Diet, Exercise, and Gut Bacteria Together Extend Healthy Lifespan in Flies

One of aging research's persistent dilemmas is that interventions extending lifespan often compromise physical performance or fertility. Methionine restriction (MR), for example, robustly extends lifespan across species but frequently impairs reproductive capacity and functional fitness. This study asked whether strategically combining MR with taurine supplementation and exercise could preserve—or even enhance—healthspan alongside longevity.

Using Drosophila melanogaster on a fully chemically defined diet (CDD), the researchers randomized flies into control, MR (10% of normal methionine), taurine (10 mM), and MR+Tau groups, with and without a moderate exercise protocol. Lifespan, climbing performance, food intake, body weight, gut metabolomics, brain metabolomics, microbiome composition, and mitochondrial flux were all measured. Stable isotope tracing with uniformly labeled glucose (U-¹³C-glucose) was used to quantify carbon flux through glycolysis and the TCA cycle.

MR and taurine individually extended lifespan in both sexes and delayed age-related locomotor decline. Combined, they produced additive—not merely additive—benefits: greater lifespan extension and further improved physical endurance. Notably, MR-Tau flies ate less food yet maintained body weight, suggesting metabolic efficiency gains rather than caloric deprivation. Whole-body metabolomics showed distinct profiles across groups, with MR-Tau uniquely activating glutathione biosynthesis, mitochondrial redox regulation pathways, and carnitine metabolism—indicators of enhanced antioxidant capacity and mitochondrial fatty-acid oxidation. Stable isotope tracing confirmed markedly increased TCA cycle flux in MR-Tau flies, accompanied by improved NAD+/NADH redox balance.

Critically, the gut emerged as a central hub. The bacterium Lactiplantibacillus plantarum was enriched under MR-Tau plus exercise conditions, and germ-free recolonization experiments showed that restoring L. plantarum partially reproduced the longevity and metabolic benefits. This suggests a causal—though not sole—role for this microbe in mediating the intervention's effects through arginine-spermidine metabolism and antioxidant pathway upregulation.

The authors propose a 'nutrition–behavior–microbiota' framework in which precision dietary composition, physical activity, and gut microbial ecology converge on mitochondrial redox homeostasis to collectively reshape aging trajectories. This framework importantly suggests that MR's traditional trade-offs (reduced fertility, compromised performance) can be substantially mitigated by concurrent taurine supplementation and exercise. Caveats include the use of an invertebrate model and the inherent complexity of translating fly microbiome findings to mammals.