Dietary intake of live microbes and its association with frailty in older adults: a NHANES analysis (1999-2018)

Background Diet plays a crucial part in maintaining a healthy body, and microbes, as an essential dietary component, have attracted more attention in recent years. In this study, we will explore the link between dietary intake of live microbes and frailty in the elderly. Methods Older participants from the 1999-2018 National Health and Nutrition Examination Survey (NHANES) who were not less than 60 years of age were enrolled in this research. Participants' dietary microbe intake was assessed by a self-report questionnaire. Participants were stratified into low, medium, and high intake groups according to their consumption of foods with varying microbial content. The frailty index was assessed by 49 frailty indicators. Frailty was defined as a frailty index > 0.21. Logistic regression was used to analyze the link between dietary intake of live microbes and frailty in older adults. Results A total of 15,179 older adults' basic information was collected for this study. The frailty index was higher than 0.21 in 32.8% of participants. Older adults with low, medium, and high dietary microbe intake accounted for 33.5%, 47.0%, and 19.5%, respectively. In models adjusted for confounders, the prevalence of frailty was lower in participants with the medium (OR = 0.825, 95%CI: 0.749-0.908) and high (OR = 0.779, 95%CI: 0.679-0.894) dietary microbe intake groups, compared with in participants with the lowest intake group. The RCS analysis revealed a significant non-linear association between dietary live microbe intake and frailty prevalence, with the strongest reduction observed below an inflection point of 161.82 (P for non-linearity < 0.05). In addition, stratified analyses did not reveal interactions between the study variables. Conclusion This study demonstrates a negative and non-linear association between dietary live microbe intake and frailty in older adults. These findings provide evidence of a potential link between live microbe intake and frailty, warranting further longitudinal and interventional studies to explore this relationship and its implications for healthy aging.