Dairy isn’t the only food that’s beneficial for bone health. Prunes may also help protect bone structure and strength in postmenopausal women, according to a new study by Penn State researchers. Published in Osteoporosis International, the study suggests that daily consumption of prunes can slow down age-related bone loss and lower the risk of fractures.
“This is the first randomized controlled trial to explore three-dimensional bone outcomes in terms of bone structure, geometry, and estimated strength,” said Mary Jane De Souza, a distinguished professor of kinesiology and physiology at Penn State. “We observed that daily prune consumption affected factors related to fracture risk, which is clinically invaluable.”
Bones consist of dynamic tissues that are continuously undergoing remodeling. Specialized bone cells remove old bone and replace it with new bone. As people age, the balance shifts, and the body starts breaking down bone faster than it can be rebuilt.
This accelerated bone loss can lead to osteoporosis, a condition where bones become less dense and their structure weakens, increasing the risk of fractures. According to the Centers for Disease Control and Prevention, over 10 million Americans suffer from osteoporosis, which is more prevalent in women and older adults.
Postmenopausal women are particularly at risk. Estrogen, a hormone vital for bone health, decreases during this phase, accelerating bone density loss. While medications exist to treat osteoporosis, many women who need them are not taking them.
Prunes offer a promising alternative, according to De Souza. They contain bioactive compounds like polyphenols that may inhibit the inflammatory pathways leading to bone loss.
Previous studies mainly used dual-energy X-ray absorptiometry (DXA) to assess 2D bone mass density and diagnose osteoporosis. However, DXA scans cannot differentiate between types of bone tissue or measure structural properties, which are proxies for bone strength and quality, the researchers noted.
“When we examine bone mineral density, we assess how much bone is present, but we also need to know about the quality of the bone. A three-dimensional image allows us to evaluate bone structure, geometry, and micro-architecture. Essentially, it tells us about the bone’s integrity,” De Souza said.
To investigate whether daily prune consumption affected bone quality, the research team conducted a 12-month randomized controlled trial with 235 postmenopausal women. Participants were divided into three groups: no prunes; 50 grams (4 to 6 prunes) daily; or 100 grams (10 to 12 prunes) daily. Every six months, participants underwent a peripheral quantitative computed tomography (pQCT) scan, which provides cross-sectional imaging to measure 3D bone mass density, bone geometry, and bone strength.
After one year, the researchers found that measures of bone mass density and bone strength in the tibia (shin bone) decreased in women in the control group. In contrast, those who consumed at least four to six prunes daily maintained their bone density and strength and preserved bone structure, especially in cortical bone. Although both prune groups saw benefits, four to six prunes a day appeared to be a more feasible dose, as women in the 100-gram group were more likely to drop out due to the difficulty of consuming so many prunes daily.
“The data from this 12-month study is quite exciting,” De Souza said. “We were able to maintain and preserve bone in the weight-bearing, cortical bone of the tibia. Maintaining cortical bone and bone strength is key to preventing fractures.”
De Souza explained that prune consumption could potentially reduce the risk of osteoporosis, though more research is needed.
This study builds on a body of research examining the relationship between prunes and bone health. In a previous study with the same cohort, the research team found that daily prune consumption for a year also preserved total bone mass density at the hip. They have also explored potential mechanisms behind prunes’ bone-protective effects, including their impact on gut microbiome bacteria. De Souza mentioned that they hope to continue expanding these findings in future studies.
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