Ageing is an inevitable part of life, bringing changes in physical strength, immune function, and overall well-being. For many, growing older means experiencing a decline in energy levels and an increased risk of chronic health conditions. Among the most concerning aspects of ageing is frailty, a condition that reduces resilience and increases vulnerability to diseases and injuries.
Frailty is not an isolated problem but a state of overall decline in physiological function. It affects movement, strength, endurance, and the ability to recover from illness. As the world's population ages, researchers are working to understand the factors that contribute to frailty and identify ways to delay or prevent it.
One area of increasing interest is the relationship between diet and frailty. While exercise, medication, and lifestyle adjustments all play roles in supporting ageing, diet remains a critical yet often overlooked factor. Among the various components of diet, one stands out as particularly promising—live dietary microbes.
Understanding Frailty and Its Impact
Frailty is more than just physical weakness. It represents a decline in multiple body systems, including musculoskeletal function, immune response, and metabolism. This state makes individuals more prone to falls, disability, hospitalization, and even death.
There are two widely accepted models for defining frailty. One, proposed by Fried et al., focuses on physical signs such as muscle weakness, slower walking speed, exhaustion, weight loss, and reduced physical activity. If an individual has three or more of these characteristics, they are considered frail.
The second model, developed by Rockwood et al., describes frailty as an accumulation of health deficits. This approach calculates a frailty index based on multiple health indicators. The more health issues a person has, the higher their frailty index, making them more vulnerable to illness and reduced quality of life.
Growing Interest in Gut Health
In recent years, researchers have explored how gut health influences overall well-being. The human digestive system is home to trillions of microorganisms, including bacteria that help digest food, regulate metabolism, and protect against harmful pathogens. This gut microbiome plays a vital role in maintaining health, particularly in older adults.
Ageing is often accompanied by changes in the gut microbiota, leading to imbalances that can trigger inflammation, digestive problems, and weakened immunity. Some studies suggest that restoring gut balance through diet may help counteract age-related decline. Among the most promising dietary components for gut health are live microbes, commonly found in fermented foods.
What Are Dietary Live Microbes?
Live microbes exist naturally in various foods, particularly fermented products like yogurt, kefir, kimchi, miso, and sauerkraut. These beneficial bacteria, including probiotics, survive digestion and contribute to gut health. They help maintain a balanced microbiome by increasing the presence of beneficial bacteria while reducing harmful microorganisms.
Many studies suggest that consuming live microbes regularly may improve digestion, reduce inflammation, and support immune function. Researchers now believe that dietary live microbes could also play a role in reducing frailty among older adults. This hypothesis has led to investigations into whether higher microbial intake correlates with better overall health and lower frailty levels.
The NHANES Study on Microbial Intake and Frailty
A recent study examined the relationship between dietary live microbe intake and frailty among older adults using data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018. The study included 15,179 participants aged 60 and older, analyzing their dietary habits and overall health.
Researchers classified participants into three groups based on their intake of live microbes. The low-intake group consumed mostly pasteurized or heat-treated foods with minimal microbial content. The medium-intake group included those who ate unpeeled fresh fruits and vegetables, which contain moderate microbial levels. The high-intake group regularly consumed fermented foods and other items rich in live microbes.
Frailty was measured using a frailty index, which evaluates health deficits across various indicators. Individuals with a frailty index above 0.21 were classified as frail.
Relationship Between Microbial Intake and Frailty
The study found that higher microbial intake was linked to a lower risk of frailty. Participants in the medium-intake group had a 17.5% lower risk of frailty, while those in the high-intake group had a 22.1% lower risk. These findings suggest that dietary live microbes could play a role in maintaining strength and resilience in older adults.
Further analysis showed that the relationship between microbial intake and frailty followed a non-linear pattern. The greatest reduction in frailty occurred when microbial intake was below a threshold of 161.82 units. Beyond this point, additional intake provided diminishing benefits, indicating that moderate consumption might be sufficient for significant health improvements.
Science Behind Live Microbes and Ageing
The connection between live microbes and reduced frailty is likely due to several physiological mechanisms. The gut microbiome influences metabolism, immune function, and inflammation levels, all of which impact ageing and frailty.
One key benefit of live microbes is their ability to regulate the gut microbiota. A diverse and well-balanced gut microbiome improves digestion and nutrient absorption. It also strengthens the intestinal barrier, reducing the risk of infections and inflammatory responses.
Live microbes also contribute to the production of short-chain fatty acids, which help maintain gut health and reduce systemic inflammation. Lower levels of inflammation are associated with better muscle function, reduced risk of chronic disease, and overall improved health.
Differences in Microbial Intake Across Demographics
The study also examined how microbial intake affects different demographic groups. The benefits of higher microbial intake were evident across all groups, but some variations were observed.
Men appeared to experience slightly greater protective effects from high microbial intake compared to women. Among racial and ethnic groups, non-Hispanic White participants showed the strongest association between microbial intake and lower frailty levels.
Socioeconomic status also played a role. Participants with higher education levels and greater financial resources had higher microbial intake and lower frailty rates. This suggests that access to a variety of nutrient-rich foods may influence overall health outcomes.
Dietary Recommendations for Older Adults
Given the potential benefits of live microbes, older adults may want to increase their intake of probiotic-rich foods. Fermented dairy products, such as yogurt and kefir, contain beneficial bacteria that support digestion and immune function. Similarly, fermented vegetables, including sauerkraut and kimchi, provide fiber and probiotics that contribute to gut health.
Other sources of live microbes include fermented soy products like miso and tempeh. While probiotic supplements are also available, researchers suggest that consuming live microbes through food offers additional nutritional benefits.
Considerations and Challenges
While the study provides strong evidence linking microbial intake and frailty, several factors require further investigation. The research relied on a 24-hour dietary recall method, which captures short-term dietary habits but may not reflect long-term consumption patterns.
Another limitation is that microbial content in foods can vary based on storage conditions, processing methods, and preparation techniques. Future research should explore these variables to better understand how different foods contribute to overall microbial intake.
Need for Longitudinal Studies
The NHANES study used cross-sectional data, meaning it analyzed health and diet at a single point in time. While the findings suggest a strong association, longitudinal studies are necessary to determine whether increasing microbial intake over time directly prevents frailty.
Future research should also investigate which specific strains of bacteria provide the greatest benefits. Different microbes may have varying effects on metabolism, inflammation, and immune function. Identifying the most effective strains could lead to more targeted dietary recommendations for older adults.
Role of Diet in Promoting Longevity
As the global population ages, maintaining health and independence becomes increasingly important. Frailty is a significant challenge, but dietary strategies may offer a practical way to support ageing individuals.
Live dietary microbes represent a promising tool for improving gut health, reducing inflammation, and enhancing resilience in older adults. Incorporating fermented foods into daily meals may help individuals maintain their strength, mobility, and overall well-being.
While more research is needed, the existing evidence suggests that simple dietary changes could have profound effects on ageing. A balanced diet that includes live microbes may not only help prevent frailty but also contribute to a longer, healthier life.
The study is published in the journal BMC Geriatrics. It was led by researchers from Fujian University of Traditional Chinese Medicine.
