I happen to be working on that at the office. Here is a snapshot of the opinion landscape (all from PubMed):
Iwamoto J. Vitamin K₂ therapy for postmenopausal osteoporosis. Nutrients. 2014 May 16;6(5):1971-80.
DiNicolantonio JJ, Bhutani J, O'Keefe JH. The health benefits of vitamin K. Open Heart. 2015 Oct 6;2(1):e000300.
Huang ZB, Wan SL, Lu YJ, Ning L, Liu C, Fan SW. Does vitamin K2 play a role in the prevention and treatment of osteoporosis for postmenopausal women: a meta-analysis of randomized controlled trials. Osteoporos Int. 2015 Mar;26(3):1175-86.
Falcone TD, Kim SS, Cortazzo MH. Vitamin K: fracture prevention and beyond. PM R. 2011 Jun;3(6 Suppl 1):S82-7.
Maresz K. Proper Calcium Use: Vitamin K2 as a Promoter of Bone and Cardiovascular Health. Integr Med (Encinitas). 2015 Feb;14(1):34-9.
Hamidi MS, Cheung AM. Vitamin K and musculoskeletal health in postmenopausal women. Mol Nutr Food Res. 2014 Aug;58(8):1647-57.
Stevenson M, Lloyd-Jones M, Papaioannou D. Vitamin K to prevent fractures in older women: systematic review and economic evaluation. Health Technol Assess. 2009 Sep;13(45):iii-xi, 1-134.
Fang Y, Hu C, Tao X, Wan Y, Tao F. Effect of vitamin K on bone mineral density: a meta-analysis of randomized controlled trials. J Bone Miner Metab. 2012 Jan;30(1):60-8.
Vermeer C, Theuwissen E. Vitamin K, osteoporosis and degenerative diseases of ageing. Menopause Int. 2011 Mar;17(1):19-23.
Azuma K, Ouchi Y, Inoue S. Vitamin K: novel molecular mechanisms of action and its roles in osteoporosis. Geriatr Gerontol Int. 2014 Jan;14(1):1-7.
Hamidi MS, Gajic-Veljanoski O, Cheung AM. Vitamin K and bone health. J Clin Densitom. 2013 Oct-Dec;16(4):409-13.
Shah K, Gleason L, Villareal DT. Vitamin K and bone health in older adults. J Nutr Gerontol Geriatr. 2014;33(1):10-22.
Iwamoto J, Takeda T, Sato Y. Menatetrenone (vitamin K2) and bone quality in the treatment of postmenopausal osteoporosis. Nutr Rev. 2006 Dec;64(12):509-17.
Pearson DA. Bone health and osteoporosis: the role of vitamin K and potential antagonism by anticoagulants. Nutr Clin Pract. 2007 Oct;22(5):517-44.
Gundberg CM, Lian JB, Booth SL. Vitamin K-dependent carboxylation of osteocalcin: friend or foe? Adv Nutr. 2012 Mar 1;3(2):149-57.
Bügel S. Vitamin K and bone health in adult humans. Vitam Horm. 2008;78:393-416.
Booth SL. Vitamin K status in the elderly. Curr Opin Clin Nutr Metab Care. 2007 Jan;10(1):20-3.
Shea MK, Booth SL. Update on the role of vitamin K in skeletal health. Nutr Rev. 2008 Oct;66(10):549-57.
Iwamoto J, Sato Y, Takeda T, Matsumoto H. High-dose vitamin K supplementation reduces fracture incidence in postmenopausal women: a review of the literature. Nutr Res. 2009 Apr;29(4):221-8.
Iwamoto J, Matsumoto H, Takeda T. Efficacy of menatetrenone (vitamin K2) against non-vertebral and hip fractures in patients with neurological diseases: meta-analysis of three randomized, controlled trials. Clin Drug Investig. 2009;29(7):471-9.
Iwamoto J, Sato Y. Menatetrenone for the treatment of osteoporosis. Expert Opin Pharmacother. 2013 Mar;14(4):449-58.
Cranenburg EC, Schurgers LJ, Vermeer C. Vitamin K: the coagulation vitamin that became omnipotent. Thromb Haemost. 2007 Jul;98(1):120-5.
Guralp O, Erel CT. Effects of vitamin K in postmenopausal women: mini review. Maturitas. 2014 Mar;77(3):294-9.
What's the best quantity/form to supplement it in? (In your opinion.) Some guy on Amazon compared a bunch of K2 supplements and recommended this one, but it has worrisome negative reviews.
I've been eagerly waiting for the analysis and conclusion to your Magnesium experiment #2 When will that be out?
"When I was one-and-twenty / I heard a wise man say, / 'Give crowns and pounds and guineas / But not your heart away; / Give pearls away and rubies / But keep your fancy free.' / But I was one-and-twenty, / No use to talk to me."
My past year of completed writings, sorted by topic:
Genetics:
AI:
Reinforce.js
demoBiology:
Statistics:
Cryptography:
Misc:
gwern.net
itself has remained largely stable (some CSS fixes and image size changes); I continue to use Patreon and send out my newsletters.