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Clinician’s Corner: Vitamin K

Let’s wrap the last fat-soluble vitamin.  This one your Thompson Pharmacist never gets to recommend over the counter. We get plenty from our diet, as well as make our own in our gut.  Fat soluble vitamins usually accumulate, and water-soluble vitamins are quickly removed.  Not the case for Vitamin-K which doesn’t’ hang around in our system for more than one week.

Sources for Vitamin K:  leafy vegetables, vegetable oils, liver, & synthesis by intestinal bacteria. Phylloquinone (Vitamin K-1) is present primarily in green leafy vegetables and is the main dietary form of vitamin K. Menaquinones (Vitamin K-2), are produced by bacteria in the human gut.

  • Function: essential for formation of clotting factors, necessary to form blood clots

Deficiency States: When we ingest Vitamin-K the body retains only about 30% to 40% of an oral dose, while about 20% is excreted in the urine and 40% to 50% in the feces via bile. This rapid metabolism accounts for vitamin K’s relatively low blood levels and tissue stores compared to those of the other fat-soluble vitamins.

  • May be due to excessive antibiotic use. Newborns & preemies at increased risk. Deficiency cause hemorrhage due to prothrombin deficiency.
  • Cystic fibrosis patients because of fat malabsorption and broad-spectrum antibiotic use (that kills off bacteria that produces Vitamin-K) should be supplemented with Vitamin-K
  • Vitamin-K stores are small and deficiency may develop in a week.

Interactions:  warfarin, a blood thinner antagonizes the Vitamin K in the clotting cascade.  Your doctor may prescribe a couple of tablets of Vitamin-K if a patient’s warfarin levels are too high, and the blood is too “thin”.

Counseling points:

Lots of the foods we are told to eat to maintain a healthy and balanced diet are loaded with Vitamin-K.  Here are some rough guidelines for Vitamin-K consumption if our patients are being managed on warfarin (Coumadin®).

  • High in vitamin K foods: limit to (1) serving per day
    • (kale, spinach, collard greens, Swiss chard, parsley)
  • Moderately high: limit (3) servings per day
    • (broccoli, Brussels sprouts, endive, green lettuce)

Best advice: eat a consistent diet, an always ask your Thompson Pharmacist for advice on vitamins and prescription medications.  Go Ahead and ASK… at Thompson Pharmacy it’s all for YOU!