The best fish oil is obtained from the tissues of rich-in-fats pelagic fish. It is thought valuable due to the high content of omega-3 fatty acids: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Also, it works as a source of vitamins A and D3. The human body cannot function normally without these substances, yet it does not fully produce them on its own. Their lack provokes various health and well-being problems, so it is important to regularly replenish the stock from a correctly planned ration — or with the help of active supplements.
You should approach the choice of fish oil most carefully. They are significantly different in composition, as well as indications for use. For example, omega-3 acids are scant in shark liver oil; however, this latter one has another, no less nutritious active substance. At the same time, cod liver oil is rich in vitamins A and D, which may be a contraindication to use.