PROTEIN

Protein is a macro-nutrient required mainly for growth and repair functions of body. They also provide energy when stores of carbohydrates and fats are diminished. They produce 4 calories per gram which is equal to that of carbohydrates and half that of fats. Proteins are made up of amino acids. There are 20 amino acids present in human body out of which about half are essential amino acids. These essential amino acids should be taken from diet as the body cannot produce them by itself. 

Sources of Protein

Proteins are present in both animal and plant foods. They are abundant in meat, eggs, milk, fish, cereals, pulses, nuts etc. Animal proteins are better than plant proteins as all the essential amino acids are present in animal proteins in appropriate amount while plant proteins usually lack one or more amino acids. E.g. cereals lack the essential amino acid lysine while pulses are deficient in another essential amino acid methionine. The combination of both cereals and pulses can be a good trick for vegetarians but even than they’re not as good source of protein as animal proteins due to difference in quantity of different amino acids while they’re present in appropriate amount in animal protein. Therefore, a diet should constitute some animal proteins to remain healthy. 

Importance of Protein

·         Proteins are major constituents of muscles, bones, skin, hair, blood cells, immune system, many hormones, enzymes etc.

·         Proteins are the second most abundant kind of molecules in the body after water.

·         A healthy male between 19-70 years of age requires 56 grams of protein per day for remaining healthy while women of same age needs 46 grams of protein per day.

Protein during Exercise

The normal value for protein required by the body is 0.8 g/kg body weight. During exercise, this normal amount should be increased to repair the damage caused by hard exercise. Normal Aerobic exercise or endurance training don’t cause much wear and tear to body muscles but if they’re exercised for prolonged  time than it is  required to repair muscle break down by consuming extra amount of proteins in their diet. They should consume protein a maximum of 1.4 g/kg body weight.

On the other side, Anaerobic exercise or strength training cause much wear and tear to body muscles and large quantity of proteins are required along with anaerobic exercise to repair damaged muscle cells. The strength trainers should consume a maximum protein of 1.8 g/kg body weight to repair amino acid loss and enhance the synthesis of muscle protein. Doing strength training without taking extra amount of good proteins can be very harmful for body. 

Protein Deficiency

Severe protein deficiency can cause general learning disability and kwashiorkor (especially in children). The symptoms of kwashiorkor include fatty liver, diarrhea, apathy, swelling of belly, flaky skin etc. proteins are required by many parts and systems of body as mentioned above, so performance of all these organs and systems decreases with decrease in protein intake or consuming low quality protein (vegetarians who consume no animal foods).

Hormones effects on Protein Metabolism

Many hormones increase the retention of proteins (anabolism) in the body. These include growth hormone, insulin, testosterone and estrogen while few cause their breakdown (catabolism). Cortisol is most important among them.