Vitamin K

Background Info:

  • Fat-soluble vitamin

Health Benefits:

  • Plays a role in preventing bone loss
  • Blood clotting


  • Synthesized by plants in the form of vitamin K1 or pytonadione
  • Vitamin K 1 is also available in supplement or “free form”
  • Produced in the lower gut of humans by bacteria in the colon in the form of vitamin K2 or menaquinone
  • Vitamin K2 can also be found in some animal products such as dairy & fermented foods

Adequate Intake:

  • Birth to 6 months: 2 mcg
  • 7-12 months: 2.5 mcg
  • 1-3 years: 30 mcg
  • 4-8 years: 55 mcg
  • 9-13 years: 60 mcg
  • 14-18 years: 75 mcg
  • 19+ male: 120 mcg
  • 19+ female: 90 mcg


  • Blueberries = 14 mcg in 1/2 cup
  • Broccoli = 110 mcg in 1/2 cup
  • Collards = 530 mcg in 1/2 cup
  • Grapes = 11 mcg in 1/2 cup
  • Kale = 113 mcg in 1 cup
  • Spinach = 145 mcg in 1 cup


  • Better absorbed as a supplement than from food sources because it can be bound to compounds within plants


  • Bleeding & hemorrhaging occur in severe cases
  • Could also reduce bone mineralization and contribute to osteoporosis

Daily Upper Limit:

  • There is low potential for toxicity

Drug Interactions:

  • Warfarin and similar anticoagulantsVitamin K can have a serious and potentially dangerous interaction with anticoagulants such as warfarin. These drugs antagonize the activity of vitamin K, leading to the depletion of vitamin K-dependent clotting factors. People taking warfarin and similar anticoagulants need to maintain a consistent intake of vitamin K from food and supplements because sudden changes in vitamin K intakes can increase or decrease the anticoagulant effect
  • AntibioticsAntibiotics can destroy vitamin K-producing bacteria in the gut, potentially decreasing vitamin K status.
  • Bile acid sequestrantsBile acid sequestrants are used to reduce cholesterol levels by preventing reabsorption of bile acids. They can also reduce the absorption of vitamin K and other fat-soluble vitamins, although the clinical significance of this effect is not clear
  • OrlistatOrlistat is a weight-loss drug that reduces the body’s absorption of dietary fat and in doing so, it can also reduce the absorption of fat-soluble vitamins, such as vitamin K. Combining orlistat with warfarin therapy might cause a significant increase in prothrombin time


  • Hultin, Ginger. “Vitamin K.” Food & Nutrition Magazine. May/June 2016. 24.
  • “Vitamin K.” (February 11, 2016). Retrieved from


3 thoughts on “Vitamin K

  1. Michelle: I truly believe you should forward these Secrets to (now) the St. Petersburg newspaper. For that matter, why not also to Orlando’s biggest daily newspaper. I think one of these guys will publish it and you will start your road to fame as a known name as a Registered Dietician. Just get their email…it should be listed on the left side of the editorial page in any newspaper. Or one of those slick tourist magazines. Send it out to a dozen places, each Secret, one at a time. Or “Health” magazine, et cetera. Really. You must.

    hugs/ gma


  2. Pingback: Hass Avocado | Michelle Smith, RD

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