Peripheral artery disease (PAD) is a common vascular disorder in the elderly, often accompanied by frailty syndrome, which is associated with increased inflammation, oxidative stress, and functional decline. Nutritional strategies, particularly those involving bioactive compounds like flavonoids and omega-3 fatty acids, have been suggested as potential approaches to modulate these pathological processes. This narrative review summarizes current evidence regarding the anti-inflammatory and antioxidant effects of flavonoids and omega-3 fatty acids, and their possible roles in mitigating frailty syndrome in patients with PAD. We examine mechanistic pathways including NF-κB, AMPK, PI3K/Akt/mTOR, and Nrf2, which are implicated in chronic inflammation, endothelial dysfunction, and muscle wasting. Although studies in general and aging populations suggest beneficial effects of these compounds on vascular and muscle health, specific evidence in PAD patients remains limited. Flavonoids may reduce pro-inflammatory cytokine production and enhance antioxidant responses, while omega-3 fatty acids have shown potential in modulating inflammatory signaling and supporting vascular repair. Current data provide a basis for further investigation into the dietary modulation of frailty syndrome in PAD. Understanding the impact of these nutrients may offer insights into adjunctive strategies for improving patient outcomes.

Graft-versus-host disease (GVHD) is one of the principal complications seen in the recipients of allogenic hematopoietic stem cell transplantation (allo-HSCT), and persists as a leading cause of post-transplant morbidity and mortality. Increasing evidence highlights the crucial influence of the gut microbiome (GM) on transplant outcomes. Microbial dysbiosis, characterized by reduced bacterial diversity and pathogenic overgrowth, is strongly associated with higher rates of complications and mortality. Patients with lower microbial diversity exhibit poorer overall survival (OS) and an increased incidence of acute GVHD (aGVHD). Conversely, restoration of beneficial commensal communities has been shown to enhance immune homeostasis, mitigate GVHD severity, and decrease infection risk. Emerging therapeutic strategies now focus on modulating the intestinal microbiome through dietary interventions, probiotics, prebiotics, and fecal microbiota transplantation (FMT). It has been demonstrated that bacterial metabolites, such as short-chain fatty acids (SCFAs) from the diet, especially a diet rich in fibers, reduce the occurrence/severity of GVHD by inducing regulatory T cells (Tregs), which release anti-inflammatory cytokines and regulate the host immune system. Hence, the implementation of dietary fibers (DFs) could increase beneficial commensals, Treg induction, and improve outcomes such as GVHD and OS in recipients of allo-HCT. Hereupon, this review addresses how a fiber-rich diet modulates GM composition, reinforces epithelial barrier integrity, and improves the efficacy of Treg-based immunotherapy by stabilizing their regulatory phenotype and increasing their functional persistence, ultimately leading to a reduction in GI complications associated with GVHD. Unlike prior reviews that primarily cover the microbiome–GVHD axis or Treg therapies in isolation, this review emphasizes fermentable dietary fibers as a mechanistically grounded, clinically actionable strategy to support Treg stability and persistence via microbiota-derived metabolites. We integrate mechanistic evidence with emerging clinical feasibility data and ongoing trials of prebiotic supplementation in allogeneic HSCT.