Vitamin K

 Vitamin K

(Anti hemorrhagic factor)

Introduction

Dam discovered this vitamin during his studies on hemorrhagic disease in chickens from 1930 to 1933.

Chemistry

It is a Napthoquinone derivative. Two naturally-occurring vitamins K are-

·        vitamin K₁ (phylloquinone, phytonadione) having a phytyl chain attached at position 3 of menadione nucleus, and

·        vitamin K₂ (flavinoquinone, farnoquinone) having a difarnesyl chain attached at petition 3.

·        Synthetic vitamin K is called vitamin K₃ (menadione).

Properties

·        fat-soluble

·        heat stable and can stand cooking

·        Vitamin K₁ is a yellow viscid oil

·        Vitamin K₂ is a yellow, crystalline solid.

·        The K vitamins are readily destroyed by light, alkali and alcohol

 

Distribution

Plant sources

·        Green leafy vegetables

·        cabbage

·        spinach

·        alfalfa

·        tomato

·        soybean

Adequate amounts are synthesized by normal intestinal bacteria. 

Animal sources-

·        Very poor

Functions

(1) It helps to maintain the formation of normal prothrombin and factor VII in the blood and thus takes part in normal coagulation.

(2) The principal overall effect of vitamin K is to shorten the prothrombin time. Bile salts are necessary for the absorption of vitamin K.

Deficiency signs

Defects in blood coagulation and hemorrhage

Daily requirement

Normal mixed diet and intestinal flora supplies this vitamin in adequate amount.