Abundance and Diversity of GI Microbiota Rather than IgG<sub>4</sub> Levels Correlate with Abdominal Inconvenience and Gut Permeability in Consumers Claiming Food Intolerances

Abstract

Food intolerances are an increasing global health problem. Interactions between genetics and environmental changes such as microbial- and stress factors remain poorly understood. Whereas the analyses of IgE mediated allergic responses is based on solid concepts, the roles of microbiota, gut permeability, and IgG antibodies remain widely unclear and are under fierce discussion for scientific relevance. The present pilot study analyzes forty participants, under consultation of nutritional health professionals, for gastrointestinal discomfort and claimed food intolerances. Food frequency questionnaire addresses nutrition, lifestyle and present discomfort. Feces samples are analyzed for dominant microbiota using 16S rDNA based methods and the fecal marker Calprotectin. Blood samples are analyzed for IgG4 levels. The total microbial abundance significantly correlates with claimed discomfort (R=-0.37; p=0.02). The abundance and diversity of microbiota significantly correlates with low Calprotectin values (R=-0.35; p=0.01) and with higher abundance of Faecalibacterium prausnitzii (R=0.78; p<0.01) and Akkermansia (R=0.82; p<0.01). Participants with low discomfort show enhanced Clostridium Cluster XIVa (p=0.008). An increased diversity is also correlating with reduced antibodies against IgG4 of egg white (R=0.68; p<0.01). Data suggest an interaction of low gut permeability and reduced inflammation with an established microbial equilibrium. Self-reported abdominal inconvenience of participants relates mainly to characteristics of microbiota and gut permeability. Anti-inflammatory effects of Faecalibacterium prausnitzii or Lactobacilli and gut barrier functions of Akkermansia may have a key role in food intolerances. The role of IgG4 linking food immune responses with intolerances remains unclear.