What role does ACTN3 play in gut health?

ACTN3 encodes alpha-actinin-3, a protein primarily expressed in fast-twitch skeletal muscle fibers and linked to athletic performance. A direct role in gut health is not scientifically established. No robust studies demonstrate that ACTN3 variants (e.g., rs1815739) affect gut barrier function, microbiome composition, or intestinal motility. Theoretical speculation that alpha-actinin-3 might influence smooth muscle in the gut remains unsupported. Evidence is therefore unclear. Consumers should not infer any gut-health implications from ACTN3 genetic testing.