Home / Carbohydrates / Resistant Starches

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

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