Food additives, while enhancing taste and appearance, may pose significant health risks, according to research led by ERC grantee Mathilde Touvier. Touvier is investigating the complex mixtures of chemicals in ultra-processed foods to understand their potential role in increasing the risk of diseases such as cardiovascular diseases and cancer. Her work aims to provide critical data for evidence-based food safety policies.

Ultra-processed foods, including savory snacks, pre-packaged meals, sausages, and certain breakfast cereals, often contain additives like nitrates and titanium dioxide—substances more commonly associated with chemistry labs than dinner plates. “Such products, on average, have a lower nutritional quality and contain more salt and fat,” Touvier notes. “Most importantly, they are generally full of food additives such as sweeteners, dyes, or emulsifiers that help maintain a smooth texture and flavor. Besides, the industrial process itself, sometimes with high temperatures, can produce toxic substances like acrylamide, acrolein, and furan.”

The ADDITIVES project, spearheaded by Touvier, seeks to elucidate the relationship between food additives and health risks. Central to this research is the NutriNet-Santé cohort, the world’s largest ongoing web-based study on dietary behaviors and health. Since its inception in France in 2009, the cohort has tracked the food intake of 173,000 adults through regular online dietary records, documenting everything participants consume over 24-hour periods at six-month intervals.

“We have collected very detailed information over a period of 13 years, not just about the quantities of products participants have eaten but also of which brand,” Touvier explains. “This is important because, depending on the brand, a chocolate cookie, for instance, may have very different compositions of food additives. Also, when we eat ultra-processed food, we do not just eat one type of artificial sweetener or other additive, but often mixtures that may have synergistic or antagonistic interactions.”

Researchers found that higher consumption of ultra-processed foods correlates with an increased risk of several chronic diseases, with food additives being a primary hypothesis for these associations. “No one escapes food additives, but some people consume significantly higher amounts,” says Touvier. The study tries to avoid influencing participants' eating habits and considers various potential confounding factors, such as physical activity and smoking. This allows researchers to correlate spontaneous dietary patterns and additive exposures with chronic disease incidence during follow-up.

One significant finding linked higher consumption of artificial sweeteners with an increased risk of cancer and cardiovascular diseases. Additionally, exposure to nitrates and nitrites in processed meat was associated with a higher risk of cancers, particularly breast and prostate cancers.

While these findings are significant, Touvier acknowledges that other unknown factors may have influenced the results. She notes that while randomized controlled trials would ideally complement these findings, ethical considerations prevent administering potentially harmful additives to participants. Therefore, the evidence must rely on multiple observational studies and mechanistic data.

In parallel with observational studies, Touvier is exploring the biological mechanisms behind the associations between additives and health. Experimental research with partner teams transposes exposure to food additive mixtures observed in cohort participants to in vitro and animal models. This allows examination of their impact on the gut barrier, genotoxicity, and other parameters not testable in real life.

One hypothesis involves emulsifiers, which help mix incompatible processed food components. “Emulsifiers appear to allow toxic bacteria to invade protective mucus layers and enter the digestive system,” Touvier explains. “This, in turn, causes inflammation as the body’s defenses mobilize to destroy them. Emulsifiers may also disturb natural bacteria in the digestive system.”

Researchers will analyze five biomarkers in blood and urine samples to understand additives' exact impact. They aim to determine if the link between additive exposure and disease is mediated by increased inflammation. Metabolomic analysis will investigate metabolic disturbances associated with additive exposure. Additionally, fecal material analysis will assess the effects of additives on beneficial digestive bacteria, oxidative stress, and metabolic disturbances.

The ADDITIVES project has the potential to generate crucial data for evidence-based guidelines and legislative measures. Touvier advocates for nuance in the debate. “There are more than 330 food additives authorized on the European market, and probably, many of them do not have an adverse effect. Therefore, not all substances should be treated the same way. For public health, it is important to distinguish between additives that may have adverse effects but are beneficial for food preservation or microbiological safety, and those that are potentially harmful without any expected health benefit. If the food industry wants to make beautiful products and uses inoffensive additives: why not, as long as consumer safety comes first.”