Why fish oils are good for us

Available as a food supplement in capsule or liquid form, fish oils can be divided into two categories: fish liver oils (from cod, halibut and shark), and fish body oils, normally derived from anchovies, sardines and capelins and menhaden (small fish from North Atlantic waters).

The term cod liver oil defines oils derived from cod and also from Pollack, saithe and whiting. The oil extracted from the fish livers is deodorized and then Vitamin E and antioxidantsdefine are added to prevent it from going rancid.

The oil is an excellent source of vitamins A and D. Two teaspoons (10ml) of cod liver oil typically provides about 1200µg of retinol (Vitamin A), 20µg of Vitamin D and about 2g of omega-3 fatty acids – more than enough to meet an adult’s recommended daily intake and to offer some protection against various circulatory and skin disorders.

Fish oil capsules are usually fortified with vitamins A and D but contain less omega-3 fatty acids. Because of its high concentration of these vitamins, cod liver oil has long been used to prevent and treat conditions such as xerophthalmia, a progressive eye disease due to vitamin A deficiency, and rickets, a bone disease caused by lack of vitamin D.

Halibut liver oils and shark liver oils contain higher concentrations of retinol and there have been occasional cases of vitamin A poisoning in people who have taken excessive amounts. Shark liver oil also contains squalene, which the body synthesizes to produce cholesterol and which may raise blood cholesterol levels. As a result, researchers are divided on the benefits of these oils.

However, it has been claimed that other substances in shark liver oil called glyceryl ethers may help to protect against cervical cancerdefine.