Gianluca Ghilardi, Nutritionist Biologist, graduated in Biology applied to the Sciences of Nutrition at the University of Milan illustrates the ideal diet to nourish and strengthen the immune system.
It may seem bizarre, but our immune system originates from the intestine, the organ used for the absorption of nutrients. Inside the intestine there are about 100 billion bacteria called Microbiota with more than 1000 species and amounting to about 10 times the number of human cells. Numerous scientific articles highlight the interaction between the microbiota and the immune system.
To nourish ourselves it is not only necessary to consider the interaction between food and human being, but increasingly it is considered that food is metabolized and digested by intestinal bacteria and then transferred to our body; in essence, food first passes through bacteria and then passes through humans.
The intestine is not composed of a series of drawers that we can open and close at will by taking probiotics, prebiotics or antimicrobials and giving it the shape we would like. We cannot choose which microbes to increase or decrease, but the effect of what we eat and lifestyle will have a positive or negative effect on the entire ecosystem over time.
The "key" food for our Microbiota is fiber. Fibers are a heterogeneous group of substances that differ according to their structural, physical and chemical characteristics such as solubility, viscosity or being fermentable by the human microbiota. They are divided into soluble and non-soluble fibers. The latter can be found in legumes, vegetables and whole grains and are made up of cellulose, hemicellulose and resistant starches. Soluble fiber is found in fruits, vegetables, Psillium seeds and some cereals such as barley and oats. They consist of Pectins, Galactomannans, gums (such as guar gum), Beta-glucans and mainly Inulin. Inulin is a substance defined as a prebiotic that is a biochemical compound present in some plant foods such as oats, barley, bananas and artichokes that nourishes some beneficial species of our microbiota in the same way as beta glucans and pectins. The soluble fibers, therefore, are fermented by the Microbiota to short-chain fatty acids (acetic acid, butyric acid and propionic acid) which are very powerful modulators of the immune system underlying the intestine which is also a source of nourishment for intestinal cells.
Berries, grapes (and even wine for drinkers) and chocolate are very powerful modulators of the intestinal microbota, and therefore of the immune system; in fact, according to a study published in the British Journal of Nutrition , high doses of cocoa enhance the T-helper cells, a subgroup of lymphocytes, capable of improving the adaptation of defenses to changing infections.
As the last essential food for the health of the microbiota and therefore of the immune system, we could not fail to mention dried fruit . Dried fruit contains fiber, unsaturated fatty acids and polyphenols which, as known, can affect the composition of the intestinal microbiota and the general health of the intestine. The analysis of faecal samples revealed the presence of a similar richness in some bacterial species when following the diet with walnuts and the diet comparable in terms of α-linolenic acid content, an effect probably due, therefore, to the composition of fatty acids. Other studies show that the consumption of nuts significantly increases Clostridium, Dialister, Lachnospira and Roseburia species and significantly reduces Parabacteroides.
Garlic has been, since ancient times, one of the most faithful allies of the immune system, thanks to its antibacterial and anti-inflammatory properties. The high sulfur content counteracts bacterial growth and helps keep the intestine clean and healthy, while allicin has antimicrobial and antibiotic effects that significantly contribute to boosting the immune system .