Dried plums to prevent or treat osteoporosis?
See this link for a discussion of the upcoming study in postmenopausal women to test the effect of dried plums on osteoporosis.
Background on previous studies using dried plums to treat or prevent osteoporosis. There have been three relevant studies on this topic. The first two were done on Sprague-Dawley rats who were used because they can have osteoporosis induced surgically and then have the efficacy of therapy for that osteoporosis evaluated during the relatively brief period of 90 days or so. One of these studies involved female rats ovariectomized and fed a normal diet for 40 days to create surgical osteoporosis, then to test if dried plums could TREAT osteoporosis. The second study involved male rats that were orchidectomized but never fed the normal diet (unless they were controls) to see if the dried plums could PREVENT osteoporosis. The third study was one done in postmenopausal women looking at serum indices of bone formation after feeding the women three different diets containing dried plums. These marker results could provide indirect evidence of bone formation or resorption due to a diet high in dried plums. For my review page on biochemical markers see this page.
Bone, 2006 Dec;39(6):1331-42, Dried plum prevents bone loss in a male osteoporosis model via IGF-I and the RANK pathway. Franklin, M and others, PMID: 16890505. The basic model for this study on male rats and the one that follows on female rats was the same (except where noted), so I won't discuss those details twice. The main difference between the two studies was that the ovaries (OVX) were removed in the females and the testes (ORX) in the males. There was a control that was sham-treated that was later feed a normal diet. So this animal had it's estrogen/testosterone hormone system intact and it received a normal diet. There were four surgically treated groups: 1) surgical treatment followed by normal diet (control), 2), 3) and 4) had surgical treatment followed by a diet that contained LD = 5%, MD = 15%, HD = 25% (by weight) of dried plums, respectively. There was no change in whole body, femur, and lumbar vertebral bone mineral density in the MD and HD groups. Mechanical stress tests were done and microscopic analysis of the trabecular architecture was also done. These tests showed the MD and HD diets prevented the mechanical and microscopic changes that occurred in the ORX-treated control group fed a normal diet. Evaluating the serum biochemical markers showed that insulin-like growth factor (IGF-I) was increased in the dried plum groups and there was no increase in urinary deoxypyridinoline (DPD) in the dried plum groups, totally overcoming that effect noted in the ORX-treated controls. The authors note, “We conclude that dried plum prevents osteopenia in androgen deficient male rats, and these beneficial effects may be attributed in part to a decrease in osteoclastogenesis via down-regulation of RANKL and stimulation of bone formation mediated by IGF-I.” Editor's comment: So here is a shorthand summary of what happened in each group: Sham control: Normal diet -> No change in BMD or markers of bone resorption or formation. ORX Control: Normal diet -> Severe loss of BMD indicating osteoporosis -> Mechanical and microscopic evidence of loss of strength and microarchitectural defects -> Decreased serum IGF-I and increased urinary DPD. MD and HD dried plum diets: Prevented loss of BMD, loss of bone strength and microarchitectural defects -> Increased serum IGF-I and prevented the increase of urinary DPD. For more on RANKL see this recent Update which has a link to another update with RANKL information.
Menopause. 2005 Nov-Dec;12(6):755-62. Dried plum reverses bone loss in an osteopenic rat model of osteoporosis. Deyham F and others. PMID: 16278620. In this study, as noted above, all the animals were fed a normal diet long enough to create osteoporosis before the LD, MD and HD dried plum diets were started in three of the OVX-treated groups. There was a general dose-related improvement in BMD, mechanical bone strength and microstructural improvement with each of the three dried plum diets. The urinary DPD was mildly reduced by the dried plum diet, indicating mild antiresorptive properties for that diet. Only the group that received estradiol had a significant increase in uterus weight, indicating the dried plum diet doesn't function the same as estradiol. This was also reinforced by the differing effects on serum IGF-I of estrogen and the dried plum diets. The authors comment that, “Dried plum, in addition to being a good source of several vitamins and minerals that can influence bone health, are a rich source of phenolic compounds that act as antioxidants.” These constituents of dried plums may be responsible for their positive effect on bone. This could be a combined effect of the antioxidants scavenging free radicals so as to decrease the rate of bone loss along with the phenolic compounds having a bone-forming effect. The authors hope to eventually isolate the active components of the dried plums and to determine the lowest effective dose of those along with their mechanism of action. They state, “In summary, the findings of the present study support our hypothesis that dried plum dose dependently reverses the loss of bone density and the deterioration of microarchitectural properties in an ovariectomized rat model of postmenopausal osteoporosis.”
J Womens Health Gend Based Med. 2002 Jan-Feb;11(1):61-8. Dried plums improve indices of bone formation in postmenopausal women. Arjmandi BH and others. PMID: 11860726. This was an interesting study in that postmenopausal women ate either 100 g dried plums (12 dried plums) or 75 g dried apples for three months. Then markers of bone turnover were tested to see what, if any, effect the test diets had. Only the dried plums had a significant effect on both IGF-I and bone-specific alkaline phosphatase (BSAP). Since IGF-I and BSAP are associated with bone formation, and none of the markers of bone resorption were elevated, the dried plums appear to have their effect mainly by increasing bone formation. Additionally the tests done in this study would have found an estrogenic effect from the dried plums, but none was detected. The authors commented that the increase in BSAP may be quite significant because studies testing other medications known to increase bone formation, such as parathyroid hormone, showed little change in BSAP in the first year of therapy. In contrast, there was a 5.8% increase in BSAP in the three months Arjmandi and others study. Although there was the preconceived idea that people in the study would have gastrointestinal problems due to the high intake of dried plums, only one participant dropped out of the study due to diarrhea. Women also consumed an additional 380 Kcal/day with the dried plums, but there were no weight, BMI, waist/hip ratio, nor percent body fat changes during the study. The authors state, “In summary, the increased rates of markers of bone formation by dried plums further support our animal findings that dried plum consumption may be beneficial in maintaining skeletal health in postmenopausal women.”
Editor's comments: These studies, and the one coming up, are interesting because they show the potential of a natural product to help those who want to prevent or treat osteoporosis. Unfortunately the next study to be done will provide no information as to whether dried plums might improve bone health for people already on another form of osteoporosis therapy, such as one of the bisphosphonates. So we are, at best, a few years away from having an answer on this issue. My thoughts are that there would be little to lose by self-prescribing the 12 dried plums per day. A check at my local Sam's Club showed that a package of dried plums would cost $5.36. I calculate that would be a fourteen day supply at a cost of $0.38/day. People who might want to add this to their regimen would be anyone who is not responding as expected to other approved therapies. So I leave that up to each individual with the option to also discuss it with their care provider. It would be ideal if there were some way to test the effectiveness rather than just hoping the added dried plums were helping. The only way I can see might be to have a baseline IGF-I test done and then another in about three months. Otherwise the next DXA might provide some guidance, especially if BMD is improved after not seeing improvement before adding the dried plums to your diet. Or just wait until further details emerge from future studies if your current osteoporosis therapy is working all right anyway.