Proteins of high biological value: what they are, characteristics and their sources
The term protein comes from the Greek word "proteios", which means fundamental or essential. The etymological origin of the word is not a simple coincidence, far from it, since proteins are essential elements for the proper development and functioning of the cells that make up our body.
Proteins form a very broad and diverse family at a structural and functional level, in which we find some that act like hormones, such as insulin, which regulates sugar levels in blood; others that function as enzymes, such as lipases (essential in digestive processes) and even Proteins with a defensive role in the body, such as antibodies, so much on everyone's lips today in day.
Today we are going to know a little more about the so-called proteins of high biological value, those that contain essential organic molecules for our body, which must be incorporated through the diet, the essential amino acids.
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What are proteins?
Proteins are large molecules, or macromolecules, made up of linear chains of amino acids
. Generally, they are made up of between 100 and 300 of these amino acids, although they can form longer chains. Depending on the amino acids that compose it and the order in which they are arranged, each protein will have a specific function in the body.All proteins are made up mainly of four elements: nitrogen (N), carbon (C), oxygen (O) and hydrogen (H); although they can contain sulfur (S) and phosphorus (P), and other elements in smaller proportions.
In addition to the functions that we have described above, proteins act as an essential structural component in the different types of tissues and can also be used as a source of energy for the body, although they are not the most widely used energy source habitual.
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Types of amino acids
Amino acids are organic molecules that combine to form proteins. Until now, Some 500 different types of amino acids have been identified, but only 20 of them will be part of our proteins, all of them being necessary for the correct functioning of the human organism.
When we eat food, our metabolism will be able to break down the proteins they contain in the amino acids that make them up, so that these can be used for different functions bodily
These amino acids can be classified into two groups based on whether the human being has the ability to synthesize them by himself or not: the essential amino acids and the non-essential amino acids.
1. Essential amino acids
Essential amino acids are those that cannot be produced by man, and, therefore, we have to incorporate them through the diet. When any of these amino acids is absent in the body or is below the levels necessary, the correct functioning of the different tissues that make up the body can be put at risk human.
Within this group we find 8 amino acids: valine, leucine, isoleucine, phenylalanine, tryptophan, threonine, methionine and lysine. In the case of newborns, another amino acid has to be added to this list, histidine, since your body is not developed enough to be able to produce it properly autonomous.
2. Nonessential amino acids
For its part, non-essential amino acids are those that can be produced by our body from other protein components, and therefore, it is not necessary that they be consumed through the diet. This group of amino acids includes: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine (in adults), proline, serine and tyrosine.
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What are proteins of high biological value?
Having defined the difference between essential amino acids and non-essential amino acids, we can delve a little deeper into the concept of high biological value protein. According to the European Food Information Council (EUFIC), when we say that a protein has a high biological value, we mean that contains essential amino acids in a proportion equal to or similar to that required by humans.
On the other hand, in those cases in which one or more of these essential amino acids is not present, or the levels at which it is found are not sufficient, we are talking about proteins of low biological value. The essential amino acid that has the lowest values compared to the required levels is called the limiting amino acid..
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Calculation of biological value
The biological value (BV), as we have indicated in the previous section, refers to the quality of a protein. To calculate it, the nitrogen used in the formation of the tissues that make up the body has to be divided by the nitrogen that is absorbed through the food we eat..
The final result of the biological value is expressed as a percentage of nitrogen used and gives us an idea of the efficiency with which our body uses the proteins ingested through the diet.
The biological value acquires values between 0 and 100, so that a 100% BV indicates that all the protein that has been ingested is used and incorporated into the proteins of our body. On the contrary, negative values can also occur, when more protein is eliminated than is ingested.
We can conclude then that a protein source of high biological value is correlated with a contribution adequate amount of essential amino acids, which will be used by our body in different functions.
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Dietary sources of protein of high biological value
We can find proteins in different types of food, both of animal origin and of vegetable origin. The differences between the protein intake that one food or another can make us will be mainly marked by the amounts of protein in each type of food, rather than by the types of proteins present. Beyond the final quantity that a food provides us, we must look at the quality of these proteins, which depends on the amino acids that form it.
In general, protein sources of animal origin have a higher biological value than those proteins that come from plant sources. However, each food of plant origin usually has a different limiting amino acid, that is, an amino acid that is found in a lower proportion than the rest with respect to the required values.
This fact will allow us to make up for these deficiencies in protein sources of vegetable origin by combining several foods in the same meal. In this way, making the simultaneous intake of two vegetable sources, for example, legumes and cereals, the amino acids of a protein will compensate for the limitations present in the other type of protein and vice versa, allowing us to achieve a combination of a much higher biological value.
People who follow an omnivore-type diet do not usually have problems when it comes to obtaining the right amount and type of protein according to their nutritional requirements. It is in the case of diets that avoid or eliminate foods of animal origin in which adequate monitoring must be carried out, since that may present some difficulties in supplying the body with the necessary levels of protein for its correct functioning.
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Animal sources
Among the foods with proteins of animal origin, the following stand out.
1. Egg
The proteins present in the egg are of excellent quality and are considered to have the highest biological value.. The white is the portion of the egg that has the highest protein concentration.
2. Dairy products
They are a source of high quality protein, which also provide another essential element for our development, calcium. Its biological value is also very good, especially that of milk proteins.
3. meats
They provide us with a good amount of quality protein, although they also provide saturated fat, especially red meat. We must take into account the type of meat that we consume, as well as the type of piece, since we can reduce the amount of fat ingested in this way.
4. Fish
In addition to very good quality proteins, they will provide us with polyunsaturated fats of the omega 3 type, being especially abundant in blue fish (sardines, salmon, tuna or anchovies).
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Plant-based sources
Here are some examples of quality plant-based protein sources.
1. Nuts
They contain a large amount of protein and also provide healthy fats. Its consumption should be moderate, given its high caloric content.
2. Vegetables
They are another very good source of protein and a very complete food. The quality of these proteins improves when they are ingested in combination with cereals, such as rice.as it contains amino acids that complement each other. For example, soybeans are one of the legumes with the highest protein content and of the best quality.
3. Cereals and pseudo-cereals
Cereals provide proteins, which complement very well with those provided by legumes. Quinoa stands out, a pseudocereal very widespread today, which contains all the essential amino acids.
