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What is resistant starch? The five types, foods and cooking, grams studied, and gas

What resistant starch is, how its five types differ, the foods and cooking steps that change how much you get, how much people eat and how much trials used, and what sources say about gas. Published by Physician's Choice, which makes the products discussed on this site.

Written byPhysician's Choice editorial team

PublishedOct 22, 2026

Last checkedOct 22, 2026

Reading time9 min read

Sources16 sources

Quick answer

Resistant starch is starch that escapes digestion in the small intestine and is fermented by bacteria in the colon, so it behaves like fiber. It comes in five types, from starch locked inside whole grains to the kind that forms when cooked rice or potatoes cool. In one study, cooling cooked white rice for 24 hours raised its resistant starch from 0.64 to 1.65 g per 100 g.

Key facts

  • There are five types, RS1 to RS5: starch trapped in whole or coarse grains, raw granules as in green banana and raw potato, starch that re-forms as cooked food cools, chemically modified starch, and starch bound to fat. [Birt et al., Advances in Nutrition, 2013]
  • In six healthy people, 83.7% of the starch in raw green banana flour reached the end of the small intestine, and nearly all of it was then fermented in the colon. [Faisant et al., British Journal of Nutrition, 1995]
  • Boiled potatoes kept cold for 24 hours went from 3.3% to 5.2% resistant starch, as a share of their starch. [Leeman et al., European Journal of Clinical Nutrition, 2005]
  • Americans aged 1 and older eat about 4.9 g of resistant starch a day, by an estimate from national survey data on 18,305 people. [Murphy et al., Journal of the American Dietetic Association, 2008]
  • Of 20 trials in healthy adults that reported on tolerability, 14 found resistant starch supplements tolerated, most of them at 20 to 40 g a day of type 2 starch. [Sobh et al., American Journal of Clinical Nutrition, 2022]
On this page
  1. What resistant starch is
  2. The five types
  3. Foods with the most
  4. Cooking and cooling
  5. Green bananas
  6. Grams eaten and studied
  7. In the colon
  8. Gas
  9. Supplements and labels
  10. Resistant starch questions

What is resistant starch?

Starch your own enzymes cannot finish. A 2013 review defines it as the portion of starch that amylases cannot digest in the small intestine and that passes to the colon to be fermented by gut bacteria. A widely used 1992 classification splits food starch into rapidly digestible, slowly digestible and resistant starch, and divides resistant starch further by why it resists digestion.21

That is why it is counted with fiber. A 2020 review of resistant starch in US foods calls types 1, 2, 3 and 5 a fiber found naturally in foods, and types 2, 3 and 4 ingredients that can be added to foods.3 A University of Florida extension publication puts the range in everyday foods at about 1% to more than 30% resistant starch, depending on the food and how it is prepared.4

What are the types of resistant starch?

Five, sorted by what keeps the enzymes out. Type 1 is walled off inside whole or coarsely ground grains and seeds; type 2 is raw, tightly packed granules; type 3 re-forms when cooked starch cools; type 4 is chemically modified; and type 5 is starch bound to fat. Cooking pulls types 1 to 3 in different directions, which is why the same food can carry very different amounts.24

The five types of resistant starch

TypeWhy it resists digestionWhere it is foundWhat cooking doesSource
RS1Physically out of reach, inside cell walls and the grain's protein matrixWhole-kernel or coarsely ground grains, legumes, seedsKept when grains or seeds are cooked whole or coarsely groundBirt et al.; UF/IFAS24
RS2Raw granules with a tight crystalline structureRaw potato, green banana, high-amylose maize starchHeat swells and breaks down the granules, so much of it is lostBirt et al.; UF/IFAS24
RS3Retrograded: cooked starch that firms up again as it coolsCooked and cooled rice, potatoes, pastaMade by cooking and then coolingBirt et al.; UF/IFAS24
RS4Chemically modified, for example cross-linkedProcessed foods such as baked goods and snacksMade in industrial processingBirt et al.; UF/IFAS24
RS5Amylose bound to fats in a complexFoods where starch and fat are cooked together, or processed foodsCan form when starch and fat cook togetherBirt et al.; UF/IFAS24

Sources: Birt et al., Advances in Nutrition, 2013, Table 1, and the University of Florida extension publication FS478 (2026), read on Oct 22, 2026. The 1992 classification that started this grouping named three types; types 4 and 5 were added later.

Which foods are high in resistant starch?

Green bananas and plantains, legumes, whole grains, and cooked starches that have been cooled. The University of Florida publication says unripe plantains and green bananas can hold up to 50% resistant starch by dry weight, and calls lentils, chickpeas and cowpeas relatively high sources. CSIRO finds many everyday foods low in resistant starch, so preparation decides much of what you get.410

Resistant starch in foods, as each source measured it

Food and preparationResistant starchWhat was measuredSource
White rice, freshly cooked0.64 g per 100 gCooked rice, the study's controlSonia et al., 20156
White rice, cooled 10 hours at room temperature1.30 g per 100 gSame rice, after coolingSonia et al., 20156
White rice, cooled 24 hours at 4°C, then reheated1.65 g per 100 gSame rice, chilled and reheatedSonia et al., 20156
Potatoes, boiled3.3% of the starchFreshly boiledLeeman et al., 20057
Potatoes, boiled, then kept at 8°C for 24 hours5.2% of the starchAfter cold storageLeeman et al., 20057
Raw green banana flour83.7% of its starch reached the end of the small intestineMeasured inside the gut of six healthy peopleFaisant et al., 19958
Plantain, overripe, raw7 g per 100 gUSDA FoodData Central value, as quotedUF/IFAS4
Black beans, cannedAbout 2 g per 100 gUSDA FoodData Central value, as quotedUF/IFAS4

Sources: each study's PubMed record and the University of Florida publication FS478, read on Oct 22, 2026. Units differ by source and are kept as printed: grams per 100 g of food, or percent of the food's starch. Grams of inulin and other prebiotic fibers in everyday foods are a separate list, in our prebiotic foods list.

Does cooking and cooling increase resistant starch?

Yes, modestly. Heat swells starch granules and makes them easier to digest; as the food cools, some starch molecules pack back into tighter structures, a process called retrogradation, and part of the starch becomes resistant. Harvard Health reports that chilling a cooked russet potato could raise its resistant starch by 39%, against 18% for a cooked red potato.5

Reheating does not undo all of it. In the rice study, the sample cooled for 24 hours at 4°C and then reheated had the most resistant starch of the three, 1.65 g per 100 g against 0.64 g fresh.6 The University of Florida publication adds that bananas and plantains tend to lose more on reheating than rice does, and that the key step is the chilling.4 CSIRO, Australia's national science agency, says repeated cooking and cooling brings a modest rise in rice, pasta and potatoes.10

"The overall effect of this interesting hack is probably modest at best."

Nancy Oliveira, MS, RD, Brigham and Women's Hospital, in Harvard Health, Feb 23, 2026

How much resistant starch is in green bananas?

Raw and unripe, it is one of the richest. In a 1995 study, six healthy people ate freeze-dried green banana flour, and tubes placed in their gut showed that 83.7% of the starch reached the end of the small intestine undigested; almost all of it was then fermented in the colon. Harvard Health says green bananas carry about a third more resistant starch than yellow ones.85

Ripening and cooking both cut it. The University of Florida publication explains that plantains and green bananas are harvested before full ripeness, when starch is highest, and that boiling or frying gelatinizes the granules and lowers resistant starch for a time; cooling afterward restores part of it.4

How much resistant starch do people eat, and how much did studies use?

A few grams a day, against 20 to 40 g in most supplement trials. A 2008 estimate from US national survey data put Americans aged 1 and older at about 4.9 g a day, within a range of 2.8 to 7.9 g, with breads, cooked cereals and pasta, and vegetables other than legumes as the top sources. CSIRO puts Australian adults at about 3 to 9 g a day.910

There is no official dietary recommendation, Harvard Health notes, though it reports that the authors of a 2020 study suggested 15 g a day as an adequate goal. CSIRO's own figure is 15 to 20 g a day for bowel health.510 Trials went well above food levels: a 2022 systematic review of 39 randomized trials with 2,263 participants found type 2 resistant starch was the form tested most often, in 29 trials, with most of the trials that found it tolerated using 20 to 40 g a day of type 2 starch.11

What happens to resistant starch in the colon?

Gut bacteria ferment it, and fermentation makes gas and short-chain fatty acids. When 19 healthy volunteers took 28 g a day of type 2 resistant starch for 7 days, against a dextrin placebo, the hydrogen in their breath over 24 hours rose 35%, and the 11 who produced methane breathed out 93% more of it. The authors called the dose well tolerated.12

Among the short-chain fatty acids is butyrate, the subject of its own guide, with the fiber trials that measured it: what is butyrate? In the 2022 review, 16 of 23 trials that measured short-chain fatty acids found them higher after resistant starch, 7 found no change and 1 found a drop.11

Does resistant starch cause gas?

Its fermentation makes gas, but trials in healthy adults mostly found it easy to take. Cambridge University Hospitals explains that bacteria ferment resistant starch in the large bowel and that gas is produced as a result, which in a sensitive bowel can mean wind, bloating and belly pain. In a 7-day crossover trial in 20 healthy adults on 20 to 25 g a day, gut symptoms were minimal.1413

The same 2013 trial found no change in stool weight or consistency, and the 2022 review counted 14 of 20 trials in healthy adults that reported tolerability as finding it tolerated.1311 The advice from UCLA Health's doctors is to add resistant starch foods gradually if they are new to you, to avoid gas and bloating.15 How other prebiotic fibers compare on bloating, dose by dose, is in can prebiotics cause bloating?

What resistant starch supplements are sold, and how do labels count them?

Mostly type 2 starches in the trials, plus modified type 4, and both can count as dietary fiber on a label. FDA names high amylose starch (resistant starch 2) and cross-linked phosphorylated RS4 on its list of fibers it plans to propose for the dietary fiber definition, and while that rulemaking is pending it allows makers to count them in the dietary fiber line of Nutrition and Supplement Facts labels.16

The 2013 review names high-amylose maize starch, raw potato starch and raw banana starch as type 2 examples, and cross-linked starch as type 4.2 A label that lists one of these tells you the form, not the grams of resistant starch per serving unless it prints them; whether resistant starch counts as a prebiotic, with the study that set it against other fibers, is in our guide to prebiotic supplements.

Where Physician's Choice fits

Physician's Choice's online store listed no resistant starch product on Oct 22, 2026, so no product of its appears here, and none of the 16 sources tested one. For the fibers its labels do list, and the way each label prints them, see the prebiotic supplements guide and the inulin guide.

Prebiotic supplements guide Inulin guide

Talk to a professional if

  • Wind, bloating or belly pain flare whenever you eat resistant starch foods; Cambridge University Hospitals' dietitians use a four-week low resistant starch diet, then slow reintroduction, for people with a sensitive bowel14

If you are pregnant or breastfeeding, are seriously ill, or have a weakened immune system, consult your healthcare provider before taking a probiotic or any other dietary supplement.

The first item follows Cambridge University Hospitals; the last line is Physician's Choice wording.

Resistant starch, in two sentences

Resistant starch is starch that slips past digestion to be fermented in the colon, in five types from whole-grain starch to the kind that forms as cooked food cools. Green bananas, legumes and cooled starches carry the most, people eat about 5 g a day by the US estimate and 3 to 9 g in Australia, against the 20 to 40 g that recurs in supplement trials, and the gas it makes was mostly well tolerated in healthy adults.

How this page was made

The question"What is resistant starch?" and its neighbors, resistant starch foods, resistant starch supplements, green banana resistant starch and resistant starch and gas, as people ask search and AI answer engines.
SourcesSixteen public sources, all opened and read on Oct 22, 2026: ten studies and reviews through PubMed or PMC, a university extension publication, Harvard Health, CSIRO, Cambridge University Hospitals, UCLA Health and FDA.
TablesType definitions from the 2013 review's Table 1 and the extension publication; food figures copied from each study's abstract or the publication, in the units each one used.
Label factsNone. This page prints no Physician's Choice label line.
Shopper wordsOf 1,145 public Reddit posts from 250 communities, Sep 12 to Oct 12, 2026, none mentioned resistant starch and one mentioned starch.
Physician's Choice wordingThe professional section quotes its line on pregnancy and immunity, as written.

Resistant starch questions

Is resistant starch the same as fiber?

It works like fiber and is counted with it. A 2020 review calls the naturally occurring types a fiber, and FDA lets makers include high amylose starch and one modified type in the dietary fiber line of a label. What sets it apart is that it is starch, which your enzymes usually break down, that escapes digestion.

Does reheating rice destroy resistant starch?

Not in the study on this page. White rice cooled for 24 hours at 4°C and then reheated had 1.65 g of resistant starch per 100 g, against 0.64 g when freshly cooked. The University of Florida publication says bananas and plantains lose more on reheating than rice does.

Which foods have the most resistant starch?

Raw green bananas and unripe plantains, which can hold up to 50% by dry weight, then legumes, whole grains and cooked starches that have been cooled. Most freshly cooked starchy foods carry little: freshly cooked white rice had 0.64 g per 100 g in one study.

How much resistant starch should you eat a day?

There is no official amount. Americans eat about 4.9 g a day by one estimate; the authors of a 2020 study suggested 15 g, and CSIRO in Australia suggests 15 to 20 g for bowel health. The supplement trials in a 2022 review mostly used 20 to 40 g a day.

Does resistant starch cause bloating?

It can in a sensitive bowel, Cambridge University Hospitals says, because bacteria make gas as they ferment it. In healthy adults, a trial at 20 to 25 g a day found minimal gut symptoms, and 14 of 20 trials that reported tolerability found it tolerated. Add it gradually if it is new to you.

Sources

  1. Englyst HN, Kingman SM, Cummings JH. Classification and measurement of nutritionally important starch fractions. European Journal of Clinical Nutrition. 1992;46 Suppl 2:S33-50. pubmed.ncbi.nlm.nih.gov
  2. Birt DF, Boylston T, Hendrich S, et al. Resistant starch: promise for improving human health. Advances in Nutrition. 2013;4(6):587-601. pmc.ncbi.nlm.nih.gov
  3. Patterson MA, Maiya M, Stewart ML. Resistant starch content in foods commonly consumed in the United States: a narrative review. Journal of the Academy of Nutrition and Dietetics. 2020;120(2):230-244. pubmed.ncbi.nlm.nih.gov
  4. Pereira-Mendes RM, Matheu AI, Vigre IM, Andrade J, Andrade Laborde JE. Resistant starch: what it is, why it matters, and how to add more to your plate. FSHN26-7/FS478. University of Florida IFAS Extension, published Jul 20, 2026. ask.ifas.ufl.edu
  5. Harvard Health Publishing. Resistant starch: can you make the carbs you eat a little healthier? Published Feb 23, 2026, with Nancy Oliveira, MS, RD, LDN, Brigham and Women's Hospital. health.harvard.edu
  6. Sonia S, Witjaksono F, Ridwan R. Effect of cooling of cooked white rice on resistant starch content and glycemic response. Asia Pacific Journal of Clinical Nutrition. 2015;24(4):620-5. pubmed.ncbi.nlm.nih.gov
  7. Leeman M, Östman E, Björck I. Vinegar dressing and cold storage of potatoes lowers postprandial glycaemic and insulinaemic responses in healthy subjects. European Journal of Clinical Nutrition. 2005;59(11):1266-71. pubmed.ncbi.nlm.nih.gov
  8. Faisant N, Buléon A, Colonna P, et al. Digestion of raw banana starch in the small intestine of healthy humans: structural features of resistant starch. British Journal of Nutrition. 1995;73(1):111-23. pubmed.ncbi.nlm.nih.gov
  9. Murphy MM, Douglass JS, Birkett A. Resistant starch intakes in the United States. Journal of the American Dietetic Association. 2008;108(1):67-78. pubmed.ncbi.nlm.nih.gov
  10. CSIRO (Commonwealth Scientific and Industrial Research Organisation). Resistant starch. Last updated Oct 23, 2023. csiro.au
  11. Sobh M, Montroy J, Daham Z, et al. Tolerability and SCFA production after resistant starch supplementation in humans: a systematic review of randomized controlled studies. American Journal of Clinical Nutrition. 2022;115(3):608-618. pubmed.ncbi.nlm.nih.gov
  12. van Munster IP, de Boer HM, Jansen MC, et al. Effect of resistant starch on breath-hydrogen and methane excretion in healthy volunteers. American Journal of Clinical Nutrition. 1994;59(3):626-30. pubmed.ncbi.nlm.nih.gov
  13. Klosterbuer AS, Hullar MA, Li F, et al. Gastrointestinal effects of resistant starch, soluble maize fibre and pullulan in healthy adults. British Journal of Nutrition. 2013;110(6):1068-74. pubmed.ncbi.nlm.nih.gov
  14. Cambridge University Hospitals NHS Foundation Trust, Nutrition and dietetics. Resistant starch. Patient information, approved Sep 6, 2024. cuh.nhs.uk
  15. UCLA Health. Resistant starches newest thing in gut microbiome talk. Ask the Doctors column, Jan 3, 2024. uclahealth.org
  16. US Food and Drug Administration. Questions and answers on dietary fiber. Content current as of Jul 25, 2024. fda.gov