Some of the most widespread food additives promote the occurrence of cancer

Since ultra-processed foods have flooded supermarket shelves, the quantities of additives have gradually exploded on our plates. Among them, emulsifiers which improve the texture and flavor of food products while extending their shelf life. They are found in biscuits, industrial desserts, fats (crème fraîche, margarine, etc.) and even prepared meals. They even hide in some seemingly “healthy” products such as yogurt and some breads. Since they are approved for food use, these emulsifiers have permeated our food for a long time without anyone suspecting their possible harm to health.

However, in recent years, several suspicions have begun to emerge in studies. Certain emulsifiers are particularly involved in chronic inflammation of the intestine in animals. In humans, they are suspected of promoting cardiovascular diseases. While the evidence of their harmfulness is increasing, French researchers grouped within the nutritional epidemiology research team (Cress-Eren), suggest that their chronic consumption could promote the development of cancers.

The results published in PLOS Medicine are based on the analysis of health data from 92,000 adults who were part of the NutriNet-santé cohort. Between 2009 and 2021, participants regularly reported the food products and drinks they consumed using questionnaires. Based on laboratory dosages of these products, the team estimated the average quantity of emulsifiers ingested daily by each participant. Using statistical approaches, the researchers then evaluated the link between these intakes (high, intermediate or low) and the occurrence of cancers.

A total of 2,604 people were diagnosed with cancer during follow-up. Out of around thirty additives tested, three emerged as potential contributing factors: monoglycerides and diglycerides of fatty acids, called E471, and carrageenans (E407 and E407a). “These additives are very common in sauces, cream desserts, flavored yogurts, industrial biscuits and cakes and even certain soups. They serve as texturing agents to give a homogeneous appearance to the products,” explains Mathilde Touvier, research director at Inserm in nutritional epidemiology who led this study.

Generally speaking, participants who consumed the greatest quantity of the E471 additive had a 15% higher risk of cancer compared to the lowest consumers. This risk was increased by 24% for breast cancer and 46% for prostate cancer. The other two additives (E407 and E407a) were associated with a 32% higher risk of breast cancer. “A strong point is that they took into account most of the “classic” risk factors that could have interfered with the results such as age, sex, smoking, physical activity or even family history,” underlines Mathilde His, researcher in the Environmental Cancer Prevention department at the Léon Bérard Center in Lyon. This raises concerns because the incidence of breast and prostate cancers, the most common in the general population, has continued to increase since the mid-20th century. And this concomitantly with the advent of processed foods.

Also read: What should we remember about the links between nutrition and cancer?

For the moment, scientists do not know how these additives could act, nor why they are more associated with certain cancers. “They could present different modes of action depending on their properties but also the type of cancer,” suggests Benoît Chassaing, specialist in chronic inflammatory diseases and co-author of the study. “We also do not know whether the additives act alone or in combination through a cocktail effect that is more complex to study,” he adds.

In animals, a study had already pointed to an increased risk of colorectal cancer linked to the consumption of polysorbate 80 (E433) and carboxymethylcellulose (E466). The authors then suggested that these emulsifiers could alter the composition of bacteria in the digestive system, which would promote chronic tissue inflammation. According to the work carried out by Dr Chassaing's team, this lead in favor of an imbalance in the "intestinal microbiota" could also apply to humans. “In a human trial, we showed that doses much higher than average of the additive E466 modify the composition of the microbiota linked to an increased capacity to induce inflammation of the intestine,” explains the Professor Chassaing. “However, this inflammatory terrain is conducive to the establishment of cancers. » For scientists, it is therefore likely that this local mechanism observed in the intestine extends more generally to other organs.

So should we eliminate emulsifiers altogether? The authors remain cautious because this work reflects at best an association between the development of cancer and the consumption of additives, without demonstrating a clear cause and effect link. “This is the first study to quantify exposure to additives and its association with cancer. We are therefore at an early stage of research and further work is necessary,” insists Mathilde Touvier.

This nevertheless gives food for thought, especially since the same authors had already established a link between the consumption of these additives and an increased cardiovascular risk. Since 2019, the national Health Nutrition program has also recommended favoring the use of “raw products, not or minimally processed”, limiting the consumption of non-essential additives. “This is an important aspect of prevention because we know that ultra-processed foods rich in fats or sugars promote obesity, itself associated with an increase in the risk of numerous cancers through various known or suspected mechanisms, such as “chronic inflammation,” adds Mathilde His. An update of the safety assessment of certain additives could therefore be initiated in the coming years.