A randomized clinical trial conducted at San Diego State University investigated the potential of prunes to mitigate bone loss in young adult women using oral contraceptives. The study was motivated by concerns that oral contraceptives may promote bone loss, potentially leading to suboptimal bone health later in life.
The 12-month parallel-arm randomized controlled trial, published in Current Developments in Nutrition, involved 90 women aged 18 to 25 years divided into three groups: a control group not using oral contraceptives (OCs; n=30), an OC group not consuming prunes (n=28), and an OC group consuming 50 g of prunes daily (n=28).
Key Findings
Trabecular density of the distal tibia decreased significantly (by 2.45%) over 12 months in the OC group not consuming prunes (P = 0.016; effect size: 0.508; 95% confidence interval [CI] = 0.094–0.912).
Bone mineral density (BMD) at the ultradistal radius increased significantly in the non-OC group (3.44%, P = 0.003; effect size: 0.595; 95% CI = 0.202, 0.979) and the OC group consuming prunes (2.4%, P = 0.020; effect size: 0.468; 95% CI = 0.074–0.855), but not in the OC-only group.
C-reactive protein (CRP) levels were significantly higher in both OC groups compared to the non-OC group (P < 0.001). Vitamin D concentrations were significantly higher at baseline in both OC groups compared to the non-OC group (P < 0.001).
The study found no significant changes in BMD at other sites such as the lumbar spine or femur across the groups. Additionally, biomarkers such as bone alkaline phosphatase (BAP) and tartrate-resistant acid phosphatase-5b (TRAP-5b) did not show significant changes between or within groups.
Methods
Bone density and geometry were assessed using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Blood samples were collected at baseline, 6 months, and 12 months to analyze bone biomarkers, including BAP, TRAP-5b, CRP, vitamin D, and parathyroid hormone.
Limitations of the study included variations in OC formulations among participants, differences in age at menarche between groups, and lower compliance rates for prune consumption. The authors also noted that age at menarche and OC formulations might have influenced bone health outcomes. They recommended that future research focus on evaluating bone health in users of OCs with early-life initiation of the agents and the potential for prune consumption to offset any longer-term adverse events among this population.
The authors reported no conflict of interest.