Researchers reveal that the combination of a nutrient-rich diet and diverse oral microbes may hold the key to reducing frailty, offering a new path to healthier aging.
Study: Diet-microbiome synergy: unraveling the combined impact on frailty through interactions and mediation. Image credit: PeopleImages/Shutterstock.com
A new study published in Nutrition Journal reports that U.S. adults with a high-quality diet and greater oral microbiome diversity are less likely to exhibit frailty, a clinical state associated with physical disability and poor health outcomes.
Background
Recent advancements in medical science have significantly increased human lifespan. However, this progress is accompanied by a growing prevalence of frailty, a multifactorial clinical condition characterized by reduced functioning of multiple organ systems in the body. The condition primarily affects older adults and increases their vulnerability to adverse health outcomes, including falls, hospitalization, disability, and even death.
The human microbiome, the entire community of microorganisms that live in the human body, plays a crucial role in health and disease. The gut and oral cavity harbor the largest and second-largest microbial communities in the human body, respectively.
The oral microbiome influences systemic health via inflammatory and metabolic pathways. It has been linked to oral diseases and systemic health conditions, including diabetes, cardiovascular disease, Alzheimer’s disease, and certain cancers.
Diet plays a significant role in shaping oral microbiota dynamics. A high-quality diet has been found to improve microbiota diversity and composition. Recent evidence suggests that changes in dietary patterns can lead to marked alterations in oral microbiome composition. The oral microbiome can regulate host dietary preferences by influencing their taste thresholds for sweet, sour, salty, and bitter flavors.
Given the potential interaction between diet and oral microbiome and its impact on human health, researchers at The First Hospital of China Medical University aimed to investigate how diet quality and oral microbiome diversity, either individually or in combination, influence the likelihood of frailty in adults residing in the United States.
Study design
The study included 6,283 adult individuals from the 2009–2010 and 2011–2012 cycles of the National Health and Nutrition Examination Survey (NHANES), which is an ongoing survey conducted by the Centers for Disease Control and Prevention (CDC) to assess the health and nutritional status of the U.S. general population.
Participants’ frailty index scores were calculated, with higher scores representing greater frailty. Dietary intake was assessed using two 24-hour dietary recalls. Four dietary indices based on dietary intake data were calculated to assess diet quality.
The oral microbiome diversity representing community richness and evenness was assessed using α-diversity indices that measure within-subject microbial diversity.
Appropriate statistical analyses were conducted to determine the individual and combined effects of oral microbiome diversity and diet quality on the frailty index. A mediation analysis was also carried out to explore oral microbiome diversity as a mediator between diet quality and the frailty index.
Key findings
The study analysis revealed that participants with the highest level of oral microbiome diversity were associated with significantly lower frailty scores than those with the lowest. Similarly, a lower likelihood of frailty was observed among participants consuming the highest quality diet.
Among the four dietary indices analyzed in the study, the dietary inflammatory index was significantly associated with the frailty index. Participants with the highest dietary inflammatory index scores exhibited a higher risk of frailty than those with the lowest scores.
Regarding the combined impact, the study found a significant interaction between oral microbiome diversity and dietary inflammatory index concerning frailty risk reduction. Participants with the highest microbial diversity and the lowest dietary inflammatory index scores exhibited a significantly lower likelihood of frailty.
The mediation analysis revealed that oral microbiome diversity partially mediates the relationship between diet quality and frailty risk.
Study significance
The study reveals that adult individuals with a higher-quality diet and greater oral microbiome diversity are associated with a significantly lower risk of developing frailty. Notably, the study finds that the interaction between the dietary inflammatory index and the oral microbiota diversity exerts a particularly substantial influence on frailty risk.
A high-quality, healthy diet typically includes higher intakes of fruits, vegetables, and whole grains and lower intakes of ultra-processed foods. These typically represent higher intakes of anti-inflammatory and antioxidant nutrients and lower intakes of pro-inflammatory nutrients.
The dietary inflammatory index, which showed the most significant interaction with oral microbiome diversity in relation to frailty risk reduction, is primarily used to evaluate the anti-inflammatory or pro-inflammatory properties of a diet, and this index is closely associated with systemic inflammation in the body.
Chronic low-grade inflammation is a significant factor in frailty, which can lead to metabolic and endocrine disruption, muscle protein degradation, and nutritional imbalance. All these factors can potentially increase the risk of frailty. Furthermore, a state of frailty itself can increase the production of pro-inflammatory mediators and disrupt anti-inflammatory pathways. These interactions may help explain the observed associations between dietary inflammatory index, oral microbiome diversity, and frailty.
Unhealthy dietary patterns characterized by high intakes of refined and processed foods impair oral microbiome composition and diversity by increasing the abundance of acid-producing and acid-tolerant microorganisms. This shift can promote a more acidic environment within the oral cavity, leading to increased growth of harmful microorganisms and heightened inflammatory responses.
These interactions between diet quality and oral microbiome can collectively increase the risk of frailty by triggering inflammation and impairing immune response. This justifies the observed mediating effect of oral microbiome diversity on the association between dietary inflammatory index and frailty.
Overall, the study findings suggest that enhancing diet quality and promoting oral microbiome diversity represent potential avenues for strategies aimed at reducing frailty risk, though further longitudinal research is needed to confirm causality.
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