We are what we eat, how many times have we read or heard this sentence. And today we have confirmation of it. In fact, as demonstrated by a very recent scientific research published in the prestigious journal Nature thanks to the collaboration between Harvard Medical School in Boston, Seoul National University and the Australian Monash University, diet influences the intestinal microbiota that in turn influences the immune system, regulating the inflammatory response (Sungwhan et al, Nature, Nov 2021).
Immune system and inflammation
For the first time, scientists have been able to understand the mechanism that links nutrition, gut microbiota and immune response. This discovery will also pave the way for new medicines capable of regulating the immune system, treating inflammatory conditions, such as ulcerative colitis, and also avoiding excessive inflammation. In fact, inflammation is the way our body responds to a threat, it is therefore a defense mechanism. However, if this defense is excessive and the inflammation is out of control, this is harmful to the body itself and increases the risk of clot formation.
The link between diet and immune defenses
The study was carried out on animals which were given foods containing a particular type of amino acid, the branched chain amino acids. The branched chain amino acids are leucine, isoleucine and valine (which you can find, for example, in Parmesan, tuna, salmon, pine nuts, cashew, almonds, walnuts, eggs, soy, lupins, lentils and pumpkin seeds), and they are named so because they have a branched structure. Well, the researchers were able to observe the process triggered by these amino acids. One of the bacteria that populate the gut microbiota, Bacteroides fragilis, captures these amino acids and converts them into other molecules, which in turn activate APC cells, or antigen presenting cells. These cells induce natural killer T cells, or NK T cells, of the immune system to go into action. These NK T cells, in addition to counteracting viral infection and promoting the clearance of viruses from the body, also play a role in regulating the immune response. In particular, they are able to avoid an excessive inflammatory response by acting on the genes that control inflammation. Here is another proof that what we eat determines how our body will react to an external threat.
How diet can help counteract excessive inflammation
Finally, scientists have also tried to treat animals with ulcerative colitis with the same molecules produced by B Fragilis bacteria starting from branched amino acids. Well, the inflammation was counteracted and the animals were also able to gain weight, compared to those who did not receive treatment with these molecules. Therefore, this fascinating research paves the way for the future development of medicines to treat inflammatory diseases.