Vitamin K: K1 and K2

Until the past decade or so, vitamin K was mostly regarded as of importance only to blood clotting functions. But in the past several years, scientists have increasingly shown that vitamin K is essential to bone and cardiovascular health. There is also growing evidence that vitamin K is essential to dental, brain, and pancreatic health.

Vitamin K is really more accurately thought of as two separate vitamins with similar structures. K1 is the better known form. But it turns out that K2 may be more important for overall health than K1 because K2 is much more difficult to get in the diet and K2 helps to keep calcium in the bones where it belongs so that it does not calcify and damage tissues and organs such as the blood vessels, heart, kidney, and liver.

K1 is the form that is found in leafy green plants. The human body seems to be able to absorb around 200 mcg to maybe as much as 1000 mcg (micrograms) of this per day from diet and supplements. Estimates are that basic needs for blood clotting proteins alone require in excess of 50 mcg per day of vitamin K1.

K2 is the form that is found in animal foods such as cheeses, animal organs (liver, bone marrow, etc.), and fermented foods such as natto. The quantity of K2 needed is not clear today.

Some medical treatments developed in Japan use vitamin K2 supplements to prevent or reverse osteoporosis using 15 mg of K2 taken three times per day for a total of 45 mg per day.

Most supplements containing vitamin K2 include much smaller dosages such as 1 mg.

Most K2 in food is the MK4 (menatetranone or menaquinone-4) form that is rapidly used by the body. Bacterially produced K2 forms such as MK7 (menaquinone-7) are thought to persist in blood circulation for longer periods of time. It is not yet clear which form is better for the human body.

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Further Reading

Vitamin K strengthens bones, protects arteries, and may help prevent cancer and other degenerative diseases

Greater vitamin K intake associated with lower diabetes risk

Vitamin K: Stunning new research shows that vitamin K may be one of the most extraordinary anti-aging vitamins ever discovered. It has unique powers no other vitamin possesses.


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