Aging is often accompanied by the slowing-down of several bodily functions, or the presence of inflammatory conditions, all of which contribute to what is referred to as “frailty.” Frailty, in medical terms, is considered highly prevalent in old age.

It is characterized by disability and comorbidity. It may have a biologic basis and is recognized as a distinct clinical syndrome, with a heightened risk for poor health outcomes in the context of falls, incident disability, hospitalization, and mortality.

While a standardized definition has not yet been established, frailty is a state of increased vulnerability and decline in function across multiple physiologic systems.

A frail person will have all of these characteristics:

• Low grip strength
• Low energy
• Slowed walking speed
• Low physical activity
• Unintentional weight loss

Benefits of the Mediterranean Diet in the context of frailty

Since the Mediterranean diet has been beneficial to the gut microbiome in various situations and medical conditions, research has been conducted to see if it has any impact on frailty. The findings are quite encouraging.

Deterioration of bodily functions and an increase in inflammation both signal the onset of frailty. Moreover, older people, especially those in long-term residential care, happen to be on restrictive diets.

The research tested the theory that the Mediterranean diet might alter the gut microbial population in a manner that slows down the onset of physical frailty as well as the cognitive decline typical of old age.

One possibility might be that the diet is useful in retaining the population of the types of gut bacteria that can promote a more healthy aging curve.

The Mediterranean diet was tested on 612 “pre-frail” individuals aged between 65 and 79, in five European countries. Their gut microbiome was analyzed before and after 12 months of continuing their usual diet (in one group) versus a version of a Mediterranean diet full of fruits, vegetables, legumes, nuts, fish and olive oil devised to suit older people.

The findings were quite positive in favor of a Mediterranean diet:

• Beneficial changes to the gut microbiome
• Maintaining better levels of bacterial diversity
• An increase in types of bacteria associated with indicators of reduced frailty:
• Better walking speed
• Increased handgrip strength
• Improved brain function
• Sharper memory
• Decreased production of inflammatory chemicals.

On a microbial level, these changes were reflected by an increase in the population of bacterial types that produce important short-chain fatty acids (SCFA) and a decrease in the population of bacterial types known to produce certain harmful chemical compounds including carbon dioxide and bile acids.

Overproduction of such bile acids has been tied to an increased risk of insulin resistance, fatty liver, bowel cancer, and cellular damage.

An interesting additional finding was that the bacteria that became more abundant as a result of following the Mediterranean diet acted as “keystone” species, edging out the bacterial taxa associated with frailty indicators, and laying the foundation for a more stable gut ecosystem. These findings were stable across the group irrespective of age or body weight (specifically, their BMI).

The researchers emphasized that while these findings highlight the “three-way interplay” between diet, microbiome, and host health, the phenomenon is a complex one. Other factors, such as existing disease status and prior dietary patterns, may exert an influence.

The study also suggested some “candidate taxa” that warrant further investigation as live biotherapeutic agents that could be directly administered to older people, in an effort to slow down the onset of frailty.