Fish can be classified into two groups, oily and white. The oils in white fish are concentrated in the liver, hence, cod liver oil! While those in oily fish , for example mackeral are spread throughout the body. In the 1970s, research into eating habits of the Greenland Eskimos shows that oily fish positively influences cardiovascular health. Further investigation showed thsat two fatty acids known as EPA (eicosapentaenoic acid and DHA (docosahexaenoic acid), which accounted for the beneficial effects of oily fish on the heart and circulation. EPA and DHA are components of the omega 3 family of polyunsaturated fats. These help to thin the blood, regulate blood pressure and reduce inflammation.
Fish contain protein and is one rare sources of iodine which helps prevent goitre, a disease caused by iodine deficiency.
Fish is also rich in selenium, a cell-protective antioxidant mineral, and when fish is eaten with its bones, as in canned salmon, it is also rich in calcium and phosphor