Nutrients | Proteins

Proteins are complex organic molecule made up of carbon , hydrogen , oxygen, nitrogen and also sulphur and phosphorus. They are Caloriegenic Macro nutrients. Protein are made of Amino acid. Around , 10000 to 15000 Amino acid makes 1 protein. It is the only nutrients that can make new cells , rebuild tissue. The protein content of any food can be estimated by measuring Nitrogen content of food. 

Requirements :-

1 GM/ 1 kg of body weight 
1.5 GM/ 1 kg of body weights


Proteins are classified based on function as :-

1. Complete protein :- They contain all essential Amino acid . They promote growth and maintains essential body process. Animal origin protein are complete protein .

2. Totally incomplete protein :- Incomplete protein are those in which one or more than one amino acid are missing completely. They cannot perform growth and repair of body.    e.g maize.

3. Partially complete protein :- Amino acid are present but at incomplete amount . Plant origin protein are partially complete protein. They are capable of maintaining life but cannot promote growth. They do not contain all essential amino acid in required amount.

On the basis of characterization , proteins are classified as :-

  • Simple protein :- Those proteins which yields amino acid on hydrolysis are simple protein.  e. g albumin in egg white. 

  • Compound protein :- Those protein which are combined with non protein molecules are compound protein. e. g casein - protein and phosphoric acid . Haemoglobin - protein and haemo.

  • Derived protein :- Those protein produce by action of heat or enzyme on native protein are derived proteins. Native protein are protein found in cell and in fluid of animals.

The protein quality can be improved by mutual supplementation and fortification. Fortification is external addition of protein.


Those Amino acids which cannot be synthesized in sufficient amount by the body and must be provided by diet are essential amino acid. Human required 8 essential amino acid while growing children require 10 essential amino acid. e.g lysine, leucine, tryptophan


It doest not meant these are non require. They are not dietary essential because if they are lacking in diet they synthesized on body from other amino acid. e.g glycine , cystine


1. All body tissue and fluids except urine and bile are  made of protein.

2. It is continuous require for maintenance of all cell of body.

3. Plasma proteins maintain water balance

4. Amino acid tyrosine when combined with iodine forms Thyroxin

5. All enzymes , Hormones are made up of protein

6. Haemoglobin an iron containing protein in red blood cell transports oxygen to tissue and cell.

7. Proteins also provide energy when broken down by body. It provides equal energy as carbohydrates.

8. Lack of protein cause poor healing of wounds and anaemia, loss of weight

9. No antibodies production and kwashiorkor


1. loss of calcium through urine

2. Kidney and liver over functioning thus chance of failure

3. Risk of cholesterol .

4. Uric acid.

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