In a new study, researchers found that eating a Mediterranean diet for a year boosts the types of gut bacteria linked to ‘healthy’ aging, while reducing those linked to harmful inflammation in older people.
As aging is linked to deteriorating bodily functions and increasing inflammation, both of which herald the onset of frailty, this diet might act on gut bacteria in such a way as to help curb the advance of physical frailty and cognitive decline in older age.
The research was conducted by a team at the University College Cork and elsewhere.
Previous research suggests that a poor/restrictive diet, which is common among older people, 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 proliferation of bacteria associated with ‘healthy’ aging.
They analyzed 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, and specially tailored to older people.
The participants lived in five different countries: France, Italy, Netherlands, Poland, and the UK.
The team found sticking to the Mediterranean diet for 12 months was associated with beneficial changes to the gut microbiome.
It was linked to stemming the loss of bacterial diversity; an increase in the types of bacteria linked to reduced frailty, such as walking speed and handgrip strength, and improved brain function, such as memory; and with reduced harmful inflammatory chemicals.
More detailed analysis showed that the gut microbiome changes were linked to an increase in bacteria known to produce beneficial short-chain fatty acids and a decrease in bacteria involved in producing particular bile acids, overproduction of which are linked to a heightened risk of bowel cancer, insulin resistance, fatty liver, and cell damage.
What’s more, the bacteria that proliferated in response to the Mediterranean diet acted as ‘keystone’ species, meaning they were critical for a stable ‘gut ecosystem,’ pushing out those microbes associated with indicators of frailty.
The changes were largely driven by an increase in dietary fiber and associated vitamins and minerals—specifically, C, B6, B9, copper, potassium, iron, manganese, and magnesium.
And 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.
The team says older people may have dental problems and/or difficulty swallowing, so it may be impractical for them to eat a Mediterranean diet.
But the beneficial bacteria implicated in healthy aging found in this study might help develop a new method to ward off frailty.
The lead author of the study is Tarini Shankar Ghosh from the University College Cork.
The study is published in the journal Gut.
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