Effects of Ultra-Processed Foods on Gut Microbiota and Health

Several studies have shown a potential link between ultra-processed foods (UPFs) and chronic inflammation.His 1 recent review published in The Lancet Gastroenterology and Hepatology We describe the mechanistic links between UPF intake and chronic diseases, especially those involving the gut microbiota.

Investigation: Ultraprocessed Foods and Human Health: From Epidemiological Evidence to Mechanistic Insights. Image credit: Dawid Rojek / Shutterstock.com

study: Ultraprocessed foods and human health: from epidemiological evidence to mechanistic insights. Image credit: Dawid Rojek / Shutterstock.com


Over the past centuries, many techniques have been developed for processing food in order to preserve it and enhance its taste and digestibility. Modern industrially processed foods take advantage of the availability of salt, sugar, vegetable oils, animal fats, and flour.

The manufacture of these products typically utilizes mechanical and physical techniques such as roller milling, extrusion, and pressure rendering, as well as chemical techniques such as hydrogenation. Artificial flavors, preservatives, anti-caking agents, and other additives are also used to achieve the final desired texture, color, and taste of these foods.

These technologies enabled the mass production and manufacturing of mass-produced processed foods that were available year-round.

These highly processed foods are typically hygienic, convenient, affordable, and readily available, making them an ideal product for many high-income countries (HICs). Recently, low and middle income countries (LMICs) have also increased their dependence on these foods.

Consistent with this trend, the number of chronic inflammatory cases such as metabolic syndrome and inflammatory bowel disease (IBD) is increasing. The current paper explores the evidence for a correlation between contemporary His UPF and chronic diseases mediated by the gut microbiota.

Type of processed food

There are several classification systems used to describe foods based on their processing. The most commonly used is NOVA, which classifies foods into groups 1 through 4.

Group 1 includes unprocessed or minimally processed foods such as fresh, chilled, dried, frozen, fermented and pasteurized foods. Group 2 consists of processed ingredients such as vegetable oils, sugar, salt, butter, or other food extracts added to Group 1 foods.

Group 3 includes all typical processed foods such as salted canned foods, candied dried fruits, cured meats, cheeses and fresh bread. In other words, Group 3 represents Group 2 products added to Group 1 foods.

Group 4 includes UPFs that have undergone one or more of the aforementioned industrial processes. These may contain non-domestic ingredients such as those used in flavors, colors, sweeteners or emulsifiers.

UPF intake increases HIC, accounting for up to 30%, 50% and almost 60% of caloric intake in France, UK and US respectively.

Survey results

Nearly 50% of the 100 prospective studies analyzed in the current study investigated associations between UPF and various health or mortality outcomes.


Seven studies showed an association between UPF and all-cause mortality, with a 20% to 60% increased risk in the highest UPF intake category compared to the lowest. Five studies showed an increased risk of illness and death from cardiovascular disease and stroke. Four studies showed he had an increased risk of type 2 diabetes, while one reported an increased risk of gestational diabetes.

high blood pressure

Four studies reported an increased risk of hypertension by up to 30%, one study reported cancer risk, and several studies reported overweight and obesity. Many of these studies also reported associations with increased body weight, waist circumference, and serum lipid levels in children.


In the 2021 Prospective Urban Rural Epidemiology (PURE) study, UPF intake was associated with a higher risk of IBD, specifically in Crohn’s disease, but not in ulcerative colitis. Intake has been associated with increased risk of depression, abnormal lipid levels, decreased renal function, and fatty degeneration of the liver.

weight gain

A short-term randomized intervention trial is currently being conducted, assigning UPF and unprocessed food to different cohorts for a short period of time. Following this, the researchers observed that in the UPF group he averaged an increase in energy intake of over 500 kcal per day and an average weight gain of 0.8 kg. Conversely, the unprocessed food cohort reported weight loss of >1 kg on average.

Mechanism of chronic inflammation by UPF

There are a number of mechanisms that may result from the weight gain and chronic inflammation observed with higher UPF consumption. One example is the low nutritional value of many UPFs.

According to the French Open Food Facts database, only one-fifth of UPFs had higher nutritional scores. continue to demonstrate relevance, therebyFactors Beyond Nutrition Play a Role

Another issue is the presence of potentially toxic substances in the UPF, such as polycyclic aromatic hydrocarbons, furans, end-products of saccharification, trans fatty acids from hydrogenation of fats, and acrylamide from high-temperature cooking of starchy foods. That’s it. The latter chemical is found in common foods such as French fries, potato chips, and biscuits, whether home-made or industrially made. However, these industrial products often have high levels of acrylamide.

Other contaminants such as phthalates, bisphenols, mineral oils and microplastics can leach from packaging into food, especially if the food remains in contact for an extended period of time. This can occur with foods that can be stored for a long time.

Ready-to-eat meals are usually UPF and require microwave heating. This can lead to accelerated bisphenol leaching from polycarbonate packages and increased acrylamide formation.

The consequences of such exposure are unknown. However, previous studies have suggested associations with cancer, cardiovascular disease, insulin resistance, type 2 diabetes, obesity, and endocrine abnormalities.

Another issue is the structural changes that processing causes to various components of food. This can affect bioavailability through changes in digestibility, satiety, eating speed, and chewing, all of which may contribute to increased UPF energy intake. This area is very under-researched.

Over 300 food additives are permitted in Europe, some of which may be involved in chronic inflammation, possibly through their effects on the gut microbiota. Groundbreaking research has established that dietary patterns influence the gut microbiota profile, which can alter host metabolism and promote obesity.

Gut bacteria are often able to ingest and process simple sugars when exposed to a high-fat diet. Gut stressors include certain food colors, emulsifiers, artificial sweeteners, E171 ( including nanoparticles such as titanium dioxide).

These additives not only alter the proportions of key bacterial genera in the gut and affect the protective mucosal layer and the expression of key defense molecules such as β-defensins, but also the ability of microorganisms to reach the sterile zone of the mucosa. This causes endotoxin accumulation and subsequent methane inflammation and IBD.

At the same time, the altered molecular profile promotes increased energy extraction from the ingested food, leading to metabolic dysregulation and obesity.

This links calorie extraction from the food eaten to diet-induced metabolic abnormalities. This dysregulated metabolism is characterized by mild inflammation and altered gut microbiota. The result is leakage of bacterial products such as lipopolysaccharide (LPS) from the gut into the host system.

LPS from the cell walls of Gram-negative bacteria contains lipid A, a molecule that crosses the intestinal mucosa. When Lipid A reaches the blood, it can cause inflammation in various target tissues such as the liver and body fat deposits.

This cycle is called “metainfrastructure”. Metainflammation can be defined as a metabolic inflammatory state defined by low-grade chronic inflammation generated by metabolic cells and stress sensors.

This suggests the need for interventions in UPF intake to produce beneficial changes in the gut microbiota that promote the production of ‘good’ bacterial metabolites through appropriate gene expression by intestinal mucosal cells. These include anti-inflammatory short-chain fatty acids (SCFAs).


The findings highlight the need to improve our current understanding of how food processing affects human health. Large-scale studies are needed to identify the components that are causally associated with methamin inflammation and obesity.

Public education is also essential to support consumption of healthier foods, preferably those with minimal processing and no additives. Such dietary choices are emphasized by the Food and Agriculture Organization (FAO) recommendations and by several national dietary directives.

Using financial incentives, legislation, and instruments such as mobile phone applications that provide evidence of food choices, federal policy must shift toward prioritizing the production and distribution of healthy, high-quality food. there is.

Governments and the food industry should cooperate in efforts to establish policies that promote a healthier food environment for consumers to effectively combat the increasing incidence of chronic inflammatory conditions.

Journal reference:

  • Srour, B., Kordahi, MC, Bonazzi, E., and others. (2022). Ultraprocessed foods and human health: from epidemiological evidence to mechanistic insights. The Lancet Gastroenterology and Hepatologydoi:10.1016/S2468-1253(22)00169-8.

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