Resistant starch
Encyclopedia
Resistant starch is starch
and starch degradation products that escape digestion
in the small intestine
of healthy individuals. Resistant starch is considered the third type of dietary fiber
, as it can deliver some of the benefits of insoluble fiber and some of the benefits of soluble fiber.
Some carbohydrates, such as sugars and most starch, are rapidly digested and absorbed as glucose
into the body through the small intestine and subsequently used for short-term energy needs or stored. Resistant starch, on the other hand, resists digestion and passes through to the large intestine
where it acts like dietary fiber.
Resistant starch has been categorized into four types:
There is some discussion about resistant dextrins being described as "resistant starch". Resistant dextrins are not starches, and they can be soluble or insoluble. They might be described as "starch degradation products", which is literally included in the EURESTA definition, but their characteristics and performance are very different than insoluble resistant starches.
(grams)
|-
| Navy beans || 1/2 cup cooked || align=center | 9.8
|-
| Banana, raw || 1 medium, peeled || align=center | 4.7
|-
| Cold potato || 1/2” diameter || align=center | 3.2
|-
| Lentils || 1/2 cup cooked || align=center | 2.5
|-
| Cold pasta || 1 cup || align=center | 1.9
|-
| Pearl barley
|| 1/2 cup cooked || align=center | 1.6
|-
| Oatmeal || 1 cup cooked || align=center | 0.7
|-
| Wholegrain bread || 2 slices || align=center | 0.5
|}
Starch
Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...
and starch degradation products that escape digestion
Digestion
Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones....
in the small intestine
Small intestine
The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
of healthy individuals. Resistant starch is considered the third type of dietary fiber
Dietary fiber
Dietary fiber, dietary fibre, or sometimes roughage is the indigestible portion of plant foods having two main components:* soluble fiber that is readily fermented in the colon into gases and physiologically active byproducts, and* insoluble fiber that is metabolically inert, absorbing water as it...
, as it can deliver some of the benefits of insoluble fiber and some of the benefits of soluble fiber.
Some carbohydrates, such as sugars and most starch, are rapidly digested and absorbed as glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
into the body through the small intestine and subsequently used for short-term energy needs or stored. Resistant starch, on the other hand, resists digestion and passes through to the large intestine
Large intestine
The large intestine is the third-to-last part of the digestive system — — in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body...
where it acts like dietary fiber.
Resistant starch has been categorized into four types:
- RS1 Physically inaccessible or digestible resistant starch, such as that found in seeds or legumes and unprocessed whole grains
- RS2 Resistant starch that occurs in its natural granular form, such as uncooked potato, green banana flour and high amyloseAmyloseAmylose is a linear polymer made up of D-glucose units.This polysaccharide is one of the two components of starch, making up approximately 2-30% of the structure...
corn
- RS3 Resistant starch that is formed when starch-containing foods are cooked and cooled such as in legumes, bread, cornflakes and cooked-and-chilled potatoes or retrogradedRetrogradation (starch)Retrogradation is a reaction that takes place in gelatinized starch when the amylose and amylopectin chains realign themselves, causing the liquid to gel....
high amylose corn
- RS4 Starches that have been chemically modifiedModified starchModified starch, also called starch derivatives, are prepared by physically, enzymatically, or chemically treating native starch, thereby changing the properties of the starch. Modified starches are used in practically all starch applications, such as in food products as a thickening agent,...
to resist digestion. This type of resistant starches can have a wide variety of structures and are not found in nature.
There is some discussion about resistant dextrins being described as "resistant starch". Resistant dextrins are not starches, and they can be soluble or insoluble. They might be described as "starch degradation products", which is literally included in the EURESTA definition, but their characteristics and performance are very different than insoluble resistant starches.
As functional fiber
Resistant starch is considered a functional fiber. The U.S. Institute of Medicine has defined total fiber as equal to functional fiber plus dietary fiber, and U.S. food labeling doesn't distinguish between them.(grams)
|-
| Navy beans || 1/2 cup cooked || align=center | 9.8
|-
| Banana, raw || 1 medium, peeled || align=center | 4.7
|-
| Cold potato || 1/2” diameter || align=center | 3.2
|-
| Lentils || 1/2 cup cooked || align=center | 2.5
|-
| Cold pasta || 1 cup || align=center | 1.9
|-
| Pearl barley
Pearl barley
Pearl barley is barley processed to remove its hull and bran. Barley must have its fibrous outer hull removed before it can be eaten; pearl barley is taken a step further, polished to remove the nutritious bran layer....
|| 1/2 cup cooked || align=center | 1.6
|-
| Oatmeal || 1 cup cooked || align=center | 0.7
|-
| Wholegrain bread || 2 slices || align=center | 0.5
|}
In 1971, Painter and Burkitt suggested that a significant gap exists between the amount of dietary fiber urbanized people consume and the optimal amount of fiber for health and wellness, but some skepticism remains. In 1982, Englyst et al. gelatinized starch then post-processed it with both alpha-amylase
Alpha-Amylase
α-Amylase is an enzyme that hydrolyses alpha-bonds of large alpha-linked polysaccharides such as starch and glycogen, yielding glucose and maltose. It is the major form of amylase found in humans and other mammals...
and pullulanase
Pullulanase
Pullulanase is a specific kind of glucanase, an amylolytic exoenzyme, that degrades pullulan. It is produced as an extracellular, cell surface-anchored lipoprotein by Gram-negative bacteria of the genus Klebsiella. Type I pullulanases specifically attack α-1,6 linkages, while type II pullulanases...
in order to analyze it, found that some starch remained, and called it resistant starch. In 1986, Berry formed functional RS3 dietary fibers by a process of heating and cooling a variety of starch sources, one of which was amylopectin
Amylopectin
Amylopectin is a soluble polysaccharide and highly branched polymer of glucose found in plants. It is one of the two components of starch, the other being amylose.Glucose units are linked in a linear way with α glycosidic bonds...
pre-processed with the enzyme pullulanase. That source had the second highest alpha-amylase resistant starch level, while amylomaize
Amylomaize
Amylomaize was a term coined by Robert P. Bear of Bear Hybrids Corn Company in Decatur, Illinois to describe his discovery and commercial breeding of a unique cornstarch with high amylose content, also called high amylose starch...
or high-amylose
Amylose
Amylose is a linear polymer made up of D-glucose units.This polysaccharide is one of the two components of starch, making up approximately 2-30% of the structure...
starch had the highest. In 2007, the Federal Register published a 2001 U.S. Institute of Medicine (IOM) Panel on the Definition of Dietary Fiber's response to a request from the U.S. Food and Drug Administration. The IOM Panel proposed two definitions: functional fiber as "isolated, nondigestible carbohydrates that have beneficial physiological effects in humans", and dietary fiber as "nondigestible carbohydrates and lignin that are intrinsic and intact in plants." They also proposed that the prior classifications of soluble versus insoluble be phased out and replaced with viscous versus fermentable with respect to each specific fiber.
Resistant starch assists in increasing total fiber consumption because it can be incorporated into foods without having as negative an impact on the taste or texture as would classic dietary-fiber sources. The National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
of the Institute of Medicine within the United States has recommended a daily fiber intake of 38 grams for adult men and 25 grams for adult women. Many countries around the world recommend 25-30 grams for their populations.
Health benefits
Public health authorities and food organizations such as the Food and Agricultural Organization, the World Health OrganizationWorld Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
, the British Nutrition Foundation and the U.S. National Academy of Sciences recognize resistant starch as a beneficial carbohydrate. The WIC
WIC
The abbreviation WIC can mean:*Walta Information Center, a news agency based in Ethiopia.*Dutch West India Company, a former trading cooperation that led to the establishment of some Dutch colonies....
program (Women, Infants, Children) includes many foods high in resistant starch. The Joint Food and Agricultural Organization of the United Nations/World Health Organization Expert Consultation on Human Nutrition stated, "One of the major developments in our understanding of the importance of carbohydrates for health in the past twenty years has been the discovery of resistant starch.”
Research of natural resistant starches from high amylose
Amylose
Amylose is a linear polymer made up of D-glucose units.This polysaccharide is one of the two components of starch, making up approximately 2-30% of the structure...
corn indicates benefits in intestinal/colonic health as well as metabolic benefits in glycemic management. Studies have shown that different classes of resistant starch are digested and/or fermented differently and thus must be considered individually.
Weight management
Consumption of foods containing natural resistant starch seems to positively affect weight management in four ways.- FiberFiberFiber is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread.They are very important in the biology of both plants and animals, for holding tissues together....
fortification: When added to foods such as bread, biscuits, sweet goods, pasta, nutritional bars and cereal, resistant starch can increase fiber content without affecting taste or texture. In 2003, the World Health OrganizationWorld Health OrganizationThe World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
concluded that dietary fiber was the only dietary component that had convincing evidence showing a protective effect against weight gain and obesityObesityObesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems...
. While the exact mechanisms of fiber protecting against weight gain are still under investigation, its ability to increase satiety and decrease subsequent hunger, along with altering the secretion of hormones related to food digestion, are considered likely mechanisms.
- CalorieCalorieThe calorie is a pre-SI metric unit of energy. It was first defined by Nicolas Clément in 1824 as a unit of heat, entering French and English dictionaries between 1841 and 1867. In most fields its use is archaic, having been replaced by the SI unit of energy, the joule...
reduction: Resistant starch lowers the caloric content of foods when it is used to replace flour or other rapidly digested carbohydrates. Natural resistant starch delivers between 2-3 kilocalories/gram (8-12 kilojoules/gram) versus 4 kilocalories/gram (16 kilojoules/gram). Consequently, resistant starch is a valuable tool for formulators of reduced-calorie foodsDiet foodDiet food refers to any food or drink whose recipe has been altered in some way to make it part of a body modification diet...
.
- Satiety: Multiple recent studies have shown that naturally occurring resistant starch increases satiety and reduces food intake in the short term (within a few hours) and longer-term (for 20–24 hours).
- LipidLipidLipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
oxidation: Resistant starch may help burn fat and may lead to lower fat accumulation. A recent clinical trial with high amylose corn resistant starch showed that it increased fat oxidation after a meal. These findings suggest a possible metabolic effect of resistant starch that may affect body weight.
Blood sugar response/glycemic management
Studies suggest continual exposure to elevated levels of insulin as a result of a high glycemic diet may contribute to reduced sensitivity by cells to the insulin (insulin resistanceInsulin resistance
Insulin resistance is a physiological condition where the natural hormone insulin becomes less effective at lowering blood sugars. The resulting increase in blood glucose may raise levels outside the normal range and cause adverse health effects, depending on dietary conditions. Certain cell types...
) and a higher risk of diabetes. As insulin resistance increases, the body produces more insulin to maintain adequate blood sugar control. With rising resistance, even more insulin is required, and the body may not be able to keep up or the pancreatic cells producing insulin may stop functioning.
Consumption of natural resistant starch by humans has been shown to result in decreased glycemic response in healthy individuals, decreased glycemic response in diabetics, increased insulin sensitivity in healthy individuals, individuals with Type II diabetes as well as insulin resistant individuals. One additional study found that 12 grams of ingredients containing resistant starch did not improve insulin sensitivity in African American adults at risk for diabetes.
Digestive/colonic health
Natural resistant starch helps maintain a healthy colonColon (anatomy)
The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a...
and a healthy digestive system via several mechanisms.
- It encourages the growth of healthy bacteria in the bowel and discourages the growth of potentially harmful bacteria, and, therefore, is called “prebiotic fiber.” The fermentation of natural resistant starch reduces intestinal pH and the production of potentially harmful secondary bileBileBile or gall is a bitter-tasting, dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the process of digestion of lipids in the small intestine. In many species, bile is stored in the gallbladder and upon eating is discharged into the duodenum...
acids, ammoniaAmmoniaAmmonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
and phenolsPhenolsIn organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of a hydroxyl group bonded directly to an aromatic hydrocarbon group...
.
- It is predicted to help maintain "regularity” with a mild laxativeLaxativeLaxatives are foods, compounds, or drugs taken to induce bowel movements or to loosen the stool, most often taken to treat constipation. Certain stimulant, lubricant, and saline laxatives are used to evacuate the colon for rectal and/or bowel examinations, and may be supplemented by enemas under...
effect due to increased microbial activity in the large intestine, but as of 2001, evidence for this effect is sparse.
- It helps to keep colon tissue healthy by producing protective compounds called short-chain fatty acids. One of these, called butyrateButyrateButyrate is the traditional name for the conjugate base of butanoic acid . The formula of the butanoate ion is C4H7O2-. The archaic name is used as part of the name of butyrates or butanoates, or esters and salts of butyric acid, a short chain fatty acid...
, is particularly important for colon health because it is the primary energy source for colonic cells and has anti-carcinogenic as well as anti-inflammatory properties that are important for keeping colon cells healthy. Published research has shown that butyrate inhibits the growth and proliferation of tumor cell lines in vitro, induces differentiation of tumor cells, producing a phenotypePhenotypeA phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
similar to that of the normal mature cell, and induces apoptosisApoptosisApoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
or programmed cell death of human colorectal cancer cells.
- Resistant starch contributes to oral rehydration solutions for the treatment of diarrheaDiarrheaDiarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
.
Gluten free
Resistant starch can act as a replacement for wheat products in foods that are required to be glutenGluten
Gluten is a protein composite found in foods processed from wheat and related grain species, including barley and rye...
-free.
External links
- Resistant Starch Portal - National Starch Food Innovation
- British Nutrition Foundation
- Carbohydrates in human nutrition - FAOFood and Agriculture OrganizationThe Food and Agriculture Organization of the United Nations is a specialised agency of the United Nations that leads international efforts to defeat hunger. Serving both developed and developing countries, FAO acts as a neutral forum where all nations meet as equals to negotiate agreements and...
/ WHOWorld Health OrganizationThe World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...