Vitamin K deficiency in adults is rare but does occur in infants. The main symptom of a vitamin K deficiency is excessive bleeding caused by an inability to form blood clots.

In this article, we look at the function of vitamin K in the body, as well as the symptoms and treatments for a vitamin K deficiency.

What is vitamin K?

Vitamin K supplements

Vitamin K is found in some plant foods, such as leafy green vegetables, and is also produced by the body.

Vitamin K comes in two forms.

The first type is known as vitamin K-1 or phylloquinone and can be found in plants, such as spinach and kale.

The second is known as vitamin K-2 or menaquinone and is found in the body and created naturally in the intestinal tract.

Both vitamin K-1 and vitamin K-2 produce proteins that help the blood to clot. Blood clotting or coagulation prevents excessive bleeding internally and externally.

While vitamin K deficiency is rare, it means a person’s body cannot produce enough of these proteins, increasing the risk of excessive bleeding.

Most adults obtain an adequate supply of vitamin K through the foods they eat and through what their body naturally produces.

Certain medications and medical conditions can reduce vitamin K production and inhibit absorption, meaning adults can become deficient.

However, vitamin K deficiency is much more likely to occur in infants. When it does, it is known as vitamin K deficiency bleeding or VKDB.

Causes and risk factors

Adults are at an increased risk of vitamin K deficiency and the associated symptoms if they: