A Randomized Controlled Trial of Dietary Supplementation with Prunes (Dried Plums) on Inflammatory Markers in Postmenopausal Women

Abstract

The prevalence of osteoporosis among women aged 50 years and older is expected to reach 13.6 million by 2030. Osteoporosis is characterized by compromised bone strength due to reduced bone mineral density (BMD) and bone quality, representing a major public health issue that necessitates effective treatment regimens that are safe, cost‐effective, and associated with fewer adverse effects than pharmaceutical agents. Alternative dietary interventions such as prunes (dried plum) have been extensively studied to mitigate bone loss in preclinical models of osteoporosis. In postmenopausal women, estrogen deficiency triggers an upregulation of inflammatory pathways, which promotes bone loss, thus increasing risk of fractures. Our understanding of the effect of prune consumption on inflammatory markers in humans is limited, warranting further investigation. This study aimed to evaluate the effects of 12 months of prune consumption (two doses) on inflammatory mediators. Postmenopausal women (n=106, 55‐75 years old) with low BMD were randomized to consume 0g prunes/day (control), 50g prunes/day, or 100g prunes/day for 12 months. All participants received 1200mg calcium and 800 IU vitamin D3 as standard of care. We hypothesized that prune consumption at 50g/day and 100g/day will reduce inflammatory markers in postmenopausal women with low BMD compared to control group (0g/day). At baseline and after 12 months of prune consumption, serum and peripheral blood mononuclear cells (PBMCs) were isolated to quantify C‐reactive protein (CRP) using a high‐sensitivity CRP immunoassay, the number of circulating monocytes using flow cytometry, and pro‐inflammatory cytokines [interleukin (IL)‐1β, IL‐6, IL‐8, monocyte chemoattractant protein (MCP)‐1, and tumor necrosis factor (TNF)‐α] from lipopolysaccharide (LPS)‐stimulated PBMCs using a multiplex enzyme‐linked immunosorbent assay. Differences among groups were assessed using one‐way ANOVA or Kruskal‐Wallis test. No significant differences in baseline characteristics were found among the three treatment groups. Prune consumption did not alter serum CRP or the number of monocytes. However, consumption of 100g prunes/day resulted in a significant reduction from baseline in IL‐1β (p=0.013), IL‐6 (p=0.007), and IL‐8 (p=0.049) secretion and consumption of 50g prunes/day resulted in a significant reduction from baseline in TNF‐α (p<0.001) secretion from LPS‐stimulated PBMCs compared to the control group. Our findings demonstrate that 12 months of prune consumption suppresses inflammatory cytokines from LPS‐stimulated PBMCs. Thus, daily consumption of 50g‐100g of prunes may reduce inflammatory mediators that can contribute to bone loss in postmenopausal women.