Impact of food additives on intestinal microbiota and inflammation

Introduction
Accumulating evidence demonstrates a contribution of dietary emulsifiers in the increase of prevalence of diseases associated with intestinal inflammation, such as inflammatory bowel disease (IBD; Naimi et al., 2021; Chassaing et al., 2017). The impact of other food additives on the intestinal microbiota composition and function is less known. Some mucolytic bacteria such as Mucispirillum schaedleri, Ruminococcus and Anaeroplasma has been related directly with fibrosis induction while other bacteria such as Oscillospira and Coprococcus were negatively related (Jacob et al., 2018). The aim of this work is to determine how food additives influences intestinal microbiota towards an inflammation, a dysbiosis and the subsequent formation of fibrosis.
Materials and Methods
Six food additives (polysorbate 80, maltodextrin, titanium dioxide, sodium nitrite, sucralose) were tested in in vitro batch cultures model of intestinal microbiota for 72 hours. The tested concentrations were based on the acceptable daily intake (ADI) or on the estimated daily exposure assuming in both cases an average weight of 70 kg. A mix of fecal samples from 5 healthy donors was used in the in vitro batch models. Changes in microbiota were assessed every 24h using qPCR targeting bacterial groups involved in short-chain fatty acid (SCFA) production or in inflammation. In addition, SCFA production was assessed using GC/MS.
Results and discussion
The main changes observed were for polysorbate 80 who after 72h of fermentation dramatically decreased butyrate and propionate. This was confirmed by qPCR analysis with a decrease of Clostridium cluster XIVa (butyrate producing bacteria) and Bacteroides/Prevotella spp. (propionate producing bacteria). Titanium dioxide increased propionic acid after 24h of fermentation with promotion of Bacteroidetes and the inhibition of Bifidobacterium, Streptococcus spp., Enterococcus spp. and Clostridium clusters IV and XIVa. After 72h, maltodextrin, induced an increase of acetic acid, propionate, butyrate and total SCFA. In addition, maltodextrin promoted the growth of Bifidobacterium, Clostridium clusters IV and XIVa.