Bone health

Key vitamins for bone health — vitamins K₁ and K₂

by Dr. Susan E. Brown, PhD

While vitamin K is best known for its role in blood clotting, this nutrient also plays an important part in the maintenance of healthy bones. Noted nutrition authority Dr. Alan Gaby has suggested that vitamin K is as important to bone as calcium. So let’s follow Dr. Gaby’s lead and delve a little deeper into its role in bone health.

Vitamin K is required for the synthesis of osteocalcin, the bone protein matrix upon which calcium crystallizes. Osteocalcin provides the structure and order to bone tissue; without it bone would be fragile and easily broken. Vitamin K also aids in the binding of calcium to the bone matrix — in essence, it serves as the “glue” that binds calcium onto the skeleton.

Just as vitamin K is central to bone formation, it also appears to play an important role in fracture healing. Vitamin K levels fall during recovery from fracture, and it appears that this nutrient is actually drawn from the rest of the body to the site of fracture.

Vitamin K is not a single nutrient, but the name given to a group of vitamins of similar composition. The two main groups that occur naturally are phylloquinone, or K1, which is found in plant-based foods, particularly green leafy vegetables; and the menaquinones, or K2, which are produced by bacteria in fermented foods and to some minor extent in our intestinal tracts. In combination with vitamin D and calcium, both vitamins K1 and K2 increase bone quality. But vitamin K2 is more bioavailable, longer lasting, and provides for greater increase in bone strength.

The more we learn about this vitamin, the more we see it takes various forms and roles in the body. To date most of the research has been done on K1. But a new wave of research is now focusing on K2 — in particular the subset of K2 known as menaquinone–7, or MK–7. This research documents the superior ability of MK-7 over K1 to enhance both bone and heart health. Getting enough of the K2 forms of this vitamin has been found to be especially important for healthy bones in patients being treated with oral anticoagulants, such as warfarin (Coumadin).

Aside from getting K through dietary sources, vitamin K can also be produced in the body by certain beneficial intestinal bacteria. By compromising this process, long-term use of antibiotics can lead to vitamin K deficiency. Aside from oral antibiotic and anticoagulant use, culprits in vitamin K inadequacy include the freezing of foods, mineral oil laxatives, rancid and hydrogenated fats, radiation, impaired fat absorption, sulfa drugs, and certain liver diseases.

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Original Publication Date: 01/01/2009
Last Modified: 02/16/2010
Principal Author: Dr. Susan E. Brown, PhD