Inulin is a prebiotic fibre, a chain of fructose units that the body cannot break down but that gut bacteria adore. Stored by plants as an energy reserve, it reaches the colon untouched and there becomes a feast for beneficial microbes such as bifidobacteria. The everyday heroes are humble alliums: garlic and onion carry far more inulin than most people realise, with asparagus and slightly underripe bananas adding a useful contribution. A little inulin in the diet helps cultivate a thriving, diverse gut microbiome.
What is Inulin?
Inulin is a prebiotic fibre that plays a critical role in passing undigested into the colon, where it is selectively fermented by beneficial bacteria such as bifidobacteria, acting as a prebiotic that shapes a healthier and more diverse gut microbiome. While many general diets overlook it, maintaining optimal levels of Inulin is frequently tracked by people working to optimize their Gut microbiome health.
Top Foods High in Inulin
A data-driven breakdown of the foods with the highest concentration of Inulin per 100 g.
| Food | Inulin |
|---|---|
| Garlic | 12.5 g |
| Onion | 4.3 g |
| Asparagus | 2.5 g |
| Wholewheat Pasta | 1 g |
| Whole Wheat Bread | 1 g |
| Banana | 0.5 g |
How Inulin Impacts Gut microbiome health
Research links diets rich in Inulin to changes in Gut microbiome health. Optimizing intake of these foods can support healthy Gut microbiome health levels via selectively feeding beneficial gut bacteria, encouraging their growth and the production of short-chain fatty acids that lower colonic pH and crowd out less desirable microbes.
Written by the Nutrition Encyclopedia team · medically reviewed by Dr. Sunaina Tariq, MBBS
Last updated 22 June 2026
How we source & verify data · Medical disclaimer
Nutrition values are approximations compiled from public food-composition databases (USDA FoodData Central) and are provided for educational purposes only — not medical advice.
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