In addition to its critical role in blood clotting, vitamin K may increase bone mineral density and reduce the risk of hip fracture when used in combination with adequate intake of calcium and vitamin D. Studies also suggest that certain forms of vitamin K may reduce the risk of death from heart attack and cancer.
So what's the best vitamin K supplement?
Our tests found several high quality products which provide 50 mcg of vitamin K for as little as 1 cent per day. But we also found products that contained incorrect amounts of vitamin K or other key ingredients. In fact, one contained none of its listed K2 (MK-7) — a more potent, and typically more expensive, form of vitamin K.
We also checked combination products to see if they contained their claimed amounts of other bone health ingredients, like vitamin D, calcium and magnesium. Unfortunately, not all did. Products were further checked for contamination with lead, arsenic and cadmium, and tablets were tested to be sure they properly break apart to be fully available for absorption.
You must become a member to get the full test results and quality ratings for eleven supplements with vitamin K -- six selected for testing by ConsumerLab.com and five others that passed the same tests through CL's voluntary, Quality Certification Program.
In this comprehensive report, you'll discover:
- Which vitamin K supplements failed our quality ratings and which passed -- including vitamin K-only supplements and combinations including vitamin D, calcium, and magnesium
- Cost comparisons to help you choose a vitamin K supplement offering the best value
- The differences in potency among vitamin K1 and the two forms of vitamin K2 now sold -- menaquinone-4 (MK-4) and menaquinone-7 (MK-7)
- Dosage of vitamin K for specific uses
- Foods containing vitamin K
- Potential drug interactions and side effects of vitamin K, including concerns about soy allergy
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