Vitamin K


Vitamin K is a fat-soluble vitamin that plays a major role in the blood-clotting process.  In fact, the “K” comes from the German “Koagulationsvitamin”, as it was called when the initial discovery was announced in a German scientific journal.

In addition to its function in blood-clotting, Vitamin K is also involved in calcium-bonding processes in bone cells that protect against osteoporosis and in the blood vessels, to protect against atherosclerosis.

Healthy men and women need 120 mcg and 90 mcg respectively of Vitamin K each day.  Children require smaller amounts that vary according to age.  People who might need more than the average intake of Vitamin K include those who have had stomach surgeries or inflammatory bowel disease, liver disease, certain kinds of cancer and bone diseases such as osteopenia and osteoporosis.

The best food sources of Vitamin K include leafy greens such as parsley, spinach, romaine lettuce, cabbage and kale, fermented foods such as tofu, miso, and Emmental and Jarlsberg cheeses.

Vitamin K interacts with many other vitamins, supplements and medications.  In particular, you should be cautious about supplementing Vitamin K if you take any of these:

  • Blood thinners such as Warfarin (Coumadin)
  • Co-enzyme Q10
  • tiratricol
  • Vitamin A
  • Vitamin E

If you take any of these substances, please consult an MD, ND or pharmacist before increasing your intake of Vitamin K.