Diet influences knee osteoarthritis osteophyte formation via gut microbiota and serum metabolites

Zhu D, Wang X, Xi Z, Chen K, Feng Y, Zi C, Pan Z, Ma X, Zeng X, Feng H, Guo D · iScience

Uses a regional diet difference as a natural experiment. Three bacterial genera and five serum metabolites were associated with osteophyte formation; Blautia abundance correlated negatively with meat, cheese and bean intake, and the five metabolites negatively with dairy, beef, cheese, sugar and salt. The Inner Mongolian patients, with different cheese-eating habits, had lower Blautia, lower expression of the five metabolites and less osteophyte formation. LTB4 and PGD2 are proposed as biomarkers.

Population

20 healthy volunteers and 180 knee OA patients across two Chinese regions (Guangdong and Inner Mongolia), with 16S rDNA sequencing and untargeted metabolomics on stool and serum

Intervention

Habitual regional diet

Comparator

Between-region and case-control comparison

Limitations

Cross-sectional correlation across two regions that differ in far more than diet — genetics, altitude, climate, activity and healthcare all vary. Two hundred people, no adjustment framework capable of separating region from diet, and the causal language in the abstract runs ahead of the design.