A major recent study shows that a diet high in saturated fat, simple sugars and salt causes an overactivation of the immune system, similar to that observed during a bacterial infection. Junk food is therefore perceived by the body as a real threat to fight, which creates an inflammatory response with disastrous effects on health, worse, the regular consumption of processed products modifies our genetic material.
One of the greatest upheavals in the history of human nutrition is the massive arrival on the market of a wide range of hyper-transformed products, overloaded with fat, simple sugars and salt. These industrial products are very attractive because they have been expertly formulated to take advantage of our innate biological attraction towards these substances and thus create a unique cerebral experience that encourages their consumption. The impact of this industrialization of food has been quite remarkable: while these products did not even exist barely a century ago, they currently account for around half of the total calories consumed in Western countries.
Unfortunately for us, what pleases our brain is not necessarily good for our health! Hyper-processed, high-calorie foods, junk foods in particular, are one of the main causes of the current obesity epidemic, and thus contribute to the burden of diseases that are associated with excess weight such as type 2 diabetes, cardiovascular disease and certain cancers.
Junk food perceived by the body as an infection
In addition to these longer-term adverse effects, a study recently published in the prestigious journal Cell suggests that junk food could also exert a very rapid negative impact on the body, this time by activating the immune response. After feeding mice for a month with a typical Western diet, that is to say rich in saturated fat, sugar and salt, but low in plants and fiber, German scientists observed a very significant increase in number of circulating pro-inflammatory immune cells in the blood. This response is similar to that triggered by a bacterial infection, ie it involves a structure called the inflammasome which plays an essential role in activating the inflammatory response. In other words, the junk food ingested by animals is interpreted by the immune system as a threat as serious as that posed by a pathogen!
Junk food reprograms our genetic material
Further analysis of the phenomenon revealed that the immune system even retains a memory of this aggression caused by junk food: the cells of the bone marrow of the mice, responsible for the production of immune cells, showed a reprogramming of their genetic material characterized by an overactivation of the genes that control the proliferation and maturation of these cells. In other words, exposure of animals to junk food leads to a profound and lasting change in the immune response, which causes sustained inflammation for long periods of time.
Processed diet: 44% risk of developing colorectal cancer
This reprogramming of bone marrow immune cells by junk food is very interesting, because it could explain the close link between Western diets and certain diseases such as atherosclerosis or colorectal cancer. In the latter case, for example, a study recently showed that men whose diet had the highest inflammatory potential (meats, cold meats, sugary drinks, refined flours) had a 44% greater risk of developing colorectal cancer than those whose diet was less inflammatory. In short, it is important to limit the consumption of processed industrial foods to a minimum, especially junk foods. Not only do these foods promote excess weight, but they are also toxic aggressors that generate a strong inflammatory response that can support the development of serious diseases.
Moubarac JC. Ultra-processed foods in Canada: consumption, impact on diet quality and policy implications. Montreal: TRANSNUT, University of Montreal; December 2017. (https://mma.prnewswire.com/media/615057/Heart_and_Stroke_Foundation_Time_to_curb_our_appetite_for_ultra_.pdf)
Christ A et al. Western diet triggers NLRP3-dependent innate immune reprogramming. Cell 2018; 172: 162-175.
Tabung FK et al. Association of dietary inflammatory potential with colorectal cancer risk in men and women. JAMA Oncol. 2018; 4: 366-373.