1. Highest Mediterranean diet quintile had ~32% fewer RA cases.
2. A 66-metabolite plasma signature showed a stronger gradient.
3. Both measures remained independent after mutual adjustment.
4. The signature mediated 22.4% of the diet–RA relationship.
5. Lipid markers (omega-3 measures, DHA, unsaturation) drove most mediation.
6. Results were robust across genetics, subgroups, and sensitivity analyses.

Source: The American Journal of Clinical Nutrition