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Short-Chain Fatty Acids (SCFA)

What are short-chain fatty acids?

Short-chain fatty acids (SCFA) contain 2-5 carbon (C) atoms. They are mainly produced during fermentation of the soluble dietary fiber by beneficial large intestinal bacteria. They include [2]:

  • Acetic acid (2 C atoms)
  • Propionic acid (3 C atoms)
  • Butyric acid (4 C atoms)

SCFA Functions

SCFA are considered the main nutrients for the large intestinal lining cells; they also increase the blood flow, muscle activity and water absorption in the colon [1,2]. SCFA are partly used as food for beneficial bacteria and partly they are absorbed and metabolized – this is why soluble dietary fiber, from which colonic bacteria produce SCFA, has 1-3.8 Calories per gram [1].

SCFA Food Sources

The following soluble dietary fiber produces most SCFA in the large intestine [2,3]:

Butyrate in Dairy

Butter, certain cheeses and cow’s milk contain considerable amounts of butyric acid in the form of butyrate (a compound of butyric acid and glycerol) [4]; note that these foods are also high in saturated fats.

In rancid butter, butyric acid appears in the free form–not bound to glycerol as in normal butter–and causes unpleasant odor.

SCFA (Butyrate) Supplements

Short-chain fatty acid supplements, mostly butyric acid salts, such as sodium, potassium, calcium and magnesium butyrate, are available without prescription (over-the-counter).

Butyrate supplements are–like other fatty acids–absorbed in the small intestine, so they cannot promote the growth of beneficial colonic bacteria or clean the large intestine (colon), as advertised. There is no scientific evidence about their effectiveness as liver or biliary tree cleansers, or ammonia or neurotoxin detoxifiers.

Possible Short-Chain Fatty Acids (SCFA) Benefits

  • Adding resistant starches (which generate SCFA in the colon) to oral rehydration solution (ORS) may help to reduce acute diarrhea in small children [5], including diarrhea in cholera [1]. Cooked green bananas (high in resistant starches) or pectin (which is a soluble fiber), which both generate SCFA in the colon, may help to relieve chronic diarrhea in children [6].
  • When feeding by mouth is not possible for certain periods of time, like after a gastrointestinal surgery, colonic lining may undergo a rapid degradation (atrophy). Short-chain fatty acids (SCFA) used in intravenous infusion help to nourish colonic lining and thus prevent its degradation [7].

There is INSUFFICIENT EVIDENCE about the effectiveness of short-chain fatty acids (SCFA) in the prevention or treatment of colorectal cancer [2,8,9], ischemic stroke, treating obesity, high blood cholesterol, diabetes type 2, sickle cell disease, Crohn’s disease and ulcerative colitis [10,11,12,13], post-infectious irritable bowel syndrome (IBS) [7], increasing calorie delivery in cystic fibrosis [14], prevention ammonia or toxins absorption from the intestine, constipation, antibiotic-associated diarrhea.

The role of SCFA produced by the intestinal bacteria in immunity is not clear yet: they may either promote or inhibit inflammation in the body [17,18,19].

Ethyl Butyrate, Methyl Butyrate, Propionate

Ethyl butyrate and methyl butyrate are esters of butyric acid and ethanol or methanol. They have a fruity odor, so they can be used as food flavors added to orange juice, other fruit products or alcohol beverages, such as martini. Butyric acid is industrially produced by fermentation of starch by the bacterium Bacillus subtilis.

Propionic acid is also produced by bacteria from the genus Propionibacterium and is responsible for a specific flavor of Swiss cheese [15]Propionic acid (E-number = E280) and its salts sodium propionate (E281), calcium propionate (E282) and potassium propionate (E283) can be used as food preservatives or flavorings; they are Generally Recognized As Safe (GRAS) by the U.S. Food and Drug Administration (FDA) [16].

Another short-chain fatty acid that is different than above ones is alpha-lipoic acid.

  1. Corman ML, Colon and Rectal Surgery, 5th Edition, p.34
  2. Topping DL et al, 2001, Short-Chain Fatty Acids and Human Colonic Function: Roles of Resistant Starch and Nonstarch Polysaccharides  Physiological Reviews
  3. Rossi M et al, 2005, Fermentation of Fructooligosaccharides and Inulin by Bifidobacteria: a Comparative Study of Pure and Fecal Cultures  PubMed Central
  4. Foods high in butyric acid  Wholefoodcatalog.info
  5. Binder HJ, 2010, Role of colonic short-chain fatty acid transport in diarrhea  PubMed
  6. Rabbani GH et al, 2004, Green banana and pectin improve small intestinal permeability and reduce fluid loss in Bangladeshi children with persistent diarrhea  PubMed
  7. Berni Canani R et al, 2011, Potential beneficial effects of butyrate in intestinal and extraintestinal diseases  PubMed Central
  8. Wong JM et al, 2006, Colonic health: fermentation and short chain fatty acids  PubMed
  9. Hinnebusch HN et al, 2002, The Effects of Short-Chain Fatty Acids on Human Colon Cancer Cell Phenotype Are Associated with Histone Hyperacetylation  The Journal Of Nutrition
  10. Hallert C et al, 2006, Increasing fecal butyrate in ulcerative colitis patients by diet: Controlled pilot study  Wiley Online Library
  11. Breuer RI et al, 1997, Short chain fatty acid rectal irrigation for left-sided ulcerative colitis: a randomised, placebo controlled trial  PubMed Central
  12. Vernia P et al, 2000, Combined oral sodium butyrate and mesalazine treatment compared to oral mesalazine alone in ulcerative colitis: randomized, double-blind, placebo-controlled pilot study  PubMed
  13. Di Sabatino A et al, 2005, Oral butyrate for mildly to moderately active Crohn’s disease  PubMed
  14. Vaisman N et al, 1992, Short-chain fatty acid absorption in patients with cystic fibrosis  PubMed
  15. Drake SL et al, 2007, Sources of umami taste in Cheddar and Swiss cheeses  PubMed
  17. Renan Corrêa-Oliveira R et al, 2016, Regulation of immune cell function by short-chain fatty acids  PubMed Central
  18. Kim HC et al, 2014, Gut Microbiota-Derived Short-Chain Fatty Acids, T Cells, and Inflammation  PubMed Central
  19. Park J et al, 2016, Chronically Elevated Levels of Short-Chain Fatty Acids Induce T Cell-Mediated Ureteritis and Hydronephrosis
    PubMed Central

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