Protein : The Building Blocks of Life
Healthy Living

Protein : The Building Blocks of Life

Kaynat  Khan profile Authored by Kaynat Khan on 7 Apr 2014 - 20:05.

The word Protein is derived from the Greek word 'Proteus' meaning'very important', speaks volumes about the nutrient. They are the building blocks of the body tissue and are essential nutrients for the body for growth and maintenance.

Protein composition: A protein is composed of a chain of amino acid molecules. There are 20 different amino acids needed to make a protein. Some amino acids can be made in the body but others cannot be made in the body and need to be supplied through food proteins in the diet. Accordingly there are three types of amino acids: essential amino acids (cannot be synthesized in the body and needs to be supplied through the diet), conditionally essential amino acids (synthesized in the body but in conditions like stress and illness are needed as a must) and non-essential amino acids (that can be synthesized in the body if nitrogen is available in the diet).

Classification of proteins:

From nutritional point of view, proteins are classified into 3 categories

  • Complete proteins or first class quality protein - have all the 10 essential amino acids and promote good growth e.g. egg albumin, milk casein.
  • Partially Incomplete proteins or second class quality proteinpartially lack one or more amino acids and promote moderate growth. e.g. wheat and rice protein.
  • Incomplete proteins completely lack one or more amino acids and do not promote growth at all. e.g. gelatin, zein (corn).

Importance of proteins:

  • Proteins are vital for sustenance of life as structural components of muscle, tissues and vital body fluids like blood (e.g. albumin), as enzymes and hormones (e.g. insulin) for metabolism, as antibodies for immunity and for growth and repair.
  • Protein is also utilized for energy under conditions of intense exercise or inadequate carbohydrates.
  • Protein helps in the transport of nutrients from intestine across intestinal wall to blood, from blood to tissues of body and across the membranes of cells of the tissues.
  • Protein helps in regulating water balance in the body. Low protein level in the blood causes fluid accumulation in the cells resulting in edema.
  • Proteins maintain the body’s pH as they act as buffers due to their ability to neutralize an acidic or basic pH, thereby reducing the risk of acidosis or alkalosis.
  • When proteins are digested they are simplified into amino acids. Individual amino acids have various targeted effects such as growth hormone elevation, blood ammonia detoxification, increased mental alertness or mental relaxation, improved immunity, healing and recovery, antioxidant and anti-inflammatory properties.

Protein Energy Malnutrition:

Lack of enough protein in the diet results in protein energy malnutrition, which actually is a clinical condition and occur due to inadequate protein and calorie intake. It is observed, especially in children which initially results in growth retardation and later in Kwashiorkor and Marasmus.  

Kwashiorkor: is a form of severe deficiency of protein-energy, which may be characterized by irritability, anorexia, dermatoses and enlarged liver.

Marasmus: Is also a condition where the patient has severe deficiency of proteins, carbohydrates and fats.

  Meeting the requirements:

  • 0.8-1gm/kg/day is required by a non-exercising sedentary individual.
  • 1.6gm/kg/day is required for elite male endurance athletes and 1.2gm/kg/day by moderate-intensity endurance athletes.
  • 1.4-1.7gm/kg/day is required by football players, power sports and resistance athletes.
  • Female athletes require ~15% lower protein than male athletes.
  • For children RDA refers to protein requirements, for different age groups.
  • Pregnant women require 82.2gm/day and lactating women require 77.9(0-6months) and 70.2(6-12months) gm/day.


First Class Quality Proteins

Second Class Quality Proteins

Whey, whole egg, milk, curd, paneer, chicken, fish, meats and egg white.

Soya, tofu, soy milk, quinoa, lentils, sprouts, whole pulses like chole/chana/rajmah and nuts.

To summarize, protein is an essential macronutrient required in appropriate quantity as well as quality, by the body for optimum growth, maintenance and repair. Inadequate and improper protein intake could lead to slow metabolism and greater susceptibility to fat storage and obesity resulting in more harm than good.



Nutrition Science-B. Srilaxmi
K11 Sports Nutrition Manual- Kaizzad Capadia, Gauri Murthy.
RDA draft 2010.



*Disclaimer: This is not medical advice. The content is for educational purposes only. Please contact your doctor for any health care issues.