Quick answer
Butyrate is a short-chain fatty acid that colon bacteria make when they ferment fiber; it is the charged form of butyric acid, and Cleveland Clinic says it meets about 70% of colon cells' energy needs. Which fiber matters: in a 2019 trial, 43 healthy young adults on resistant potato starch raised stool butyrate by 29% on average in 2 weeks, while 49 on chicory inulin showed no significant change.
Key facts
- Butyric acid is the four-carbon fatty acid C4H8O2, also called butanoic acid, and butyrate is the form it takes once it gives up a hydrogen ion. [PubChem]
- In a healthy colon, acetate, propionate and butyrate run at a ratio of roughly 60:25:15, a 2021 review says. [Siddiqui and Cresci, Journal of Inflammation Research, 2021]
- The two most abundant groups of butyrate makers in the human colon are relatives of Eubacterium rectale and Roseburia, and of Faecalibacterium prausnitzii. [Louis and Flint, FEMS Microbiology Letters, 2009]
- In 46 healthy adults, a diet with 22 g a day of added resistant starch for 4 weeks raised fecal butyrate in most of them, though it often fell in people who started with high levels. [McOrist et al., Journal of Nutrition, 2011]
- Salted butter holds 3.226 g of butyric acid, listed as fatty acid 4:0, per 100 g. [USDA FoodData Central; PubChem]
On this page
What is butyrate, and is it the same as butyric acid?
It is the same molecule in another form. PubChem describes butyric acid, or butanoic acid, as a straight-chain saturated fatty acid with four carbons and the formula C4H8O2, and butyrate as the short-chain fatty acid anion that is its conjugate base, the form left when the acid's carboxy group gives up a hydrogen ion. Cleveland Clinic calls butyric acid one type of butyrate.123
Butyrate is one of the short-chain fatty acids, with acetate and propionate. A 2021 review says these acids are made mainly in the colon when gut microbes ferment fermentable fiber and resistant starches, and to a lesser extent proteins from food and from the body, and that in a healthy colon they occur at roughly 60:25:15, acetate to propionate to butyrate. The same review says these weak acids lower the pH in the colon, which favors the bacteria that make butyrate.4
What does butyrate do in the gut?
It feeds the cells that line the colon. Cleveland Clinic says butyrate provides the main energy source for colon cells and meets about 70% of their energy needs. Much of what is said about it beyond that rests on early work: the same article says early evidence comes mostly from animal studies.3 A 2021 review says challenges remain for butyrate, naming low bioavailability, a short half-life and levels that vary in healthy people.4
That is why this page lists no health effect of butyrate in people. It sets out what butyrate is, who makes it and what raised it in trials, and leaves outcomes to studies that have tested them.
Which gut bacteria make butyrate?
Mostly oxygen-sensitive Firmicutes in the colon. A 2009 review says human colonic butyrate producers are Gram-positive Firmicutes that are phylogenetically diverse, and that the two most abundant groups are related to Eubacterium rectale and Roseburia species and to Faecalibacterium prausnitzii. A 2021 review adds that they are strictly anaerobic bacteria, found mainly in clostridial clusters IV and XIVa.54
Often they work in a chain. A 2017 review of how gut bacteria make propionate and butyrate stresses cross-feeding, in which one species uses what another leaves behind, lactate and succinate in particular.6 In the 2019 fiber trial, people whose Ruminococcus bromii or Clostridium chartatabidum rose on resistant potato starch, the bacteria that break the starch down first, were more likely to reach higher butyrate, especially if their gut was already rich in Eubacterium rectale. Bifidobacteria, though good at breaking down resistant starch and inulin, may not add to butyrate in the short term, the authors write.8
Which fibers raise butyrate?
Fermentable fiber in general, and in the three trials below, some resistant starches most clearly. Cleveland Clinic says gut bacteria make butyrate from soluble, fermentable fibers and lists fruit, legumes, vegetables, whole grains and resistant starches like boiled potatoes and rice. In healthy adults, resistant potato starch, and a diet with added resistant starch, raised stool butyrate, though not in everyone; in a 2019 trial, chicory inulin and resistant maize starch did not raise it significantly.3789
Fiber trials in healthy adults that measured stool butyrate
| Fiber tested | Daily amount and length | People | Stool butyrate | Source |
|---|---|---|---|---|
| Resistant potato starch | 40 to 48 g of potato starch, 28 to 34 g of it resistant starch, for 2 weeks | 43 healthy young adults | 13 to 16 mmol/kg on average, up 29%; rose in 63% of people | Baxter et al., 2019 8 |
| Resistant potato starch | 48 g of raw potato starch, about half resistant starch, for 1 week after a 3-day build-up | 20 healthy young adults | 8 to 12 mmol/kg across the group; rose in 11 people, stayed high in 3, stayed low in 6 | Venkataraman et al., 2016 7 |
| Resistant starch with other fiber | 25 g of non-starch fiber, alone or with 22 g of resistant starch, 4 weeks each | 46 healthy adults aged 31 to 66 | Higher on the resistant starch diet overall; rose in most people, often fell in those who started high | McOrist et al., 2011 9 |
| Chicory inulin | 20 g for 2 weeks | 49 healthy young adults | 11 to 13 mmol/kg; not a significant change | Baxter et al., 2019 8 |
| Resistant maize starch | 40 to 48 g, 20 to 24 g of it resistant starch, for 2 weeks | 43 healthy young adults | 9.3 to 9.7 mmol/kg; not a significant change | Baxter et al., 2019 8 |
mmol/kg = millimoles of butyrate per kilogram of stool, before and during each fiber, as each paper reports it. The 2016 and 2019 trials were funded in part by a consumer-products company; the 2011 trial's authors work at Australia's national science agency. No trial here tested a supplement sold by Physician's Choice.
The inulin row is about butyrate only. In the same 2019 trial, inulin raised the share of four Bifidobacterium species, a fiber effect our guide to what inulin is covers in full.8 Grams of prebiotic fiber in everyday foods are in our prebiotic foods list, and the fiber types sold as supplements, with the grams studied for each, are in prebiotic supplements. If you add fiber, Cleveland Clinic says to add it slowly and drink plenty of liquids, and that any gas or bloating should begin to subside in a couple of days.3 What resistant starch is, its five types and how cooking and cooling change it, is in what is resistant starch?
Which foods contain butyrate?
Butter and other milk fats carry some, as butyric acid. USDA lists fatty acid 4:0, which PubChem identifies as butyric acid, at 3.226 g per 100 g of salted butter. Cleveland Clinic calls butter a good source of butyrate but says you would need to eat far more of it than is recommended, and points instead to more fiber from plant foods, from which your gut bacteria make butyrate themselves.1013
Butyric acid (fatty acid 4:0) in four dairy foods, USDA data
| Food, as USDA names it | Per 100 g | Per portion, our arithmetic | USDA record |
|---|---|---|---|
| Butter, salted | 3.226 g | About 0.46 g in 1 tbsp (14.2 g) | FDC 173410 |
| Butter oil, anhydrous | 3.226 g | About 0.41 g in 1 tbsp (12.8 g) | FDC 173412 |
| Cheese, parmesan, hard | 1.299 g | About 0.37 g in 1 oz (28.35 g) | FDC 170848 |
| Milk, whole, 3.25% milkfat, with added vitamin D | 0.075 g | About 0.18 g in 1 cup (244 g) | FDC 171265 |
Source: USDA FoodData Central, SR Legacy records published Apr 1, 2019; portion weights are USDA's own. Per-portion figures are our arithmetic, rounded to two decimals. These foods carry butyric acid in their fat; they are not sources of fiber.10
What are butyrate supplements, and do they work?
They come in a few forms, and the human evidence behind them is thin. Cleveland Clinic names sodium butyrate as a form used in supplements and says most supplements use butyric acid and some kind of salt, "but they haven’t been proven to be beneficial." NIH's Dietary Supplement Label Database also holds labels that list tributyrin, and labels that list calcium and magnesium butyrate.312
Tributyrin is a fat: PubChem describes it as a triglyceride made by joining three butyric acids to glycerol, and lists it as a prodrug, a compound the body converts into the active one.11 Getting butyrate down to the colon is the hard part. In a 2007 test, a coated 1 g sodium butyrate tablet released its butyrate 2 to 3 hours later than an uncoated one, which moved the release to where the small intestine meets the colon, and into the colon; 12 of the 24 people tested were healthy, and the rest had a digestive condition, which this page does not cover.13
The 2021 review's list of challenges for butyrate also includes a lack of consistent clinical data.4 Cleveland Clinic's advice is to talk to your healthcare provider before taking any.3
Is butyrate a postbiotic?
Not on its own, under ISAPP's 2021 consensus. Its definition of a postbiotic does not include substantially purified metabolites without the microbial cells, and it says such molecules should go by their chemical names, butyric acid for example.14 Butyrate made by gut bacteria is a metabolite of their fermentation. What does count, case by case, is in what is a postbiotic?
Where Physician's Choice fits
This page is about a molecule and names no Physician's Choice product, and no source on it tested one. The fibers sold as supplements, and how labels print them, are covered in our guides to prebiotic supplements and to inulin.
Read the prebiotic supplements guide Read the inulin guideTalk to a professional if
- You are thinking of taking a butyrate supplement; Cleveland Clinic says to talk to your healthcare provider before taking any3
- You are pregnant or breastfeeding and looking at a butyric acid supplement; Cleveland Clinic says some healthcare providers suggest avoiding them3
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 two items follow Cleveland Clinic; the last line is Physician's Choice wording.
Butyrate, in two sentences
Butyrate is the charged form of butyric acid, a short-chain fatty acid that anaerobic gut bacteria make from fermentable fiber and that colon cells use as their main fuel. Resistant potato starch and a diet with added resistant starch raised it in trials in healthy adults while chicory inulin did not, butter carries a little as butyric acid, and the human evidence for butyrate supplements is thin.
How this page was made
| The question | "What is butyrate?" and its neighbors, butyrate foods, how to increase butyrate, what butyric acid is and what short-chain fatty acids are, as people ask search and AI answer engines. |
|---|---|
| Sources | Fourteen public sources, all opened and read on Oct 18, 2026: three PubChem entries, a Cleveland Clinic article, four reviews, three fiber trials in healthy adults, USDA food records, NIH's label database and a 2007 tablet test. |
| Tables | Trial figures copied from each paper's abstract, text or tables; food figures from four USDA records, with portion arithmetic done by us and labeled as ours. |
| Label facts | None. This page prints no Physician's Choice label line. |
| Shopper words | Of 1,145 public Reddit posts from 250 communities, Sep 12 to Oct 12, 2026, none mentioned butyrate or short-chain fatty acids. |
| Physician's Choice wording | The professional section quotes its line on pregnancy and immunity, as written. |
Butyrate questions
What foods are high in butyrate?
Butter, other milk fats and some cheeses carry butyric acid: USDA lists 3.226 g per 100 g of salted butter and 1.299 g per 100 g of hard parmesan. Cleveland Clinic says you would need far more butter than is recommended, and points instead to fermentable fiber from fruit, legumes, vegetables, whole grains and resistant starches.
How can I increase butyrate in my gut?
By feeding the bacteria that make it. Cleveland Clinic points to soluble, fermentable fiber and resistant starches like boiled potatoes and rice. In a 2019 trial, resistant potato starch raised stool butyrate by 29% on average in 2 weeks, though responses varied; chicory inulin and resistant maize starch did not raise it significantly.
What does butyrate do?
It is the main fuel for the cells lining the colon, meeting about 70% of their energy needs, Cleveland Clinic says. It is also one of the short-chain fatty acids whose weak acidity lowers the pH in the colon, a 2021 review says. Much of the rest comes from early research, mostly in animals.
Is butyric acid the same as butyrate?
They are two forms of one molecule. PubChem describes butyric acid, also called butanoic acid, as a four-carbon fatty acid, C4H8O2, and butyrate as its conjugate base, the form left when the acid gives up a hydrogen ion. Cleveland Clinic calls butyric acid one type of butyrate.
Do butyrate supplements work?
Cleveland Clinic says butyrate supplements, mostly butyric acid with some kind of salt, haven't been proven to be beneficial, and to talk to your healthcare provider before taking any. A 2021 review lists low bioavailability, a short half-life and a lack of consistent clinical data among the challenges still standing.
Sources
- PubChem (National Library of Medicine). Butyric acid, compound summary, CID 264. pubchem.ncbi.nlm.nih.gov
- PubChem (National Library of Medicine). Butyrate, compound summary, CID 104775. pubchem.ncbi.nlm.nih.gov
- Cleveland Clinic. What is butyrate? Benefits and side effects. Health Essentials, Jul 11, 2022, with registered dietitian and gut microbiome researcher Gail Cresci, PhD, RD. health.clevelandclinic.org
- Siddiqui MT, Cresci GAM. The immunomodulatory functions of butyrate. J Inflamm Res. 2021;14:6025-6041. pmc.ncbi.nlm.nih.gov
- Louis P, Flint HJ. Diversity, metabolism and microbial ecology of butyrate-producing bacteria from the human large intestine. FEMS Microbiol Lett. 2009;294(1):1-8. pubmed.ncbi.nlm.nih.gov
- Louis P, Flint HJ. Formation of propionate and butyrate by the human colonic microbiota. Environ Microbiol. 2017;19(1):29-41. pubmed.ncbi.nlm.nih.gov
- Venkataraman A, Sieber JR, Schmidt AW, et al. Variable responses of human microbiomes to dietary supplementation with resistant starch. Microbiome. 2016;4(1):33. pmc.ncbi.nlm.nih.gov
- Baxter NT, Schmidt AW, Venkataraman A, et al. Dynamics of human gut microbiota and short-chain fatty acids in response to dietary interventions with three fermentable fibers. mBio. 2019;10(1):e02566-18. pmc.ncbi.nlm.nih.gov
- McOrist AL, Miller RB, Bird AR, et al. Fecal butyrate levels vary widely among individuals but are usually increased by a diet high in resistant starch. J Nutr. 2011;141(5):883-889. pubmed.ncbi.nlm.nih.gov
- US Department of Agriculture, FoodData Central. SR Legacy records 173410 (butter, salted), 173412 (butter oil, anhydrous), 170848 (cheese, parmesan, hard) and 171265 (milk, whole, 3.25% milkfat, with added vitamin D), published Apr 1, 2019. fdc.nal.usda.gov
- PubChem (National Library of Medicine). Tributyrin, compound summary, CID 6050. pubchem.ncbi.nlm.nih.gov
- NIH Office of Dietary Supplements. Dietary Supplement Label Database. dsld.od.nih.gov
- Roda A, Simoni P, Magliulo M, et al. A new oral formulation for the release of sodium butyrate in the ileo-cecal region and colon. World J Gastroenterol. 2007;13(7):1079-1084. pubmed.ncbi.nlm.nih.gov
- Salminen S, Collado MC, Endo A, et al. The International Scientific Association of Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics. Nat Rev Gastroenterol Hepatol. 2021;18(9):649-667. pmc.ncbi.nlm.nih.gov