Vitamin K Supplements: Benefits, Dosage, & Side Effects

by Vanya Sharma last updated -

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If you’re suffering from a vitamin K deficiency or if you have recently been feeling weak in your bones, then you may be in need to add a vitamin K supplement to your diet. And we have all the information you need. From what is a  vitamin K supplement to how it works and dosage, this article talks about it all. Let’s find out!

What is a Vitamin K Supplement?

There are many natural sources of vitamin K, including kale, collard greens, and spinach, among other green vegetables, and some animal and fermented foods. Although, as per research at the University of Wisconsin, there may be times you may still face a vitamin K deficiency, either due to a lack of these vegetables in your diet or health-related conditions such as malabsorption or/and a vitamin K deficiency at birth. This makes it necessary for you to have an appropriate regular dosage of a good vitamin K supplement in your diet. As per a study published in NIH, the main purpose of a vitamin K supplement is to build up certain proteins, such as prothrombin and osteocalcin, in your body, required mainly for blood clotting and bone health.

Typically, to curb a deficiency, vitamin K can be taken through multivitamins or multimineral supplements. They are usually available at a DV of less than 75 percent. But for higher doses, you can also go for supplements, with only vitamin K in them or other supplements with a combination of other nutrients like calcium, vitamin D, and magnesium. These supplements are usually available at 5,063 percent DV or even higher amounts.

vitamin D3 supplement yellow capsules on a plate next to an open bottle

Note: For the correct DV, specific to your condition/deficiency, we recommend you consult a medical care practitioner or doctor, in order to best prevent any side effects.

For dietary supplements, vitamin K is available in many different forms, including “vitamin K1 as phylloquinone or phytonadione and vitamin K2 as MK-4 or MK-7”, as per NIH. There is yet another synthetic form of vitamin K, which is K3. However, various studies and trials conducted during the 1990’s show it has adverse effects on the hepatic cells which means liver damage, and therefore it is no longer used in supplements.

Benefits and Uses of Vitamin K Supplements

There are many benefits of vitamin K supplements, they include the following.

  • Help with calcium absorption
  • Improve bone health
  • May increase bone mineral density
  • May help prevent osteoporosis
  • Help maintain healthy blood vessels
  • Promote blood clotting when necessary
  • Prevent the breakdown of cartilage
  • Prevent vitamin K deficiency
  • Reduce arterial stiffness
  • Promote heart health
  • Reduce the risk of coronary heart diseases
  • May help reduce dark circles
  • Help dissolve fat
  • Control blood glucose

Dosage

The dosage for vitamin K varies from age to age as per a Harvard Medical Review, let’s take a detailed look at it below.

  • Children: For children up till the age of 13, a dosage below 60 micrograms per day is advised; ranging from 2 micrograms per day for a six-month-old baby to 60 micrograms per day for a 13-year-old child.
  • Girls & Boys: For girls and boys between the age group of 14-18 years, a dosage of 75 micrograms per day is advised.
  • Women: Women above the age of 19 are advised a daily dosage between 75-90 micrograms. For pregnant or breastfeeding women, it is best to consult a doctor before taking any supplements.
  • Men: Men above the age of 19 are advised a daily dosage of about 120 micrograms.

For a vitamin K supplement, the UCSD School of Medicine advises taking one tablet of 100mcg each day, with or without food. While you can take it with other medicines, if you’re taking warfarin, they suggest taking it 8-12 hours before or after it.

According to a review done in the Linus Pauling Institute, both phylloquinone and menaquinones, in the form of multivitamins and other supplements, are available without a medical prescription in the US. They range in doses from 25-100 mcg per tablet.

Side Effects

According to the research, there can be a few side effects of vitamin K supplements, when taken in excess or otherwise. Let us take a look at them below.

  • Toxicity: Vitamin K supplements can cause an allergic reaction. And synthetic menadione or vitamin K3 can also cause toxicity. It interferes with glutathione in the body and causes oxidative damage to the cell membranes, leading to liver toxicity, jaundice, and hemolytic anemia in infants.
  • Nutrient Interactions: Vitamin E and A, in large doses, are known to have an antagonizing effect on vitamin K absorption.
  • Drug Interactions: Vitamin K drug interactions include that with anti-coagulants like warfarin, as they can increase the risk of hemorrhage. Continued use of antibiotics such as cephalosporins and salicylates can also interfere with vitamin K compound. Other drug interactions include amiodarone, which is used for regulating an irregular heartbeat and with cholesterol-lowering medications like colestipol and orlistat.
  • Pregnant or Breastfeeding Women: Pregnant or breastfeeding women taking anticonvulsants like phenytoin and anti-tuberculosis drugs like rifampin and isoniazid can increase the risk of a vitamin K deficiency for their infants.

Other common side effects include the following:

  • Decreased appetite
  • Difficulty breathing
  • Muscle stiffness
  • General body swelling

5 Best-selling Vitamin K Supplement

If you are looking for a vitamin K supplement, then there is a whole wide range of them available online and over the counter. Below we have listed down five of the most popular vitamin K supplements.

  • Doctor’s Best Natural Vitamin K2 (MK-7 with MenaQ7, Non-GMO, Vegan, Gluten-Free, Soy Free, 45 mcg)
  • Biotech MK-7 ((Vitamin K2) 150 Mcg)
  • Healthvit Vitamin K (1.5 mg)
  • Jarrow Formulas (MK-7 90 mcg)
  • Life Extension Super K with Advanced K2 Complex

Note: Please speak to your doctor or health care professional before making any supplementary or dietary change in your routine.

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About the Author

Vanya Sharma handles the medical expert collaboration for Organic Facts. A writer at heart, she joined the website while she was still pursuing her English Literature degree from IGNOU, Delhi, India. She is also responsible for the website’s monthly newsletter and website content and contributes to Facebook, Instagram, and YouTube regularly. Currently pursuing an e-course offered by Stanford University, ‘Introduction to Food and Health’, she aims to bring unbiased and helpful information to all those seeking to make their health and lifestyle a priority.  

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