The California Prune Board (CPB) is leading the way in investigating a connection between prunes and favorable bone through a growing body of evidence spanning two decades. Building on this remarkable and extensive research, the organization is announcing recently published scientific data supporting the role prunes may play in optimal bone health, while previewing a pipeline of clinical trials currently underway.

“The science has shown us that something unique is going on with prunes, as we’ve uncovered some remarkable connections to bone health,” said Donn Zea, executive director, California Prune Board. “With every study we learn something more compelling further piquing our curiosity. Our research program has more to explore, and we’re excited to see where this takes us in terms of learning more about the benefits of prunes for bone health.”

Recently published highlights

In a recent review paper published in Advances in Nutrition titled, “The Role of Prunes in Modulating Inflammatory Pathways to Improve Bone Health in Postmenopausal Women,” researchers from Pennsylvania State University examined the relationship between prune consumption, oxidative stress, inflammation, and favorable bone health outcomes, summarizing the results of preclinical and clinical trials. They reported that the bone-protective effects of prunes found in postmenopausal women appear to be connected to the antioxidant and anti-inflammatory activity that prunes stimulate within the body. Moreover, the authors also suggested that prunes’ favorable effect on bone may be partially explained by changes in the gut microbiota that can come from regular prune consumption. 

Additionally, in a USDA-funded clinical trial recently published in Nutrients, titled “The Short-term Effects of Prunes in Improving Bone in Men,” investigators from Florida State University sought to test the effect of daily prune consumption on bone metabolism in 35 men over the age of 50 who had some bone loss. The early findings showed a reduction in osteocalcin, a biomarker of bone turnover, and an increase in what’s known as the OPG:RANKL ratio, indicating prunes may have a positive effect on bone status after just three months of eating this whole fruit daily. These preliminary findings are a subset of a larger study with results that have not yet been published but are anticipated in the next 12-18 months.

“As a researcher it’s exciting to see a positive change in bone turnover in these men from prune consumption after a relatively short period of time. We anticipate even more favorable results in bone status once the men have completed a full year of eating prunes every day,” said Principal Investigator Bahram Arjmandi, PhD, RDN, professor and director, Center for Advancing Exercise and Nutrition Research on Aging, Florida State University. 

Research underway

In addition to this recently published data, the following nutrition studies from highly credentialed research institutions are currently in progress and working toward completion or journal publication:   

Randomized Controlled Trial of Dietary Supplementation with Prunes on Bone Density, 
Bone Geometry, and Bone Strength in Postmenopausal Women
Principal Investigator: Mary Jane De Souza, PhD - Pennsylvania State University 
With a cohort of over 200 postmenopausal women, this is the largest clinical trial to date to investigate the effect of prunes on bone status as a non-pharmaceutical plant-based strategy to combat bone breakdown. 

The Effects of 12-months of Prune Consumption on Bone Mineral Density and Bone Turnover Markers in Korean Postmenopausal Women with Osteopenia
Principal Investigator: Peter Clifton, PhD - University of South Australia
Co- Principal Investigator: Yoona Kim, PhD, RD, Gyeongsang National University, Korea
This clinical trial in South Korea is the first study outside of the United States to investigate the bone protective benefits of daily consumption of prunes in Korean osteopenic postmenopausal women. 

The Impact of Consuming California Prunes on Bone Health of Young Women Using 
Hormonal Contraceptives
Principal Investigator: Shirin Hooshmand, PhD, RD - San Diego State University
The study is investigating the impact of prune consumption on bone formation and in preventing or slowing bone loss in young women 18-25 years old taking hormonal contraceptives.

“Bone health, whether optimizing bone formation early in life or preventing bone loss in adulthood, is critical at all life stages given that the human skeleton is dynamic, undergoing a continuous cycle of building and breaking down bone,” said Andrea N. Giancoli, MPH, RD, nutrition advisor, California Prune Board. “We are aiming to better understand the role of prunes in this cycle that is strongly correlated to gut health, inflammation, and oxidative states within the body.” 

While it remains unclear what bioactive compounds in prunes are responsible for the beneficial effects on bone, the prune-positive bone health story may be partially due to the array of vitamins and minerals in California Prunes known to influence bone status, namely boron, potassium, copper, and vitamin K. Prunes are also rich in phenolic compounds, which research suggests may inhibit bone breakdown and stimulate bone formation. Key future directions to bridge the gap in the areas of bone and the gut-bone axis are on the research horizon.

Creating a vision for the future

Advancing bone-focused nutrition research and expanding the connection to the gut-bone axis, while also exploring clinical trials in various life stages and international populations is at the heart of the California Prune Board’s strategic vision for continued research into the next decade. 

The integrity of the California Prune Board’s nutrition research program is demonstrated by the renowned research and academic institutions with whom it has partnered and the rigorous process that ensures credible research decisions.

A top-caliber nutrition research advisory panel, led by Mary Jo Feeney, MS, RDN, FADA, FAND, helps to guide these California Prune nutrition research efforts. The panel is comprised of highly experienced researchers and nutrition experts from academic institutions, including Tufts University, Cleveland Clinic, Pennsylvania State University, University of Minnesota, and San Diego State University. This independent advisory panel provides vision and oversight of the nutrition research program and ensures scientific rigor for every project that explores the nutritional and health benefits of California Prunes.

The California Prune Board is deeply committed to the scientific rigor of nutrition research. For more details on previously published research, click here. 

REFERENCES

Damani JJ, De Souza MJ, VanEvery HL, Strock NCA, Rogers CJ. The Role of Prunes in Modulating Inflammatory Pathways to Improve Bone Health in Postmenopausal Women. Adv Nutr. 2022 Jan 3:nmab162. Epub ahead of print.

George KS, Munoz J, Ormsbee LT, Akhavan NS, Foley EM, Siebert SC, Kim JS, Hickner RC, Arjmandi BH. The Short-Term Effect of Prunes in Improving Bone in Men. Nutrients. 2022 Jan 10;14(2):276.