Inulin is a soluble dietary fiber and fructan carbohydrate that is made up of chains of fructose molecules; it is found naturally in various plants and serves as an energy storage form. It is resistant to human digestion and reaches the large intestine, where it acts as a food source for gut microbes and promotes the production of beneficial compounds and the growth of healthy bacteria.

Inulin primarily benefits gut health by promoting the growth of beneficial bacteria like Bifidobacterium and may also improve blood sugar regulation, reduce LDL cholesterol, enhance satiety, and improve bowel movement frequency. However, the effects vary between studies and are generally small in magnitude.

Inulin is generally safe, but it can cause gastrointestinal side effects like bloating, gas, and diarrhea, especially at higher doses or with short-chain forms due to faster fermentation. Starting with a lower dose and gradually increasing intake may help improve tolerance, though individual responses can vary due to gut microbiome differences.

Inulin functions primarily as a fermentable fiber; it influences the gut microbiome and promotes the production of bioactive metabolites like short-chain fatty acids (SCFAs), which may improve health. However, clinical trials have yielded mixed results on SCFA production, and establishing a direct association between gut microbiome changes and beneficial health outcomes in humans remains challenging.