Diet plays a crucial role in our overall and microbiome health, and the elderly are particularly vulnerable to suffering age-related health complications which could be related to changes in their diets.
Unfortunately, aging is associated with increased inflammation and a deterioration in multiple body systems which can lead to frailty. Frailty has also been linked to low cognitive function, muscle loss, and chronic diseases like diabetes.
Many elderly people have restricted diets due to chewing and swallowing problems, reduced saliva production or other health reasons which can lead to low microbial diversity of the gut microbiota composition, which is a marker of health. On the other hand, adhering to a Mediterranean diet, which is predominantly plant-based and emphasizes plenty of vegetables, fruits, legumes, whole grains, nuts, olive oil and a balanced consumption of red meat and dairy products and saturated fats, has been associated with overall good health and beneficial changes to the gut microbiota including an increase in bacteria that have been positively associated with lower frailty and improved cognitive function in the elderly population.
Scientists from 8 different countries combined forces and investigated how diet affects the gut microbiome and frailty in a European elderly population. They analyzed the gut microbiota from 612 pre-frail and non-frail people aged 65-79 from different European countries (Poland, Netherlands, UK, France and Italy) before and after following a Mediterranean diet for 12 months. Frail and pre-frail subjects were categorized depending on various criteria including weight loss, low physical activity, and weakness.
The researchers discovered that following a Mediterranean diet positively impacted the gut microbiota which was associated with lower inflammation and frailty and improved cognitive function.
Prior to adopting a Mediterranean diet, the subjects showed clear differences in gut microbiota compositions, likely due to differences in fiber, fat, vitamin and mineral intake. However, upon following a Mediterranean diet, the subjects showed similar gut microbiomes that had undergone clear shifts, which the authors attribute to an increase in fiber, vitamin and mineral intake, compared to the individuals in the control group whose changes were associated with increased fat consumption.
The researchers discovered that following a Mediterranean diet positively impacted the gut microbiota which was associated with lower inflammation and frailty and improved cognitive function
The Mediterranean diet group also had increased amounts of beneficial bacteria that produce the anti-inflammatory metabolite short chain fatty acids, and increased adherence to this diet was associated with more microbial diversity. On the other hand, the control group showed higher levels of bacteria that are associated with colorectal cancer and type 2 diabetes and other inflammatory diseases as well as gut bacteria-derived inflammatory metabolites.
In conclusion, following a Mediterranean diet long-term, with plenty of plant based foods, leads to a higher consumption of fiber, whole grains, polyunsaturated fats and vitamins and decreased consumption of saturated fats, alcohol, sodium and sugar which confers positive effects for the gut microbiome. One of the most notable positive changes in the gut microbiome composition following a Mediterranean diet for a year, included an increase in beneficial bacteria capable of producing anti-inflammatory metabolites.
Although age, body mass index and disease status indeed play a role in shaping the gut microbiome, diet likely plays a major role in determining how these factors interact with each other and affect health. Despite these promising findings, it is important to note that adhering to a Mediterranean diet is not necessarily possible in all countries where certain key ingredients are not available or not available year-round. Moreover, it should be considered that this diet may not be a realistic option for elderly patients who have trouble swallowing, reduced saliva production or irritable bowel syndrome.
Overall, this study shows promising results for following a Mediterranean diet in the elderly population to ensure a healthy gut microbiome and for preventing frailty.
Ghosh TS, Rampelli S, Jeffrey IB, et al, Mediterranean diet intervention alters the gut microbiome in older people reducing frailty and improving health status: the NU-AGE 1-year dietary intervention across five European countries. BMJ Gut; 2020: 69(7).