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Vitamin K1

When it comes to listing nutrients that are important for good health and metabolism, vitamin K is not often at the top of most lists. But as the population ages, and bone health becomes more of a concern to many people, foods that are good sources of vitamin K may become more important in our diets.


The Vitamin K story is a bit more complicated than other vitamins. To start off, there are in fact two forms of vitamin K. Vitamin K1 is also known as phylloquinone, phytomenadione, or phytonadione. Vitamin K1 is a family of chemically related compounds that differ in the length of their side chains. Vitamin K1 is found in plant sources and Vitamin K2 is found in animal sources. There are bacteria in our intestines that convert vitamin K1 to vitamin K2 which is the biologically active form for humans. The vitamin K found in food, combined that produced by our intestinal bacteria, play an important role in our metabolism.

Vitamin K is important in the building of bones. Vitamin K prevents the over-activation of osteoblast cell; this helps regulate the breakdown of bone.

Anyone who has compromised intestinal absorption due to such conditions as Crohn's disease or Celiac disease may be at risk of being Vitamin K deficient. Drugs such as colestyramine, salicylates, rifampin, isoniazid and barbiturates have been shown to reduce Vitamin K absorption. Heavy drinkers of alcohol are also at risk.

Chemical Structure of Vitamin K
Vitamin K1 Vitamin K2
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Vitamin K status can be evaluated using a simple blood sample. Low levels of circulating Vitamin K have been linked with low bone density. The US Institute of Medicine recently has increased the dietary reference intakes of vitamin K to 90 µg/d for females and 120 µg/d for males which is an increase of approximately 50% from previous recommendations.

Although Vitamin K is not as well known as many other vitamins, the role it plays in maintaining good bone health is an important one.

Good Dietary Sources of Vitamin K
Food Amount ug/100g
Kale, boiled:817
Spinach, boiled:494
Dandelion greens, boiled:551
Brussel sprouts:140


Vitamin K and bone health
Nutrition 2001,17:880-887

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