Fish is one of the essential foods in any balanced and healthy diet. According to the Healthy and sustainable dietary recommendationsthe Spanish authorities recommend including this product at least three times a week at lunch or dinner and that we give priority to blue fish – such as sardines, anchovies or mackerel – and then white fish – such as whiting or blue whiting. We are talking about a serving of about 125-150 grams or, in other words, an individual fillet.
But how are these two types of fish different? Broadly speaking, the fat content in the tissues is usually used to differentiate fish into two large groups: on the one hand, we have white fish, which has less fat and, on the other hand, blue fish, which has higher values of this compound. This is a classification that responds more to dietary and gastronomic criteria than to biological reasons. Therefore, we are referring to a nutritional criterion, a classification that is widely accepted and generalized.
Fat content: the big difference between white and blue fish
As we have seen, white and blue fish differ in terms of nutritional properties. White fish has a maximum fat content that is between 0.2% and 2%. This characteristic is the result of its own nature because we find sedentary species that do not need to store reserve fat in their tissues, but are rich in proteins, minerals such as phosphorus, calcium, copper and iron and vitamins, especially group B. .
It is also a fish, white, low in calories, with about 70-120 kilocalories per 100 grams of fish. In this case we are talking about fish such as sole, monkfish, hake or maira or blue whiting.
As for oily fish, we have already seen that it has a higher fat content, which is around 5%, although it is beneficial fat. Unlike whitefish species, these do have a more active life and need to make large movements throughout their entire biological cycle. With powerful muscles, its consumption provides us with omega-3 and omega 6 fatty acids. The former, in addition to acting as a powerful anti-inflammatory, also helps us reduce the level of cholesterol and triglycerides in the blood.
The importance of this contribution of omega-3 lies above all in the fact that our body does not produce this type of fatty acids on its own, so it is important and essential that we obtain it through our diet.
Oily fish also provides us with other interesting nutrients such as proteins and minerals such as iodine, magnesium or iron and fat-soluble vitamins (D, E and A). Unlike white fish, its calorie content is slightly higher, between 110-200 kilocalories per 100 grams. These are fish such as salmon, tuna, sardine, anchovy, anchovy, bonito, mackerel, squid, swordfish or pomfret.
How can we distinguish blue fish from white
When it comes to differentiating both types of fish, it is not necessary for us to be experts in the field or to have great knowledge about marine fauna. We only have to pay attention to certain physical and visual particularities that, not because they are simple, are less effective. Broadly speaking, these are some of the main differences:
- The white fish is smaller than the blue: it is one of the main differences and what we can use by just taking a look at the fish is its size, although it is not advisable to stop at this clue alone.
- Blue fish adopts a bluish tone: the color of the scale area of blue fish adopts a bright bluish appearance that also helps us to identify it easily. On the other hand, white fish does not have these reflexes.
- Observe the final tail: this part is another of the great clues that the fish gives us and one of the definitive tricks to know if we are dealing with a blue fish. The fish’s tail acts as a kind of rudder and is what gives us key information: if it is shaped like a C or an arrow, with sharper ends and a more arched shape, we are dealing with a type of blue fish. Anything that does not have this particular shape is considered white fish, which in most cases has a flat, rounded, fan-shaped tail. This anatomical peculiarity is mainly explained by what we have mentioned about the fact that oily fish spices travel long distances throughout their life.
- The meat inside: if with all these clues we have not been able to identify whether it is blue or white fish, we will still have another chance: the meat of white fish is, obviously, white. On the other hand, in the rest of the fish we can find a great variety of colors, which can range from the orange of salmon to the maroon of tuna.
What type of fish to choose?
With so many varieties of fish to choose from, which one should you choose? Which option is the healthiest? As in everything in general, but in food in particular, variety is the essence. If we alternate between different species of fish, we will find greater benefits and obtain the different nutrients we need. Because, from a nutritional point of view, one option is not more correct than another when we talk about fish, since both one and the other allow us to obtain animal protein.
Both types of fish provide an interesting source of essential micronutrients such as iodine, as well as selenium, calcium and vitamins A and D. They also have a good lipid profile and polyunsaturated fatty acids. The Spanish Agency for Food Safety and Nutrition (AESAN) recommends the consumption of three or four servings of fish a week, trying to vary the species between white and blue fish.
And what about mercury? This environmental contaminant that we can find in certain fish means that, according to one survey conducted by the Spanish Federation of Nutrition, Food and Dietetics Society (FESNAD), one in ten participants does not consume the recommended weekly rations due to the possible content of mercury and other contaminants, especially in species such as swordfish, bluefin tuna , the shark and the pike.
Despite everything, the European Food Safety Authority (EFSA) clarifies that fish provides benefits and its consumption is recommended. To achieve these benefits and minimize the risk of excessive exposure to methylmercury, the key is to limit the consumption of species with a high content of this contaminant.
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