(P31-33-26) Acute Prune Intervention Increases Calcium Absorption and Femur Calcium Uptake in Adult Female Rats With Estrogen Deficiency

Objectives: Previous studies demonstrate beneficial effects of dietary prunes on improving overall bone health in humans and animal models, but mechanisms remain unclear. This is the first study to investigate the effect of prune intervention on calcium uptake from diet. We evaluated the effects of increased prune content (0%, 5%, 15%, 25%) in a purified rodent diet on calcium-utilization efficiency in ovariectomized (OVX) rats.

Methods: Forty-three OXV Sprague-Daley rats, 12 weeks old, were assigned to a control (no prune, n=13), and 5% (n=10), 15% (n=10), 25% (n=10) prune powder (w/w) diet. Calcium metabolic balance was assessed over 4 days. Oral and i.v. administered stable and radioactive Ca isotopes were used to assess calcium absorption efficiency in femur.

Results: Total food intake decreased by 27% in the 25% prune group compared with control (p < 0.001). Despite a significantly lower food intake, prune intervention had a positive trend towards increased total calcium absorption (average control: 41.7 mg/day and average 25% prune: 74.6 mg/day; p=0.063) and increased calcium retention (average control 37.7 mg/day, and average 25% prune: 70.4 mg/day; p=0.06). Fecal calcium excretion significantly decreased in a dose-response manner with increased dietary prune (average control: 77.8 mg/day, and average 25% prune: 22.05 mg/day; p=0.0002). Direct quantification of Ca isotope tracers in femur demonstrated a significant dose-response increase with increased prune content in the diet (p = < 0.0001), with averaged Ca isotope uptake 25% for control, and 32%, 40% and 50% for 5%, 15%, and 25% prune diet respectively.

Conclusions: Acute prune dietary intervention significantly increased calcium absorption and femoral calcium uptake in a dose-dependent manner. These results support the benefits of prune to the bone.

Funding Sources: California Prune Board funded and provided prune powder used in this study.