Vitamin K plays an important role in proper blood clotting as well as with calcium utilization in bones and the cardiovascular system, but do most people need a vitamin K supplement? And do products on the market contain what’s claimed on their labels? To find out, ConsumerLab.com, White Plains, NY, reviewed the clinical evidence, and purchased and rigorously tested popular vitamin K supplements sold in the U.S. 

ConsumerLab.com’s tests revealed that three products contained less vitamin K or other key ingredients than claimed, took longer than normally expected to break apart in disintegration testing, and/or were contaminated with lead. Among products which were approved, ConsumerLab.com identified its top picks. Its selections include vitamin K-only supplements as well as combination products containing vitamin D, calcium and/or magnesium. The results are available in ConsumerLab.com’s new Vitamin K Supplements Review. 

As explained in the review, supplements containing vitamin K can be helpful in treating poor blood clotting caused by deficiency. Although deficiency is also associated with atherosclerosis, lower bone mass and, in women, a higher risk of hip fracture, most people get enough of the vitamin through their diet.

The review explained the clinical evidence for vitamin K, how to get vitamin K from foods, how to choose the best vitamin K supplement and dosage based on individual needs, and difference in potency among the popular forms of vitamin K, including vitamin K1 and two forms of vitamin K2—menaquinone-4 (MK-4) and menaquinone-7 (MK-7). It also provides information about drug interactions with vitamin K supplements and other safety concerns.  

ConsumerLab.com’s review includes test results and quality comparisons for the following 12 products, including eight supplements selected for testing by ConsumerLab.com and four others which passed the same testing through CL’s voluntary Quality Certification Program: AdvoCare Calcium Plus, AlgaeCal Plus, Carlson Vitamin K2, Doctor’s Best Artery Prime With MenaQ7, Garden of Life Vitamin Code Raw K-Complex, GNC K-2, Healthy Origins Natural Vitamin K2 As MK-7, Jarrow Formulas Bone-Up, Nature’s Way Alive Calcium Bone Formula, NOW Vitamin D-3 & K-2, USANA Vitamin D, and Viactiv Calcium Plus D – Milk Chocolate.