We are what we eat

The diet determines the composition of the intestinal flora, which in turn produces metabolites that cause epigenetic changes and determine the expression of our genes.

We are what we eat. An assertion attributed to the German anthropologist and philosopher Ludwig Feuerbach, seems to be gaining, at least in the field of health, a greater veracity. And there is no doubt that our intestinal flora is what we eat. And the composition of this bacteria that inhabit our intestines influences, much, our cognitive function or the risk of developing different diseases. But how do they do it? According to a study conducted by researchers at the University of Wisconsin, altering the expression of genes and thus the production of proteins.

The director of this research published in the journal Molecular Cell, explains, this is the first of a long series of studies to understand the connection between the intestinal flora and its influence on the health of the host. Specifically, the aim of this work was to observe how the intestinal microbiota influences the epigenetic programming of a variety of different host tissues.

The study carried out with an animal model analyzed the possible effect of diet on the composition of the intestinal flora. And what the results showed is that, as many previous research had pointed out, the quantity and variability of intestinal bacterial species differed largely in terms of diet, for example, the intestinal flora was ‘poorer’ in If the animals were fed a ‘western diet’, that is, low in complex carbohydrates and fiber and high in fat and simple sugars. When the host received a diet rich in complex polysaccharides of plant origin, fiber case, there was more food available for intestinal microorganisms, because unlike what happens with the Simple sugars, our cells can not use them. The results also showed the ability of the intestinal flora to alter the host epigenome in different tissues, mainly in the colon, liver and adipose tissue. And also, that animals fed a ‘western diet’ did not produce certain metabolites at the same level as those who were offered a healthier diet. These metabolites, such as short-chain fatty acids like acetate, propionate and butyrate, which are produced primarily from the fermentation of fiber by bacteria, can play an important role In some of the epigenetic effects we have observed in the tissues of mice.

But, exactly, what are these epigenetic effects? For alterations that, while not altering the DNA sequence, modify the way in which the genes contained in this DNA are expressed.

The next step was to analyze how the production of metabolites gave rise to epigenetic changes, for which the tissues of animals fed different types of diet were analyzed. And according to the results, the type of diet influences, much, in two types of molecular modifications – concretely, the acetylation and the methylation – that are carried out in the histones – proteins that bind to the DNA to form the chromatin Which, once folded, will give rise to the chromosomes.

The findings suggest a profound effect on the host at the level of chromatin alteration. And as a whole, this mechanism influences the health of the host itself through differences in gene expression. In short, a diet influences the composition of our intestinal flora, which in turn will produce metabolites that will cause changes in epigenetic patterns and, therefore, alter the expression of many of our genes.

But does the diet, whether through the intestinal microbiota, actually modify gene expression? To prove this, the authors used an animal model genetically modified to lack intestinal flora and fed it with short-chain fatty acids. And what they saw was that the tissues of the animals showed the same epigenetic marks as mice that, having enjoyed a healthy diet, had a rich and varied microbiota.

Logically, this study has been carried out with mice, so research with humans should be done to confirm the results. But already this is clear that the communities of microorganisms that inhabit humans also produce these short-chain fatty acids which are also found in the blood plasma of anyone. Therefore the effect of the diet will be the same.