Fish oil is a source of the omega-3 fatty acids. Fatty acids are incorporated into every cell membrane in the body, in the form of compounds called phospholipids. Cell membranes play the vital role of regulating what goes into, and what comes out of each cell. The integrity and fluidity of the cell membrane is determined by the type of phospholipid that is available for the body to use. Cell membranes made up mainly of phospholipids derived from polyunsaturated fatty acids are more fluid and function better than cell membranes made up of saturated fat or trans-fatty acids. A cell membrane working at optimal levels retains vital nutrients and electrolytes, has the ability to communicate with other cells and is responsive to hormones.

Omega-3 fatty acids found in deep sea oily  fish are generally regarded as having a positive effect in the human body. They are important components of substances known as prostaglandins and leukotrienes. Prostaglandins and leukotrienes are important in immune function, smooth muscle function, platelet aggregation and inflammation. Fish oils have a positive action because prostaglandins and leukotrienes from omega-3 fatty acids have less negative activity than prostaglandins and leukotrienes derived from other types of fatty acids.