Moderate consumption of freeze-dried blueberry powder increased net bone calcium retention compared with no treatment in healthy postmenopausal women: a randomized crossover trial
Joanna K. Hodges, María Maiz, Sisi Cao, Pamela J. Lachcik, Munro Peacock, George P. McCabe, Linda D McCabe, Dennis P. Cladis, George S. Jackson, Mário G. Ferruzzi, Mary Ann Lila, Regan L Bailey, Berdine R. Martin, Connie M. Weaver
Abstract
Preclinical studies suggest that blueberry consumption is associated with improved bone health. We conducted a blueberry dose-response study in ovariectomized (OVX)-rats that informed a study in postmenopausal women using urinary appearance of calcium tracers from prelabeled bone to reflect changes in bone balance. We hypothesized that blueberry consumption would reduce bone loss in a dose-dependent manner compared with no treatment. OVX-rats were fed four doses of blueberry powder (2.5, 5, 10, and 15%) in randomized order to determine bone 45Ca retention. Fourteen healthy, non-osteoporotic women at least 4 years past menopause were dosed with 50 nCi of 41Ca, a long-lived radioisotope, equilibrated for 5-mo to allow 41Ca deposition in bone (NCT02630797). Following a 6-wk baseline, participants were assigned to a random sequence of three 6-wk interventions, a low (17.5 g/d), medium (35 g/d), or high (70 g/d) dose of freeze-dried blueberry powder equivalent to 0.75, 1.5, or 3 cups of fresh blueberries incorporated into food and beverage products. Urinary 41Ca:Ca ratio was measured by accelerator mass spectrometry. Serum bone resorption biomarkers and urinary polyphenols were measured at the end of each control and intervention period. Data were analyzed using a linear mixed model and repeated measures ANOVA In both OVX-rats and postmenopausal women, blueberry interventions benefitted net bone calcium balance at lower, but not at higher doses. In women, net bone calcium retention increased by 6% with the low (95% CI: 2.50, 8.60; p < 0.01) and 4% with the medium (95% CI: 0.96, 7.90; p < 0.05) dose compared with no treatment. Urinary excretion of hippuric acid increased dose-dependently with blueberry consumption. No significant relationships were found between bone resorption biomarkers, 25-hydroxyvitamin D, and interventions. Moderate consumption (<1 cup/day) of blueberries may be an effective strategy to attenuate bone loss in healthy postmenopausal women. NCT02630797