Human Nutrition 3(3+0)

Lesson 14 : Lipids

Triglycerides and fatty acids

Triglycerides comprise about 95 percent of the food lipids and body lipids. They are the storage form of fat. When we eat a high calorie diet, the calories in excess of our energy needs are converted into triglycerides and stored in the body.

All triglycerides have a similar structure. It is composed of three fatty acids attached to a glycerol molecule. Glycerol is a short-chain carbohydrate molecule that is soluble in water. When triglycerides are metabolized, the glycerol is converted to glucose. Fatty acids may differ in their length and their degree of saturation. They are commonly composed of a series of 16–18 carbon molecules attached to hydrogen molecules. The number of hydrogen molecules determines the saturation of the fat. When each carbon has its maximum number of hydrogens attached, the fat is said to be saturated i.e. filled to capacity with hydrogen.

1. Saturated fats

2. Unsaturated fats

3. Essential fatty acids

4. Hydrogenation
   This is a process involving chemically induced hydrogen saturation of the carbon bonds, by which the structure of unsaturated oils is changed. This alters the way the body metabolizes these fats and often changes the physical form. Margarine and vanaspathi are hydrogenated fats.