Micronutrient Monday: Vitamin K

Vitamin K is the last of the four fat-soluble vitamins for me to post about! You can learn more about all the other fat-soluble vitamins by checking out the Micronutrient Monday series.

There are 2 main forms of vitamin K,

• • Phylloquinone (also known as vitamin K1)
    • Phylloquinone is the primary form of vitamin K found in the diet, and are mainly found in leafy, green vegetables.
  • Menaquinones (also known as vitamin K2)
    • There are many subtypes of menaquinones. These forms of vitamin K can be found in some foods including animal-based and fermented foods.

Role of Vitamin K in the Body

Although vitamin K plays many roles throughout the body, it plays essential roles in the formation of blood clots and the maintenance of healthy bones.

Blood Clotting

Vitamin K is required for activation of many enzymes in the blood clotting pathway including, prothrombin and carboxylase. Without adequate amounts of vitamin K, our cuts and grazes will take longer to stop bleeding as the blood clotting pathway will occur more slowly.

How Much Vitamin K Do I Need?

Health Canada recommends healthy males over the age of 18 consume 120 mcg of vitamin K each day, and healthy females consume 90 mcg each day. You can find a list of Health Canada’s recommendations for vitamin K intakes for other populations by visiting their Dietary Reference Intakes page.

Am I At Risk of Vitamin K Deficiency? 

In Canada, vitamin K deficiency is very rare. This is partially because the bacteria found in our digestive tract produce vitamin K, which may be absorbed by our bodies. Additionally vitamin K can be found in many founds in our diets including many leafy green vegetables.

Although vitamin K deficiency is rare, some populations are at an increased risk of deficiency including,

• • Individuals with fat mal-absorption conditions (such as celiac disease and cystic fibrosis)
  • Individuals taking coagulants (such as warfarin)
  • Individuals on antibiotics

Some signs of vitmain K deficiency are,

• • Easily bruising
  • Excessive bleeding from cuts
  • Oozing blood from nose or gums

Can I Have Too Much Vitamin K? 

Studies have not found any adverse effects from excessive vitamin K consumption. However, excessive intakes of any vitamin are not recommended.  

Where Can I Find Vitamin K?

Vitamin K is naturally found in a variety of foods. Vitamin K1 (phylloquinone) is primary found in green, leafy vegetables, while vitamin K2 (menaquinones) are found in animal-products and fermented foods. Some vitamin K-rich foods include, 

• • Kale
  • Broccoli
  • Lettuce
  • Turnip
  • Edamame
  • Pumpkin
  • Meat
  • Cheese
  • Soybeans
  • Blueberries
  • Figs

Dietary Supplements

Like many other micronutrients, vitamin K can also be found in supplements including multi-vitamins and individual supplements. Supplements can include either vitamin K1, vitamin K2 or both. Although you can find vitamin K supplements on the shelf in most pharmacies, I encourage you to discus supplementation with your doctor or your health care team before purchasing as it can have some negative interactions with some medications.

Vitamin and some medications are known to interact with each other. These include,

• • Anticoagulants
    • Anticoagulants reduce the rate of blood clotting. Many anticoagulants work by inhibiting the activity of vitamin K in the blood clotting pathway. This leads to a longer time for blood clots to form.
  • Antibiotics
    • Antibiotics can reduce the number of vitamin K-producing bacteria found in our digestive tract and can potentially decrease our vitamin K intake.
  • Bile acid sequestrates
    • These medications reduce the amount of bile re-absorbed in our digestive tract, but can also reduce the absorption of vitamin K and other fat-soluble vitamins.
  • Orlistat
    • Orlistat reduces the amount of fat we absorb from meals. This can also reduce our absorption of fat-soluble vitamins, including vitamin K.

It is important to talk with your health care team prior to starting vitamin K supplements to minimize the risk of adverse reactions with other medications. 

For more on the role of vitamins and minerals in promoting health and supporting our bodies, check out the Micronutrient Monday series.