NR and Berberine Team Up to Rescue Aging Mitochondria via Overlapping Pathways

Mitochondrial dysfunction is now widely recognized as a unifying driver of aging and chronic disease—spanning type 2 diabetes, cardiovascular disease, neurodegeneration, and ocular conditions like glaucoma. Beyond ATP production failures, compromised mitochondrial signaling disrupts redox control, immune regulation, and tissue-specific stress responses. This 2026 narrative review from researchers at the University of Catania and affiliated Italian institutions synthesizes preclinical and clinical evidence on two prominently studied mitochondrial modulators: nicotinamide riboside (NR) and berberine (BBR).

NR is a vitamin B3 derivative and the most bioavailable NAD+ precursor identified to date. By replenishing declining NAD+ pools—a hallmark of cellular aging—NR activates sirtuin deacylases (especially SIRT1 and SIRT3), which in turn drive PGC-1α-mediated mitochondrial biogenesis, improve oxidative phosphorylation efficiency, and trigger the mitochondrial unfolded protein response (UPRmt). Clinical trials have confirmed NR's ability to raise blood NAD+ metabolites safely, though translation to consistent functional outcomes remains variable.

Berberine, an isoquinoline plant alkaloid with centuries of medicinal use, acts primarily through AMPK activation and mild inhibition of mitochondrial respiratory complex I. This dual action lowers cellular energy charge, triggering compensatory improvements in mitochondrial bioenergetics, reducing mitochondrial ROS generation, and enhancing mitophagy and organelle quality control. BBR has shown efficacy in metabolic syndrome, NAFLD, and type 2 diabetes in clinical settings, though its poor oral bioavailability remains a practical limitation.

The review's central contribution is demonstrating that, despite distinct upstream mechanisms, NR and BBR converge on shared downstream pathways: AMPK-SIRT1 crosstalk, PGC-1α activation, suppression of NF-κB-driven inflammation, mitophagy induction, and modulation of the mtDNA-cGAS-STING innate immune axis. Mitochondrial DNA released from dysfunctional organelles can trigger inflammatory cascades via pattern-recognition receptors; both compounds appear to reduce this pathological signaling. The authors also highlight disease-specific evidence, noting NR's neuroprotective effects in retinal ganglion cells relevant to glaucoma and BBR's efficacy across cardiometabolic conditions.

The review concludes by framing NR and BBR as a rational combinatorial strategy. Their mechanistic complementarity—NR supplying the NAD+ substrate for sirtuin activity while BBR activates AMPK upstream—suggests synergy rather than redundancy. However, the authors candidly acknowledge limitations: most evidence is preclinical, clinical trials are heterogeneous in design, and robust biomarkers of mitochondrial function for trial endpoints remain elusive. They call for rigorous combination trials with standardized mitochondrial readouts to validate this integrative approach.