Gut bacteria linked to osteoporosis risk in primary hyperparathyroidism

Researchers from Emory University and Columbia University found that specific gut microbes, especially Bifidobacterium longum, were tied to bone loss in primary hyperparathyroidism. The study suggests the microbiome could help identify PHPT patients at higher risk for osteoporosis and points to new prevention strategies.

Why it matters: - Primary hyperparathyroidism can cause severe bone loss in some patients while leaving others with similar hormone levels relatively protected. - The study points to a gut-microbe signal that could help explain that difference and improve osteoporosis risk prediction in PHPT. - The findings also suggest new prevention options, including microbiome-based therapies.

What happened: - Researchers from Emory University and Columbia University linked gut microbiome patterns to bone loss in primary hyperparathyroidism. - The team published the study on 25 May 2026 in Bone Research. - The research focused on Bifidobacterium longum as a potential driver of skeletal damage. - Prof. Roberto Pacifici led the study.

The details: - The team analyzed stool samples, bone density measurements and immune-cell profiles from 50 people with PHPT. - Gut microbial composition tracked closely with bone health and immune activity. - Fecal microbiota transfer experiments moved gut bacteria from PHPT patients with osteoporosis, osteopenia or normal bone density into germ-free mice. - Mice that received microbiota from osteoporotic patients developed greater bone loss and more inflammatory immune cells than mice that received microbiota from patients with healthier bones. - Prof. Pacifici said the severity of skeletal impact from PHPT correlated with the abundance of Bifidobacterium longum, which the team found could expand TNF+ T cells and Th17 cells in the gut and bone marrow. - The study identified TNF-producing T cells and Th17 cells as key mediators linking the microbiome to bone deterioration. - Higher levels of those immune cells were associated with lower bone density in PHPT patients and in recipient mice. - Increased Bifidobacterium longum abundance was associated with higher expression of TNF and IL-17, inflammatory molecules tied to bone resorption. - In germ-free mice, colonization with Bifidobacterium longum expanded TNF-producing T cells and Th17 cells in the intestine and bone marrow. - The bacterium also increased migration of those immune cells from the gut to the bone marrow, where they released inflammatory factors that accelerated bone breakdown. - When mice with Bifidobacterium longum were exposed to elevated parathyroid hormone levels, they lost more bone than control animals. - The original paper is titled "Bacterial specificity of the gut microbiome predicts bone density in primary hyperparathyroidism." - The paper DOI is https://doi.org/10.1038/s41413-026-00529-1. - Emory University is based in Atlanta and says the study was supported by NIH grants DK124821, RR028009 and DK09839, plus Emory research cores and a Veterans Affairs award.

Between the lines: - The overall microbiome was not significantly different among patients with osteoporosis, osteopenia or normal bone density. - The risk signal appeared to depend on specific bacterial species, not broad shifts in the gut ecosystem. - That makes Bifidobacterium longum and related immune signatures more interesting as potential biomarkers than a generic microbiome score. - The results also fit a larger idea in osteoimmunology: immune activation can translate gut signals into bone loss.

What's next: - The findings could support microbiome-based tests to identify PHPT patients most vulnerable to skeletal complications. - Future interventions may include selective microbial modulation, antibiotics, precision probiotics or other microbiota-directed strategies. - The study suggests those approaches could complement existing PHPT treatments and enable more personalized care. - Prof. Pacifici said the data support a model in which Bifidobacterium longum helps PTH drive TNF+ T cell and Th17 cell expansion and bone loss.