Proteins – (strands of amino acids) are compounds containing carbon, hydrogen, oxygen and nitrogen. The nitrogen component of proteins is what differs its structure from carbohydrates and fats. Proteins in the body are referred to as “cellular machines” and they come in many forms: enzymes, antibodies, transport vehicles, cellular “pumps”, oxygen carriers, tendons, ligaments, bones and teeth, hair filaments and others. The primary function of proteins is to support growth, maintain, and repair tissues. They also act as antibodies, hormones, and enzymes or catalysts.
Proteins are the main building blocks of the human body and they are made up of units called amino acids that are strung together in several different or complex formations. As complex molecules, Proteins are broken down in the body much slower than Carbohydrates, but is a longer-lasting source of energy. The energy content in a gram of Protein is four (4) calories.
So, how is protein in food processed for bodily function? Well, your body breaks down food proteins into their unit building materials called Amino Acids. It is then transported to the “building sites” – the cells. Then, they are reassembled into a specific format to form specific tissue proteins. For example, proteins in the diet build the proteins of new tissues, such as an embryo, and a growing baby. Proteins also rebuild tissues that are lost through hemorrhage, burns, and surgery or other worn out cells. Proteins are also needed to make neurotransmitters. Neurotransmitters are used by nerve cells in sending messages to perform activities, such as thinking, eye blinking and more.
After protein is broken down for its main function, some residues need to be placed or sent somewhere else. For example, the nitrogen residue is converted by the liver from ammonia to urea and sent to the kidneys to be excreted in the urine. A very minute amount of residue comes out as sloughed off skin, nails and hair. The remaining residue is converted to glucose and used for energy. If the blood glucose supply from a carbohydrate source is not available, the preceding pattern would not take place. This is because most of the protein breakdown will be converted to glucose for energy. Likewise, if you do not eat enough protein or your protein is sacrificed for energy use due to low carbohydrate intake, your body starts to breakdown protein stores from the muscles and blood supply in the body.
Your heart is a muscle and if the muscle is broken down and the protein supply in the blood is used up, what else is left for the body to survive? So, it runs out of fuel and dies. On the other hand, if too much protein is eaten, the surplus will also be converted similar to the way excess carbohydrate intake is processed. Remember that energy is the body’s top priority and the rest are secondary. This means that if glucose from a carbohydrate source is not readily available, proteins will have to halt major functions so that energy can be produced.
The human body’s need for daily Proteins vary in age group. For example, children need more Proteins than adult for growth and development. Just remember that, except for that group of population, adults consuming more Proteins than what the body needs does not provide added benefits because the body would not build more protein (muscle) than it needs. Therefore, excess Proteins are broken down into fragments which the body promptly store as Fats for later use.
Ofelia B. Mutia, MS.,RDN.,LD.