Recently, I got the below post from Dr. Tina Kaczor in response to the blog spot Vitamin K, Osteocalcin and Bone Health
It prompted me to devote a brand new blog spot to vitamin K and more! Read on…
Kara and company,
Hey Kara! I think reading the article on osteoporosis and vitamin K I just wrote for the Natural Medicine Journal might be interesting for y'all. It appears that while BMD improvements are not always found, a reduced fracture risk is more strongly correlated with K intake/intervention ... one explanation is that bone geometry, not density, is improved resulting in better bone strength and less fractures. This is not my theory, it is cited in my article ... you can check it out at www.naturalmedicinejournal.com
Tina Kaczor, ND, FABNO
Senior Medical Editor, Natural Medicine Journal
Hey Tina!
Congrats on your gig as medical editor at Natural Medicine Journal.
Rock on, grrrrl!
Per your suggestion, I hopped over to Natural Medicine Journal, and read your article: Vitamin K and Osteoporosis. I highly recommend it to my vast blog-reading audience. It’s a well-referenced read with useful factoids.
I found the reference about 50% of vitamin K being produced by GI bacteria1 to be an interesting idea, if only speculative.
My guess is that the actual percent would vary widely among individuals, as its dependent on having adequate vitamin K producing bugs. (Cursory Pub Med and Google searches didn’t produce anything worth listing here in the way of K-producing GI bugs. I’ll keep looking.)
It would be cool to crunch data on ucOC (undercarboxylated osteocalcin, a functional vitamin K marker) and GIFx microbiota data to see if there is a correlation with dysbiosis and vitamin K deficiency.
Biotin is another vitamin reliant upon robust GI microbiota for production.
Anecdotally, we see B-hydroxyisovalerate, the organic acid biotin marker, elevated (demonstrating biotin insufficiency) in folks presenting with evidence of dysbiosis. I particularly notice a pattern of biotin deficiency in (autism spectrum disorder) ASD individuals, who almost always have pronounced GI challenges.
I found this connection when I was delivering a lecture on case studies in ASDs for the lab. It was an “ah ha!” moment for me when I noticed that four of the five ASD cases had biotin deficiencies
Incidentally...
I recently read in my fave-rave magazine The Scientist that a 7 day course of clindamycin was associated with alterations in commensal Bacteroides ssp. and resistance gene expression for 2 years. (You can grab the full text here)
2 years! That is no joke.
The researchers couldn’t determine if it was clinically significant. The gut remains the black box of the body. It will be a long time coming before subtle and lasting perturbations in the microbiota are traced out in their entirety.
Looking at the impact on microbiota-dependent nutrients (e.g. vitamin K and biotin) could be an important line of inquiry.
Anyway, back to your article:
Vitamin K is fat soluble of course. I found it interesting that you said phylloquinone (plant-derived vitamin K) is transported on triglyceride rich lipoprotein. Did you mean VLDL? Whereas menaquinones (animal-derived) are primarily transported on LDL and HDL.
What are the implications of utilizing different lipoproteins for transport, do you think?
Another question: don’t you think that the negative interaction you mention between vitamin A and K could be at the nuclear receptor subfamily-1 level? Perhaps at the vitamin A retinoid-X-receptor (RXR)? Or perhaps they modulate another nuclear receptor subfamily-1 player, like the vitamin D receptor (which forms a heterodimer with RXR)? I wonder this because you mention in your article that vitamin K interacts with another nuclear receptor subfamily-1 member: SXR.2
My guess is you’ve chewed on this one.
Getting esoteric. Or I am already there?
Adios 
References
- Suttie JW. The importance of menaquinones in human nutrition. Annu Rev Nutr. 1995;15:399-417.
- Tabb MM, Sun A, Zhou C, et al. Vitamin K2 regulation of bone homeostasis is mediated by the steroid and xenobiotic receptor SXR. J Biol Chem. Nov 7 2003;278(45):43919-43927.
