We eat so many kinds of foods – the main item that we eat are carbohydrates- which are cereals, fruits, vegetables and sugar. All these give rise to glucose – the main source of energy to our body. The second kind of foods that give calories are fats – the oils, seeds and nuts. Plus all the food that we eat have some minimum amount of fat. They are also the second source of calories in our body. Fat – besides helping in making the cell wall, some hormones mainly serve as a store house of calories. The third kind of foods that can give calories to the body are proteins. They are needed by our body mainly to build the structure and maintain the function of the body. They make cell wall and nucleus of all the living cells of the body. They make muscle, lots of hormones and enzymes. They are present in many of the foods that we eat and when broken gives Amino acids- which are the smallest units of the protein. When the amino acids are joined together they are called polypeptides. There are four other items in the food besides the three – carbohydrates, proteins and fat- and they are fibre, vitamins, minerals and water. But none of the last four give calories to the body.
There are some important roles of protein in our body:
• We have 10000 billion cells in the body. The nucleus of each of these cells are made up of DNA and RNA. These nuclear Chemicals are made up of protein.
• We need enzymes to digest all the foods we eat. Almost all these enzymes like amylase(breaking carbohydrates), lypase(breaking fats) and pepsin(breaking proteins) are made up of protein/amino acids.
• Hemoglobin is responsible for our oxygen transport and a major component of red blood cells(RBCs) this is made up of proteins.
• Proteins have significant contribution in the formation of all the walls of the cells besides formation of nucleus.
• All muscles of the body also need proteins called myosin, actin etc including cardiac muscles.
• Important hormones and neurotransmitters of the body including insulin are made up of Amino acids- which are the smallest part of proteins.
• Proteins also take an important part in body’s defence system by making all antibodies which is our second line of Defence after the white blood cells.
• At the time of need, proteins also can significantly contribute to the body’s need for calories at the rate of 4 calories per gram.
• All the repairs of the body are carried out by protein.
• Bones of the body also need protein start at actin, tubular and keratin for maintaining their structure.