Impact of food additives on intestinal microbiota

Accumulating evidence demonstrates a contribution of dietary emulsifiers in the increase of prevalence of diseases associated with intestinal inflammation, such as inflammatory bowel disease. Two emulsifiers in particular, polysorbate 80 and carboxymethylcellulose, profoundly impact intestinal microbiota leading to gut inflammation. 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. The aim of this work is to determine how food additives influences intestinal microbiota towards a dysbiosis, an inflammation and the subsequent formation of fibrosis. Six food additives (polysorbate 80, maltodextrin, titanium dioxide, sodium nitrite, sucralose and kappa - carrageenan) 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) established by the Expert Committee on Food Additives (JECFA) or on the estimated daily exposure calculated by the European Food Safety Authority (EFSA) 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. 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.