A new study shows how intestinal bacteria can explain the highly praised benefits of the “Mediterranean diet”.
The Mediterranean diet is a broad and vague term that generally alludes to to the food consumed in Greece, southern Italy and parts of Spain. Unfortunately, that doesn’t mean eating a pepperoni pizza and a bottle of wine every night, but it does mean a rich diet in vegetables, fruits, vegetables, nuts, beans, cereals, grains, fish and unsaturated fats, such as olive oil. Eating these types of foods regularly has been associated with all kinds of positive health effects, especially for the heart and cardiovascular system.
In a new study, reported this week in the journal Nature Medicine, scientists argue that some of the health benefits of the Mediterranean diet may lie in the way the diet interacts with the intestinal microbiome.
The trillions of bacteria, viruses, protozoa and fungi that live in the human intestinal tract are much more than passive hosts. They are also known for play a central role in the metabolism, nutrition and immune function of our bodies, which can influence our general health and even our mood.
Researchers at the Harvard TH Chan School of Public Health analyzed the health and intestinal microbiome of more than 300 healthy men. In addition to collecting poop samples every six months for two years, they were also asked to complete a questionnaire about their diet. They found that those who adhered to a Mediterranean diet had a remarkably different composition of intestinal bacteria, that is, high concentrations of the main dietary fiber metabolizers, such as Faecalibacterium prausnitzii and Bacteroides cellulosilyticus.
In addition, the presence of a species of bacteria, known as Prevotella copri, revealed to have an especially interesting connection with cardiovascular health. The researchers found that people with reduced levels of P. copri seem to have experienced more positive effects of the Mediterranean diet on cardiometabolic diseases. In other words, people with little or no P. copri reap more benefits from the Mediterranean diet.
Researchers are not sure why P. copri seems to have that link, but they have some ideas. First, it may simply be that unhealthy diets, which increase the risk of cardiovascular disease, tend to promote the growth of P. copri. Alternatively, individuals who do not carry P. copri in the intestinal microbiome it can metabolize components of the Mediterranean diet more efficiently and effectively, obtaining more of its cardioprotective effects.
However, the exact nature of this relationship remains speculation for now. The researchers point out that their study was purely observational and they are limited in their ability to understand the underlying mechanism behind the patterns they observed. They also note that the interactions between the microbiome and the diet are extremely complicated. For example, many different subclades of P. copri can be found in different populations around the world, most likely due to differences in diet and lifestyle, and not all clades can interact with the Mediterranean diet in the way that we see here.
That said, this research is a good example of how new research is shedding light on the mechanisms that underlie the relationship between microorganisms that live inside us and diseases.