The deficiency of which one of the following vitamins causes delayed clotting of blood and haemorrhaging ?

Vitamin K is a fat-soluble nutrient essential for the synthesis of several coagulation factors, specifically factors II (prothrombin), VII, IX, and X [t3][t7]. It acts as a cofactor for the enzyme that carboxylates these proteins, enabling them to bind calcium and participate in the clotting cascade [t3][t9]. A deficiency in Vitamin K leads to defective coagulation, resulting in delayed blood clotting and an increased risk of spontaneous or excessive bleeding, known as haemorrhaging [t2][t7]. This condition is particularly critical in newborns, where it is termed Vitamin K deficiency bleeding (VKDB) or haemorrhagic disease of the newborn [t5][t7]. While Vitamin C deficiency causes scurvy and gingival bleeding [t4], and Vitamin E deficiency can lead to mild haemolytic issues [t1], Vitamin K is the primary vitamin responsible for the physiological mechanism of blood clotting. Consequently, its absence directly causes the symptoms described.

Sources

1. [1] https://www.healthdirect.gov.au/vitamin-k-deficiency
2. [2] https://www.sciencedirect.com/topics/medicine-and-dentistry/vitamin-k-antagonist
3. [3] https://www.ncbi.nlm.nih.gov/books/NBK536983/
4. [4] https://www.ncbi.nlm.nih.gov/books/NBK493187/
5. [5] https://pmc.ncbi.nlm.nih.gov/articles/PMC11242131/