Vitamin K is one of the critical components in your blood that ensures you have proper clotting. Without it, you would likely hemorrhage and die.

Blood clotting is a complex bodily function, requiring the action of at least a dozen different proteins and calcium as well as vitamin K. (Hemophilia is not related to vitamin K deficiency; it is, rather, caused by the body’s inability to create several of these proteins.)

A lack of vitamin K also contributes to the bone fractures tht so often plague the elderly. If you don’t have enough vitamin K, one protein bone cells normally produce that adds strength to their stucture is synthesized incorrectly, leading to faulty bones or bone sections that are brittle. And researchers are starting to realize that we know less about vitamin K than we thought we did; it functions in a variety of other protein synthesis reactions affecting many different organs and organ systems.

Fortunately, vitamin K deficiency is rare. Our bodies don’t produce it directly, as we can with vitamin D, but the bacteria in our large intestines do produce it. This means that only a few people are at risk for deficiency: infants, people with intestinal disorders, and the like. Infants are most at risk; not only do they not have the critical bacteria (intestinal flora aren’t established for several weeks after birth), but they also have a number of other factors that create a clotting or hemorrhagic danger. To prevent this, most newborns are given oral or injected vitamin K as a supplement. Some people have questioned the possiblity of this leading to cancer in the baby, but research shows this to be unlikely.

It is rare that people get too much vitamin K, but if you’re recommended for some reason to take vitamin K supplements, it can happen. Toxicity results in dangers like jaundice, increased chance of blood clotting, and even brain damage. Those who are taking anticoagulants are at the most increased risk of suffering harm from too much vitamin K; the vitamin interferes with proper action of these drugs.

The Least You Should Know

Fat-soluble, so must be taken with a meal or a glass of milk. Most people don’t need to take anysupplements, as their intestinal bacteria provide all they need.
Adult RDA: 120 micrograms/day
Max recommended dose: Unknown, but probably no more than the recommended RDA unless
advised otherwise by a doctor.