Verification of an alteration in the gut microbiota that increases nutritional risk in patients on hemodialysis

In end-stage kidney disease requiring hemodialysis, patients at nutritional risk have a poor prognosis. The gut microbiota is important for maintaining the nutritional status of patients. However, it remains unclear whether an altered gut microbiota correlates with increased nutritional risk in patients undergoing hemodialysis. Therefore, we retrospectively analyzed patients who underwent hemodialysis at our hospital between April and December 2022. Nutritional risk was evaluated using the Geriatric Nutritional Risk Index (GNRI), and patients were divided into low- and high-GNRI groups. Patients' clinical conditions and alterations in the gut microbiota were compared between the two groups. The study included a total of 38 patients with moderate to severe frailty. The low-GNRI group had 18 patients, and the high-GNRI group had 20 patients. The low-GNRI group had more severely frail patients. Serum transthyretin, cholinesterase, total cholesterol, and β2-microglobulin were significantly lower in the low-GNRI group than in the high-GNRI group. Significant differences in the relative abundances of the Actinobacteria and Proteobacteria phyla were observed between the two groups. The genus Bifidobacterium was significantly less abundant in the high-GNRI group than in the low-GNRI group. At the species level, Bifidobacterium adolescentis and Bifidobacterium bifidum were significantly lower in the low-GNRI group. Our results indicated that GNRI can be a useful nutritional risk index that accurately reflects the comprehensive differences in clinical condition in patients undergoing hemodialysis. The deficiency of B. adolescentis and B. bifidum was strongly associated with an increased nutritional risk in patients undergoing hemodialysis.