Research & Innovation

Eating a Mediterranean diet for a year boosts the types of gut bacteria linked to ‘healthy’ ageing, while reducing those associated with harmful inflammation in older people, according to a five-country study by APC Microbiome Ireland, a Science Foundation Ireland Research Centre at University College Cork.

As ageing is associated with deteriorating bodily functions and increasing inflammation, both of which herald the onset of frailty, this diet might therefore be acting on gut bacteria to help curb the advance of physical frailty and cognitive decline in older age, suggest the researchers whose work has been published online in the journal Gut.

Previous research suggests that a poor/restrictive diet, which is common among older people, particularly those in long term residential care, reduces the range and types of bacteria (microbiome) found in the gut and helps to speed up the onset of frailty.

The researchers therefore wanted to see if a Mediterranean diet might maintain the microbiome in older people’s guts, and promote the retention or even the proliferation of bacteria associated with ‘healthy’ ageing.

They analysed the gut microbiome of 612 people aged 65 to 79, before and after 12 months of either eating their usual diet or a Mediterranean diet rich in fruits, vegetables, nuts, legumes, olive oil and fish and low in red meat and saturated fats, specially tailored to older people.

The participants, who were either frail, on the verge of frailty, or not frail at the beginning of the study, lived in five different countries: France, Italy, Netherlands, Poland, and the UK.

Sticking to the Mediterranean diet for 12 months was associated with beneficial changes to the gut microbiome.

It was associated with stemming the loss of bacterial diversity; an increased abundance of the types of bacteria previously associated with several indicators of reduced frailty, such as walking speed and hand grip strength, and improved brain function, such as memory; and with reduced production of potentially harmful inflammatory chemicals.

The findings were independent of the person’s age or weight (body mass index), both of which influence the make-up of the microbiome.

While there were some differences in the make-up of a person’s gut microbiome depending on country of origin to start with, the response to the Mediterranean diet after 12 months was similar and consistent, irrespective of nationality.

CAPTION:

Dr Tarini Ghosh, Marta Neto and Professor Paul W. O’Toole of APC Microbiome Ireland and School of Microbiology University College Cork. (Picture: Tomás Tyner).