Vitamin K: A Nutrient Worth Knowing

A nutrient typically thought of in relation to bone health—if it’s thought of at all—is vitamin K, which is sometimes referred to as “the forgotten vitamin”.  A bit like the vitamin B complex, it is in fact not a single nutrient, but the name given to a group of vitamins of similar composition.

The two main groups of vitamin K that occur naturally are phylloquinone (vitamin K1) and menaquinone (vitamin K2). Vitamin K1 is found in many vegetables, while vitamin K2 is primarily produced by bacteria. There is a third variety as well—menadione—which is entirely synthetic.

Physiologically, vitamin K plays a role along with magnesium in what is referred to as The Calcium Paradox: this refers to the potential for dietary or supplemental calcium to accumulate in arterial walls, rather than in bones where it belongs. Proper intake of vitamin K helps to biologically direct calcium to the skeletal system, which in turn greatly reduces the likelihood of calcium arriving at the arteries.

Another very interesting study suggests that vitamin K may have potential to assist in cancer treatment. This is due to its promotion of apoptosis (or cell death) in malignant tissue, thereby interfering with progression of the disease. Finally, there appears to be a correlation between vitamin K deficiency and the presence of Alzheimer’s disease. While the exact nature of the relationship is not known, it is thought to involve the antioxidant properties vitamin K displays, which possess neuroprotective qualities.

Currently the average vitamin K intake in the U.S. is approximately 75 to 125 mcg daily. The current recommended intake is anywhere between 100 to 200 mcg daily, and as it has been with vitamin D in the past, there are certain researchers advocating much higher amounts (up to 1,000 mcg) for maximum benefits. Apart from supplemental sources, leafy greens such as spinach, kale and collard greens provide the most abundant amounts of this lesser known but highly beneficial nutrient.