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Resistant Starches

What are resistant starches?

Resistant starches (RS) resist digestion in the small intestine, so they pass unchanged to the large intestine, where beneficial colonic bacteria partially break them down (ferment) to short-chain fatty acids (SCFA) and gases. They can provide about 2.1-2.8 kilocalories per gram (regular starch = 4.2 kcal/g) [1,2]. Resistant starches are considered “functional fiber;” they are not true fiber, but they still have properties of both soluble fiber–they are fermented by intestinal bacteria–and insoluble fiber–they absorb water and therefore increase the bulk of stool [1].

List of Foods High in Various Types of Resistant Starches

Chart 1. Resistant Starches

Types and Properties

Foods

RS1 Starch physically protected from digestive enzymes Beans, lentils, wholegrain bread and other whole grains, pearly barley, brown rice, bulgur wheat, sorghum [3]
RS2 Raw starch Raw foods: unripe (green) bananas, green plantains, raw potatoes, modified (non-genetically) high-amylose corn (amylomaize) and starch produced from it: high amylose corn starch (HACS), also called high amylose maize starch (HAMS)  [3,4-p.380]
RS3 Retrograde starch Cooked and cooled starchy foods: bread, potato salad [5], pasta (noodles, spaghetti) rice, cornflakes, ready-to-eat cereals, canned red kidney beans and chickpeas ) [4-p.380]
RS4 “Modified food starches,” “resistant maltodextrins” or starch hydrolysates” are chemically changed starch derivatives. Added to commercial breads, cakes, or frozen desserts to improve their texture or increase fiber content [1,4-pp.381-384]

Chart 1. sources: [1,14], NOTE: Resistant starches added to commercial foods may be RS2, RS3 or RS4.

Possible Benefits of Resistant Starches

Resistant starches are POSSIBLY EFFECTIVE in:

Constipation. RS, in amounts about 30 g/day, can increase the bulk of stool [1].

Diarrhea. RS2, when added to oral rehydration solution (ORS) may shorten the duration of acute diarrhea in children [6,15,16].

Some authors recommend consuming 20 g resistant starches per day for beneficial health effects [1].

Resistant Starches as Prebiotics

Resistant starches may act as prebiotics: they may stimulate the growth of beneficial Bifidobacteria in the colon [1,9]. The exact health benefits of prebiotics are not known yet, though.

There is INSUFFICIENT EVIDENCE about the effectiveness of resistant starches in prevention or treatment of high blood cholesterol and triglyceride levels, high glucose levels in diabetes 2 [7,8,14], gallstones, colonic cancer, weight loss, or increasing intestinal absorption of calcium and iron [1].

Safety and Side Effects

Ingestion of excessive amount of resistant starches may cause abdominal bloating and pain and excessive gas (flatulence) [8,14]. Resistant starches may worsen the symptoms of irritable bowel syndrome (IBS) in some individuals [13].

Modified Starches

Modified starches are obtained by treatment of starch (from corn or wheat) with heat, alkali, acids or enzymes [10]. They are not genetically modified (non-GMO). They are used as food additives. In the human intestine, they may act as soluble or insoluble and more or less fermentable fiber [11].

Modified starches used as food additives [10,12]:

  • Dextrin roasted starch (E1400)* is GRAS**
  • Acid treated starch (E1401) is GRAS
  • Alkaline treated starch (E1402)
  • Bleached starch (E1403) is GRAS
  • Oxidized starch (E1404)
  • Enzyme-treated starch (E1405)
  • Monostarch phosphate (E1410) is GRAS
  • Distarch phosphate (E1412) is GRAS
  • Phosphated distarch phosphate (E1413) is GRAS
  • Acetylated distarch phosphate (E1414) is GRAS
  • Starch acetate (E1420)
  • Acetylated distarch adipate (E1422) is GRAS
  • Hydroxypropyl starch (E1440)  is GRAS
  • Hydroxypropyl distarch phosphate (E1442) is GRAS
  • Starch sodium octenylsuccinate (E1450) is GRAS
  • Acetylated oxidized starch (E1451)

* Food additives with E numbers (in brackets) are permitted in the European Union. ** GRAS = Generally Recognized As Safe by the US Food and Drug Administration

Modified Starches Uses

Modified starches can be used as:

  • Food thickeners, stabilizers, emulsifiers and texturizers in baked goods, ice creams, jams, canned foods, confections, sauces, etc.
  • Fiber supplements, for example resistant dextrin and resistant maltodextrin
  • Binders in pills

Modified Starches Safety, Side Effects

All modified starches listed above, except acetylated oxidized starch, have an “Acceptable Daily Intake (ADI) not specified” status by JECFA, meaning toxicity has not been found at any amount [10], and some are Generally Recognized As Safe (GRAS) the US Food and Drug Administration (FDA) [12]. Resistant dextrin, resistant maltodextrin and other soluble modified starches may cause abdominal bloating and flatulence.

Related Nutrients

  1. Sajilata MG et al, 2006, Resistant starch ─ a review  Wiley Online Library
  2. Elia M et al, 2007, Energy values of macronutrients and specific carbohydrates in foods  European Journal of Clinical Nutrition
  3. Platel K et al, 1994, Resistant starch content of Indian foods  PubMed
  4. Mitchell, H., 2006, Sweeteners and Sugar Alternatives in Food Technology
  5. Vinegar dressing and cold storage of potatoes lowers postprandial glycaemic and insulinaemic responses in healthy subjects  PubMed
  6. Raqhupathy P et al, 2006, Amylase-resistant starch as adjunct to oral rehydration therapy in children with diarrhea  PubMed
  7. Potential Health Benefits of RS2 from High Amylose Corn  National Center for Biotechnology Information
  8. Robertson MD et al, 2005, Insulin-sensitizing effects of dietary resistant starch and effects on skeletal muscle and adipose tissue metabolism  The American Journal of Clinical Nutrition
  9. Slavin J, 2013, Fiber and Prebiotics: Mechanisms and Health Benefits  PubMed Central
  10. Modified starches  Food and Agriculture Organization of the United Nations
  11. Haub MD et al, 2010, Different Types of Resistant Starch Elicit Different Glucose Reponses in Humans  Europe PubMed Central
  12. SCOGS (Select Committee on GRAS Substances)  US Food and Drug Administration
  13. Irritable Bowel Syndrome in Adults: Diagnosis and Management of Irritable Bowel Syndrome in Primary Care  National Center for Biotechnology Information
  14. Birt DF et al, 2013, Resistant Starch: Promise for Improving Human Health  PubMed Central
  15. RamaKrishna BS et al, 2000, Amylase-Resistant Starch plus Oral Rehydration Solution for Cholera  The New England Journal of Medicine
  16. A Randomized Controlled Trial of Glucose versus Amylase Resistant Starch Hypo-Osmolar Oral Rehydration Solution for Adult Acute Dehydrating Diarrhea  PubMed Central

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