Well, this isn't the first time this has been suggested in rats and/or cell lines; but probably the most discussed as it was what subsequently fueled a patent on taking in Vitamin K2 (MK-4 +/- MK-7) to increase testosterone and while there MAY be merit to suggested claims; understand that it always hasn't been "clear."
Still, this probably more closer approximates the story with Vitamin D3...in suggested areas of deficiency; correction of the deficiency could potentially prove beneficial. Keep in mind that, fat-soluble vitamins are not without fault and should not simply be taken blindly BUT the problem is all we can do sometimes is extrapolate from data we have (unfortunately moreso from osteoporosis data versus speckled studies on testosterone) rather than have direct evidence of the fact.
In the articles reviewed, however, there was no evidence of toxicity associated with the intake of phytonadione or menaquinone even at a daily dose of the latter of 45 mg (some unexplained skin lesions BUT few and far between). Adequate intake of phylloquinone for the carboxylation of blood coagulation factors was recently set at 90 µg per day for adult women and 120 µg daily for adult men, based on median dietary intake data from the Third National Health and Nutrition Examination Survey. In the treatment of osteoporosis, Schurgers and Vermeer suggested a µg phytonadione dosage of 1000 daily. Braam et al. used the same daily dose to inhibit the loss of carotid artery elasticity. However, several trials of osteoporotic, postmenopausal women have used menaquinone dosages as high as 45 mg per day.
Because of the very low toxicity of phytonadione and menaquinone, a 1000-µg daily dose of each is warranted. Doses of menaquinone exceeding 1 mg are not readily available in the United States at this time, but it was being produced in 15-mg capsules by a Canadian nutraceutical company, AOR - for those familiar. I don't think the 15mg caps sat well with governing bodies however and the product was withdrawn from the market.
Still, I am uncertain you need that kind of quantity if you are interpreting the data which may also explain why the same company subsequently released a product with a much lower dose on the mcg level. As a safety net; I would probably suggest 1-5mg; but 1mg is more than sufficient to prevent deficiency and probably give you all that it's going to. If you are expecting supraphysiologic response from Vitamin K2 supplementation; I wouldn't rest my hat on that offering....but I would be inclined to say deficiency is bad.
Now I am also going to remind those that have read my stuff over the years; I didn't use to be a believer in need to supplement this one; but the cardiovascular arterial calcification; prostate pathology; and osteoporosis studies are much more persuasive and compelling a rationale to incorporate it into your supplement regimen than the testosterone data.
- Vitamin K monograph. Natural Medicines Comprehensive Database.
- Vitamin K monograph. Micromedex Healthcare Series. Englewood, CO: Micromedex Inc.
- McEvoy GK, ed. AHFS drug information. Bethesda, MD: American Society of Health-System Pharmacists; 1998.
- Schurgers LJ, Vermeer C. Differential lipoprotein transport pathways of K-vitamins in healthy subjects. Biochim Biophys Acta. 2002; 1570:27-32.
- Braam LA, Hoeks AP, Brouns F et al. Beneficial effects of vitamins D and K on the elastic properties of the vessel wall in postmenopausal women: a follow-up study. Thromb Haemost. 2004; 91:373-80.
- Iwamoto J, Takeda T, Ichimura S. Effect of combined administration of vitamin D3 and vitamin K2 on bone mineral density of the lumbar spine in postmenopausal women with osteoporosis. J Orthop Sci. 2000; 5:546-51.
- Shiraki M, Shiraki Y, Aoki C et al. Vitamin K2 (menatetrenone) effectively prevents fractures and sustains lumbar bone mineral density in osteoporosis. J Bone Miner Res. 2000; 15:515-21.
- Miki T, Nakatsuka K, Naka H et al. Vitamin K2 (menaquinone 4) reduces serum undercarboxylated osteocalcin level as early as 2 weeks in elderly women with established osteoporosis. J Bone Miner Metab. 2003; 21:161-5.
- Douglas AS, Robins SP, Hutchison JD et al. Carboxylation of osteocalcin in postmenopausal osteoporotic women following vitamin K and D supplementation. Bone. 1995; 17:15-20.
- Takahashi M, Naitou K, Ohishi T et al. Effect of vitamin K and/or D on under-carboxylated and intact osteocalcin in osteoporotic patients with vertebral or hip fractures. Clin Endocrinol. 2001; 54:219-24.