Anxiety, stress, mood swings, Maria Rescigno: «I’ll explain the gut-brain axis and the diet to protect it»

Any of us will have noticed it at least once in our life: when we are under stress or anxious even for some small event that makes us agitated, the very common stomach ache appears. As if mind and intestines were directly connected. But it is not just a trivial empirical observation without any scientific basis. Today science is managing to prove the existence of a real “connection axis between the intestine and the brain”. A communication channel regulated by intestinal microbiota, that is, the billions of microorganisms that live in our bodies. What does this mean? “That it is possible heal the intestines to heal the mind. And that it is even possible to prevent and treat brain diseases, from anxiety to depression, from sleep and mood disorders to schizophrenia, while preserving a healthy intestinal barrier”. In other words, with the diet. In short, by eating certain foods that are friendly to the intestine and by following a few rules, we can protect ourselves from the most common ailments of our age, such as anxiety, stress, mood swings. Scientist’s word Maria Rescignobetween leading international microbiota experts, professor of general pathology at Humanitas, where she directs the Unit of immunology of the mucous membranes and microbiota and is vice-rector with responsibility for research. Her field of research? The study of the mechanisms that regulate the interaction between the mind and the intestine. Author in 2020 of Microbiota, secret weapon of the immune systemis now going out to the bookstore with Brilliant microbiota (Vallardi, from 6 June), a guide to modulate the microbiota thanks to probiotics, postbiotics and fermented foods. And thus protect us from many neurological diseases.

The functioning of the gut-brain axis

“Many patients with inflammatory bowel disease, such as colitis and Crohn’s disease, or even with metabolic syndrome or non-alcoholic fatty liver disease, often suffer from anxiety and depression. In a completely specular way – writes Rescigno – patients with pathologies of the nervous system, such as neurodegenerative diseases, autism and schizophrenia, often suffer from intestinal disorders. Starting from this evidence, it has long been postulated that there was an axis of connection between the intestine and the brain. And so indeed it is. “In the intestine – he explains – there is a real second brain formed by a neuronal network – the enteric nervous system – which continuously receives impulses from the external environment and transfers them to the primary brain – the central nervous system”. In 2015 Rescigno and his study team identified a vascular barrier in the intestine (Gut Vascular Barrier, or GVB), which controls everything from the intestine to the blood vessels. In 2021, then, he discovered another barrier, this time in the brain, he said vascular barrier of the choroid plexus (Plexus Vascular Barrier, or PVB), a structure located in the deepest region of the brain (the cerebral ventricles). These discoveries have therefore highlighted an intestinal-brain vascular axis which is added to other pathways of interaction between the two organs, all in some way modulated by the intestinal microbiota. And here we are at the crucial point: because “it is we who, with our diet and our lifestyle, control its composition”. Moral: we can positively influence our mood at the table and even prevent or delay the development of neurological diseases. «A real revolution, destined to change the horizon of medicine and of the life of all of us – Rescigno is convinced -. And I had – and continue to have – the privilege of participating personally in this revolution».

Few animal fats

How to behave at the table, then? First rule: avoid a diet high in animal fat. «A diet with a high content of animal fats, especially if associated with a high level of simple sugars (such as, for example, glucose), creates a devastating cocktail for our intestines». We must therefore try to reduce animal-derived fats as much as possible, such as those contained in red meats and fatty cheeses. «This does not mean – explains Maria Rescigno – that we can no longer eat a slice of meat or a piece of cheese if we feel the desire, but that we limit our consumption to few times a weekalternating meat and cheese with other foods».

Lots of fiber and good fats

The fibre stimulate the development of good bacteria. «At the top of the list we find foods that contain inulin, such as i artichokes and chicory, and whole foods, such as bread and pasta made with wholemeal flours. In case of deficiencies or to help our microbiota a little faster, we can also take inulin as a food supplement. In the powder format, we can add it to our preparations, giving the dish new nutritional properties». Finally, let’s not forget theolive oil and omega-3sparticularly healthy for our cells and for those of the microbes that live there.

The Mediterranean diet is a concentrate of beneficial substances for the microbiota and for our health: complex carbohydrates, fibres, unsaturated fats, polyphenols and few animal fats or simple sugars. «But following the Mediterranean diet does not mean swelling with pasta». Rather privilege vegetables, fruit, wholemeal flours, legumes in combination with cereals (rice and peas, pasta and beans, spelled and chickpeas …), dried nuts. «Carbohydrates associated with the Mediterranean diet are predominantly complex, consisting of the starch contained in pasta, rice, potatoes or bread. If these foods are then left to coolas in the case of rice, pasta or potato salad, part of the starch is chemically modified and acquires a new structure that our enzymes are unable to digest: the so-called ‘resistant starch’ is formed‘, a real fiber, which also lowers the glycemic load of the food. In short, a double advantage!». Similarly, the bread obtained from sourdough following a long fermentation it transforms part of the complex carbohydrates into resistant starch, thus favoring the expansion of good bacteria.

Fermented foods…

Fermented foods are also excellent for the microbiota (such as yogurt, kefir, kimchi, miso), which have the second advantage of not generally causing stomach discomfort: «The gases that are produced during fermentation are eliminated with the preparation of the food itself, eliminating the root of the problems of bloating and flatulence».

…And the pre-fermented foods in the kitchen

The trick that Rescigno is studying? «Eating certain foods containing fermentable molecules causes the production of gas resulting in bloating, tension and very annoying abdominal pain. We often think of solving it by eliminating all or part of these fiber-rich foods, first of all vegetables and legumes, which instead would greatly help the proper functioning of the intestine”. So what to do? «At the Humanitas Hospital, together with the Gastroenterology unit directed by Professor Repici, we are conducting a clinical study which has so far led to very encouraging results. We provide patients with a range of in vitro pre-fermented foods such as beans or milk. This treatment ensures that the food does not ferment in the patient’s belly, avoiding the production of gas”. In other words, we can pre-ferment the legumes out of the belly, in the kitchen. It goes like this: take some already cooked beans (canned or glass jars are fine) and mix them with the homemade yoghurt, using a spoonful of yogurt for every 250 g of cooked legumes. In the yogurt maker leave the beans to ferment overnight (about 12-14 hours). “At this point the beans are ready to be eaten, forgetting swelling, pain, flatulence and digestive problems”. For the good of the intestine but above all of the brain.