Dietary exposure to food additives in ultra-processed foods: implications for gut microbiome, metabolic health, and risk assessment

Background: The increasing consumption of ultra-processed foods has led to a substantial rise in dietary exposure to food additives, making them a consistent component of modern dietary patterns. While food additives are generally considered safe within established regulatory limits, their long-term health effects remain a subject of growing scientific interest, particularly from a nutritional epidemiology perspective. Methods: This narrative review, conducted following PRISMA-informed principles, synthesizes recent experimental, clinical, and epidemiological evidence on the health effects of major food additive categories, including emulsifiers, non-nutritive sweeteners, preservatives, and synthetic colorants. Literature searches were performed in Web of Science, Scopus, and PubMed, covering studies published between 2010 and 2024. A qualitative assessment of study quality was performed based on study design, sample size, and potential sources of bias. The results of this assessment are summarized in Table 2. Results: Dietary exposure to food additives through ultra-processed foods has been associated with changes in the gut microbiome, metabolic function, and low-grade inflammation. Experimental studies consistently report biological effects, particularly for emulsifiers and artificial sweeteners, whereas epidemiological findings remain heterogeneous and influenced by overall dietary patterns. Conclusion: Current evidence supports the need to evaluate food additives within the context of dietary patterns rather than as isolated compounds. While most approved additives remain safe at regulated intake levels, emerging data suggest that cumulative exposure and diet-microbiome interactions may not be fully captured by existing risk assessment frameworks. Integrating nutritional context into future safety evaluations may improve their relevance for public health.