Introduction: Inflammation has been shown to play a role in a variety of disease states including osteoporosis and cardiovascular disease. The purpose of this study was to determine the effects of daily prune consumption on inflammatory markers, bone biomarkers, cardiovascular health, and the gut microbiome in an osteopenic male population. Methods: Forty healthy men between the ages of 55 and 80, whose lumbar spine bone mineral density (BMD) t-score was between -1.0 and -2.5 were randomized to 0, 50, or 100g of prunes and 450 mg calcium and 800 IU vitamin D daily for three months. Changes in fecal microbiome were assessed at baseline, one, and three months (uBiome Explorer). Additionally, measurements of body composition (via anthropometrics), lower limb (calf) blood flow (via strain-gauge plethysmography), as well as blood pressure (BP), heart rate (HR) mean arterial pressure (MAP), and resting blood flow (BF), were collected at each time point. Serum and plasma samples were subjected to ELISA for the assessment of inflammatory markers including C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), interluekin-6 (IL-6) and lipopolysaccharide binding protein (LBP). Changes in bone turnover were estimated by serum osteoprotegerin levels (OPG). Fecal microbiome was analyzed via 16S rRNA sequencing (uBiome Explorer). Results: All participants were compliant with the daily supplements. Three-month measures of CRP, TNF-α, OPG, and IL-6 were not different from baseline (p>0.05). Two-way ANOVA analysis of LBP revealed a significant effect of prune consumption (p=0.045). LBP was significantly increased in the 50g group compared to both baseline (p=0.010) and to the 0g control at 3-months (p=0.014). Prune consumption produced no significant changes in BF, MAP, HR, or BP. Measures of alpha diversity at baseline and 3-months revealed that prune consumption significantly decreased diversity as measured by Chao1 (p=0.02), Shannon Diversity (p=0.008), and the number of observed operational taxonomic units (OTU) (p=0.03). There was no significant change in Pielou’s evenness (p= 0.08). Beta diversity measures revealed a significant difference between 50g and 100g groups as measured by Bray-Curtis (p=0.001), Weighted UniFrac (p=0.02), and Unweighted UniFrac (p=0.01). Conclusions: Although most measures of cardiovascular and bone health in osteopenic males were not altered by a three-month treatment with prune, there were changes in gut microbiome diversity. These findings suggest that prune consumption does shape the colonization of the gut microbiome in osteopenic men. More research must be done to determine longer term impact of these microbial changes on gut, cardiovascular, and bone health.
