A high contribution in rich foods in saturated fat, like those typical of junk food, disturbs the immune system of the intestine and very quickly causes the development of inflammatory conditions.
Chronic inflammation has become one of the main health problems, not only because of its involvement in various inflammatory diseases (rheumatoid arthritis, ulcerative colitis, Crohn’s disease), but also because it contributes to the development of all chronic diseases that currently affect the population (ischemic heart disease, brain vascular accidents, cancer, type 2 renal, non-alcoholic hepatic steatosis and autoimmune and neurodegenerative diseases)1.
Although certain genetic factors can predispose to some of these inflammatory diseases, the sharp increase in several of these pathologies in recent decades necessarily imply that external factors, associated with lifestyle, accelerate their development.
Intestinal barrier
One of these factors is certainly modern industrial food, rich in fat, sugar and additives such as emulsifiers.
On the one hand, the too high calorie intake of this type of diet increases the risk of obesity, a condition which is in itself pro-inflammatory.
On the other hand, this type of food is also recognized to disturb the mucus barrier which protects intestinal cells and could therefore deregulate the activity of the immune system located throughout the intestine (around 75% of all of our immune cells reside within the digestive system, which shows how crucial is crucial).
Pro-inflammatory fatty
A recent study shows that this disturbance of the intestinal barrier by a high fatty intake occurs and is much faster than you might have thought2.
The researchers observed that the inclusion of saturated fat to the food of animal models caused in less than 48 hours a marked disruption of ILC3 (innate lymphoid cells of type 3), a type of immune cells present in the intestine which play an essential role in the control of adaptive immunity and defense against pathogens.
This loss of function is associated with a marked debaling of the type of bacteria present in the intestine (dysbiosis) and an increase in the permeability of the intestinal barrier caused by a loss of production of interleukin 22 (IL-22), a molecule involved in the production of mucus.
The slimming of this protective barrier then promotes the translocation of pathogenic bacteria in the blood circulation, which creates conditions conducive to the development of inflammation.
Fatty sources
An interesting point of the study is to show that this pro-inflammatory effect of saturated fat is not at all observed for unsaturated fats, those present in oils of plant origin.
On the contrary, these fats stimulate the production of IL-22 and therefore contribute to maintaining the protective function of the mucus barrier.
This is a good example that it is not necessarily the amount of fat in the diet that matters, but especially the type of fat that is consumed.
The Mediterranean diet, for example, is very rich in fat (up to 40% of calories in certain regions), but these fats mainly come from olive oil and are therefore unsaturated. Far from being harmful, this high intake of unsaturated fats is on the contrary recognized as one of the main factors responsible for the marked decrease in the incidence of several chronic diseases (cardiovascular diseases, in particular) observed in people who adopt this mode of food.
References
1Furman F et coll. Chronic inflammation in the etiology of disease across the life span. Night with. 2019; 25: 1822-1832.
2Xiong L et coll. Acute exposure to high-fat diet impairs ILC3 functions and gut homeostasis. Immunity 2025; 58: 1185-1200.e8.
