Reference
Hooshmand S, Chai SC, Saadat RL, Payton ME, Brummel-Smith K, Arjmandi BH. Comparative effects of dried plum and dried apple on bone in postmenopausal women. Br J Nutr. 2011 Sep;106(6):923-930.
Design
Randomized non-blinded comparative study
Participants
All 160 participants in this study were women, 1–10 years postmenopausal, not on hormone replacement therapy or any other prescribed medication known to influence bone metabolism. The participants were randomly assigned to 1 of 2 treatment groups.
Study Medication and Dosage
One group consumed dried plums (100 gram/day). The second group acted as a comparative control and ate dried apples instead of dried plums (100 gm/day). Participants in both groups took calcium (500 mg/day) and vitamin D daily (400 IU/day).
Outcome Measures
Bone mineral density (BMD) of lumbar spine, forearm, hip, and whole body was assessed at baseline and at the end of the study using dual-energy X-ray absorptiometry. Blood samples were collected at baseline and 3, 6, and 12 months to assess bone biomarkers. Physical activity recall and 1-week food frequency questionnaire were obtained at baseline and 3, 6, and 12 months to examine physical activity and dietary confounders as potential covariates.
Key Findings
Consumption of dried plums significantly increased the bone mineral density of ulna and spine in comparison with dried apple. Only the dried plum significantly decreased serum levels of bone turnover markers, including bone-specific alkaline phosphatase and tartrate-resistant acid phosphatase-5b.
Practice Implications
These finding confirm the results of a series of earlier studies that suggested consumption of dried plums improved bone mineral density (BMD) by suppressing rate of bone turnover.1 Daily consumption of prunes should now be considered a valid strategy for prevention and treatment of osteoporosis.
Many women are hesitant to utilize the current drug treatments prescribed for osteoporosis. This research confirms the benefit of the "prune diet" treatment for osteoporosis and provides an alternative treatment option.
[NOTE: Prunes underwent an official name change in 2000 and are now, under Food and Drug Administration (FDA) rules called dried plums.]
Bahram Arjmandi, who is listed as a coauthor of the current paper, has been investigating dried plums for more than a decade; his first paper was published in 2001.2
The current report is very similar to a pilot study Arjmandi published in 2002. He had previously shown that dried plums were “highly effective in modulating bone mass in an ovarian hormone-deficient rat model of osteoporosis.” So Arjmandi conducted a study “to examine whether the addition of dried plums to the diets of postmenopausal women positively influences markers of bone turnover.” In that study, 58 post-menopausal women were randomly assigned to eat either 100 grams of dried plums or 75 grams of dried apples every day. The prunes but not the apples “significantly increased serum levels of insulin-like growth factor-I (IGF-I) and bone-specific alkaline phosphatase (BSAP) activity.”
High levels of both of these chemicals are associated with faster bone formation. Serum and urinary markers of bone resorption, however, were not affected. The drugs typically used to treat osteoporosis focus on the other side of the equation; they slow bone resorption.
Since then Arjmandi has written a string of papers using animal models of osteoporosis in order to better understand the action dried plums have on bone. In a 2005 paper using ovariectomized rats, he reported that dried plum restored femoral and tibial bone density, increased lumbar bone density, and improved bone quality and trabecular microarchitectural properties.
Arjmandi pointed out the unique action dried plums had on bone: “Loss of bone volume accompanied by loss of trabecular connectivity is generally believed to be an irreversible process, but our observations suggest that dried plum improves trabecular microstructure of tibia after losses have already occurred.”3
Similar benefits were obtained using castrated male rats and reported in 2006, with dried plum completely preventing the castration-induced decrease in whole body, femur, and lumbar vertebra bone mineral density. The bone resorption biomarker deoxypyridinoline (DPD) rose by 36% in the castrated rats but dropped 57% in those rats consuming dried plums.4
In 2007, another rat study found that while dried plums were effective, parathyroid hormone was even more effective at restoring bone mass.5
In 2007, another rat study found that while dried plums were effective, parathyroid hormone was even more effective at restoring bone mass.
Several additional papers of interest have been published while this trial was underway. A 2008 paper explained, “Dried plum polyphenols inhibit osteoclastogenesis by downregulating NFATc1 and inflammatory mediators.”6 A 2009 publication tells us that the polyphenols in dried plums "attenuate the detrimental effects of TNF-alpha on osteoblast function.”7
Of particular interest is a 2010 paper reporting that combining dried plum and fructo-oligo-saccharide (FOS) supplements increased both of their bone-restoring effects. In fact this combination had a greater effect at increasing bone density than any other functional foods yet tested.8 Also of note, an additional mouse study published in 2010 showed that dried plum supplements could restore lost bone mass in aged mice.9
This current study leaves little doubt that consuming dried plums can preserve bone. The pertinent question then is what percentage of patients can actually be compliant with this treatment? The daily dose of dried plums, 100 grams, is equivalent to about a dozen prunes. Although the mechanism has yet to be delineated, the fact is well accepted that prunes have a laxative effect. Some patients may find it difficult to comfortably consume a therapeutic dose. One option is to simply prescribe dried plums “to bowel tolerance” and to then increase the dose as tolerance improves over time.
Another option would be to combine the prunes with other agents or foods that have the opposite effect on bowel transit times (BTT). Calcium has long been associated with slowing BTT. Poppy seeds also have a pronounced slowing effect on BBT. It is perhaps noteworthy that both ground poppy seed pastes and prune pastes have been traditionally consumed in close proximity in certain cultures. It also may be possible at some future point to isolate either the active factors that impact bone density and concentrate them or identify which elements create the laxative effect and remove them.
Fortuitously, a fair percentage of patients who may benefit from “prune therapy” have relatively slow BTT, and this prescription for osteoporosis may relieve their constipation.
