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Oral dosing of vitamins K1 and K2 in ovariectomized rats: Effects on bone loss and serum/bone levels
Author(s) -
Moreines Judith,
Fu Xueyan,
Booth Sarah
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.537.3
Subject(s) - ovariectomized rat , medicine , endocrinology , osteocalcin , bone mineral , chemistry , bone density , osteopenia , vitamin , vitamin k2 , osteoporosis , estrogen , alkaline phosphatase , biochemistry , enzyme
Vitamin K (VK) exists in multiple forms that share common biochemical structures to support VK‐dependent protein carboxylation. Vitamin K may benefit bone by carboxylating the bone protein, osteocalcin. The unique side chains of the menaquinones (MKn) may further enhance K bone benefits. Despite plausible biological mechanisms, a causal role of vitamin K in bone and differential abilities of MKn and VK1 to benefit bone remains unclear. To assess this, ovariectomized (OVX) rats were randomized to 6 dosing groups of 16/group [Sham OVX (SOVX); OVX; OVX + Bisphosphonate (BP) (100ìg/kg/100 ìg/mL saline sc); OVX + VK1; OVX + MK4; and OVX + MK7] for 12 weeks. Equimolar doses of 107 mg K1/kg, 147 mg MK4/kg, and 201 mg/Kg MK7 were added to vitamin K deficient diets daily. As expected, OVX significantly increased weight and decreased bone strength vs. SOVX (p<0.05). OVX failed to significantly alter serum or bone vitamin K concentrations vs. SOVX. BP significantly increased bone strength and bone mineral density (BMD) vs. OVX (p<0.05). However, VK failed to prevent bone loss. VK1 supplementation significantly increased serum/bone concentrations of VK 1 vs. the concentrations of MK 4 or MK 7 following their supplementation (p<0.05). Unexpectedly, an MK7 epoxide was found in serum, not bone. Further studies evaluating the safety of MK 7 and potential efficacy of other doses of K vitamers are warranted. (Funding: Wyeth)