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NU-AGE MedDiet causes gut bacteria changes linked to improvements in cognitive function and memory, immunity and bone strength for healthy ageing

People are living longer than ever before so it’s important that we find ways of helping them live healthier for longer. While, exercise and diet are important for maintaining good health, recent research is beginning to look at the role our gut bacteria in how we age.

Paul O’Toole’s group have previously shown 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 found in the gut and helps to speed up the onset of frailty.

The latest NU-AGE study has found that eating a Mediterranean diet for a year causes microbiome changes linked to improvements in cognitive function and memory, immunity and bone strength.

This study involved 612 people aged 65-79, from the UK, France, the Netherlands, Italy and Poland. Half of the participants changed their normal diet to a Mediterranean diet for a full year. This involved eating more vegetables, legumes, fruits, nuts, olive oil and fish, and eating less red meat, dairy products and saturated fats. The remaining  participants stuck to their usual diet.

The study found that participants who followed the Mediterranean diet had a small but insignificant change in their microbiome diversity – meaning there was only a slight increase in the overall number and variety of species present.

However, two different gut microbe groups were identified amongst the Mediterranean diet cohort: diet-positive microbes that increased on the Mediterranean diet, and diet-negative microbes whose abundance was reduced while following the diet.

Diet-positive microbes were linked with less frailty and inflammation in the body, and higher levels of cognitive function. Diet-negative microbes either couldn’t metabolise the diet, or were unable to compete with diet-positive microbes. Losing the diet-negative microbes was associated with similar health improvements to the flourishing diet-positive microbes.

When the study compared the changes in the number of these microbes in those on the Mediterranean diet with the control, it found that the people who strictly followed the Mediterranean diet increased their diet-positive microbes.

And those who continued their regular diet became frailer over the course of the one-year study, whereas those that followed the Mediterranean diet were less frail.

The link between frailty, inflammation, and cognitive function, to changes in the microbiome was stronger than the link between these measures and dietary changes. This suggests that the diet alone wasn’t enough to improve these three markers. Rather, the microbiome had to change too – and the diet caused these changes to the microbiome.

Although the changes were small, these finding were consistent across all five countries – and small changes in one year can make for big effects in the longer term.

Further studies are required to narrow down what components of the Mediterranean diet are important for these microbiome changes so that food ingredients or supplements can be developed for people who may be too frail to pursue a Mediterranean diet.

Reference: 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. Gut https://gut.bmj.com/content/early/2020/01/31/gutjnl-2019-319654?rss=1

PHOTO courtesy of Tomas Tyner, UCC (left to right): Dr Tarini Ghosh, Ms Marta Neto and Prof Paul W. O’Toole, APC Microbiome Ireland and School of Microbiology, University College Cork

READ Paul’s article in The Conversation

LISTEN to Paul’s interview on RTE Drivetime (starts at 17.35)