Emulsifiers: Food additives that increase the risk of cardiovascular disease?

One of the most important changes in modern eating habits is the increasingly important place occupied by foods manufactured by the food industry, particularly those that are “ultra-processed”, i.e., that have undergone several industrial treatments intended to improve their appearance, taste, texture and shelf life. In several industrialized countries, and more particularly in North America, surveys show that more than half of daily calories come from ultra-processed foods, a proportion that can be as high as 67% among American children (Figure 1).

Figure 1. Comparison of the contribution of ultra-processed foods to the diet (as a % of daily energy) in different countries around the world. Adapted from Srour et al. (2022).

However, this popularity of ultra-processed foods masks a more worrying reality: numerous epidemiological studies report that high consumption of these foods is associated with an increased risk of several health problems, particularly cardiovascular ones, and premature mortality (Table 1).

Table 1. Examples of epidemiological studies reporting an association between high consumption of ultra-processed foods and an increased risk of cardiovascular disease, premature mortality (from cardiovascular causes or all causes), and various factors involved in the development of cardiovascular disease (obesity, hypertension, diabetes, depression). *HR= hazard ratio.

The mechanisms responsible for this increased risk of disease remain poorly understood but are likely linked to three main intrinsic characteristics of ultra-processed foods (Figure 2). The first is their lower nutritional quality: compared to fresh, unprocessed foods, ultra-processed foods generally contain much higher amounts of sugar, sodium or saturated fat (and often all three) while being essentially devoid of fibre and several micronutrients. Furthermore, the resulting higher energy density encourages overconsumption of these products, which can quickly lead to excess energy and weight gain. Ultra-processed foods also undergo several treatments that modify their organoleptic properties, particularly in terms of their texture. These modifications make them more attractive, which can also lead to overconsumption and generate certain potentially toxic products (acrolein, acrylamide, etc.). Finally, another characteristic of ultra-processed foods is that they contain several additives designed to improve their appearance and shelf life, both in the foods themselves (colourings, emulsifiers, stabilizers, etc.) and in the materials used for their packaging (phthalates, PFAS). All of these factors are known to favour the development of conditions that increase the risk of cardiometabolic diseases (obesity, hypertension, insulin resistance, etc.), and it is therefore possible that one or more of these factors contribute, at least in part, to the increased risk of chronic diseases and premature mortality observed in people who regularly consume ultra-processed foods.

Figure 2. Main characteristics of ultra-processed foods and their possible involvement in increasing the risk of cardiometabolic diseases. Note that a common characteristic of ultra-processed foods is to promote the overconsumption of food, whether due to their high calorie content (sugars, fats) or their organoleptic properties (appearance, taste, texture). Adapted from Touvier et al. (2023).

Food additives
Food additives are an extremely diverse class of chemical compounds that are absolutely essential to the formulation of ultra-processed foods, both to enhance the appearance, taste and texture of these foods (and thus to please the consumer), and to increase their shelf life (Figure 3). Several hundred additives with their own chemical, physical or biological properties are commonly used by industry: for example, an analysis of 126,556 food products available on the French market revealed that 54% of these products contained food additives, with more than 10% containing 5 or more.

Figure 3. Main classes of additives used by the food industry. Note that in the list of ingredients, additives appear either under their name or as a code starting with the letter E (for Europe) followed by 3 or 4 numbers corresponding to a class of additives (for example, food colours correspond to codes E100-199).

Most of these additives are considered to have no negative health effects and can even be considered beneficial since they improve food safety (e.g., antioxidants). Others, however, are more controversial: certain dyes, for example, have been singled out as responsible for hyperactivity in some children; sweeteners like aspartame or sucralose seem to disrupt glucose metabolism; certain preservatives such as nitrites have been associated with an increased risk of digestive cancers.

Emulsifiers are another class of additives whose effect on the human body currently raises many questions. These molecules are widely used by industry because of their ability to bind both fat and water (like a detergent), allowing them to give a smooth and homogeneous texture to ultra-processed foods (Figure 4).

Figure 4. Mechanism of action of emulsifiers. In the food industry, emulsifiers are used to create a mixture of two substances that are not miscible when brought together, for example, water and oil. The simultaneous presence of a portion with an affinity for oil (hydrophobic) and a portion that can bind to water (hydrophilic) allows emulsifiers to create suspensions of small fat droplets that disperse evenly in water, which are called colloids or, more commonly, emulsions. Adapted from the European Food Information Council.

However, the ability of these emulsifiers to dissolve fats could disrupt certain protective barriers whose function requires that they be insoluble in water. The layer of mucus that covers the surface of the intestine, for example, must remain intact to prevent hundreds of billions of intestinal bacteria from coming into contact with the bloodstream and causing uncontrolled activation of the immune system, which can lead to an inflammatory reaction. A study carried out in animal models suggests that this barrier could indeed be affected by the presence of emulsifiers, because the addition of small quantities of polysorbate 80 or carboxymethylcellulose to the diet causes inflammation in the intestine, as a result of bacterial infiltration through the mucus barrier, and these inflammatory conditions could promote the development of various pathologies, including colorectal cancer (Figure 5).

Figure 5. Pro-inflammatory effect of emulsifiers on the intestinal mucosa. A. Repeated exposure of the intestine to emulsifiers from ultra-processed foods (green circles) causes changes in the composition of the microbiota, with an increase in the proportion of pro-inflammatory bacteria (red). B. The production of certain molecules (lipopolysaccharides, flagellin) by these bacteria increases their mobility and their ability to migrate through the layer of mucus lining the mucosa. C. This movement is facilitated by the thinning of the mucus layer caused by the presence of emulsifiers and can lead to the penetration of bacteria into the mucous membrane. D. These phenomena lead to the activation of inflammatory pathways in intestinal cells, in particular those using the transcription factor NFkB. E. Activation of these pathways leads to the secretion of cytokines (TNF-α, IL-6) and the creation of an inflammatory climate. Adapted from Bancil et al. (2021).

Emulsifiers and cardiovascular disease
A recent study suggests that a high intake of emulsifiers could also increase the risk of cardiovascular disease. In this study, researchers analyzed in detail the intake of ultra-processed foods in a cohort of 95,442 healthy French adults (mean age 43 years) and examined the potential association between intake of emulsifiers from these foods and the incidence of cardiovascular disease (coronary heart disease and stroke) over the following seven years.

The study found positive associations between the risk of cardiovascular disease and the consumption of five specific emulsifiers, widely used in processed foods, namely cellulose (E460), carboxymethylcellulose (E466), sodium triphosphate (E339), and mono- and diglyceride esters of citric and lactic acids. Among the largest daily consumers of emulsifiers (nearly 10 mg per day), there was a small but significant increase of about 5% in the risk of cardiovascular disease.

Interestingly, the emulsifiers identified by the study that can potentially increase the risk of cardiovascular disease are known to exert inflammatory effects at the intestinal level. This is particularly the case for carboxymethylcellulose which, as mentioned earlier, increases intestinal permeability and the development of inflammatory bowel diseases in animal models. More recently, a study showed that the administration of this emulsifier for 11 days to human volunteers caused an increase in inflammatory markers and reduced the diversity of the microbiota compared to a diet without food additives. Given the crucial role of inflammation in the progression of atherosclerosis and the development of cardiovascular disease, it is therefore possible that the negative effects of these emulsifiers on the risk of these diseases are linked to the creation of a climate of chronic inflammation caused by a disruption of the intestinal microbiota.

Since these types of studies are, by definition, observational in nature, it is not possible to demonstrate a direct causal link between the consumption of emulsifiers and cardiovascular disease. For example, a high intake of emulsifiers may simply reflect a lower quality diet, high in ultra-processed foods and low in fresh foods like fruits and vegetables. But, regardless of the exact contribution of emulsifiers to the increased risk observed in the study, these results should remind us that the best way to maintain good cardiovascular health is to favour the consumption of “real” foods, particularly those of plant origin.