Since it was observed that cardiovascular diseases in Eskimos – who consumed significant amounts of fats of marine origin – were significantly lower than in the Danes, numerous epidemiological investigations have been carried out that show the positive effects of consuming polyunsaturated fatty acids of the Omega-3 series, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In addition to the benefits of these fats, fish is a good source of proteins, vitamins and minerals.
Proteins
The protein content of fish ranges from 10 to 27% and varies from one species to another, also according to age, time of capture and geographical location. Fish muscle differs from that of land animals in that it is more digestible and is metabolized efficiently, more than 80%, so that the nutritional utilization of fish is very high. It should be remembered that proteins are the main constituent of cells which, in addition to providing energy, have the function of forming and repairing body structures.
Fats
On the other hand, fats are part of cell membranes, transport fat-soluble vitamins, contain fatty acids that humans cannot synthesize (essential), and also contribute to the palatability of the diet and are involved in the regulation of plasma lipid concentration.
And marine products are a rich source of omega-3 fatty acids, specifically eicosapentaenoic (EPA), which is hypotensive and antithrombotic, docosapentaenoic (DPA), with similar functions to EPA, and docosahexaenoic (DHA), considered as an antitumor agent.
Regarding Omega 3 DHA, it is related to brain health during all periods of our life, it is crucial for the correct neuronal and visual development in times of growth as well as for its maintenance in adulthood.
Regarding Omega 3 EPA, it is a potent anti-inflammatory as it competes with arachidonic acid (Omega 6) counteracting its inflammatory potential.
Thus, the intake of fish (especially fatty fish) balances the Omega 6/Omega 3 ratio, which currently stands at 15/1 in the Western world, a situation that favors the production of inflammatory eicosanoids, so we should approach 1/1, which was the ratio of human beings in their origins.
Minerals
Fish is a source of minerals such as calcium, phosphorus, sodium, magnesium, iron, zinc, selenium, copper and especially iodine. Of these, selenium is perhaps not as well known, but it is an effective antioxidant that enhances the activity of vitamin E. For example, the enzyme glutathione peroxidase, a potent endogenous antioxidant enzyme, contains selenium. And in seafood the average concentration of selenium is 40µg/100 g, so that 200 g of fish covers 150% of the recommended daily requirement. Iodine, an essential component of the thyroid hormone, is also essential. Marine species – especially mollusks and crustaceans – contain 100µg/100g, so that 200g of fish cover the daily requirement of iodine.
Vitamins
Vitamins are divided into fat-soluble and water-soluble, and fish contains both groups. Oily fish contains more vitamin A and D than lean fish, as marine plankton is very rich in carotenes that are converted into vitamin A, a vitamin that is usually concentrated in the fish liver.
In addition, fish is the main source of vitamin D in our diet. The average concentration ranges between 200-600 IU/100g, although in oily fish it can reach 1500 IU/100g. To give us an idea, the recommended intake is 200 IU/day in those under 50 years of age, and 400 IU/day in those over 50. In elderly women, for the prevention of femur fracture, the amount amounts to 800 IU/day.
We can therefore conclude that fish and marine products in general are of great interest in a healthy diet. In view of this, our advice is: prioritize small species over predatory fish, since they do not feed on other fish and therefore accumulate less heavy metals such as lead, cadmium and mercury. And whenever possible you should avoid farmed fish.