The nutritional significance of fish lipids.

In all fish commonly used as food the predominant lipid is triglyceride fat. There are species which contain, in the flesh or elsewhere, lipids largely other than true fat. Thus, the flesh lipid of the castor-oil fish (Ruvettus pretiosus) is a wax and the liver lipid of certain sharks is mainly alkoxydiglycerides or squalene or both. But such biochemically interesting variants have no significance in human nutrition since the fish tissues in question are not normally eaten. There are, however, two lipids of widespread occurrence in fish which, although very minor constituents on a weight basis, cannot be ignored nutritionally. These are vitamins A and D. I shall confine my attention to the significance in human nutrition of the triglyceride fat and of the vitamins A and D of fish.