Impacts of food additive sweeteners and emulsifiers on the gut microbiome: research trends and future directions

As human diets shift toward increased consumption of processed foods and dietary additives, including sweeteners and emulsifiers, mounting evidence suggests that these food additives may disrupt the gut microbiome, impacting intestinal and metabolic health. However, the literature reports both beneficial and adverse effects of food additives, complicating cross-study comparisons and risk assessment. In this review, we (i) identify trends and gaps in research on the effects of sweeteners and emulsifiers on the gut microbiome (encompassing both microbial communities and/or their functional activities), (ii) assess methodologies used for studying the gut microbial communities in existing studies, and (iii) provide recommendations for future research. Our findings show that at least part of the inconsistencies reported in literature are related to the large variety of methods used to study gut microbiota composition and its functional activities. In critical evaluation of existing studies, we highlight the need for longitudinal randomized clinical trials to evaluate long-term health effects, except where clear hazards can be shown in pre-clinical studies using animal models. Moreover, future investigations should include direct measurements of relevant health outcomes to achieve a comprehensive view on the impacts of sweeteners and emulsifiers on the gut microbiome and human health. To enable meta-analyses and allow comparisons across studies, future research should improve data sharing practices, and focus on standardizing study designs, including consideration of relevant dose and dietary covariates. We conclude by translating criticism into 10 practical recommendations to improve future studies in the field by using best practices from microbiome research. • We critically assessed literature on the effects of sweeteners and emulsifiers on gut health. • Reports of their impacts on the gut microbiome and host health vary widely across studies. • Our review identifies common issues in methodologies and experimental approaches. • Most reviewed studies do not comply with FAIR data sharing principles, limiting data reuse. • We offer 10 practical recommendations to improve future studies in the field.