When we eat spinach or salad, we chew and swallow without thinking. However, such a simple and apparently unimportant gesture triggers a truly fascinating chain reaction in our body that guarantees us well-being and health and that helps us understand that it is important to eat in a healthy and varied way, without excess of any food. But let's try to better understand the results of a recent scientific research published in The ISME Journal: Multidisciplinary Journal of Microbial Ecology by a team from the University of Vienna (Hanson et al, ISME, 2021).
When we eat, for example, spinach, hundreds of compounds enter our digestive tract. At this point these compounds are metabolized by the bacteria that make up the intestinal flora, the so-called gut microbiota. Well, all these reactions at the microbiota level determine our state of health. Unfortunately, nowadays we have just begun to study the microbiota and little is known about the metabolic processes that affect many of these intestinal bacteria. That is, we don't know what these bacteria eat and what by-products they release.
The anti-inflammatory properties of a small bite of spinach
Precisely to shed more light on this aspect, the Austrian researchers have tried to understand what happens when you eat spinach and, in particular, what happens to a compound contained in spinach, the sulfoquinovose, a sugar that is also found in lettuce and other leafy green vegetables. By analyzing biological samples, scientists were able to state that, while glucose feeds a large number of bacteria in the microbiota, sulfoquinovose instead stimulates the growth of only certain types of bacteria, such as Eubacterium rectale. This bacterium is one of the ten most common bacteria in the microbiota of healthy people and produces butyrate, which is an anti-inflammatory substance capable of increasing the intestine's defenses against pathogens. Not only that, Eubacterium rectale is also less present in the case of diseases that affect the intestinal tract such as Crohn's disease or ulcerative colitis, making it clear that its presence is therefore connected to a healthy state of the gut. But that's not all. In fact, this bacterium, feeding on sulfoquinovose, produces another substance, a sulfur compound called DHPS.
The difference is in the dose
Well, DHPS is an energy source for other bacteria in the microbiota, such as Bilophila wadsworthia, which in turn, in its metabolic mechanisms, produces hydrogen sulfide. This substance, when present in small quantities, is beneficial and protects the gut and the body from inflammation. On the other hand, when its presence is increased, such as in case of a diet that is not varied and too rich in meat, a food linked to an excessive presence of hydrogen sulphide, can on the contrary trigger chronic inflammation.
The importance of a varied diet
Here, what determines whether a food is beneficial or not is the quantity in which that food is eaten. Indeed, a varied diet that includes little meat and a regular intake of all types of vegetables, also of leafy greens among others, guarantees, without excess, the intake of the compounds that give balance to the gut microbiota.