Inulin is a chain of fructose units that people cannot digest, which makes it a soluble fiber in the soluble fiber group. “Fructans” is the wider family, any carbohydrate whose bonds are mostly fructose-to-fructose links, and “inulin” is the name for the linear kind with beta(2→1) bonds. Chicory inulin, the kind sold as a food ingredient, has chains of 2 to 60 units with an average of 12. Because the bonds resist our digestive enzymes, inulin reaches the colon, where bacteria ferment it, and it supplies about 1.5 kcal a gram.
That one property makes inulin two things at once. In the nutrition literature it is a prebiotic, a fiber that feeds bifidobacteria, and EU law allows a claim that chicory inulin increases stool frequency at 12 g a day. In the dietitian’s clinic the same fructans are a FODMAP, one of the fermentable carbohydrates that can set off bloating and pain in people with irritable bowel syndrome. This page covers both sides, with the trials, and sets inulin beside beta-glucan, the other soluble fiber with strong claims.
Two facts surprise most readers. First, the fructan values on this page are total fructans, measured by a method (AOAC 999.03) that counts inulin, oligofructose and other fructans together, so they are not inulin alone. Second, wheat, not chicory, was the biggest source of inulin and oligofructose in a US national survey: about 70% came from wheat and about 25% from onions. And in one trial, 2.1 g of fructans bloated people who believed they were sensitive to gluten more than 5.7 g of gluten did.
Health benefits of inulin and fructans
The best-supported findings are modest. For bowel function, the EU authorizes a claim for chicory inulin at 12 g a day, and a meta-analysis of constipation trials found softer and more frequent stools, though pain and bloating did not improve. Inulin-type fructans reliably raise bifidobacteria, which is a marker and not a health outcome. A rise in calcium absorption in adolescents and small falls in LDL cholesterol, triglycerides and body weight rest on fewer or lower-certainty trials. In irritable bowel syndrome the picture flips: prebiotic fructans did not help symptoms and made flatulence worse, and fructans are one of the triggers the low-FODMAP diet removes. Most trials use chicory inulin or oligofructose powders at 5 to 21 g a day, which is far more than food supplies (about 5 g of inulin and oligofructose a day in a US survey, our sum), and each card gives the dose. Studies of foods rich in fructans are scarce, and none of the trials below measured fractures, heart attacks or cancer. Here is what 20 studies found, strongest evidence first, including the trials that found nothing. Head-to-head studies of forms are in the section on forms below.
EU law allows the claim that chicory inulin contributes to normal bowel function by increasing stool frequency, at 12 g a day
Commission Regulation (EU) 2015/2314 of 7 December 2015 added the claim to the list in Regulation (EU) No 432/2012 after EFSA found a cause and effect relationship between native chicory inulin and maintenance of normal defecation by increasing stool frequency. “Native chicory inulin” is defined as a non-fractionated mixture of monosaccharides (under 10%), disaccharides, inulin-type fructans and inulin extracted from chicory, with a mean degree of polymerization of 9 or more. Consumers must be told that the effect comes with a daily intake of 12 g, and the claim can be used only for food that provides at least 12 g a day. For five years from 1 January 2016 the claim was restricted to the applicant, BENEO-Orafti, and after that any food business operator may use it. The wording and conditions are in the table below.
Across 5 trials with 252 people with constipation, inulin made stools softer and more frequent, but pain and bloating did not improve
Meta-analysis of randomized controlled trials. Inulin had a significant overall effect on stool frequency (standardized mean difference 0.69, range 0.04 to 1.34), on stool consistency on the Bristol scale (1.07, range 0.70 to 1.45), on transit time (−0.57) and on stool hardness (relative risk 0.42, range 0.26 to 0.70). Only 5 of 24 articles found were pooled and the interval for stool frequency is wide, so the size of the effect is uncertain. One author is affiliated with a food company.
In 44 people with constipation, 12 g a day of chicory inulin for 4 weeks raised stool frequency from a median of 3.0 to 4.0 a week against placebo
Randomized, double-blind, placebo-controlled crossover trial with a 2-week washout. People took 3 × 4 g of inulin or maltodextrin a day for 4 weeks each. Stools also became softer, and satisfaction trended higher (P=0.059, not significant). Two authors work at the BENEO-Institute and the inulin was the maker’s product. Gut bacteria from this same trial were analyzed in a later paper (Vandeputte et al., 2017, in the sources below): Bifidobacterium rose, Bilophila fell, and the fall in Bilophila went with softer stools.
Pooling 50 studies with 2,525 people, 3 to 20 g a day of chicory inulin-type fructans raised Bifidobacterium abundance (standardized mean difference 0.83)
Systematic review and meta-analysis of randomized trials of at least 7 days, in people aged 0 to 83 years. The rise was significant in healthy people and in groups with health problems other than gastrointestinal disorders, and bowel function measures improved in healthy people. Bifidobacterium counts are a marker, not a health outcome. Two authors are affiliated with the BENEO-Institute, and the company BENEO-Orafti applied for the EU chicory inulin claim.
Show 16 more studies
In pubertal adolescents, 8 g a day of short- and long-chain inulin-type fructans raised calcium absorption by 8.5% at 8 weeks and 5.9% at 1 year against a placebo
Randomized trial with a maltodextrin placebo. Calcium absorption was measured with stable isotopes. After 1 year the fructan group had gained 35 g more whole-body bone mineral content and 0.015 g/cm2 more bone mineral density than the control group. Adolescents with the ff genotype of the vitamin D receptor Fok1 gene responded least at first. A related report by the same group (Abrams et al., 2007, in the sources below) found that not every adolescent responded.
Pooling 55 trials with 2,518 adults, inulin-type fructans lowered LDL cholesterol by 0.14 mmol/L, triglycerides by 0.06 mmol/L and body weight by 0.97 kg
Systematic review and meta-analysis of randomized trials lasting at least 2 weeks. The certainty of the evidence was very low for LDL cholesterol (38 trials) and low for triglycerides (40 trials) and body weight (36 trials). There was little or no effect on other risk factors, including fasting blood glucose and blood pressure. The effects were larger in trials of 6 weeks or more and in people with overweight or obesity. The authors call for better trials.
In 11 trials with 729 people with irritable bowel syndrome, prebiotics did not improve symptoms, and inulin-type fructans made flatulence worse
Systematic review and meta-analysis of randomized trials against placebo in adults with IBS and other functional bowel disorders. A global response was reported by 54% on prebiotics and 63% on placebo, no difference. Abdominal pain, bloating and quality of life did not differ either. Flatulence was worse with inulin-type fructans (standardized mean difference 0.85) and better at doses of 6 g a day or less and with non-inulin-type prebiotics. Prebiotics did raise bifidobacteria. No study had a low risk of bias in every category.
In 103 people with active Crohn’s disease, 15 g a day of fructo-oligosaccharides for 4 weeks gave no clinical benefit
Randomized, double-blind, placebo-controlled trial of short-chain fructans. A clinical response was reached by 22% on fructo-oligosaccharides and 39% on placebo (P=0.067, not a significant difference). More people on the fructans dropped out before week 4 (26% against 8%). The fructans changed some immune cell responses but did not change stool bifidobacteria.
In 59 people who believed gluten bothered them, 2.1 g of fructans caused more bloating than 5.7 g of gluten or placebo
Double-blind crossover trial in people on a self-started gluten-free diet with celiac disease excluded. Each person took gluten, fructans or placebo hidden in muesli bars for 7 days, with washouts between. Overall symptom scores averaged 38.6 on fructans, 33.1 on gluten and 34.3 on placebo, and bloating scores 11.6, 9.3 and 10.1. Gluten did not differ from placebo. Responses varied: 24 people had their worst score on fructans, 13 on gluten and 22 on placebo.
In 30 people with IBS, a diet low in FODMAPs cut the overall symptom score to 22.8 mm against 44.9 mm on a typical Australian diet
Randomized, single-blind crossover trial with 21 days on each diet and a washout of at least 21 days. Almost all food was provided, with a goal of under 0.5 g of FODMAPs per meal. Bloating, pain and wind fell too. Symptoms in 8 healthy controls did not change. The low-FODMAP diet removes fructans along with the other FODMAPs, so this result is not for fructans alone.
In 13 trials with 944 people with IBS, a low-FODMAP diet ranked first for global symptoms (relative risk of not improving 0.67)
Systematic review and network meta-analysis of randomized trials against a habitual diet and other interventions. The diet also ranked first for pain, bloating and bowel habit. It beat standard British dietary advice for bloating or distension (relative risk 0.72). Most trials were run in specialist care, and most did not study reintroducing foods or personalizing the diet. Again the diet removes all FODMAPs, not fructans alone.
In 75 people with IBS, a low-FODMAP diet reduced symptoms no more than traditional dietary advice over 4 weeks
Multicenter, single-blind randomized trial in Sweden. Symptom severity fell in both groups (P<0.0001 for each) with no difference between them (P=0.62). A reduction of at least 50 points on the severity scale was reached by 50% on the low-FODMAP diet and 46% on traditional advice, which includes cutting back on beans, cabbage and onions. The authors suggest combining the two approaches.
Reviewing 15 adult trials, inulin-type fructans did not change appetite or energy intake, and weight results were mixed
Systematic review of randomized trials with 545 adults. Five trials found no effect on appetite sensations, and 11 found no effect on daily energy intake. Of 3 trials that measured body weight, 2 found a significant fall. In 97 adolescents aged 9 to 13, 8 g a day of oligofructose plus inulin for 1 year reduced the gain in body weight. The authors judge that limited data suggest long-term use may contribute to weight reduction.
In 48 adults with overweight or obesity, 21 g a day of oligofructose for 12 weeks cut body weight by 1.03 kg while the placebo group gained 0.45 kg
Randomized, double-blind, placebo-controlled trial using maltodextrin as the placebo. The oligofructose group had a lower ghrelin response, a higher peptide YY response and lower self-reported calorie intake. Active GLP-1 did not change. A rating scale suggested it was well tolerated. It is one 12-week trial, at a dose well above what food supplies.
In 12 healthy men, 20 g a day of chicory inulin for 3 weeks did not raise stool weight or speed transit
Randomized, double-blind crossover trial on a controlled diet, with inulin (chain length 2 to 60 units) baked into a low-fat ice cream. Total anaerobes and Lactobacillus rose, and ammonia and β-glucuronidase activity fell. Flatulence increased. The authors call 20 g well tolerated but of minimal effect on laxation in healthy people. The trial above, in people with constipation, used 12 g.
In 96 people with IBS, 20 g a day of fructo-oligosaccharides for 12 weeks did not improve symptoms more than placebo
Multicenter, double-blind, placebo-controlled trial after a 2-week run-in, with 52 people randomized to fructo-oligosaccharides and 46 to placebo; data from 96 were analyzed. After 4 to 6 weeks symptoms had improved more on placebo. At the end, symptoms were better in 58% on fructans and 65% on placebo and worse in 8% and 13%, not significant differences. Symptoms worsened when the fructans were first started, but 12 weeks of use did not worsen them.
In 37 people with suspected gluten sensitivity, symptoms eased on a low-FODMAP diet and gluten made them no worse than whey protein
Double-blind crossover trial in people with IBS and self-reported non-celiac gluten sensitivity. After 2 weeks on reduced FODMAPs, people ate high-gluten (16 g a day), low-gluten or control diets for 1 week each. Symptoms improved on the reduced-FODMAP diet and worsened to a similar degree with gluten or whey. Gluten-specific effects were seen in only 8% of people, and an order effect was noted. Small and short.
In 34 people with IBS controlled on a gluten-free diet, gluten brought back symptoms in 68% against 40% on placebo
Double-blind, randomized rechallenge trial, up to 6 weeks, with gluten or placebo in bread and muffins. Of 19 people on gluten, 13 said symptoms were not adequately controlled, against 6 of 15 on placebo. This trial did not control FODMAPs, and the same research group’s 2013 trial above, which put people on a reduced-FODMAP diet first, found no gluten-specific effect in most.
In 25 people with IBS, fructans left symptoms uncontrolled in 77% of patients against 14% with glucose
Double-blind, randomized rechallenge trial in people who had already improved by cutting free fructose and fructans. All food was provided low in both. Drinks with fructose, fructans, both or glucose were given with meals for up to 2 weeks, with washouts. Symptoms were not controlled in 70% on fructose, 77% on fructans and 79% on the mixture, and symptoms came on in a dose-dependent way. The authors conclude the benefit of the diet comes from restricting poorly absorbed short-chain carbohydrates in general.
In 147 people with IBS who kept 4-day food diaries, fructan intake was not linked to symptom scores
Observational food diary study. Dividing people into thirds of fructan intake showed no significant difference in IBS symptom scores. The study was mainly about gluten: people with the lowest and middle gluten intakes had worse symptoms but also ate fewer calories. A diary cannot show cause, and a challenge trial found symptoms from 2.1 g of fructans (Skodje, above).
Prebiotic, fiber and FODMAP: three names for the same molecules
Each label asks a different question about fructans. Fiber asks whether the carbohydrate escapes digestion, and inulin does. The FDA lists “inulin and inulin-type fructans” among the non-digestible carbohydrates it intends to propose adding to its definition of dietary fiber, and until that rulemaking is done it intends to exercise enforcement discretion so that makers can count them in the fiber declaration. Prebiotic asks whether gut microbes use the substance selectively to the host’s benefit. A 2017 expert panel defined a prebiotic as a substrate selectively utilized by host microorganisms conferring a health benefit, and said the benefit must be documented. A 2010 review by academic and industry experts called the prebiotic effect a well-established scientific fact but said the role of the microbiota changes in health benefits remains to be definitively proven. FODMAP asks whether the carbohydrate ferments fast enough to cause symptoms in a sensitive gut, which the trials in irritable bowel syndrome and in people who think they are gluten sensitive address.
The same fructan can therefore be a prebiotic for one person and a trigger for another. The meta-analysis in irritable bowel syndrome above found both in one set of trials: bifidobacteria rose, and symptoms did not improve.
What the EU and the FDA say about inulin
A health claim is a regulated sentence on a label, not a study result, and it comes with conditions. This table gives the wording and conditions as published, and the FDA’s fiber position.
| Authority and rule | Statement | Conditions | Source |
|---|---|---|---|
| EU, Regulation (EU) 2015/2314, adding an entry to Regulation (EU) No 432/2012 | Chicory inulin contributes to normal bowel function by increasing stool frequency | Consumers must be told that the effect comes with a daily intake of 12 g of chicory inulin. The claim can be used only for food that provides at least 12 g a day of native chicory inulin, a non-fractionated mixture of monosaccharides (under 10%), disaccharides, inulin-type fructans and inulin extracted from chicory, with a mean degree of polymerization of 9 or more. Restricted to the applicant, BENEO-Orafti, for five years from 1 January 2016; after that any food business operator may use it. | 1, 2 |
| US FDA, dietary fiber | Inulin and inulin-type fructans are on the list of non-digestible carbohydrates that FDA intends to propose adding to the dietary fiber definition | Until FDA completes rulemaking it intends to exercise enforcement discretion to allow manufacturers to include them in the dietary fiber declaration. This is not an authorized health claim. | 3 |
Sources
- Commission Regulation (EU) 2015/2314 authorising a health claim made on foods, other than those referring to the reduction of disease risk and to children’s development and health, and amending Regulation (EU) No 432/2012. Annex, native chicory inulin. Official Journal of the European Union. 2015.
- EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Scientific opinion on the substantiation of a health claim related to “native chicory inulin” and maintenance of normal defecation by increasing stool frequency pursuant to Article 13.5 of Regulation (EC) No 1924/2006. EFSA J. 2015.
- U.S. Food and Drug Administration. Questions and answers on dietary fiber. Page content current as of 25 July 2024.
- Gibson GR, Hutkins R, Sanders ME, et al. Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nat Rev Gastroenterol Hepatol. 2017.
- Roberfroid M, Gibson GR, Hoyles L, et al. Prebiotic effects: metabolic and health benefits. Br J Nutr. 2010.
- Vandeputte D, Falony G, Vieira-Silva S, et al. Prebiotic inulin-type fructans induce specific changes in the human gut microbiota. Gut. 2017.
- Abrams SA, Griffin IJ, Hawthorne KM. Young adolescents who respond to an inulin-type fructan substantially increase total absorbed calcium and daily calcium accretion to the skeleton. J Nutr. 2007.
Foods high in inulin and fructans
Garlic is by far the richest everyday source. In four Italian garlic landraces the fructans measured 45.8 to 54.4 g per 100 g of dry weight, and the list below shows the fresh-weight figure converted from that paper. Onions come next, at 1.97 g per 100 g in Slovenian samples, then wheat flour at 0.75 g per 100 g. Every other food the Slovenian team tested held less than 1 g per 100 g, and they found none in the potatoes, rice, kohlrabi or cucumbers. Australian measurements put garlic, artichoke, shallots, leek bulb and onions between 1.2 and 17.4 g per 100 g of fresh weight. See our pages on garlic, onions, barley and oats.
Two cautions apply to the list. The values are total fructans by AOAC 999.03, which counts inulin, oligofructose and other fructans together, so they are not inulin alone. They are also single sets of measurements: the Slovenian authors report that values for bread and some other foods came out lower than in earlier studies, and say method and sample can explain gaps. Small amounts add up when a food is eaten daily. In the US survey wheat supplied about 70% of the inulin and oligofructose in the diet and onions about 25%. “Gluten-free” does not mean fructan-free either: UK gluten-free breads held 1.00 g per 100 g on average, with brands from 0.36 to 1.79 g.
Our arithmetic for realistic servings: the EU claim needs 12 g a day, and a medium onion (110 g) gives about 2.2 g by the list below, so reaching 12 g from onions alone would take five to six of them every day. That is why trials use powders, and why most people eat only a few grams of fructans a day from food.
Per serving. No daily amount is set, so bars compare each food with the top food.
Per 100 g. No daily amount is set, so bars compare each food with the top food.
Per 100 kcal: the same calories of each food, for a fair comparison. Bars compare each food with the top food.
Food labels have no Daily Value or Reference Intake for fructans, so the % compares each food with the top food.
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.
- 7.
- 8.
- 9.
- 10.
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.
- 7.
- 8.
- 9.
- 10.
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.
- 7.
- 8.
- 9.
- 10.
| Food | Total fructans | What the number is | Source |
|---|---|---|---|
| Garlic, four Italian landraces | 45.8 to 54.4 g per 100 g dry weight | Measured range; not converted to fresh weight | 2 |
| Garlic, artichoke, shallots, leek bulb and onions | 1.2 to 17.4 g per 100 g fresh weight | Range for the vegetables with the most fructans among 60 vegetables and 43 fruits (Australia) | 3 |
| Wheat flour (T500) | 0.75 g per 100 g | Fresh weight as bought, Slovenia | 1 |
| Cooked pasta | 0.33 g per 100 g | Fresh weight, Slovenia | 1 |
| Hazelnut, almond, walnut | 0.73, 0.60 and 0.37 g per 100 g | Fresh weight, Slovenia | 1 |
| Canned peas, canned beans | 0.33 and 0.24 g per 100 g | Fresh weight, Slovenia | 1 |
| White bread, brown bread | 0.14 g per 100 g for each | Fresh weight, Slovenia | 1 |
| UK breads: wheat, rye and gluten-free | 0.61 to 1.94 g per 100 g; rye 1.94; gluten-free 1.00 | Measured range across breads (AOAC 999.03) | 4 |
| Couscous, rice, oats (cooked or as eaten) | 1.12, 0 and 0.11 g per portion | Per portion as eaten | 5 |
| Potatoes, rice, kohlrabi, cucumbers | Not detectable | Below the assay’s limit, Slovenia | 1 |
Sources
- Ferjančič B, Korošec M, Kočevar Baloh A, et al. Fructan content in most commonly consumed Slovenian foods and estimation of daily fructan consumption. Front Nutr. 2024.
- Lisciani S, Gambelli L, Durazzo A, et al. Carbohydrates components of some Italian local landraces: garlic (Allium sativum L.). Sustainability. 2017.
- Muir JG, Shepherd SJ, Rosella O, et al. Fructan and free fructose content of common Australian vegetables and fruit. J Agric Food Chem. 2007.
- Whelan K, Abrahmsohn O, David GJ, et al. Fructan content of commonly consumed wheat, rye and gluten-free breads. Int J Food Sci Nutr. 2011.
- Biesiekierski JR, Rosella O, Rose R, et al. Quantification of fructans, galacto-oligosacharides and other short-chain carbohydrates in processed grains and cereals. J Hum Nutr Diet. 2011.
- Moshfegh AJ, Friday JE, Goldman JP, et al. Presence of inulin and oligofructose in the diets of Americans. J Nutr. 1999.
How inulin and fructans work
Most of what we know about how inulin works comes from lab fermenters, gut models and short physiology studies in people, and what it does over months is tested in the cards above. The main ideas are that human enzymes cannot split it, that chain length sets how fast bacteria ferment it, that fermentation feeds some bacteria and makes short-chain fatty acids and gas, and that the gas is what bothers a sensitive gut. Here is each one, and what has been seen in people.
Human enzymes cannot split it
Inulin is a generic term for linear fructans with beta(2→1) bonds. Because of the beta configuration of the anomeric C2 in their fructose units, these bonds resist hydrolysis by intestinal digestive enzymes, so inulin-type fructans count as non-digestible carbohydrates and dietary fibers. Products differ in chain length, which is called the degree of polymerization (DP): chicory inulin has a DP of 2 to 60 with an average of 12, oligofructose (made by partial enzymatic hydrolysis of chicory inulin) 2 to 8 with an average of 4, and long-chain inulin 10 to 60 with an average of 25. In 10 healthy adults, breath hydrogen and venous acetate rose in proportion to the dose of chicory fructans and behaved like the response to lactulose, a sugar that is not absorbed.
Top: a fructan chain is fructose units joined by beta(2→1) bonds. Bottom: the range of chain lengths in three products, drawn to scale, with a black mark at the average. The chain drawing is schematic.
Chain length sets the pace
Short chains ferment faster. In a lab test with human fecal bacteria, short-chain oligosaccharides were fermented more rapidly and gave more short-chain fatty acids and gas than substrates with longer chains, and mixing short and long chains slowed the short-chain fermentation. In a gut simulator, inulin took longer than oligofructose to show effects, but its effect on butyrate, propionate and bifidobacteria was stronger and lasted longer in the far end of the colon. In people the pattern matches: long-chain fructans took longer to pass through (75 minutes against 30 for short chains), and symptoms rose with dose and with shorter chains.
Gut bacteria ferment it
Bacteria in the colon turn what reaches them into short-chain fatty acids and gas. Bifidobacteria are the group most often reported to increase, but not every strain can use these fructans. In a lab test of 18 Bifidobacterium strains, some could not degrade oligofructose or inulin, some degraded oligofructose but did not grow on inulin, and some could break down inulin partly. In people, the whole community shifts a little: in the constipation trial, inulin changed the relative abundance of Anaerostipes, Bilophila and Bifidobacterium while fecal metabolite profiles were not significantly changed. The starting point matters too, since a low starting count of bifidobacteria predicted a bigger rise in the 200-volunteer trial. Whether these shifts cause any health effect is not settled, as the review in the section on benefits says.
What happens to inulin after it is eaten. Not to scale.
Why fermentation can cause symptoms
The same fermentation makes gas. In people with irritable bowel syndrome who had improved on a diet low in free fructose and fructans, symptoms came back in a dose-dependent way when fructans were given as drinks with meals, and the chart shows how often. Healthy volunteers also reported more symptoms with higher doses, though the changes were mild at up to 20 g a day.
Share of 25 people with irritable bowel syndrome whose symptoms were not adequately controlled after drinks with each carbohydrate, drawn to scale. The drinks were given in graded doses with meals for up to 2 weeks, and each person took each drink in a random order.
What has been seen in people
The trials point in two directions. In constipation, 12 g a day of chicory inulin raised median stool frequency from 3.0 to 4.0 a week and softened stools. Adolescents absorbed more calcium on 8 g a day and gained more bone mineral over a year. Pooled trials found small falls in LDL cholesterol (0.14 mmol/L), triglycerides (0.06 mmol/L) and body weight (0.97 kg), at low or very low certainty. In irritable bowel syndrome the direction reversed: prebiotic fructans did not help symptoms and made flatulence worse, and in a challenge trial 2.1 g of fructans caused more bloating than gluten. None of these effects is large, and most come from powders at doses above usual food intake.
Sources
- Roberfroid MB. Introducing inulin-type fructans. Br J Nutr. 2005.
- Rumessen JJ, Gudmand-Høyer E. Fructans of chicory: intestinal transport and fermentation of different chain lengths and relation to fructose and sorbitol malabsorption. Am J Clin Nutr. 1998.
- Hernot DC, Boileau TW, Bauer LL, et al. In vitro fermentation profiles, gas production rates, and microbiota modulation as affected by certain fructans, galactooligosaccharides, and polydextrose. J Agric Food Chem. 2009.
- van de Wiele T, Boon N, Possemiers S, et al. Inulin-type fructans of longer degree of polymerization exert more pronounced in vitro prebiotic effects. J Appl Microbiol. 2007.
- Falony G, Lazidou K, Verschaeren A, et al. In vitro kinetic analysis of fermentation of prebiotic inulin-type fructans by Bifidobacterium species reveals four different phenotypes. Appl Environ Microbiol. 2009.
- Vandeputte D, Falony G, Vieira-Silva S, et al. Prebiotic inulin-type fructans induce specific changes in the human gut microbiota. Gut. 2017.
- Bouhnik Y, Raskine L, Simoneau G, et al. The capacity of nondigestible carbohydrates to stimulate fecal bifidobacteria in healthy humans: a double-blind, randomized, placebo-controlled, parallel-group, dose-response relation study. Am J Clin Nutr. 2004.
- Shepherd SJ, Parker FC, Muir JG, et al. Dietary triggers of abdominal symptoms in patients with irritable bowel syndrome: randomized placebo-controlled evidence. Clin Gastroenterol Hepatol. 2008.
- Bruhwyler J, Carreer F, Demanet E, et al. Digestive tolerance of inulin-type fructans: a double-blind, placebo-controlled, cross-over, dose-ranging, randomized study in healthy volunteers. Int J Food Sci Nutr. 2009.
- Roberfroid M, Gibson GR, Hoyles L, et al. Prebiotic effects: metabolic and health benefits. Br J Nutr. 2010.
- Micka A, Siepelmeyer A, Holz A, et al. Effect of consumption of chicory inulin on bowel function in healthy subjects with constipation: a randomized, double-blind, placebo-controlled trial. Int J Food Sci Nutr. 2017.
- Abrams SA, Griffin IJ, Hawthorne KM, et al. A combination of prebiotic short- and long-chain inulin-type fructans enhances calcium absorption and bone mineralization in young adolescents. Am J Clin Nutr. 2005.
- Talukdar JR, Cooper M, Lyutvyn L, et al. The effects of inulin-type fructans on cardiovascular disease risk factors: systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2024.
- Wilson B, Rossi M, Dimidi E, et al. Prebiotics in irritable bowel syndrome and other functional bowel disorders in adults: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2019.
- Skodje GI, Sarna VK, Minelle IH, et al. Fructan, Rather Than Gluten, Induces Symptoms in Patients With Self-Reported Non-Celiac Gluten Sensitivity. Gastroenterology. 2018.
How much inulin or fructan do you need?
No daily amount of inulin or fructans is set, and no upper limit: neither the FDA nor the EU has set a daily value, and we found no official intake for them on their own. Total fiber covers them. The US adequate intake for adults runs from 21 to 38 g of fiber a day by age and sex (14 g per 1,000 kcal), EFSA’s value is 25 g a day for adults, and inulin counts toward both, as our fiber page explains. The amount that shows an effect is a different question. The EU bowel-function claim needs 12 g of native chicory inulin a day, and the trials of bifidobacteria in the meta-analysis used 3 to 20 g a day.
Food gives far less. A US survey that used two 24-hour recalls from more than 15,000 people estimated average intakes of 2.6 g of inulin and 2.5 g of oligofructose a day, from 1.3 g for young children to 3.5 g for teenage boys and adult men. A model of Slovenian adults put total fructan intake at 1.7 g a day (range 0.21 to 5.54), and the same paper cites food-diary estimates of 3.5 g a day in Sweden and 3 g in Australia.
| Source | Group | Value | Notes |
|---|---|---|---|
| EU, Regulation (EU) 2015/2314 | Labeling rule for the bowel-function claim | 12 g a day of native chicory inulin | The claim can be used only for food that provides at least 12 g a day. Source 1. |
| National Academies (IOM) 2005, adequate intake for total fiber | Adults aged 19 to 50 | 38 g (men), 25 g (women) a day; 14 g per 1,000 kcal | From age 51: 30 g and 21 g. No tolerable upper intake level was set for dietary or functional fiber. Source 2. |
| EFSA 2010, adequate intake for total fiber | Adults from 18 years | 25 g a day | Inulin and fructans count toward total fiber. Source 2. |
| US FDA | Food labeling | No daily value for inulin on its own | FDA intends to exercise enforcement discretion so that inulin and inulin-type fructans can be counted in the dietary fiber declaration. Source 3. |
Inulin is not an essential nutrient, and we found no source that describes a deficiency of it. Low total fiber intake is a different question, covered on our fiber page.
Sources
- Commission Regulation (EU) 2015/2314 authorising a health claim made on foods, other than those referring to the reduction of disease risk and to children’s development and health, and amending Regulation (EU) No 432/2012. Annex, native chicory inulin. Official Journal of the European Union. 2015.
- Fiber. NutriScrolls. Adequate intakes from the US National Academies (2005) and EFSA (2010), as shown on that page.
- U.S. Food and Drug Administration. Questions and answers on dietary fiber. Page content current as of 25 July 2024.
- Moshfegh AJ, Friday JE, Goldman JP, et al. Presence of inulin and oligofructose in the diets of Americans. J Nutr. 1999.
- Ferjančič B, Korošec M, Kočevar Baloh A, et al. Fructan content in most commonly consumed Slovenian foods and estimation of daily fructan consumption. Front Nutr. 2024.
- Nagy DU, Sándor-Bajusz KA, Bódy B, et al. Effect of chicory-derived inulin-type fructans on abundance of Bifidobacterium and on bowel function: a systematic review with meta-analyses. Crit Rev Food Sci Nutr. 2023.
Forms of inulin and fructans: absorption and effects
Inulin is not absorbed, so “absorption” here means what reaches the colon and what chain length does there. Fructans reach people inside foods, as chicory-root powders, as short-chain oligofructose, as mixtures of short and long chains, and as an added fiber in processed foods. A review of inulin-type prebiotics notes that the terms inulin, oligofructose and fructo-oligosaccharides have been used inconsistently, and that some products are relatively high in free sugars (fructose, glucose, sucrose) while others have most of them removed. Check what a label’s “inulin” is.
The honest bottom line is that the best evidence is for chicory inulin at 12 g a day for stool frequency in people with constipation, and for a short-plus-long-chain mixture at 8 g a day for calcium absorption in adolescents. Few trials compare forms head to head; the ones we found are the cards below. Popular claims that inulin “burns fat” or “balances blood sugar” go further than the evidence: body weight fell by 1.03 kg in one 12-week trial of oligofructose, and a meta-analysis found little or no effect on fasting glucose (sources 8 and 20).
| Form | What it is | What studies show | Source |
|---|---|---|---|
| Fructans in whole foods | Onion, garlic, wheat and other plants, with their other fiber and nutrients | The challenge trials in irritable bowel syndrome and gluten sensitivity hid 2.1 g of fructans in muesli bars. Gluten-free breads are not fructan-free: they held 1.00 g per 100 g on average. | 5, 6 |
| Native chicory inulin | A non-fractionated mixture from chicory root; chains of 2 to 60 units, average 12 | The EU claim is for 12 g a day. In 44 people with constipation, 12 g a day raised median stool frequency from 3.0 to 4.0 a week. In 12 healthy men, 20 g a day did not change stool weight or transit. In 84 healthy volunteers, 5 to 20 g a day caused only mild symptoms. | 1, 2, 3, 7, 18 |
| Oligofructose and fructo-oligosaccharides | Short chains of 2 to 8 units, average 4, made by partial hydrolysis of chicory inulin or built from sucrose | Short-chain fructo-oligosaccharides at 10 g a day raised bifidobacteria in 7 days. 21 g a day cut weight by 1.03 kg in 12 weeks. 20 g a day did not help irritable bowel syndrome and 15 g a day did not help Crohn’s disease. In the lab, short chains ferment fastest and make the most gas. | 4, 8, 9, 10, 11, 18, 19 |
| Long-chain inulin | Chains of 10 to 60 units, average 25 | At 10 g a day for 7 days it did not raise bifidobacteria in healthy volunteers, while in a gut simulator inulin had a stronger and longer-lasting prebiotic effect than oligofructose. Long chains passed through more slowly and caused fewer symptoms. | 4, 12, 13, 18 |
| Oligofructose-enriched inulin (short plus long chains) | A mix of chicory oligofructose and long-chain inulin | 8 g a day raised calcium absorption and bone mineral gain in adolescents over a year. In 15 postmenopausal women, 6 weeks raised calcium and magnesium absorption versus placebo. | 14, 15 |
| Fructanase capsules | An enzyme that hydrolyzes fructans to fructose in the lab | One crossover trial in 30 healthy adults eating 25 g of inulin: the main 8-hour symptom score did not differ, though some symptoms were lower later. No trial in irritable bowel syndrome yet. | 16 |
Here are the head-to-head and form-specific studies, strongest evidence first, 5 in all.
In 200 healthy volunteers, 10 g a day of short-chain fructo-oligosaccharides raised bifidobacteria, but long-chain inulin did not
Double-blind, placebo-controlled trial of 7 days. In the screening phase, short-chain fructo-oligosaccharides, soybean oligosaccharides, galactooligosaccharides and type III resistant starch were bifidogenic, while lactulose, long-chain inulin and isomaltooligosaccharides were not. In the dose phase, 2.5, 5.0, 7.5 and 10 g a day did not differ, and a low starting bifidobacteria count predicted a bigger response.
In 84 healthy volunteers, 5 to 20 g a day of inulin-type fructans for 2 weeks caused only mild digestive symptoms
Double-blind, placebo-controlled, dose-ranging crossover study of three products with different chain lengths. Symptoms tended to rise with every product, but the change was mild (at most 19 mm on an 800 mm scale) and significant only for one mixed-chain product at 20 g a day. That product caused more symptoms than the shorter-chain product at 20 g (P=0.011). The authors call all three very well tolerated. Participants usually ate 12 g of fiber a day.
In 30 healthy adults, a fructanase enzyme capsule eased abdominal symptoms after 25 g of inulin, but the main 8-hour symptom score did not differ
Randomized, double-blind crossover trial. People ate 25 g of inulin in 40 g of oatmeal with a capsule of fructanase or maltodextrin placebo. The maximum 0 to 8 hour overall abdominal symptom score did not differ (P=0.13). The enzyme reduced abdominal pain (P=0.044) and fatigue, and from 8 to 24 hours it reduced overall symptoms, bloating, pain and flatulence. Breath hydrogen and methane did not differ. The inulin dose was far above usual intake, and the authors say trials in people with IBS are still needed.
In 10 healthy adults, abdominal symptoms after chicory fructans rose with dose and fell with longer chains
Single-blind crossover study of 10 to 30 g of short- and long-chain chicory fructans, compared with lactulose, fructose and sorbitol. Breath hydrogen and venous acetate rose in proportion to the dose, and the overall effects of short-chain fructans looked like those of lactulose. Long-chain fructans took longer to pass through (75 against 30 minutes). Very small study.
In a gut simulator, inulin (chain length 3 to 60) had more pronounced prebiotic effects than oligofructose (2 to 20)
The Simulator of the Human Intestinal Microbial Ecosystem, a laboratory model of the colon, was fed 2.5 g a day of either fructan. Both raised butyrate and propionate and lactic acid bacteria. Inulin took longer to act but gave more short-chain fatty acids, less protein breakdown, and a stronger and longer-lasting rise of bifidobacteria in the distal colon. No people were involved.
Sources
- Commission Regulation (EU) 2015/2314 authorising a health claim made on foods, other than those referring to the reduction of disease risk and to children’s development and health, and amending Regulation (EU) No 432/2012. Annex, native chicory inulin. Official Journal of the European Union. 2015.
- Micka A, Siepelmeyer A, Holz A, et al. Effect of consumption of chicory inulin on bowel function in healthy subjects with constipation: a randomized, double-blind, placebo-controlled trial. Int J Food Sci Nutr. 2017.
- Slavin J, Feirtag J. Chicory inulin does not increase stool weight or speed up intestinal transit time in healthy male subjects. Food Funct. 2011.
- Bouhnik Y, Raskine L, Simoneau G, et al. The capacity of nondigestible carbohydrates to stimulate fecal bifidobacteria in healthy humans: a double-blind, randomized, placebo-controlled, parallel-group, dose-response relation study. Am J Clin Nutr. 2004.
- Skodje GI, Sarna VK, Minelle IH, et al. Fructan, Rather Than Gluten, Induces Symptoms in Patients With Self-Reported Non-Celiac Gluten Sensitivity. Gastroenterology. 2018.
- Whelan K, Abrahmsohn O, David GJ, et al. Fructan content of commonly consumed wheat, rye and gluten-free breads. Int J Food Sci Nutr. 2011.
- Bruhwyler J, Carreer F, Demanet E, et al. Digestive tolerance of inulin-type fructans: a double-blind, placebo-controlled, cross-over, dose-ranging, randomized study in healthy volunteers. Int J Food Sci Nutr. 2009.
- Parnell JA, Reimer RA. Weight loss during oligofructose supplementation is associated with decreased ghrelin and increased peptide YY in overweight and obese adults. Am J Clin Nutr. 2009.
- Olesen M, Gudmand-Hoyer E. Efficacy, safety, and tolerability of fructooligosaccharides in the treatment of irritable bowel syndrome. Am J Clin Nutr. 2000.
- Benjamin JL, Hedin CR, Koutsoumpas A, et al. Randomised, double-blind, placebo-controlled trial of fructo-oligosaccharides in active Crohn’s disease. Gut. 2011.
- Hernot DC, Boileau TW, Bauer LL, et al. In vitro fermentation profiles, gas production rates, and microbiota modulation as affected by certain fructans, galactooligosaccharides, and polydextrose. J Agric Food Chem. 2009.
- van de Wiele T, Boon N, Possemiers S, et al. Inulin-type fructans of longer degree of polymerization exert more pronounced in vitro prebiotic effects. J Appl Microbiol. 2007.
- Rumessen JJ, Gudmand-Høyer E. Fructans of chicory: intestinal transport and fermentation of different chain lengths and relation to fructose and sorbitol malabsorption. Am J Clin Nutr. 1998.
- Abrams SA, Griffin IJ, Hawthorne KM, et al. A combination of prebiotic short- and long-chain inulin-type fructans enhances calcium absorption and bone mineralization in young adolescents. Am J Clin Nutr. 2005.
- Holloway L, Moynihan S, Abrams SA, et al. Effects of oligofructose-enriched inulin on intestinal absorption of calcium and magnesium and bone turnover markers in postmenopausal women. Br J Nutr. 2007.
- Mah E, McKenna CF, Blonquist TM, et al. Oral Fructanase Administration Reduces Gastrointestinal Symptom Severity after Acute Inulin Challenge in Healthy Adults. J Nutr. 2026.
- Kelly G. Inulin-type prebiotics: a review: part 1. Altern Med Rev. 2008.
- Roberfroid MB. Introducing inulin-type fructans. Br J Nutr. 2005.
- Roberfroid MB, Delzenne NM. Dietary fructans. Annu Rev Nutr. 1998.
- Talukdar JR, Cooper M, Lyutvyn L, et al. The effects of inulin-type fructans on cardiovascular disease risk factors: systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2024.
Is inulin safe? Gas, bloating and who should be careful
At the doses studied inulin was tolerated by healthy adults, and we found no tolerable upper intake level for inulin or fructans in the sources above; the National Academies set none for dietary or functional fiber. The usual problem is gas, which depends on dose and chain length. Anyone with a bowel condition should check with a doctor before using a supplement.
- Gas and bloating. In 84 healthy volunteers, 5 to 20 g a day of inulin-type fructans for 2 weeks gave only mild symptoms, significant for one mixed-chain product at 20 g a day. Flatulence still rose in the trial of 20 g in healthy men. In irritable bowel syndrome trials, flatulence was better at doses of 6 g a day or less, and in the 12-week trial of 20 g of fructo-oligosaccharides symptoms were worse at the start but not worse by week 12.
- Irritable bowel syndrome. Fructans caused symptoms in challenge trials, and the American College of Gastroenterology’s 2021 guideline recommends a limited trial of a low-FODMAP diet in IBS. That diet cuts many foods, most trials did not study reintroducing them, and it did no better than traditional dietary advice in one trial, so ask a doctor or dietitian rather than cutting foods alone.
- Crohn’s disease. In 103 people with active Crohn’s disease, 15 g a day of fructo-oligosaccharides gave no clinical benefit, and more people dropped out on the fructans. Ask the treating doctor before adding it.
- Allergy. Reactions are rare. A letter in the New England Journal of Medicine and a 2005 case report describe anaphylaxis from inulin in vegetables and processed foods; the woman in the case report had an earlier artichoke allergy and specific IgE to an inulin protein compound.
- Medicines. We found no study of inulin changing how medicines are absorbed.
How to get more inulin, or less if it bothers you
- Eat onions, garlic and wheat foods. Onions held 1.97 g of fructans per 100 g and wheat flour 0.75 g, and garlic far more per gram, though a clove is only about 3 g. Wheat and onions together supplied about 95% of the inulin and oligofructose in the US survey.
- Build up slowly if you use a powder. The EU claim is for 12 g a day. Gas was the main side effect, and flatulence was better at 6 g a day or less in IBS trials, so smaller steps are easier on the gut.
- If fructans bother you, ask about a guided low-FODMAP trial. The Slovenian team found none in potatoes, rice, kohlrabi or cucumbers. “Gluten-free” breads are not fructan-free (1.00 g per 100 g on average).
Sources
- Bruhwyler J, Carreer F, Demanet E, et al. Digestive tolerance of inulin-type fructans: a double-blind, placebo-controlled, cross-over, dose-ranging, randomized study in healthy volunteers. Int J Food Sci Nutr. 2009.
- Slavin J, Feirtag J. Chicory inulin does not increase stool weight or speed up intestinal transit time in healthy male subjects. Food Funct. 2011.
- Wilson B, Rossi M, Dimidi E, et al. Prebiotics in irritable bowel syndrome and other functional bowel disorders in adults: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2019.
- Olesen M, Gudmand-Hoyer E. Efficacy, safety, and tolerability of fructooligosaccharides in the treatment of irritable bowel syndrome. Am J Clin Nutr. 2000.
- Lacy BE, Pimentel M, Brenner DM, et al. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. Am J Gastroenterol. 2021.
- Böhn L, Störsrud S, Liljebo T, et al. Diet low in FODMAPs reduces symptoms of irritable bowel syndrome as well as traditional dietary advice: a randomized controlled trial. Gastroenterology. 2015.
- Black CJ, Staudacher HM, Ford AC. Efficacy of a low FODMAP diet in irritable bowel syndrome: systematic review and network meta-analysis. Gut. 2022.
- Benjamin JL, Hedin CR, Koutsoumpas A, et al. Randomised, double-blind, placebo-controlled trial of fructo-oligosaccharides in active Crohn’s disease. Gut. 2011.
- Gay-Crosier F, Schreiber G, Hauser C. Anaphylaxis from inulin in vegetables and processed food. N Engl J Med. 2000.
- Franck P, Moneret-Vautrin DA, Morisset M, et al. Anaphylactic reaction to inulin: first identification of specific IgEs to an inulin protein compound. Int Arch Allergy Immunol. 2005.
- Ferjančič B, Korošec M, Kočevar Baloh A, et al. Fructan content in most commonly consumed Slovenian foods and estimation of daily fructan consumption. Front Nutr. 2024.
- Moshfegh AJ, Friday JE, Goldman JP, et al. Presence of inulin and oligofructose in the diets of Americans. J Nutr. 1999.
- Whelan K, Abrahmsohn O, David GJ, et al. Fructan content of commonly consumed wheat, rye and gluten-free breads. Int J Food Sci Nutr. 2011.
- Fiber. NutriScrolls. Adequate intakes from the US National Academies (2005) and EFSA (2010), as shown on that page.
History of inulin and fructans
Inulin mattered to the kidney before it mattered to the gut. In 1932 Jolliffe, Shannon and Smith used sugars that the body does not metabolize to measure the glomerular filtrate in dogs, and in 1935 Shannon published a paper on how dogs excrete inulin. A 2004 essay counts these papers among four classics that developed the clearance methods for measuring kidney filtration.
The gut story begins in 1995, when Gibson and Roberfroid proposed the word “prebiotics” for nondigestible food ingredients that selectively stimulate bacteria already living in the colon, and named fructo-oligosaccharides among those that raise bifidobacteria. In 2017 an expert panel updated the definition to a substrate selectively utilized by host microorganisms conferring a health benefit, and required the benefit to be documented. In 1999 a US study gave the first published estimate of how much inulin and oligofructose Americans eat from food.
The fructan story is more recent. In 2011 a trial found that gluten brought back symptoms in people with irritable bowel syndrome who were controlled on a gluten-free diet. In 2013 the same group put 37 people with suspected gluten sensitivity on a reduced-FODMAP diet first and found gluten no worse than whey, with gluten-specific effects in 8%. In 2018 a trial that tested gluten and fructans separately found that fructans caused more symptoms than gluten. The EU adopted its chicory inulin claim on 7 December 2015, and it was authorized from 1 January 2016.
Sources
- Hostetter TH, Meyer TW. The development of clearance methods for measurement of glomerular filtration and tubular reabsorption. Am J Physiol Renal Physiol. 2004.
- Gibson GR, Roberfroid MB. Dietary modulation of the human colonic microbiota: introducing the concept of prebiotics. J Nutr. 1995.
- Gibson GR, Hutkins R, Sanders ME, et al. Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nat Rev Gastroenterol Hepatol. 2017.
- Moshfegh AJ, Friday JE, Goldman JP, et al. Presence of inulin and oligofructose in the diets of Americans. J Nutr. 1999.
- Biesiekierski JR, Newnham ED, Irving PM, et al. Gluten causes gastrointestinal symptoms in subjects without celiac disease: a double-blind randomized placebo-controlled trial. Am J Gastroenterol. 2011.
- Biesiekierski JR, Peters SL, Newnham ED, et al. No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates. Gastroenterology. 2013.
- Skodje GI, Sarna VK, Minelle IH, et al. Fructan, Rather Than Gluten, Induces Symptoms in Patients With Self-Reported Non-Celiac Gluten Sensitivity. Gastroenterology. 2018.
- Commission Regulation (EU) 2015/2314 authorising a health claim made on foods, other than those referring to the reduction of disease risk and to children’s development and health, and amending Regulation (EU) No 432/2012. Annex, native chicory inulin. Official Journal of the European Union. 2015.
Frequently asked questions about inulin and fructans
What is the difference between inulin, fructans and FOS?
Fructans are the whole family of carbohydrates built mostly from fructose-to-fructose links. Inulin is the linear kind with beta(2→1) bonds, with chains of 2 to 60 units in chicory (average 12). Oligofructose and fructo-oligosaccharides (FOS) are short-chain versions of 2 to 8 units (average 4). The fructan values on this site are total fructans, which counts all of them together.
Does inulin help constipation?
Somewhat, in people who are constipated. In 44 people with constipation, 12 g a day of chicory inulin for 4 weeks raised median stool frequency from 3.0 to 4.0 a week, and a meta-analysis of 5 trials found softer and more frequent stools. Pain and bloating did not improve, and in 12 healthy men 20 g a day did not change stool weight or transit. The EU allows the claim at 12 g a day.
Does inulin feed good gut bacteria?
It raises bifidobacteria, but the health meaning is less certain. A meta-analysis of 50 studies found that 3 to 20 g a day of chicory inulin-type fructans raised Bifidobacterium abundance. The 2017 expert definition of a prebiotic requires a documented health benefit, and the starting level matters: in one trial a low starting count predicted a bigger rise.
Why does inulin cause gas and bloating?
Bacteria in the colon ferment it, and fermentation makes gas. Symptoms rose with dose and with shorter chains in healthy adults, though they were mild at up to 20 g a day in 84 volunteers. In people with irritable bowel syndrome, inulin-type fructans worsened flatulence in a meta-analysis, and doses of 6 g a day or less did better.
Should people with IBS avoid fructans?
Many do better on less, but it is not a rule. In 25 people with IBS, fructans left symptoms uncontrolled in 77% against 14% with glucose. A low-FODMAP diet, which removes fructans and other fermentable carbohydrates, ranked first for symptoms in a network meta-analysis, and in 75 people it did no better than traditional dietary advice. A dietitian can guide a trial and reintroduction.
Is it gluten or fructans in wheat that causes symptoms?
In some people it is the fructans. In 59 people who believed gluten bothered them, 2.1 g of fructans caused more bloating than 5.7 g of gluten, and gluten did not differ from placebo. In an earlier trial, gluten-specific effects appeared in only 8% of 37 people after they cut FODMAPs. This does not apply to celiac disease, which was excluded from these trials.
Does inulin help with weight loss or cholesterol?
Only a little, and the certainty is low. Pooling 55 trials, inulin-type fructans lowered body weight by 0.97 kg, LDL cholesterol by 0.14 mmol/L and triglycerides by 0.06 mmol/L, with low or very low certainty. A review of appetite trials found that most showed no effect on appetite or energy intake. Fasting glucose and blood pressure showed little or no change.
Which foods have the most fructans?
Garlic is richest, then onions and wheat. Four Italian garlic landraces held 45.8 to 54.4 g of fructans per 100 g of dry weight, onions 1.97 g per 100 g fresh and wheat flour 0.75 g. Potatoes, rice, kohlrabi and cucumbers had none detectable. Gluten-free breads still held about 1.00 g per 100 g on average.