Protein: What exactly it is?

Protein: What exactly it is?

Protein is the most abundant nitrogen-containing compound in the diet and the body. Throughout the day there is a continual process of protein turnover, with protein being broken down and formed at the same time. The largest reservoir of protein is found in the muscles, but there is limit capacity to store new proteins. Therefore, protein intake in excess of requirements is either broke down to provide energy or stored as fat or carbohydrate.

Protein is needed for the growth and repair of tissues. During digestion proteins is broken down into smaller units called amino acids. Amino acids are commonly described as building blocks of protein. In chemistry, an amino acid is a molecules containing amine and carboxyl functional group. There are about 20 different naturally occurring amino acids, which can be combined to make a vast array of different proteins.

The terms ‘essential’ and ‘non-essential’ amino acid refer to whether the amino acid in question can be synthesized by the body at a rate sufficient to meet normal requirements for protein synthesis. There are eight essential amino acids for adults that must be supplied in adequate amounts by the diet.

The semi essential amino acid can be made in the body, providing certain essential amino acids are present in the diet in sufficient amount, for example cysteine requires methionine and tyrosine requires phenylalanine. Other amino acids, notably arginine and glutamine, are also regarded as ‘conditionally essential’ meaning that, during time of high utilization; they may require repletion via the diet.

The majority of amino acids ingested by human exist in a combined form as dietary proteins from both animal and vegetable sources. NOT ALL PROTEINS IN THE DIET HAVE THE SAME NUTRITIONAL VALUES, since they contain different proportions of essential amino acids. The complete protein food contains all the essential amino acids. In general, foods from animal sources contain substantial amount of all essential amino acids, but food from the other source can be combined with each other make complete protein foods. For example, the protein quality of plant products is improved when dairy products are added to a plant food and when plant-based foods, such as wheat and beans mixed together.