Effect of five dietary emulsifiers on inflammation, permeability, and the gut microbiome: a placebo-controlled randomized trial.

Background And Aims: Dietary emulsifier consumption might promote intestinal inflammation, eventually leading to inflammatory bowel diseases. However human data are scarce and involve a limited number of emulsifiers. We studied the effects of an emulsifier-free diet (EFD) and specific emulsifier supplementation.

Methods: Sixty healthy participants followed an EFD for two weeks. Then, using a randomized placebo-controlled trial design, participants continued an EFD for four weeks with the addition of either carboxymethyl cellulose (CMC), polysorbate-80, carrageenan, soy lecithin, native rice starch (NRS), or no additives administered through brownies. Effects on cardiometabolic markers, gut microbiota, intestinal inflammation and permeability were explored.

Results: After two weeks of EFD, cholesterol levels decreased (p=0.00006). Under emulsifier-supplementation, alpha diversity remained stable, yet microbial composition was affected by treatment and visit. Compared to placebo, concentrations of all short chain fatty acids (SCFAs) were lower in those consuming CMC, which was mirrored by other emulsifiers although not all reaching significance. No differences in faecal calprotectin, CRP, LBP, cholesterol levels or other metabolic markers were observed between placebo and emulsifiers at the end of the intervention. Serum inflammatory and cardiometabolic proteins remained unchanged. In individuals consuming carrageenan, transcellular intestinal permeability increased (p=0.04) compared to baseline.

Conclusion: In this double-blind placebo-controlled exploratory trial, emulsifier supplementation lowered SCFA concentration compared to placebo. Emulsifier supplementation did not impact intestinal or systemic inflammation, or metabolic endpoints. Cholesterol levels decreased after two weeks of EFD. These results point towards potential intestinal benefits of limiting dietary emulsifiers in the diet, requiring further investigation.