Dried plum's unique capacity to reverse bone loss and alter bone metabolism in postmenopausal osteoporosis model

Effects of dried plum supplementation on bone metabolism in adult C57BL/6 male mice

Dietary supplementation of dried plum (DP) prevents bone loss and restores bone mass in osteopenic animal models. This study was designed to determine the effects of DP supplementation on bone metabolic activity over time using adult (6-month-old) male C57BL/6 mice (n = 40) receiving control (CON = AIN93 M) or CON+DP 25 % (w/w) diets for 4 or 12 weeks. After 4 weeks of treatment, animals consuming the DP diet had a higher whole-body bone mineral density, vertebral trabecular bone volume (BV/TV), and femoral cortical thickness compared to the CON animals. In the distal metaphysis of the femur, BV/TV was increased in the DP-treated animals, but only after 12 weeks. Bone histomorphometric analyses revealed that DP decreased osteoblast surface (67 %) and osteoclast surface (62 %) at 4 weeks, but these surfaces normalized to the CON animals by 12 weeks. Coincident with these changes, the mineralizing surface (MS/BS) and cancellous bone formation rate (BFR/BS) were reduced at 4 weeks in the DP group compared to the CON, but by 12 weeks of DP supplementation, BFR/BS (~twofold) and MS/BS (~1.7-fold) tended to be increased (p < 0.10). The relative abundance of RNA for key regulators of osteoblast and osteoclast differentiation and indicators of osteoblast activity were reduced in the DP group at 4 weeks with no difference between groups at 12 weeks. These results indicate that supplementing the diet with DP initially suppressed cancellous bone turnover, but a biphasic response occurs over time, resulting in a positive effect on bone mass and structure.

A comparative study of the bone metabolic response to dried plum supplementation and PTH treatment in adult, osteopenic ovariectomized rat

Dried plum has been reported to have potent effects on bone in osteopenic animal models, but the mechanisms through which bone metabolism is altered in vivo remain unclear. To address this issue, a study comparing the metabolic response of dried plum to the anabolic agent, parathyroid hormone (PTH), was undertaken. Six month-old female Sprague Dawley rats (n=84) were sham-operated (SHAM) or ovariectomized (OVX) and maintained on a control diet for 6wks until osteopenia was confirmed. Treatments were initiated consisting of a control diet (AIN-93M) supplemented with dried plum (0, 5, 15 or 25%; w/w) or a positive control group receiving PTH. At the end of 6wks of treatment, whole body and femoral bone mineral density (BMD) were restored by the two higher doses of dried plum to the level of the SHAM group. Trabecular bone volume and cortical thickness were also improved with these two doses of dried plum. Dried plum suppressed the OVX-induced increase in bone turnover as indicated by systemic biomarkers of bone metabolism, N-terminal procollagen type 1 (P1NP) and deoxypyridinoline (DPD). Dynamic bone histomorphometric analysis of the tibial metaphysis revealed that dried plum restored the OVX-induced increase in cancellous bone formation rate (BFR) and mineralizing surface (MS/BS) to the SHAM group, but some doses of dried plum increased endocortical mineral apposition rate (MAR). As expected, PTH significantly increased endocortical MAR and BFR, periosteal BFR, and trabecular MAR and BFR beyond that of the OVX and maintained the accelerated rate of bone resorption associated with OVX. Dried plum up-regulated bone morphogenetic protein 4 (Bmp4) and insulin-like growth factor 1 (Igf1) while down-regulating nuclear factor T cell activator 1 (Nfatc1). These findings demonstrate that in the adult osteopenic OVX animal, the effects of dried plum differ from that of PTH in that dried plum primarily suppressed bone turnover with the exception of the indices of bone formation at the endocortical surface.

Analyses of mineral specific surface area and hydroxyl substitution for intact bone

Bone minerals possess two primary hydrogen sources: hydroxide ions in the nanocrystalline core and structural water in the amorphous surface layer. In order to accurately measure their concentrations using hydrogen to phosphorus cross polarization NMR spectroscopy, it is necessary to analyze the dependence of signal intensities on serial contact times, namely, cross polarization kinetics. A reliable protocol is developed to iteratively decompose the severely overlapped spectra and to analyze the cross-polarization kinetics, leading to measurement of hydroxyl and structural water concentrations. Structural water concentration is used to estimate mineral specific surface area and nanocrystal thickness for intact bone.