Vitamin B7 (Biotin): Sources, Requirements, Absorption, Deficiency and Functions
Posted on : 25-11-2017 Posted by : Admin


Vitamin B7 Introduction

In 1931, German scientist Paul György specifically discovered biotin in the liver and called it vitamin H. Later it was named Biotin /B7. Biotin is an important component of enzymes in the body that break down certain substances like fats, carbohydrates, and others. Biotin is heterocyclic, sulphur containing monocarboxylic acid. Biotin is sparingly soluble in cold water and is freely soluble in hot water.


Sources of Biotin

Biotin occurs widely both in foods of vegetable and animal origin. Wheat germ, liver, peanut, and rice polishing are rich sources. Whole cereals, legumes, mutton and egg are good sources.


Requirements of Biotin

Since, intestinal bacteria and diets supply biotin in adequate amounts the deficiency of this vitamin in human being is rare.


Absorption and storage of Biotin

Biotin is readily absorbed from the small intestine through the portal vein into the general circulation. Excess of the requirements is not stored in the body but is mostly excreted in the urine.


Egg white injury factor (Avidin)

There is a protein in egg white called avidin which is responsible for producing egg white injury. Avidin binds with biotin tightly in the intestinal tract and prevents absorption of biotin from intestines. Avidin is denatured by cooking and then loses its ability to bind with biotin. The amount of avidin in uncooked egg white is relatively small, and problems of biotin deficiency have only occurred in people eating abnormally large amounts of raw eggs for many years.


Deficiency of Biotin

Deficiency of biotin is rare in human beings.


Functions of Biotin

The following are the functions of vitamin Biotin,

  • Biotin is required as the co-factor for a small number of carboxylation reactions; it acts as the carrier for carbon dioxide. CO2 Acetyl CoA carboxylase

Eg: Acetyl CoA Malonyl CoA.

  • It helps to maintain the skin and the nervous systems in good condition.
  • It assists in the deamination of amino acids like aspartic acid, serine and threonine.
  • It helps in the synthesis of purine.
  • For the conversion of ornithine to citrulline in the synthesis of urea, biotin is required.

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