Canola oil (Can) and hydrogenated
soybean oil (H2-Soy) are commonly used edible
oils. However, in contrast to
soybean oil (Soy), they shorten the survival of
stroke-prone spontaneously hypertensive (SHRSP) rats. It has been proposed that the adverse effects of these
oils on the kidney and testis are caused at least in part by dihydro-
vitamin K (VK) 1 in H2-Soy and unidentified component(s) in Can. Increased intake of dihydro-VK1 is associated with decreased tissue VK2 levels and bone mineral density in rats and humans, respectively. The aim of the present study was to determine the effects of these
oils on
bone morphogenetic protein (BMP)-induced ectopic bone formation, which is promoted by VK2 deficiency, in relation to the role of VK in the γ-carboxylation of
osteocalcin and
matrix Gla protein. A
crude extract of BMPs was implanted into a gap in the fascia of the femoral muscle in 5-week-old mice maintained on a Soy, Can, or H2-Soy diet. Newly formed bone volume, assessed by three-dimensional X-ray micro-computed tomography and three-dimensional reconstruction imaging for bone, was 4-fold greater in the Can and H2-Soy groups than in the Soy group. The plasma carboxylated
osteocalcin (Gla-OC) and total OC (Gla-OC plus undercarboxylated
osteocalcin [Glu-OC]) levels were significantly lower in the Can group than in the Soy group (p < 0.05). However, these levels did not significantly differ between the H2-Soy and Soy groups. The plasma Gla-OC/Glu-OC ratio in the Can and H2-Soy groups was significantly lower (in Can; p = 0.044) or was almost significantly lower (in H2-Soy; p = 0.053) than that in the Soy group. In conclusion, Can and H2-Soy accelerated BMP-induced bone formation in mice to a greater extent than Soy. Further research is required to evaluate whether the difference in accelerated ectopic bone formation is associated with altered levels of VK2 and VK-dependent
protein(s) among the three dietary groups.