What are Protein?
The proteinethey are macromolecules composed of carbon, hydrogen, oxygen and nitrogen. The presence of nitrogen is what differentiates Protein from other nutrients. Since, unlike plants, humans cannot absorb nitrogen from the air, Protein are the only source of this important element. The body basically uses Protein to synthesize complex protein structures such as muscles, skin or hair. The Protein are also used in the synthesis of hormones (GH), insulin and glucagon. The Protein are composed of subunits called amino acids .
Functions of Protein
The Protein then have the following properties:
- provide the substrates necessary for protein synthesis;
- promote muscle recovery following physical activity;
- act as a substrate for gluconeogenesis
- stimulate protein synthesis and promote muscle growth;
- they favor the emergence of a hormonal profile suitable for muscle growth and weight loss.
The Protein can be classified in several ways:
- Complete and incomplete Protein . A protein is said to be complete when the smallest amounts of amino acids are present. Per example, wheat protein is usually very low in lysine but high in methionine, while legumes are low in methionine and high in lysine.
- Fast and slow Protein . The caseins are known for their properties on the slow absorption while the whey protein are known for their rapid absorption properties. In fact, different rates of absorption are found in the three different types of whey protein - whey. The protein hydrolyzate serum (WPH) can truly be considered for faster absorption, demonstrating a schedule similar to the assimilation of free amino acids. While concentrated whey Protein (WPCs) and isolated whey Protein (WPIs) , which are not subjected to hydrolysis, show an average longer assimilation time.
- Biological value (BV) . The BV provides a measurement of the amount of nitrogen supplied to the body divided by the amount of nitrogen absorbed. A BV of 100 indicates that that protein is 100% assimilable (that is, the body is able to use it 100%). That is, for 1 gram of ingested protein the body uses 1 gram. Supplements made from whey protein and supplements to egg Protein have a high biological value. The vegetable Protein have low biological value. Per this reason, supplements are offered on the market consisting of different vegetable protein sources in order to raise the biological value.
- Chemical score . To carry out the measurements, a standard protein (usually egg) is assumed as a reference value and the extent to which the tested protein differs from the standard one is determined. The whey protein of milk have a chemical score similar to that of egg protein reference.
- Protein efficiency degree (PER) . PER is a value that indicates how much weight (in grams) the intake of a certain amount (in grams) of protein gains. Per example, a PER of 2.5 means that every gram of protein consumed increases body weight by 2.5. The Protein of the whey , the protein of eggs and meat protein have a degree of protein efficiency ratio (PER) of greater than 3.0.
- PDCAAS Protein Digestibility Corrected Amino Acid Score . PDCAAS is a measurement method that takes into account both the amino acid content and the digestibility of the protein. The highest PDCAAS value is 1.0, the minimum 0. Whey protein , egg protein and casein protein have a PDCAAS value equivalent to 1.0.
Protein requirement of the sedentary
The EFSA (European Food Safety Authority) has published the quantities of reference intakes for the population (PRI) referring to Protein . A PRI indicates the amount of a single nutrient that the majority of individuals in a given population need to stay healthy, based on age and gender. The group of scientific experts has established the following PRI of protein for adults, infants and children, as well as for pregnant women and breast-feeding:
- Adults (including the elderly): 0.83 g per kg of body weight per day.
- Infants, children and adolescents : between 0.83g and 1.31g per kg of body weight per day, depending on age.
- Pregnant women : additional intake of 1 g, 9 g and 28 g per day for the first, second and third trimesters respectively.
- Lactating women : additional intake of 19 g per day in the first 6 months of breastfeeding and 13 g per day in the subsequent period.
The Protein in excess can not be stored but are broken down to produce glucose and energy. This process produces nitrogenous wastes that can overload the kidneys, so it is best not to consume an excessive amount of protein. Therefore, the use of protein supplements in sedentary subjects is to be considered useless as a correct diet already provides the right protein intake.
Protein requirement of the athlete
In athletes, the protein requirement is higher than in a sedentary. This is due to a number of causes listed here:
- a sportsman needs a surplus of Protein to be able to repair and increase their muscle mass when they are subjected to the microtraumas that generate supercompensation. When a muscle is stressed, small microtraumas are formed which must be repaired through supercompensation. Per this to happen it is essential that the body is supplied with an excess of Protein so that it can be used to repair and increase damaged tissues.
- An athlete has on average a greater muscle mass than a sedentary (except athletes dedicated to completely aerobic disciplines) and therefore needs a greater amount of protein even just to maintain the nitrogen balance in their body, without losing muscle mass.
The protein supplements are therefore suitable for sportsmen who practice strenuous physical activity. Protein contributes to the growth and maintenance of muscle mass . Researches ( Tarnopolski , 1988) suggest:
- Bodybuilder athletes (natural): 1.2 g per kg of body weight per day
- Cross-country athletes : 1.6 g per kg of body weight per day
The high-protein diets "recommended" by professional overseas bodybuilders sometimes assume values of 3-4 g per kg of weight, they are very high quantities, which on a subject in normal conditions (ie who does not use anabolic steroids) do not have no effect.
Scientific studies have shown that increasing two to three times the daily protein dose does not produce any increase in muscle mass nor in physical performance.
It should be noted that the intake of protein supplements must be considered an integral part of the protein quota recommended by the guidelines which therefore constitutes the sum of all the Protein taken with both common foods and supplements.
1) Scientific Opinion on Dietary Reference Values for protein. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA), 2012.
2) Tarnopolsky, M.A. et al. Influence of protein intake and training status on nitrogen balance and lean body mass. J Appl Physioil. 64(1): 187-193, 1988.