The combined effect of eight common food additives on the human gut microbiota

Emerging evidence suggests that food additives may contribute to disease by inducing gut dysbiosis. However, previous studies have been criticized for using unrealistic doses and not testing for the potential synergistic effect of consuming multiple food additive simultaneously, which is how they are consumed under real-life conditions. This study aimed to determine whether eight previously implicated food additives directly promote dysbiosis, individually and in combination, at physiologically relevant doses. The results showed that none of the food additives significantly affected short-chain fatty acid production or the four characteristics of dysbiosis: loss of beneficial bacteria, expansion of pathobionts, reduction in bacterial diversity, and changes in microbial community structure. Moreover, there were no indications of the previously proposed synergistic effect. Results also highlighted the importance of fecal microbiota intra-variability and how it may cause false positives. While intra-variability was accounted for in this study, it is possible that the chosen gut microbiota was resilient to food-additive-induced dysbiosis. This is the first study to have examined both the individual and combined direct effect of the eight chosen food additives at physiologically relevant doses.