Everything You Want to Know About Vitamin K

Definition

Vitamin K is known as a fat-soluble vitamin, which means that it dissolves in fat. Fat is what carries this vitamin throughout the body and aids in its absorption. Fat-soluble vitamins can be stored in the body, so it is important to get only needed amounts.

There are several different forms of vitamin K. Phylloquinone is the natural form of vitamin K. Menadione is the synthetic form of vitamin K. Menaquinone is the form that is produced by the body. Vitamin K is made in the body, as well as obtained from the diet.

Functions

The primary function of vitamin K is to help make a protein called prothrombin, which is essential for helping the blood to clot when you are bleeding. It also helps the body make some other body proteins for blood, bones and kidneys.

Foods it is found in

The best sources of vitamin K include green leafy vegetables, such as spinach, broccoli and turnip greens. Several other foods provide smaller amounts such as milk, other dairy products, meat, eggs, wheat bran, wheat germ, cereal, some fruits and other vegetables.

The body is also able to produce vitamin K from certain bacteria in the intestines.

How much you need

The RDA (Recommended Daily Allowance) of vitamin K for females age 11 to 14 years is 45 micrograms; age 15 to 18 years is 55 micrograms; age 19 to 24 is 60 micrograms; and for females 25 and over the RDA is 65 micrograms. The RDA of vitamin K for males age 11 to 14 years is 45 micrograms; age 15 to 18 years is 65 micrograms; age 19 to 24 is 70 micrograms and for males 25 and over the RDA is 80 micrograms.

Not getting enough vitamin K can cause blood to not coagulate or clot normally. Vitamin K deficiency is very uncommon except for in the cases of rare health problems. Chronic use of antibiotics can destroy some of the bacteria in the intestines that produce vitamin K, which can cause a problem.

No symptoms have been observed when consuming too much vitamin K. Moderation is always the best policy. The most toxic form is supplements. Because of this, vitamin K supplements are usually only available through prescription. People that take blood-thinning medications or anticoagulants need to eat foods containing vitamin K in moderation. If you take these types of medications make sure to ask your doctor about vitamin K.