Undercarboxylated Osteocalcin: Marker of Vitamin K Deficiency, or Booster of Insulin Signaling and Testosterone?

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New over at Mother Nature Obeyed:


Update December 17, 2016: If you enjoyed this, I encourage you to check out The Ultimate Vitamin K2 Resource. It has easy-to-read practical advice, click-to-expand technical explanations, infographics that explain the science in a fun way, supplement recommendations, and a searchable database of foods. This post as well as the resource are indexed with my other vitamin K-related writings at Start Here for Vitamin K2.

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  1. Hi Chris,

    I will be staying in Southeast Asia for a few months and I wonder how to supply myself with enough K2? They do not eat any dairy or natto there so the question is what is the main source of the vitamin?


  2. This is a difficult article for someone not familiar with molecular biology. However there is something I can take from this and perhaps impart.

    More we find that nutritionism fails to provide good advice. As soon as we learn something new about an obscure vitamin, we develop sudden interest in obtaining it. If we seek out common sources of this, we probably won't go too wrong. Fortunately with K2, there are no easily obtained excessive sources of it, and there is no 'Vitamin K2 Council' out promoting K2 testing and supplementation – but this could change in a millisecond!

    I now begin to wonder if there could be danger in consuming Natto in high quantities – has anyone ever considered whether Japanese people who consume high amounts of Natto could suffer Vitamin K2 overdoes? Of course, you would have trouble distinguishing the effects of too much K2 against too much phyto-estrogens I suppose!

  3. Hi Chris,

    Thanks for the reply. I admit it was a long shot.

    I'm in a speculative mood, so I have two more 😉
    1) Weston Price noticed that with modernized food, one of the abnormalities was "… the narrowing of the entire body, with a tendency to increase in height". A bone regulating endocrine loop that goes haywire when there is a vitamin K2 deficiency might be one of the (probably many) factors involved in this body narrowing and height increase. What do you think?
    2) Price also noticed that "[c]riminal tendencies in isolated primitives are so slight that no prisons are required". Do you find it plausible that perhaps an increase in testosterone due to a vitamin K2 deficiency could be a factor in increased agression and criminal tendencies in people eating modern foods?

    I'm looking forward to your follow up post.


  4. Hey Chris,

    Great post.
    It always fascinates me to see how much I don't know about how the body works, no matter how much I study it 🙂

    About the undercarboxylated osteocalcin as a hormone booster: couldn't this just be a "carboxy feedback loop"?

    In other words: osteocalcin carboxylation ↓ → testosterone ↑, insulin sensitivity ↑ → metabolism ↑ → carboxy/CO2 ↑ → osteocalcin carboxylation ↑.

    Increasing the amount of CO2 might be the only control the body has to increase osteocalcin carboxylation, as the body cannot simply increase the amount of vitamin K2. Obviously, if vitamin K2 is the limiting factor in the carboxylation, then increasing CO2 will not affect the carboxylation enough. In that case you are left with the "side effects" of the increased testosterone etc.


    1. Hi John,

      This is a good idea, but I doubt this is the case, or if it is the case, I doubt it is so simple. The body couldn't regulate the amount of vitamin K, but it could increase the expression of vitamin K expoxide reductase to increase its recycling, increase the carboxylase enzyme as a way of increasing carboxylation (one or the other might be more effective depending on whether vitamin K or the carboxylase is limiting), or rearrange vitamin K transport between tissues. Affecting metabolism through at least one separate hormone each from three different tissues seems like an incredibly roundabout way to increase carboxylation, especially as feedback from the carboxylation status of an entirely different tissue.

      I think it's a lot more likely this is an endocrine loop meant to regulate bone in response to bone resorption. But I'll tackle that question in my followup post.

      Good thinking!


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