Vitamin K is required for the synthesis of several of proteins required for normal blood clotting and bone structure. Vitamin K is synthesised by bacteria in the large bowel and is also present in both plant and animal foods.
Deficiency is rare as vitamin K is widely available from the diet and is also provided by gut bacteria. Thus, deficiency is generally secondary to conditions such as malabsorption or impaired gut synthesis. However, there is growing interest in the role of vitamin K in optimising bone health. Newborn babies up to six weeks old have low levels of vitamin K, which puts them at risk of potentially fatal ‘haemorrhage disease of the newborn’, and is known as vitamin K deficiency bleeding in infancy. Therefore, is it usual to give all newborn infants prophylactic vitamin K.
Few toxic reactions to Vitamin K have been identified.
Dietary vitamin K is obtained from green leafy vegetables, dairy products and meat.