As life expectancy is increasing around the world and exceeding that of all previous generations, ways must be found to stay healthy longer. Exercise and good diet are the more efficient ones. But research is now looking at the role our gut plays in the aging process.
A recent study found that a Mediterranean diet can change the microbiome composition, which improves the cognitive function, memory, immunity and bone strength.
The gut microbiome is a complex system made up of billions of microbes that live semi-permanently in our intestines. These microbes have evolved in parallel with humans and other mammals to attack indigestible ingredients such as inulin, arabinoxylan and resistant starches. They also help prevent the growth of pathogenic bacteria. It plays such an important role in our bodies that it is even associated with behavioral changes leading to anxiety and depression. But for other diseases such as type 2 diabetes and obesity, where the microbiome may partly explain the problem, other factors such as genetic inheritance and poor lifestyle habits are more important.
This microbiome is highly sensitive and can be altered by many factors, among which are diet, medications, genetic inheritance, and pathologies such as inflammatory bowel disease and irritable bowel syndrome.
Since our diet has such an effect on the intestinal microbiome, the possibility of using it to promote better health as we age should be investigated.612 people aged 65-79 from Great Britain, France, the Netherlands, Italy, and Poland were observed. Half of them were asked to adopt a Mediterranean diet for one year. This meant eating more vegetables, legumes, fruit, nuts, olive oil and fish, and eating less red meat, dairy products and saturated fats. The other participants continued to eat as usual.
The Mediterranean diet and gut Microbiome.
The study found that those who followed the Mediterranean diet had greater cognitive function and memory, as well as less inflammation and more bone strength. But what was really wanted to know was whether the microbiome was responsible for these changes.
Interestingly, but not surprisingly, the microbiome of the participants (before the starting of the study) varied according to their country of origin. This was likely due to their respective diets, as well as their place of residence. Indeed, the participants whose diets were already Mediterranean had an insignificant increase in the amount and variety of bacteria present.
However, when comparing the microbiomes of the participants before and after the diet, two groups of microbes were identified in the intestine: positive microbes that had increased following the Mediterranean diet and negative microbes whose numbers had decreased during the diet.
The positive microbes proliferated in the Mediterranean diet, while the negative microbes were unable to metabolize the diet or to compete with the positive microbes. The flourishment of the diet-positive microbes and the loss of the negative ones were associated with decreased fragility and inflammation in the body, as well as higher levels of cognitive function.
At the beginning of this study, many participants were showing symptoms of pre-brittleness – meaning that the strength and density of their bones was beginning to decline. It was observed that those who did not change their usual diet became weaker over the course of the year, while those who adhered to the Mediterranean diet were less fragile.
The association between fragility, inflammation and cognitive function with observed changes in the microbiome was greater than that observed with dietary changes. This suggests that diet alone would not be enough to improve these three markers. The microbiome would also have to change – and the diet caused these changes.
While the microbiome changes observed in this study were minimal, they were consistent across the five countries represented – and small changes over the course of a year can make a big difference in the long term.
Finally, we must recognize that the adoption of a Mediterranean diet is not always possible for all those who are beginning to consider ageing, generally around the age of fifty. It remains to be seen which key elements of a Mediterranean diet are responsible for the positive change in the microbiomes. In the meantime, it’s clear that the more you stick to a Mediterranean diet, the higher your levels of “good” bacteria will be to help you age healthily.