Food additive emulsifiers: a new risk factor for type 2 diabetes?

Type 2 diabetes is a major public health concern globally. Recent estimates reveal that more than 529 million people worldwide are living with diabetes (>90% have type 2 diabetes), with a projection of 1·31 billion cases by 2050.¹ Although the causes of type 2 diabetes are multifaceted, suboptimal dietary intakes play an important role.² Among various unhealthy dietary components, ultra-processed foods have emerged as a major risk factor for type 2 diabetes.³ However, the mechanisms underlying this association are not yet fully understood.

In light of recent evidence on dysbiosis and inflammation,^4,5 one intriguing hypothesis is that food additive emulsifiers, commonly used in ultra-processed foods to improve texture and shelf stability of processed foods, might play a role in the development of type 2 diabetes. In The Lancet Diabetes & Endocrinology, Clara Salame and colleagues⁶ delved into the relationship between exposure to food additive emulsifiers and the risk of type 2 diabetes by analysing data from a cohort of 104 139 adults from NutriNet-Santé, a large prospective cohort study conducted in France. Positive associations with type 2 diabetes were observed for total carrageenans, carrageenans gum, tripotassium phosphate, acetyl tartaric acid esters of monoglycerides and diglycerides of fatty acids, guar gum, xanthan gum, sodium citrate, and gum arabic.⁶ Although further confirmation is needed, these findings suggest that increased intake of food additive emulsifiers is a potential new risk factor for type 2 diabetes.

Through detailed quantification of a broad spectrum of emulsifiers consumed by the cohort participants, the research team has ventured into a less-explored territory in nutritional research. Epidemiological evidence on the effects of emulsifiers on human health is scarce and limited by the absence of accurate exposure assessment. The NutriNet-Santé cohort has the advantage of collecting detailed and repeated 24 h diet recall data (every 6 months), including commercial brands of industrial products consumed, and linking them to multiple food composition databases and conducting ad-hoc laboratory assays to estimate the intake of food additives at the individual level. Additionally, the authors used time-varying intakes, capturing long-term exposure, and adjusted for a comprehensive set of confounders to obtain estimates of associations between emulsifiers and the risk of type 2 diabetes. This prospective cohort study has a large sample size, a relatively long and up-to-date follow-up from 2009 to 2023, and high rates of participant responses. Moreover, the team’s previous investigation, based on the same food additive databases, revealed a distinct set of emulsifiers associated with cardiovascular disease risk,⁷ suggesting the differential biological pathways that can be affected by these compounds.

Although this research contributed novel evidence to the field, several limitations warrant consideration. Despite efforts to improve assessment accuracy, measurement errors are inevitable considering the heterogeneity of food emulsifiers used by food manufacturers. No gold standard measurements for food additive emulsifiers or known objective biomarkers are currently available. Besides developing a comprehensive food composition database, establishing objective biomarkers that can be applied to population-based studies globally will be crucial to ensure the rigour and comparability of future research. One potential approach is to integrate multi-omics approaches with traditional dietary assessment methods to identify sensitive and specific biomarkers of additive emulsifiers. For example, metabolomics profiling accounts for intrinsic variability in metabolism by measuring downstream metabolic products of foods, and might therefore better reflect true exposure to dietary components, including food additives.⁸ Considering the potential role of specific emulsifiers in altering gut microbial composition,^4,5,9 gut microbial metagenomic analysis can be used to identify microbial biomarkers for emulsifier exposures. Because ultra-processed foods contain not just emulsifiers but also a variety of other additives such as artificial flavours and colours, preservatives, sweeteners, and hydrogenated oils, it is challenging to isolate the effects of emulsifiers from other compounds in these foods. Furthermore, additional cohort investigations are essential to corroborate these findings in other populations. Randomised trials exploring dietary modifications, such as manipulating emulsifier intake, and mechanistic studies delving into biological pathways could provide a more robust causal understanding of the impact of emulsifiers on type 2 diabetes risk.

What are the implications of these findings? Given the widespread use of food additive emulsifiers in processed foods, there is a pressing need to better understand their potential health effects. These compounds are deemed generally recognised as safe (GRAS), meaning there are no quantitative limits.¹⁰ Findings from this and other studies could prompt regulatory agencies and policy makers to reconsider the rules governing the use of emulsifiers and other additives by the food industry, such as setting limits and requiring better disclosure of food additive contents to help consumers make more informed choices. For individuals, reducing the overall consumption of ultra-processed foods is the most effective approach to minimising the harmful effects of these compounds.