problem exists that interferes with the body’s ability to absorb fat, then vitamin deficiency occurs. The bottom line: Triglycerides help ensure adequate nutrition.
Good or Bad?
In the right amount, triglycerides are important and good; in excess, they contribute to disease. Like so many other nutritional guidelines, moderation is the key. A healthy weight, balanced diet and regular exercise are all necessary to maintain a healthy level of triglycerides.