A pair of Pennsylvania State University studies indicate that while inflammation has a negative effect on bone health, dietary intervention with prunes may ultimately help prevent bone loss and preserve bone strength. Conducted among 235 postmenopausal women, the collective study findings were shared via a poster session at this month’s North American Menopause Society Annual Meeting in Atlanta, Ga.
Establishing a Baseline: Inflammation and Bone Health
In the United States, about 10 million adults over the age of 50 have osteoporosis and women are four times more likely than men to experience the condition1. This is partly due to a decline in estrogen levels with the onset of menopause that results in loss of trabecular and cortical bone density2,3. Trabecular bone is the spongy, honeycomb-like interior core, while cortical bone is the strong, exterior of the bone. Along with aging itself, estrogen deficiency contributes to an increase in inflammatory mediators that further enhances bone resorption and suppresses bone formation4.
A new Penn State cross-sectional study titled – Inflammatory Cytokines are Associated with Lower Trabecular Bone Score at the Lumbar Spine in Postmenopausal Women5 – explored the relationship between circulating inflammatory mediators and various measures of bone health, including bone density, geometry, and strength. The study was conducted to establish the relationship between inflammatory mediators and bone outcome at baseline in women enrolled in the parent randomized controlled trial (outlined below) prior to the prune intervention.
“Evidence from several observational studies suggests a link between chronic inflammation and osteoporosis and fracture risk. Looking at postmenopausal women, we began our research by exploring the relationship between biomarkers of inflammation and bone. This helped us establish a baseline prior to a dietary intervention with prunes,” said Co-Investigator, Dr. Connie Rogers, PhD, MPH, Professor and Head, Department of Nutritional Sciences, University of Georgia.
The findings indicate that higher levels of inflammatory markers were associated with lower trabecular bone scores at the lumbar spine among the study participants – essentially the more inflammation, the poorer bone health.
“Our findings demonstrate that inflammatory markers are negatively associated with bone health in postmenopausal women, suggesting that inflammation might be an important mediator for postmenopausal bone loss and a potential target for nutritional therapies,” said Rogers.
Intervening with Nutrition: The “Prune Effect” on Bones
Also conducted at Penn State, the parent clinical trial – Prunes Preserve Cortical Bone Density and Estimated Strength in a 12-month Randomized Controlled Trial in Postmenopausal Women: The Prune Study6 – evaluated the influence of 50g (5-6 prunes)/day and 100g (10-12 prunes)/day on volumetric bone mineral density (vBMD), bone geometry, and estimated bone strength during a 12-month dietary intervention. Study participants were the same as those evaluated in the Penn State inflammation study discussed above.
Treatment groups among the study participants were evaluated as follows: control (no prunes), 50g (5-6 prunes)/day, 100g (10-12 prunes)/day, and a pooled group, which represented the combined group of women who ate either five to six or 10-12 prunes a day.
“Previously, we demonstrated that consuming 5-6 prunes a day for 12 months resulted in preservation of bone at the total hip, a finding that was observable at six months and persisted through month 12. In this second part of the randomized controlled trial, 3-D imaging of bone provided some additional info about the response of bone to consuming prunes daily,” said Principal Investigator, Dr. Mary Jane De Souza, PhD, FACSM, Distinguished Professor and Director of The Women’s Health and Exercise Lab, Pennsylvania State University.
De Souza’s latest findings indicate that prune consumption preserves vBMD and strength at weight-bearing tibial sites that are predominantly cortical sites.
“We observed that the pooled group of women experienced some bone benefits. In particular, estimated bone strength at the tibia was maintained in the pooled group and cortical volumetric bone density was maintained in the 5-6 prunes a day and 10-12 prunes a day groups. As such, it appears that prunes may help prevent bone loss, especially at the hip and tibia,” said De Souza.
Specific additional results include:
- Estimated strength strain index (SSI) was evaluated at the 14% diaphyseal tibia for control vs. pooled groups and it was reported that estimated strength decreased in the control group from baseline to 12 months, but not in the combined prune group.
- Cortical vBMD was evaluated in control vs. 100g prune groups, and it was reported that at the 14% diaphyseal tibia, cortical vBMD decreased in the control group from baseline to 12 months but did not change in the 100g group.
- At the 38% diaphyseal tibia, the total vBMD was evaluated, and it was reported that total vBMD decreased in the control group from baseline to 12 months, but not in the 100g group.
The abstract results are being prepared for anticipated publication in Menopause: The Journal of The North American Menopause Society, December 2022. Full papers are pending.
1Sarafrazi N et al. Osteoporosis or Low Bone Mass in Older Adults: United States, 2017-2018. NCHS Data Brief. 2021. p. 1-8.
2Khosla S et al. Estrogen and the skeleton. Trends in Endocrinology & Metabolism. 2012;23(11):576-581.
3Management of osteoporosis in postmenopausal women: the 2021 position statement of The North American Menopause Society. Menopause. 2021;28(9):973-997
4Pacifici R. Estrogen, cytokines, and pathogenesis of postmenopausal osteoporosis. Journal of Bone and Mineral Research. 1996;11(8):1043-51.
5Damani JJ, De Souza MJ, Connie J. Rogers CJ. Inflammatory Cytokines are Associated with Lower Trabecular Bone Score at the Lumbar Spine in Postmenopausal Women. North American Menopause Society Annual Meeting.; October 13, 2022; Atlanta Georgia.
6De Souza MJ, et al. Prunes Preserve Cortical Bone Density and Estimated Strength in a 12-month Randomized Controlled Trial in Postmenopausal Women: The Prune Study. North American Menopause Society Annual Meeting.; October 13, 2022; Atlanta Georgia.