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| Date: 03-31-2017 | HC# 091637-565 |
Hooshmand S, Kern M, Metti D, et al. The effect of two doses of dried plum on bone density and bone biomarkers in osteopenic postmenopausal women: a randomized, controlled trial. Osteoporos Int. 2016;27(7):2271-2279.
It is estimated that nearly half of all American women older than 50 years will suffer a fracture because of osteoporosis. A number of drug therapies are used to either reduce bone loss or increase bone formation; however, they are associated with adverse effects, high costs, and low compliance. Dried plum (Prunus domestica, Rosaceae) fruit is a functional food that has been shown to prevent and reverse bone loss in animal models of osteoporosis. In 2 randomized controlled trials (RCTs), consumption of 100 g dried plum daily improved biomarkers of bone formation and prevented the loss of bone mineral density (BMD) in postmenopausal women. Due to the purported laxative effects of dried plums (prunes), these authors conducted an RCT to determine the extent to which the consumption of a lower dose (50 g/day) of dried plum prevents the loss of BMD and improves bone biomarkers in older, postmenopausal women with osteopenia.
Between August 2012 and September 2013, postmenopausal women aged 65 to 79 years who were not on hormone replacement therapy for at least 3 months before the study were recruited from the San Diego, California, area. Recruitment occurred through flyers at local gyms, senior centers, and markets, and by word of mouth. Women with osteoporosis, women treated with any prescription medications known to alter bone and calcium metabolism within the previous 3 months, women with systemic or chronic disease, women who regularly consumed dried plum or prune juice, and women who were heavy smokers were excluded.
Of the 84 women screened, 48 postmenopausal women with osteopenia (BMD T-score between −1 and −2.5) were eligible for inclusion and were randomly assigned to 1 of the following dietary treatment groups for 6 months:
- Group A―50 g daily of dried plum (n=16)
- Group B―100 g daily of dried plum (n=16)
- Control group―No dried plum (n=16)
All subjects also consumed 500 mg of calcium carbonate plus 400 IU of vitamin D3 daily (both supplied by Nutrisystem, Inc.; Fort Washington, Pennsylvania). The dried plum fruit was provided by the California Dried Plum Board (Sacramento, California). The composition of the dried plum per 100 g was 239 kcal energy, 26.1 g protein, 0.52 g fat, 7.10 g total fiber, 51 mg calcium, 79 mg phosphorus, and 62.7 g total carbohydrates.
The subjects were asked to gradually incorporate dried plum into their diets, to monitor their compliance on a calendar, and to return any unused portion of the treatment. A baseline medical history was obtained from each subject. The subjects completed a 3-day food record at baseline, 3 months, and 6 months. Fasting blood samples were obtained at baseline, 3 months, and 6 months to measure serum concentrations of the following biomarkers: bone-specific alkaline phosphatase (BAP), insulin-like growth factor-1 (IGF-1), sclerostin, serum tartrate-resistant acid phosphatase-5b (TRAP-5b), and high-sensitivity C-reactive protein (hs-CRP). Hip, spine, and ulna BMD was assessed at baseline and at 6 months.
Baseline characteristics among the 3 groups were similar. Of the 48 subjects randomly assigned to a treatment group, 42 (16 in Group A, 13 in Group B, and 13 in the control group) completed the study. Three subjects in the control group discontinued the study due to noncompliance or personal reasons, and 3 subjects in Group B discontinued the study for noncompliance or health reasons. The subjects in the dried plum groups considered the fruit to be palatable at both doses. Compliance rates in Groups A and B were 95% and 97%, respectively. Throughout the study, no significant changes were seen in food intake, physical activity level, calcium and vitamin D intake, or kidney function in any of the groups.
Compared with the subjects in the control group, who continued to lose bone as determined by BMD values, both Groups A and B had no net changes in total body BMD. A positive trend for increased spine BMD (P=0.08) was seen in Groups A and B, but no changes in total hip and ulna BMD were seen among the 3 groups.
Significantly reduced levels of TRAP-5b, an enzyme involved in bone resorption, were seen with consumption of 50 g (P=0.01) and 100 g (P=0.04) of dried plum at 3 months and at 6 months; no changes were seen in the control group. Mean level of the growth hormone IGF-1 decreased significantly in the control group (P=0.02) but did not change in Group A or B. Conversely, BAP/TRAP-5b ratio did not change significantly in the control group but did increase at 6 months in Group A (P=0.02) and Group B (P=0.01). Mean levels of BAP, sclerostin, and hs-CRP did not significantly change in any group.
The authors conclude, "These results confirm the ability of dried plum to prevent the loss of total body BMD in older osteopenic postmenopausal women and suggest that a lower dose of dried plum (i.e., 50 g) may be as effective as 100 g of dried plum in preventing bone loss … ." Acknowledged limitations of this study are the 6-month duration, which "is not an ideal length of time to see intervention-induced effects on bone density … .," and the inclusion of only older, postmenopausal women with osteopenia, which limits extrapolation to other populations.
This study was supported by grants from the San Diego State University Research Foundation and California Dried Plum Board.
―Shari Henson