Vitamin K


Vitamin K Introduction

Of all the fat-soluble vitamins produced and consumed in our bodies, Vitamin K is the most important. It plays a key role in the manufacturing of prothrombin and other substances, and is essential for proper blood clotting. [1] Bone metabolism and functionality is also a feature influenced by our consumption of Vitamin K. Both Vitamin E and K work together synergistically to keep this important fat-soluble vitamin in an active state in our intestines and the remainder of our bodies; continuously aiding us in our life-long aging process.

Quinones are the group of compounds associated with Vitamin K. We derive Vitamin K from two major sources of these compounds:

  • Vitamins K1 - phylloquinones (Green plants and leafy vegetables)
  • Vitamins K2 - menaquionones (Formed from bacterial synthesis and animal sources; particularly organ meats)

Vitamin K Food Sources

Other than the food sources listed below, intestinal bacteria manufacture the remaining half of all Vitamin K synthesized in our bodies.

Food Serving Size%DV *
Spinach, Raw 1 cup 190
Brussels Sprouts, Boiled 1 cup 1532
Cauliflower, Raw 1 cup 476
Broccoli, Raw 1 cup 231
Chard, Boiled 1 cup 389
Carrots, Raw 1 cup 281
Green Snap/String Beans, Boiled 1 cup 155
Asparagus, Boiled 1 cup 146
Bell Pepper, Green, Raw 1 cup 25
Strawberries, Fresh 1 cup 32
Egg, Hen, Whole, Boiled 1 each 37
Tomato, Red, Raw, Ripe 1 cup 17
Green Peas, Boiled 1 cup 58
Avocado, All Varieties 1 cup 46
Apples 1 med. each 11
Milk, Cow, 2% 1 cup 16
Onions, Raw 1 cup 5

Clinical Nutrition Service, Warren Grant Magnuson Clinical Center, National Institutes of Health (NIH), Bethesda, MD, in conjunction with the Office of Dietary Supplements (ODS) in the Office of the Director of NIH. [2]

Vitamin K Uses

Vitamin K has a vast array of clinical applications. As mentioned, its most important function is within the areas of proper bone formation and blood clotting. Doctors will often medicate patients with Vitamin K to prevent excessive bleeding during surgical procedures by the use of medicines, includinng; antibiotics, salicylates (aspirin), or excessive dosages of the aforementioned warafin, a potent anticoagulant. [3]

Osteoporosis and Atherosclerosis are chronic illnesses treated with Vitamin K. This nutrient may prevent or delay the onset of osteoporosis and the damaging effects associated with the disease process. Vitamin K is capable of providing this advantage because it does well in maintaining previously developed bone density in humans.

One study evaluated the diets of over 72,000 women ranging in age from 38 to 63 years. Research found that the women who consumed greater amounts of Vitamin K in their diets had a lower risk of hip fracture (and other associated bone afflictions) than women who consumed lower amounts of Vitamin K in their diets. [5]

There is also preliminary evidence that Vitamin K2 (menadione, the intestinal bacterial derived compound) may improve a group of blood disorders known as myelodysplastic syndromes (MDS). [6] Furthermore, Vitamin K may also inhibit symptoms of Alzheimer's disease, though more research is needed to accurately assess this particular usage.

Vitamin K Dosages

In consideration to the adult diet, dosages of Vitamin K intake are very broad. Because we have the ability to store this vitamin in our bodies, the intake amount needed is very small. Micro Flora, or K2, provide one-half of our daily intake needs for this compound. Delivery forms of Vitamin K include capsules, tablets, and injectable forms, which are only obtainable through physician prescription (rx) only.

The Recommended Daily Allowance for Vitamin K, adults 25 and over, is listed below. Average mixed diets in the United States supply 300 - 500ug/day. This figure does not include bacterial synthesis. [1]

80ug/day 65ug/day

Vitamin K Toxicities and Deficiencies

Vitamin K Toxicities

Toxicities of K are very rare. However, toxicity can occur with devastating results. The only toxicity known to occur in humans is with excessive dosages of menadione (K2), which can be very toxic; causing hemolytic anemia and possible liver damage.

Additionally, because infants lack or are unable to produce sufficient amounts of the intestinal bacteria needed to create this vital fat-soluble vitamin, Jaundice is a very common occurrence.

Vitamin K Deficiencies

Deficiencies in adults are highly unlikely due to the relative abundance of this vitamin in normal body storage systems (e.g. adipose tissue). It should be noted that excess intake of antibiotics in adults may require Vitamin K therapy. Antibiotics inhibit the growth of bacteria in ones intestines causing this rare deficiency. These malabsorptions result in diseases such as celiac disease, ulcerative colitis, regional enteritis, cystic fibrosis, and sprue. Vitamin K malabsorption may also cause secondary deficiencies, which can lead to further complication. [7, 8]

Infants (primarily newborns) have been reported to suffer a deficiency that leads to an acute illness known as hemorrhagic disease of newborn. Due to a placental inadequacy of Vitamin K absorption from mother to infant, these deficiencies and symptoms usually subside rather quickly when the vitamin is re-introduced.


1. Herbert, Victor. “Vitamins and Minerals Plus Antioxidant Supplements” Total Nutrition Ed. Victor Herbert, M.D., Genell J. Subak-Sharpe, M.S. New York: Saint Martin’s Griffin, 1995. 94-118.

2. Clinical Nutrition Service, Warren Grant Magnuson Clinical Center, National Institutes of Health (NIH), NIH. Vitamin December. 9. 2002.

3. Igarashi O. Vitamin K. Nippon Rinsho.Apr1993; 51(4):910-18. aquaMEPHYTON (Phytonadione), Product Prescribing Information. Merck & Co., Inc. Whitehouse Station, NJ. May2001.

4. Panel on Micronutrients, Subcommittees on Upper Reference Level of Nutrients and of Interpretation and Use of Dietary Reference Intakes, and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc.

5.Feskanich D, Weber P, Willett WC, Rockett H, Booth SL, Colditz GA. Vitamin K intake and hip fractures in women: a prospective study. Am J Clin Nutr. Jan 199;69(1):74-9

6. Miyazawa K, Nishimaki J, Ohyashiki K, et al. Vitamin K2 therapy for myelodsplastic syndromes (MDS) and post-MDS acute myeloid leukemia: information through a questionnaire survey of multi-center pilot studies in Japan. Leukemia 2000;14:1156-7(letter) Weber P. Vitamin K and bone health. Nutrition. Oct2001; 17(10):880-7.

7. Patel RJ, Witt DM, Saseen JJ, Tillman DJ, Wilkinson DS. Randomized, placebo-controlled trial of oral phytonadione for excessive anticoagulation. Pharmacotherapy. Oct2000; 20(10):1159-66.

8. aquaMEPHYTON (Phytonadione), Product Prescribing Information. Merck & Co., Inc. Whitehouse Station, NJ. May2001.