On paper we instinctively know that ultra-processed foods are not the best for your health. But why are they so bad?
Studying the effects of ultra-processed foods on the human body is a complicated undertaking. If you are overweight or unhealthy, you may indeed be affected in other ways. Nevertheless, more and more researchers agree that these foods influence the composition of our intestinal microbiota , those billions of bacteria that line our digestive system. These disruptions could indeed increase the risk of chronic diseases.
In recent years, they have been distinguished from processed foods. In the latter are added only salt, sugar or other common substances like oil or vinegar. Canned vegetables, salted nuts and seeds, canned sardines and tuna or cheese are examples.
Ultra-processed foods are products whose manufacture involves several stages and processing techniques . They are developed mainly from substances extracted from whole foods (oils, fats, sugar, starch, proteins) or synthesized in the laboratory. The idea:to create cheap, easy-to-consume, attractive and palatable food and beverages .
In other words, ultra-processed foods are products created from scratch in the factory . They are filled with chemicals and other additives giving them an artificial color, flavor, texture and shelf life. All these treatments increase the caloric density of these foods while eliminating fiber, vitamins and nutrients.
Chicken nuggets, soda, chips, snacks or prepared meals are examples. But there are many more. In reality, these products represent approximately 80% of the current supermarket offer .
Sugar, fats, salt, modified proteins, additives… With such a composition, it is difficult to determine exactly what, in these foods, can increase the risk of illness.
Researchers are increasingly interested in the intestinal microbiota insofar as diet is now considered to be the main determinant of its composition . They also agree that the more bacterial diversity there is in our intestines, the better our health.
Research in mice has already proven that a diet based on ultra-processed foods influences the microbial composition in a negative way. In one study, rodents fed a low-fiber, high-fat diet actually displayed a different microbiota from that of rodents fed the reverse diet.
During a study in humans, researchers also analyzed stool samples from people living in hunter-gatherer cultures, who do not consume ultra-processed foods. They then compared these samples with those of people living in industrialized countries. Hunter-gatherers were found to have a much more diverse gut microbiota .
There is also a link between diets high in ultra-processed foods and inflammation in the body. The latter, then in a defensive position, then finds itself more vulnerable to viruses and diseases .
A measure of inflammation is a blood marker called C-reactive protein (CRP) . Studies have in fact linked higher levels of CRP to various chronic diseases, such as cancer, arthritis, cardiovascular disease and diabetes. It also appears that those who eat a diet high in ultra-processed foods tend to have higher levels of CRP in their bodies.
In addition to generating less microbial diversity in our intestines, it also seems that the sugar in ultra-processed foods feeds "bad bacteria in the intestine. hail , underlines Marit Zinocker, main author of a study on the subject. And this is where the inflammation begins .
The many products added to these foods may therefore explain their negative influence. But let's not forget that "what's missing" can also play an important role. This is particularly the case for fibers, totally absent from these products .
We now know that fiber is metabolized or fermented by bacteria in the gastrointestinal tract. This process then produces short-chain fatty acids, which are important food sources for our bacterial communities. Eventually, when we don't consume enough fiber, we essentially starve our gut microbiota .
Of course, this is not without consequences. A lack of fiber can then affect the mucus layer in our intestines . This acts as a protective barrier against the outside world. In other words, it prevents pathogens from entering our intestines.
This mucus is constantly regenerated by the secretions of the cells that make up our intestines, and we know that it is covered with a layer of bacteria. If the latter are starved, then we weaken this natural barrier.
A study in mice also suggests that some of these bacteria, when hungry, can even attack this layer of mucus directly. “The hypothesis is that if we stop feeding fiber to the microbiota, bacteria will more frequently resort to digesting this mucous barrier to extract nutrients .
A weakened layer of mucus then promotes the risk of infection and disease .
Carlos Monteiro, professor of nutrition and public health at the University of São Paulo (Brazil), is one of the main actors who popularized the notion of ultra-foods. processed in 2009. In light of all these findings, the Brazilian today urges lawmakers to put in place ways to make unprocessed foods more accessible and affordable . It also calls for ultra-processed foods to be taxed more.
“We started to put in place measures to fight against tobacco even before we knew all the problems it could cause , did he declare. It should be the same with ultra-processed foods ". According to him, delayed action could cost a lot of human lives.
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