ACS Chemistry for Life

In 1929, Danish scientist Henrik Dam conducted experiments to see how cholesterol functioned in the diet.  When he fed a group of chickens a diet that was limited in cholesterol, many of the chickens developed bleeding issues – their blood was less likely to clot. Surprisingly, when he reversed the trend and gave them a feed of purified cholesterol, the problem didn’t go away.  Clearly something more than cholesterol was contributing to effective blood clotting. That substance turned out to be a vitamin. Dam published his findings in a German journal, which is why ever since the vitamin he identified has been known as Vitamin K, named for the German word: ‘koagulation.’

Blood clots form through an extensive cascade of events. Platelets form an initial plug at the site of injury, followed by a series of protein reactions in which Vitamin K plays a key role in activating calcium binding to strengthen the clot and close the wound. This multistep process is why a cut may stop bleeding red blood cells, but may still “weep” colorless fluid until the clot is completely formed. In situations, where preventing blood clots from forming is desired, such as following a heart attack, doctors often prescribe anti-coagulants such as warfarin, which target Vitamin K.

In the food we eat, Vitamin K is obtained from green leafy vegetables such as kale, spinach, and Swiss chard as well as from some vegetable oils. Deficiencies are actually rare in adults both because the vitamin is fat soluble, and thus easily stored, and because it is recycled throughout the body. Newborn babies are at the greatest risk for a deficiency of Vitamin K as it does not easily cross the placental barrier, and mother’s milk contains relatively little of this nutrient. To avoid this risk, infants are often given an injection of Vitamin K shortly after birth to prevent bleeding problems.

For more information, go to http://lpi.oregonstate.edu/infocenter/vitamins/vitaminK/