Vitamin K was named for its role in coagulation (koagulation in German), but it turns out this important vitamin has significant roles beyond blood clotting. Work by Tufts researchers and others shows that vitamin K may be an important factor in bone health, cardiovascular health, and type 2 diabetes.
Vitamin K1 versus K2: The originally-identified form of vitamin K is vitamin K1. “There are actually 11 forms of vitamin K,” says Sarah L. Booth, PhD, a professor at the Friedman School of Nutrition Science and Policy and director of the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA). “Vitamin K1 is found in plants. The other 10 forms of vitamin K are collectively known as vitamin K2. One form of vitamin K2 is made in our bodies from vitamin K1. The other nine forms are produced by bacteria, either in the human gut or in foods fermented with the use of bacteria, including cheese, yogurt, and other fermented dairy products.” Our gut bacteria and fermented foods, therefore, may play an important role in what forms of vitamin K we have in our bodies.