Fish is always an important source of nutrients, it provides numerous benefits to our health and contributes to maintaining a balanced and healthy diet. In general, marine products have a low caloric intake and represent a very good source of proteins with a high biological value, as well as vitamins and minerals. Moreover, many species are rich in polyunsaturated fatty acids omega-3 and omega-6, with large and proven health benefits. This fact is irrefutable: fish should be an essential component within our dietary habits but, despite its many properties, we usually don’t include enough in our daily menu.

What is, however, the actual nutritional value of fish? The truth is that it depends on a large variety of factors, ranging from the species, age, the environment in which they live, their season of capture, etc. One of the first data we must consider is the edible portion of each kind of seafood, which ranges between 45 and 60% due to its large amount of waste during the cooking process. Water is the most abundant element in the composition of marine species, and its relationship is inversely proportional to the amount of fat in their body. This amount of fat determines, in turn, the renowned classification between white fish -or lean fish- (less than 3% fat, such as cod, sea bass and hake), semi-fat (3% to 5% fat, such as sea bream, turbot or gilt-head bream) and blue fish -or fatty fish- (more than 5% fat, such as tuna, salmon or sardines). What’s more, this amount of fat can significantly change depending on such variables as the environment (saltwater fish tend to have more fat than freshwater), eating habits of each species (determined by the characteristics of plankton in their surroundings), the temperature of the water (fish that live in cold waters incorporate more fat as thermal protection) and even the sexual maturation cycle (depending on the time of capture, fish accumulate more fat as an energy reserve before spawning). Shellfish are among the low-fat fish (between 0.5 and 2% in mollusks and up to 5% in crustaceans). Unlike other animal foods, polyunsaturated fatty acids are abundant in the fat of marine products, like the two mentioned above (omega-3 and omega-6). These are closely related to the prevention and treatment of a large number of cardiovascular diseases and their risk factors (cholesterol and triglycerides).

Fats, however, are not the only component that we must consider about fish. All proteins seafood provides have a high biological value, since they contain certain aminoacids essential for life (methionine, lysine, tryptophan…). Meanwhile, water-soluble vitamins (such as B1, B2, B3 and B12) and fat soluble ones (vitamins A & D) have a significant presence in many species, although their content is reduced due to all culinary preparations. Carbohydrates, instead, are not found in significant amounts either in fish or shellfish, where in most cases does not exceed 1% (it is only superior in some mollusks’ shells). Finally, fresh fish constitutes an important source of minerals, especially sodium, iron, potassium and magnesium, in addition to calcium, if ingested with bones.

With this succinct review of the multiple properties of fish and shellfish, it becomes plain evident that this kind of food should undoubtedly have an even more important role in our diet, mainly because of its enormous nutritional value and the high presence of heart-healthy fats. Knowing the characteristics of each species and its specific health benefits is an excellent exercise when planning our eating habits, and thus being perfectly aware of the best time to purchase every product in the market.