Table of Contents

Vitamin ‘K’ – Functions, Food Sources, Deficiencies and Toxicity

Vitamin ‘K’

The presence of vitamin K was first reported by Dr. Dam. In 1934, experiments on chicken led to the knowledge that vitamin K helps in blood clotting. This vitamin is bleeding– resistant vitamin.

Vitamin K is mainly of 2 types—

Vitamin ‘K₁ ’— It is present in green leafy vegetables. It is also known as phylloquinone.
Vitamin ‘K₂ — It is present in rotten fishes. It is also known as_menaquinone.

1. Blood clotting— Vitamin K helps in blood clotting. It is helpful in formation of prothrombin. Prothrombin converts into Thrombin which gets converted into Fibrin. Fibrin clots the blood. Platelets and other blood factors from The blood with damaged tissues form Thromboplastin. These blood factors work in combination with calcium ions and blood plasma and make prothrombin active. Active Prothrombin reacts with blood factors to form anew substance called Thrombin. A soluble protein called Fibrinogen, present in blood plasma, reacts with Thrombin and converts Fibrinogen into insoluble Protein fibrin. The blood cells get entrapped in this Fibrin and blood clots. In the absence of vitamin K Prothrombin is not formed. Therefore, blood clotting does not take place.

Low volume of Prothrombin in blood— deficiency of vitamin K decreases the volume of Prothrombin in blood, which prolongs the period of blood clotting. This causes excess of bleeding. When there is an internal or external injury, excessive blood flows caused by the rupture of a blood vessel. This is known as hemorrhage.

Vitamin K in excess causes damage of red blood cells which leads to hemolytic anemia. Symptoms of this anemia are— nausea, vomiting, dizziness, yellowing of skin, etc.

Vitamin K is present in various plant-based food products. Some bacteria in our intestines also forms vitamin K. Green leafy vegetables are main sources of vitamin K. Cereals, lentils, eggs, milk, meat and fish are also good sources.

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Que1. Which of the given was invented by Kazimierz Funk?
(a) Enzymes
(b) Hormones
(c) Vitamins
(d) Proteins

Ans. ⇒ { c }

Que2. What type of compounds are Vitamins?
(a) Organic Compound
(b) Inorganic Compound
(c) Living Organisms
(d) None of the above

Ans. ⇒ { a }

Que3. Which is also known as the “Accessory dietary factor”?
(a) Fats
(b) Vitamins
(c) Proteins
(d) Hormones

Ans. ⇒ { b }

Que4. Which is not an essential element for plant growth?
(a) Potassium
(b) Calcium
(c) Magnesium
(d) Sodium

Ans. ⇒ { d }

Que5. Which of the given has the highest calorie value per unit?
(a) Vitamins
(b) Proteins
(c) Fats
(d) Carbohydrates
Ans. ⇒ ????