A New Study Found the Hidden Bone Switch That Could Reverse Osteoporosis Before a Fracture Happens
A receptor hiding inside your bone-building cells may hold the key to reversing osteoporosis. At the same time, a 12-month clinical trial out of Penn State just confirmed that eating prunes daily can help preserve bone strength in postmenopausal women.
Two very different research threads are converging on the same urgent problem. Bone loss quietly affects nearly 1 in 5 American women over 50 and often goes undetected until a fracture forces the issue. One discovery points toward a future treatment. The other is something you can do this week.
What the GPR133 Receptor Discovery Means for Bone Loss
Researchers at Leipzig University and Shandong University identified a receptor called GPR133, also known as ADGRD1, that appears to act as a master switch for bone density. The findings, published in June 2025 in Signal Transduction and Targeted Therapy, show that when GPR133 is active inside osteoblasts, the cells that build new bone, it boosts their activity while suppressing osteoclasts, the cells that break bone down. That double action shifts the body’s internal balance toward bone formation.
In experiments, mice without the GPR133 gene developed early bone loss resembling osteoporosis. When researchers activated the receptor using a compound called AP503, that loss reversed. The team also tested AP503 in a postmenopausal bone loss model and saw key markers move back toward normal. A related Leipzig study found AP503 strengthens skeletal muscle too, a meaningful detail because bone and muscle loss often progress together in aging adults.
Why the Penn State Prune Trial Is Getting Attention From Researchers
While the GPR133 work is still preclinical, the Penn State prune research is already producing actionable results. The study, led by Dr. Mary Jane De Souza, found that postmenopausal women who ate either 50 grams or 100 grams of prunes daily preserved cortical bone density and estimated bone strength at the tibia. The control group showed bone loss at the same site over the same period.
The trial, published in Osteoporosis International, was the first randomized controlled trial to evaluate 3D bone outcomes, including volumetric bone mineral density, bone geometry and estimated strength, rather than relying solely on the standard 2D DXA scan.
Researchers believe the polyphenols in prunes blunt the inflammatory pathways that drive bone loss after menopause. A follow-up Penn State trial is now underway studying prune consumption during the perimenopause transition, funded by a USDA NIFA grant announced in 2025.
Who Is Most At Risk for Osteoporosis and When to Pay Attention
Bone loss is often called a “silent disease” because it progresses without symptoms until a bone breaks. StatPearls, updated June 2025, notes that many people first learn they have osteoporosis only after a fracture, frequently of the hip, spine or wrist. By then, significant bone density has already been lost.
The risk isn’t evenly distributed. Nearly 1 in 5 women over 50 in the U.S. have osteoporosis, and women are four times more likely than men to be affected. The years surrounding menopause are particularly critical because the drop in estrogen accelerates bone breakdown. That’s why researchers are now focused on perimenopause as a prevention window rather than waiting until osteoporosis has already taken hold.
What a Future Bone-Building Drug Could Actually Do
Most current osteoporosis treatments work by slowing bone loss. What makes the GPR133 finding notable is the possibility of a drug that actively rebuilds bone by switching the body’s own bone-building machinery into higher gear. Because AP503 also showed muscle benefits in a separate Leipzig study, researchers are interested in whether a single compound could one day address both problems simultaneously.
It’s worth keeping expectations grounded. The GPR133 research has been conducted in mice and lab models only. No human trials have begun, and the path from a promising preclinical compound to an approved medication typically takes years. Still, identifying a specific receptor that governs the bone-building balance gives researchers a clear target to work from.
What You Can Do Right Now to Support Bone Health
While the receptor research moves through its early stages, the prune findings offer something you can act on today. The Penn State trial found benefits at both 50 and 100 grams per day, roughly a small handful eaten consistently. Consistency mattered more than quantity: the women who maintained the daily habit were the ones who preserved their bone strength.
The broader takeaway from both studies is the same. Bone loss is easier to prevent than to reverse, and the window to act opens earlier than most people realize. Women approaching perimenopause, or anyone with a family history of osteoporosis, may benefit from talking to a doctor about bone density screening before a fracture forces the conversation.
This article was created by content specialists using various tools, including AI.
