Consuming up to 10 prunes a day resulted in little improvement in bone health over a year in older men susceptible to, or with, osteopenia, according to a recent study.
The finding is from a trial involving 59 older men who underwent dual-energy x-ray absorptiometry (DEXA) scans before and after prune supplementation, with the results contrary to similar studies in women, noted lead author Lauren Ormsbee, of Florida State University in Tallahassee, and colleagues.
“Our current laboratory has produced positive findings for prune supplementation, including improved bone density in post-menopausal women,” the group wrote. “However, these same therapy interventions, particularly functional food supplementation with prunes, have not been fully assessed in a male population.” The study was published June 9 in Nutrients.
Men lose roughly 0.5% to 1% of bone per year beginning around 60 years old, and one in eight men over 50 will sustain an osteoporotic fracture, the researchers noted. While prior work has shown that 100 grams of daily prune supplementation improved bone mineral density (BMD) of the ulna and spine in postmenopausal women over one year, comparable trials in men remain scarce, they noted.
To bridge the gap, the group recruited 59 men (aged 55 to 80 years old) with DEXA lumbar spine BMD T-scores between −0.1 and −2.5, a range spanning early bone loss through clinical osteopenia. Participants were randomized to 100 grams of prunes daily, 50 grams of prunes daily, or no prunes. All three groups also received 450 mg of elemental calcium and 800 IU of vitamin D3 via multivitamin throughout the trial. DEXA scans (Lunar iDXA, GE HealthCare) and blood samples were acquired at baseline, three months, six months, and 12 months.
According to the results, neither total BMD nor lumbar spine BMD changed significantly in any group over the study period, and the differences between groups were negligible. Among secondary biomarkers, osteoprotegerin, a marker of bone formation, declined in all three groups, but declined significantly more in the control group than in either prune group. In addition, tartrate-resistant acid phosphatase-5b, a marker of bone resorption, increased in all groups, though the increase was significantly greater in the control group than in the 100-gram group, the researchers reported.
“Overall, prune supplementation, regardless of dosing, did not increase total or lumbar BMD or aid in maintaining bone density beyond the levels achieved by Ca++ and vitamin D3 supplementation in older men susceptible to, or with, osteopenia,” the group wrote.
The authors noted that sclerostin, a protein that inhibits bone-forming cells, increases significantly more in men with age than in women, with one study finding that lifespan sclerostin values increase 2.4-fold in women but 4.6-fold in men. That difference may counteract any benefits of prune supplementation for men and warrants further investigation, they suggested.
"Further larger-scale and longer-duration studies in this population are needed to fully assess the effect of prune supplementation on bone density and the biomarkers of inflammation and bone metabolism," the group concluded.
The full study is available here.
