Mediterranean diet intervention alters the gut microbiome in older people reducing frailty and improving health status: the NU-AGE 1-year dietary intervention across five European countries

TLDR

Ageing is linked to frailty and inflammation, and frailty correlates with gut microbiota changes that are exacerbated by low‑diversity diets, while the Mediterranean diet is associated with better health. The study examined whether a one‑year Mediterranean‑diet intervention could modify the gut microbiome and reduce frailty in older adults. Researchers profiled the gut microbiota of 612 non‑frail or pre‑frail participants from five European countries before and after a 12‑month, elderly‑tailored Mediterranean diet. Diet adherence produced microbiome shifts that enriched taxa linked to lower frailty, improved cognition, and reduced inflammatory markers, increased short/branched‑chain fatty acid production, decreased secondary bile acids and other harmful metabolites, and positioned beneficial taxa as network keystones, supporting the potential of dietary modulation to promote healthy ageing.

Abstract

Objective Ageing is accompanied by deterioration of multiple bodily functions and inflammation, which collectively contribute to frailty. We and others have shown that frailty co-varies with alterations in the gut microbiota in a manner accelerated by consumption of a restricted diversity diet. The Mediterranean diet (MedDiet) is associated with health. In the NU-AGE project, we investigated if a 1-year MedDiet intervention could alter the gut microbiota and reduce frailty. Design We profiled the gut microbiota in 612 non-frail or pre-frail subjects across five European countries (UK, France, Netherlands, Italy and Poland) before and after the administration of a 12-month long MedDiet intervention tailored to elderly subjects (NU-AGE diet). Results Adherence to the diet was associated with specific microbiome alterations. Taxa enriched by adherence to the diet were positively associated with several markers of lower frailty and improved cognitive function, and negatively associated with inflammatory markers including C-reactive protein and interleukin-17. Analysis of the inferred microbial metabolite profiles indicated that the diet-modulated microbiome change was associated with an increase in short/branch chained fatty acid production and lower production of secondary bile acids, p-cresols, ethanol and carbon dioxide. Microbiome ecosystem network analysis showed that the bacterial taxa that responded positively to the MedDiet intervention occupy keystone interaction positions, whereas frailty-associated taxa are peripheral in the networks. Conclusion Collectively, our findings support the feasibility of improving the habitual diet to modulate the gut microbiota which in turn has the potential to promote healthier ageing.