Half the participants were asked to eat more vegetables, legumes, fruits, nuts, olive oil, and fish – and less red meat and dairy.
Since our everyday diets have such a big affect on the gut microbiome, our team was curious to see if it can be used to promote healthy ageing. We looked at a total of 612 people aged 65-79, from the UK, France, the Netherlands, Italy and Poland. We asked half of them to change 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 other half of participants stuck to their usual diet.
We initially found that those who followed the Mediterranean diet had better cognitive function and memory, less inflammation, and better bone strength. However, what we really wanted to know was whether or not the microbiome was involved in these changes.
Many of the participants were also pre-frail (meaning their bone strength and density would start decreasing) at the beginning of the study. We found the group who followed their regular diet became frailer over the course of the one-year study. However, 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.
Future studies will need to focus on what key ingredients in a Mediterranean diet were responsible for these positive microbiome changes. But in the meantime, it’s clear that the more you can stick to a Mediterranean diet, the higher your levels of good bacteria linked to healthy ageing will be.