[ Not All Proteins Are The Same ]
Courtesy From The FittyBee.com
Proteins, along with carbohydrates and fat, constitute an essential micronutrient for our body. They are very versatile macromolecules, formed by chains of amino acids, that are the building blocks of a protein (just like the bricks of a house), which will be combined in millions of different ways, originating various types proteins, designed to perform the most varied functions: plastic, metabolic, energetic; depending on the function that they perform, proteins are distinguished in enzymes, transport, contractile, structural, defense proteins. The amino acids involved in protein synthesis are 20, nine of which are essential, which means that they cannot be synthesized by the body from other amino acids, but must be introduced through the diet.
In order to have an efficient protein synthesis, ALL amino acids must be present, even the lack of one of them would compromise its success (no house without bricks!). For this reason, the amino acid content is the the key to distinguish a complete protein from a non-complete one, as only when all amino acids are present in a balanced way, the protein is deemed to be complete.
Another related factor is the biological value of a protein, that is a parameter indicating the amount of grams of human proteins that can be obtained from 100 grams of animal or plant proteins. Egg is given the highest biological value of 100, followed by milk, beef, poultry, fish, soy, rice, beans etc. Animal proteins have a better amino acid profile, as they contain all the essential amino acids in good quantity.
Legumes (such as beans, lentils, chickpeas, soy) also contain a large amount of protein (soy protein even more than meat or fish) but they lack some essential amino acids (called “limiting”), which, in legumes, are normally methionine and cysteine, and which therefore do not make them complete. Even cereals, such as rice, wheat, corn, bulgur, contain proteins (although in lower amounts than legumes) but are they are deficient in two essential amino acids that are lysine and tryptophan.
Does this mean that vegans have to renounce to assume complete proteins because they do not eat animal products? Absolutely not! They just have to pay more attention and learn how to combine food accurately. Combining a food that contains the amino acids that are lacking in the other one (e.g. a legume with a cereal) will allow to get a complete and balanced protein meal.
How much protein do we need? Differently from what many people think, especially in the fitness world, it is not necessary to massively increase the protein intake, because in any case the growth of muscle mass will not exceed a certain threshold. The RDA for proteins is of about 0.8 / 1 g per kg of body weight, but active individuals require a higher intake in order to maintain their muscle mass, that is around 1.5 up to 2 grams of proteins per day. When the goal is to increase muscle mass, as in the case of body builders, many nutritionists recommend getting up to 2.2 / 2.5 g per kg of body weight, without endangering the liver and kidneys in a healthy person. Introducing a higher amount of proteins is practically useless: we will not increase muscle mass (otherwise it would be enough to drink tons of protein shakes to put on muscle, which is obviously not true) and can be extremely counterproductive (high blood urea and weight gain, as the proteins that are not used turn into fat).
It is obvious that a food is formed by different nutrients, so, for example, to eat 100 grams of chicken is not equivalent to assume 100 grams of protein, but about 23 grams; below you can find some indications of the approximate protein intake for 100 grams of product (all “about”):
bresaola about 32 g
pine nuts 32 g
roasted peanuts 29 g
ham 28 g
chicken breast 23 g
tuna 22 g
beef 21 g
cod 17 g
oatmeal 8 g
Proteins in fitness serve as energy source and help to repair muscle damage due to prolonged effort. In more intense activities, that are mostly carried out under anaerobic regime, they restore muscles and build mass (for example in case of weight lifting). In endurance sports they represent a source of alternative energy, because our body can use them to produce glucose in order to prolong as much as possible the performance.
In addition to carbon, hydrogen and oxygen (which are also contained in fats and carbs) proteins also contain nitrogen, which is lost during protein catabolism, transformed into urea and then eliminated through the urine. In this way, also some water is lost, which is one of the reasons why high-protein diets help to lose weight faster. The bad news is that, unfortunately, with the liquids even minerals are lost, most notably calcium (for this reason especially women should be careful to follow an unbalanced high protein diet). The nitrogen that is not eliminated, can be transformed into other molecules or used as a source of energy (taking part to gluneogenesis) or turned into fat.