Bone Response to Dietary Co-Enrichment with Powdered Whole Grape and Probiotics

Nutrition is a primary modifiable determinant of chronic noncommunicable disease, including osteoporosis. An etiology of osteoporosis is the stimulation of bone-resorbing osteoclasts by reactive oxygen species (ROS). Dietary polyphenols and probiotics demonstrate protective effects on bone that are associated with reduced ROS formation and suppressed osteoclast activity. This study tested the effect of dietary enrichment with powdered whole grape and probiotics (composed of equal parts Bifidobacterium bifidum, B. breve, Lactobacillus casei, L. plantarum, and L. bulgaricus) on bone microarchitecture in a mouse model of age-related osteoporosis. Groups (n = 7 each) of 10-month-old male mice were fed one of six diets for 6 months: 10% grape powder with sugar corrected to 20%; 20% grape powder; 1% probiotic with sugar corrected to 20%; 10% grape powder + 1% probiotic with sugar corrected to 20%; 20% grape powder + 1% probiotic; 20% sugar control. Femur, tibia and 4th lumbar vertebrae from 10-month-old mice served as comparator baseline samples. Bone microarchitecture was measured by micro-computed tomography and compared across diet groups using analysis of variance. Aging exerted a significant effect on tibia metaphysis trabecular bone, with baseline 10-month-old mice having significantly higher bone volume/total volume (BV/TV) and trabecular number measurements and lower trabecular spacing measurements than all 16-month-old groups (p < 0.001). Neither grape nor probiotic enrichment significantly improved bone microarchitecture during aging compared to control diet. The combination of 20% grape + 1% probiotic exerted detrimental effects on tibia metaphysis BV/TV compared to 10% grape + 1% probiotic, and trabecular number and trabecular spacing compared to 10% grape + 1% probiotic, 1% probiotic and control groups (p < 0.05). Femur metaphysis trabecular bone displayed less pronounced aging effects than tibia bone, but also showed detrimental effects of the 20% grape + 1% probiotic vs. most other diets for BV/TV, trabecular number, trabecular spacing and trabecular pattern factor (p < 0.05). Tibia and femur diaphysis cortical bone (cortical wall thickness and medullary area) displayed neither aging nor diet effects (p > 0.05). Vertebrae bone showed age-related deterioration in trabecular thickness and trabecular spacing and a trend toward preservation of trabecular thickness by grape and/or probiotic enrichment (p < 0.05). These findings demonstrate no benefit to bone of combined compared to independent supplementation with probiotics or whole grape powder and even suggest an interference of co-ingestion.