Minimal effect of lifetime low phylloquinone intake on bone status in aged rats

Abstract

The specific action of vitamin K in bone, whether in the form of phylloquinone (K1) or menaquinone‐4, remains elusive. While there has been reports pointing to beneficial effects of VK in bone health, others have not confirmed such contribution. Furthermore, most research has focussed on the higher ranges of intakes, the potentially detrimental effect of low VK intakes having been neglected. To gain insight on this issue, we conducted a study in which bone status was investigated in 22‐month female SD rats which had been fed diets containing either very low (VL: 80; n=10), low (L: 500; n=8) or moderately high (H: 2000; n=15) levels of K1 (μg/Kg diet) since weaning. A fourth group (n=9) were fed the VL diet until the age of 14 months and the H diet until sacrifice (VL‐H). Measurements, included: area, weight, bone mineral content (BMC), and density (BMD) of whole body, tibiae and femurs; anthropometrics, BMC, BMD and biomechanical testing (Young's modulus, yield and maximum load) of excised femurs. Total body area (p=0.034) and weight (p=0.05) were higher in the VL‐H than in the L group. With respect to bone status, only the BMC of the tibiae were affected by diet, values being higher in the VL‐H than in the VL group (0.374 vs 0.329 mg; p=0.004). All other bone composition or biomechanical measures were unaffected by diet. In this model of normal aging, lifetime low K1 intake had minimal impact on bone status in old age. Supported by CIHR.