Don’t Overlook Vitamin K: The Many Roles of This Mighty Anticoagulant

Where do you get vitamin k and how much should you take?

By Roberta H. Anding, MS, Baylor College of Medicine and Texas Children’s Hospital
Edited by Kate Findley and proofread by Angela Shoemaker, Wondrium Daily

Vitamin K is often overshadowed by vitamins A, B, C, and D. However, it is still vital to your health, as Professor Anding explains.

Vitamin K concept, with healthy food options high in Vitamin K
Vitamin K plays many vital roles when it comes to your health. Photo By Tatjana Baibakova / Shutterstock

Vitamin K Origins

Vitamin K is known for its bioavailability and the fact that it comes in two primary forms. Although vitamin K plays traditional roles, the term “multitasker” applies as it performs many roles in human nutrition.

Vitamin K was first discovered in 1929. A Danish scientist by the name of Henrik Dam was researching the role and nature of cholesterol by feeding chickens a cholesterol-free diet. 

After a few weeks, the chickens on this diet started developing hemorrhages, and they were bleeding. He couldn’t repair these deficiencies by supplementing their diets with purified cholesterol.

Thus, it appeared that a second compound, together with cholesterol, had also been extracted from the diet, and this was thought to be responsible for the coagulation of blood. Because the study was published in a German magazine and “coagulation” in German is spelled with a “K,” the mysterious compound was named “vitamin K.”

Phylloquinone, vitamin K1, comes from plants, and the word “phyllo” means plants. Menaquinone, also known as vitamin K2, comes from animals, and specifically the bacteria in the gut, which makes a really true requirement difficult to set. In other words, we can’t tell how much the gut produces, and so we really can’t tell anyone how much we require from outside sources. 

There’s also a synthetic form, known as vitamin K3. Thus, we’ve got our three major forms of vitamin K—two primary and one synthetic.

Roles of Vitamin K

What is the main role of vitamin K? Remember, it comes from the German word for coagulation and is needed for the normal clotting cascade of blood by the synthesis of blood proteins. 

Vitamin K is also needed for the production of what are known as “Gla proteins,” which are needed for the normal bone protein. Some of the supplements on the market now state that vitamin K is added for the development of healthy bone. 

Osteocalcin is needed for bone remodeling. There is increasing evidence that vitamin K may aid in the prevention of osteoporosis. It forms a matrix protein, which is found in cartilage, and so matrix protein provides the framework on which bone is formed.

Good sources of vitamin K include kale, spinach—where the bioavailability is better cooked than raw—cabbage, broccoli, and Brussels sprouts. Again, there is no true requirement because we don’t know how much the gut produces, but when no RDA exists, there is compelling evidence to set a requirement, and the National Academy of Sciences sets an Adequate Intake, or an “AI.” The current AI for women is 90 micrograms, and 120 micrograms for men.

Avoiding Deficiencies

Vitamin K deficiencies are common among the following populations: breast-fed infants (because breast milk is low in vitamin K) and neonatal infants (because the mother’s placenta transmits lipids and vitamin K relatively poorly). Babies are born with a sterile gut and have no real bacteria. 

The bacteria come from the outside. Since bacteria produces vitamin K, newborns are usually given one milligram of injection at birth, so if a baby’s going to be born at home, Professor Anding recommends that the baby goes to a physician relatively early and gets a vitamin K injection to prevent a poor clotting outcome.

You may be wondering what people did before babies were given an injection of vitamin K at birth. The reality is that newborns were more prone to bleeding. An adverse reaction could be that your baby’s blood may not be able to clot, which is called “hemorrhagic disease of the newborn.”

According to Professor Anding, if newborns are given shots of vitamin K, there is no need for follow-up injections. This is because once the baby starts to nurse or drink from a bottle, an auto population of bacteria will begin to grow in the gut.

Other Considerations

When it comes to drug interactions, most notably, vitamin K can interfere with anticoagulant and antiplatelet drugs. Additionally, antibiotics kill the bacteria that can make vitamin K, so anybody taking chronic antibiotic therapy is going to be unable to synthesize that vitamin K from the bacteria in the gut. 

There is no known toxicity of vitamin K. Therapeutic doses can be prescribed to reverse the anticoagulant effects of warfarin or some of the other anti-clotting drugs. 

Most patients on anticoagulant therapy are asked to keep vitamin K intake consistent. This means that you wouldn’t eat a lot of broccoli one day and then none the next, and you should also keep any multivitamin that you might be taking consistent.

This article was edited by Kate Findley, Writer for Wondrium Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for Wondrium Daily.

Professor Roberta H. Anding is a registered dietitian and Director of Sports Nutrition and a clinical dietitian at Baylor College of Medicine and Texas Children’s Hospital. She also teaches and lectures in the Baylor College of Medicine’s Department of Pediatrics, Section of Adolescent Medicine and Sports Medicine, and in the Department of Kinesiology at Rice University.