Overview

• The University of Sydney team reports in The EMBO Journal that alpha‑defensins produced in the gut can steer which bacteria thrive.
• In mice, higher natural levels of these peptides correlated with healthier microbiomes and lower insulin resistance.
• Feeding lab‑synthesized alpha‑defensins to susceptible mice protected them from the metabolic harms of an unhealthy diet.
• Responses differed by genetic background, with some mouse strains not benefiting or doing worse, underscoring a need for precision approaches.
• The peptides also occur in humans, and the researchers caution against broad microbiome manipulation as they begin human measurements.