What’s a Prebiotic?

Inulin-rich Jerusalem artichoke

Different organisms use different food sources. While humans have food, prebiotic bacteria prefer to consume specific kinds of carbohydrates. Two particular kinds of prebiotic are oligofructose and inulin fiber.

Oligofructose literally means several fructose they are only several (1-8) saccharides long. Oligofructose ferments quickly and therefore nourishes bacteria on the right side of the colon.

Inulin has more saccharide links (9-64) so it takes longer to ferment so they nourish bacteria on the left side of the colon.

Top 10 Foods Containing Inulin Prebiotics

Food Prebiotic Fiber Content by Weight
Raw Chicory Root 64.6%
Raw Jerusalem Artichoke 31.5%
Raw Dandelion Greens 24.3%
Raw Garlic 17.5%
Raw Leek 11.7%
Raw Onion 8.6%
Cooked Onion 5%
Raw Asparagus 5%
Raw Wheat bran 5%
Whole Wheat flour, Cooked 4.8%
Raw Banana 1%

While there is no broad consensus on an ideal daily serving of prebiotics, recommendations typically range from 4-8g for general digestive health support, to 15g or more for those with active digestive disorders. Given an average 6g serving, below are the amounts of prebiotic foods required to achieve a daily serving of prebiotic fiber:

Food Amount of food to achieve 6g serving of prebiotics
Raw Chicory Root 9.3g (about 1/3 oz)
Raw Jerusalem Artichoke 19g (about 3/4 oz)
Raw Dandelion Greens 24.7g (just under 1 oz)
Raw Garlic 34.3 g (about 1.2 oz)
Raw Leek 51.3g (about 1.8 oz)
Raw Onion 69.8g (about 2.5 oz)
Cooked Onion 120g (about 1/4 lb)
Raw Asparagus 120g (about 1/4 lb)
Raw Wheat Bran 120g (about 1/4 lb)
Whole Wheat Flour, Cooked 125g (about 1/4 lb)
Raw Banana 600g (about 1.3 lb)


  1. Brigitta Kleessen*, Ludger Hartmann and Michael Blaut; Oligofructose and long-chain inulin: influence on the gut microbial ecology of rats associated with a human faecal flora British Journal of Nutrition (2001), 86, 291–300
  2. Angelo Pietro Femia, Cristina Luceri, Piero Dolara, Augusto Giannini1, Annibale Biggeri2, Maddalena Salvadori, Yvonne Clune3, Kevin J. Collins3, Milena Paglierani4 and Giovanna Caderni5; Antitumorigenic activity of the prebiotic inulin enriched with oligofructose in combination with the probiotics Lactobacillus rhamnosus and Bifidobacterium lactis on azoxymethane-induced colon carcinogenesis in rats Carcinogenesis, Vol. 23, No. 11, 1953-1960, November 2002
  3. R. Hughes and I.R. Rowland; Stimulation of apoptosis by two prebiotic chicory fructans in the rat colon Carcinogenesis, Vol. 22, No. 1, 43-47, January 2001
    Yoram Bouhnik*, , Kouroche Vahedi*, Lotfi Achour*, Alain Attar*, Jérôme Salfati*, , Philippe Pochart*, Philippe Marteau*, Bernard Flourié*, Francis Bornet, and Jean-Claude Rambaud*; Short-Chain Fructo-Oligosaccharide Administration Dose-Dependently Increases Fecal Bifidobacteria in Healthy Humans The Journal of Nutrition Vol. 129 No. 1 January 1999, pp. 113-116
  4. MAHA TAHIRI, 1 JEAN C. TRESSOL, 1 JOSIANE ARNAUD, 2 FRANCIS BORNET, 3 CORINNE BOUTELOUP-DEMANGE, 4 CHRISTINE FEILLET-COUDRAY, 1 VÉRONIQUE DUCROS, 2 DENISE PÉPIN, 5 FRED BROUNS, 3,6 ANNE M. ROUSSEL, 2 YVES RAYSSIGUIER, 1 CHARLES COUDRAY1; Five-Week Intake of Short-Chain Fructo-Oligosaccharides Increases Intestinal Absorption and Status of Magnesium in Postmenopausal Women Journal of Bone and Mineral Research, Journal of Bone and Mineral Research November 2001:16:2152-216
  5. Alanna J. Moshfegh2, James E. Friday, Joseph P. Goldman and Jaspreet K. Chug Ahuja, Presence of Inulin and Oligofructose in the Diets of Americans, Journal of Nutrition. 1999;129:1407S-1411S

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