Vitamin K for health plays a key role in helping the blood clot, preventing excessive bleeding. Unlike many other vitamins, vitamin K is not typically used as a dietary supplement.
Vitamin K is actually a group of compounds. The most important of these compounds appears to be vitamin K1 and vitamin K2. Vitamin K1 is obtained from leafy greens and some other vegetables. Vitamin K2 is a group of compounds largely obtained from meats, cheeses, and eggs, and synthesized by bacteria.
Vitamin K1 is the main form of vitamin K supplement available in the U.S.
Recently, some people have looked to vitamin K2 to treat osteoporosis and steroid-induced bone loss, but the research is conflicting. At this point there is not enough data to recommend using vitamin K2 for osteoporosis.
Why do people take vitamin K?
Low levels of vitamin K can raise the risk of uncontrolled bleeding. While vitamin K deficiencies are rare in adults, they are very common in newborninfants. A single injection of vitamin K for newborns is standard. Vitamin K is also used to counteract an overdose of the blood thinner Coumadin.
While vitamin K deficiencies are uncommon, you may be at higher risk if you:
- Have a disease that affects absorption in the digestive tract, such as Crohn’s disease or active celiac disease
- Take drugs that interfere with vitamin K absorption
- Are severely malnourished
- Drink alcohol heavily
In these cases, a health care provider might suggest vitamin K supplements.
Uses of vitamin K for cancer, for the symptoms of morning sickness, for the removal of spider veins, and for other conditions are unproven.
Can you get vitamin K naturally from foods?
What are the risks of taking vitamin K?
- Side effects of oral vitamin K at recommended doses are rare.
- Interactions. Many drugs can interfere with the effects of vitamin K. They include antacids, blood thinners, antibiotics, aspirin, and drugs for cancer, seizures, high cholesterol, and other conditions.
- Risks. You should not use vitamin K supplements unless your health care provider tells you to. People using Coumadin for heart problems, clotting disorders, or other conditions may need to watch their diets closely to control the amount of vitamin K they take in. They should not use vitamin K supplements unless advised to do so by their health careprovider.
Vitamin K Deficiency
Vitamin K deficiency is only considered clinically relevant when prothrombin time increases significantly due to a decrease in the prothrombin activity of blood . Thus, bleeding and hemorrhage are the classic signs of vitamin K deficiency, although these effects occur only in severe cases. Because vitamin K is required for the carboxylation of osteocalcin in bone, vitamin K deficiency could also reduce bone mineralization and contribute to osteoporosis .
Vitamin K deficiency can occur during the first few weeks of infancy due to low placental transfer of phylloquinone, low clotting factor levels, and low vitamin K content of breast milk . Clinically significant vitamin K deficiency in adults is very rare and is usually limited to people with malabsorption disorders or those taking drugs that interfere with vitamin K metabolism . In healthy people consuming a varied diet, achieving a vitamin K intake low enough to alter standard clinical measures of blood coagulation is almost impossible .