The Essential Function of Vitamin K

When most of us think about vitamins, we think of vitamin C, or maybe A, B, D, or E. The vitamin everybody needs but many of us don't know about is vitamin K. Here's what you need to know about vitamin K in maintaining good health.

The sole vitamin K function in your body is to make the proteins that control calcium. The physiological function of vitamin K is to convert the amino acid glutamate into gamma-carboxyglutamic acid (GCA). There are only about a dozen proteins known to contain GCA, but the tasks they perform are vital to good health. Here is the function of vitamin K in terms of this modified amino acid:

Vitamin K makes the proteins that allow blood to clot.

The K in the name of this vitamin is short for the German word "Koagulation." Vitamin K makes it possible for GCA to "siphon" calcium out of the bloodstream. The combination of calcium and specialized proteins forms a floating net in the bloodstream. This floating net forms a framework for the clot that in turn keeps blood in its proper channels. Clots prevent excessive bleeding.

If your diet or supplement program doesn't support the function of vitamin K, you are at risk of excessive bleeding. Vitamin-K rich foods and supplements are useful in keeping cuts, scratches, and other wounds from becoming "gushers" that cause an serious loss in blood volume.

Another function of vitamin K is to get calcium into bones.

The creation of mineral-dense, strong bones results from an interplay between the function of vitamin K and vitamin D. The bone making cells called osteoblasts move calcium in response to a hormone called osteocalcin. This hormone is regulated by vitamin D.

Vitamin D can't activate osteocalcin, however, except in the presence of three byproducts of glutamate. Making these three proteins from glutamate requires vitamin K. You can't get calcium into your bones if you aren't getting calcium in your diet, but too little calcium usually isn't the real reason bones are weak. Your bones can't use calcium without the function of vitamin K and D.

Another function of vitamin K is keeping calcium out of your arteries.

Everyone's heard of "hardening of the arteries," more technically termed atherosclerosis or arteriosclerosis. Hardened arteries result from calcium replacing cholesterol in the lining of a blood vessel.

This process of calcification occurs when a very small, microscopic amount of cholesterol becomes lodged in the arterial wall. A specialized group of white blood cells called macrophages feed on bacteria when there's an infection and on cholesterol when there's not. They patrol the bloodstream looking for cholesterol to surround, digest, and remove from the arteries.

In atherosclerosis, however, a macrophage gets imbedded in the arterial wall. A series of changes caused by antioxidant deficiency keep it from getting out.. It dies trying to remove, and other macrophages are signaled to act as "undertakers" and remove both the dead macrophage and the oxidized cholesterol.

Sometimes they die, too. Eventually there can be a visible mass (usually the size of the dot on top of an i, but sometimes a lot larger) consisting of a tiny bit of cholesterol and a whole lot of dead macrophages.

Over a period of weeks, months, or years, depending on antioxidant status, the detritus of macrophages and cholesterol usually is slowly replaced by artery-hardening calcium. Vitamin K, however, keeps that from happening. Just as vitamin K makes sure calcium moves into bones, another function of vitamin K is to keep calcium out of arterial clogs.

When arteries aren't clogged up with calcified cholesterol, they move more blood at a lower pressure. When arteries are open, any clots that do form are far less likely to lead to heart attack or stroke. There's a growing body of science that suggests that a function of vitamin K is to maintain the linings of blood vessels in a flexible condition - so even if there is a clot to lodge to cause a heart attack or stroke, the effects of the event will not be catastrophic.

Clinically significant vitamin K deficiency isn't very common. The definitive sign of vitamin K shortages in diet or supplementation is problems with blood clotting. It's very easy for your doctor to diagnose a vitamin K-related deficiency in blood clotting factors with a simple blood test.

Deficient function of vitamin K may also manifest itself as nosebleed, bleeding gums, heavy menstruation, blood in the stool, blood in the urine, black or tarry stools, tinted urine, or easy bruising. In the very rare case of vitamin K deficiency in infants, there can be life-threatening bleeding in within the skull.

This condition doesn't occur without other obvious symptoms, however, and it's most likely in babies who are breastfed by mothers who take anti-seizure medications.

So how do you get your vitamin K?

There was a time when nutritionists believed that most of the body's vitamin K was made by bacteria living in the colon. On the basis of this theory, pediatricians gave babies vitamin K shots. The theory was that injections were necessary because the newborn's digestive tract hadn't had enough time to make vitamin K.

There were headline reports in the 1980's and 1990's that giving newborn babies vitamin K shots could cause leukemia later in childhood. The scare mongering simply wasn't based on facts.. A follow-up study of 1.3 million babies in the United Kingdom found that this dreaded childhood disease was no more likely among children who received vitamin K in the delivery room than among children who didn't.

Nutritionists did, however, eventually learn that the best way to get your vitamin K is day by day. To maintain normal function of vitamin K, women need up to 90 micrograms a day and men need up to 120 micrograms a day.