Classification of Lipids in Nutrition

Lipids in Nutrition:

Lipids are main constituents of plant and animal cells. Cholesterol and triglycerides are lipids. They are oily to touch and insoluble in water, soluble in organic solvents. Lipids include fatty acids, oils, waxes, sterols and triglycerides.

Classification of Lipids:

Lipid is the broader group of bio-molecules whereas fats are a type of lipids. It is classified into three groups:

1. Simple Lipids: They are generally esters of fatty acids and alcohols, although free fatty acids sometimes are included in this group. The most common esters are combinations of fatty acids with glycerol, a 3-carbon alcohol with three hydroxyl groups. These compounds also referred to as neutral fats. It may contain one fatty acid called monoglycerides, two fatty acids digilycerides or three fatty acids triglycerides combined with glycerol.

2. Compound Lipids: The major constituent of many lipids is fatty acids. These compounds consist of chains carbon atoms with a methyl (CH3) group at one end and a carboxyl (CCOOH) group at the other end. Most fatty acids in foods and in the body are straight even numbered carbon chains. Those containing 4-6 carbon atoms are called short chain fatty acids, 8-12 carbon atoms are medium chain fatty acids and more than 12 are long chain fatty acids.

Most of fatty acids found in animal tissues contain 16-26 carbon atoms. Fatty acids are “saturated” or “unsaturated”. A fatty acid in which each of the carbon atoms in the chain. It has two hydrogen atoms attached to it is saturated. An unsaturated fatty acid is one in which a hydrogen atom is missing from each of two adjoining carbon atoms, thus necessitating a double bond between the two carbon atoms.

3. Derived Lipids: These include alcohols (glycerol and sterols such as cholesterol, carotenoids and the fat soluble vitamins A, D, E and K).