Which vitamin plays an essential role in helping blood to clot?

Vitamin K plays an essential role in helping blood to clot.

Vitamin K is a family of fat-soluble vitamins that the liver uses to activate several proteins involved in coagulation. It helps an enzyme modify specific proteins so they can bind calcium, a necessary part of the chain of reactions that forms a stable blood clot.

The name K comes from the Danish word “koagulation.” The main natural forms are vitamin K1, or phylloquinone, found especially in green leafy vegetables, and vitamin K2, or menaquinone, a group of related compounds found in some animal foods and produced by bacteria.

A deficiency can lead to impaired clotting and abnormal bleeding. Newborns are particularly vulnerable because they have low vitamin K stores, which is why vitamin K is commonly given soon after birth. A common mix-up is that vitamin K does not simply thicken blood; it supports the production of specific clotting factors. The anticoagulant warfarin works partly by interfering with vitamin K recycling.