Measurement of resistant starch in vitro and in vivo

Abstract

The digestibility of the starch in plant foods is highly variable, and is dependent on a number of factors, including the physical structure of both the starch and the food matrix. An in vifro technique has been developed to categorize starch in plant foods according to its likely rate and extent of digestion in the human small intestine. The in vitro method provides values for rapidly digestible starch, slowly digestible starch and resistant starch (RS). In the present study values for the RS content of foods, as measured by the analytical technique, were compared with the recovery of starch from these foods when fed to healthy ileostomates. Nine ileostomy subjects were given a plysaccharide-free diet with a breakfast supplement, on each of 2 d (two subjects) or 3 d (seven subjects), of biscuits made from wheat, potato or banana flours or from moist-heat-processed wheat or maize flours. RS intakes measured in vifro ranged from 8.5 to 15.0 g/d for the test biscuits, and mean starch recoveries in ileostomy effluent were 1004 (n 5, range 91-106) % of those values, but there was substantial variation between individuals. It is proposed that RS is defined as 'the sum of starch and starch-degradation products that, on average, reach the human large intestine'. The analytical method for the measurement of RS in vitro based on this definition is shown to provide an accurate prediction of the average amount of starch that is likely to escape complete digestion and absorption in the human small intestine.Resistant starch: lleostomy : Human small intestine In 1982 we reported that a fraction of starch in cooled, cooked foods was highly resistant to digestion by pancreatic amylase (EC 3.2.1 . 1) in vitro, and used the term resistant starch (RS) to describe this fraction (Englyst et al. 1982). Following a series of studies in healthy ileostomy subjects, who were used as a model for digestion in the small intestine (Englyst & Cummings, 1985, 1986, 1987, it became clear that this type of starch represented only a proportion of the starch that can resist digestion in the human small intestine. Starch that is trapped within whole plant cells or within the food matrix, and some starch granules that have not been fully gelatinized, are hydrolysed only very slowly by a-amylase and therefore may escape complete digestion in the small intestine. We therefore extended the term and modified the analytical procedure to include these sources, i.e. the definition of RS and its measurement in vitro were enlarged to include starch and starch-degradation products (Englyst & Cummings, 1987;Englyst & Kingman, 1990; Englyst et al. 1992a). The material included in the definition of RS reaches the human large intestine and thus becomes a substrate for microbial fermentation. The end-products are H, and CO,, CH, in about half the population, and short-chain fatty acids, which are absorbed and utilized. However, the energy yield to the body from this source is less than that provided if starch is digested and absorbed in the small intestine. The h...

Gut microbiota and energy balance: role in obesity

“…Resistant starch can also be formed during cooking and cooling of starch containing foods and is referred to as retrograded starch (17) .…”

Wholegrain cereals and bread: a duet of the Mediterranean diet for the prevention of chronic diseases

“…These fatty acids can be used by the colonocyte as an energy source. Its ingestion in the appropriate quantity is associated with lower levels of plasma cholesterol and TAG as well as a lower postprandial peak of glucose and insulin (9) . The aim of the present study is to review the fundamental studies, concerning both epidemiology as well as intervention, which support the consumption of wholegrain cereals and bread to prevent CVD, DM2, colorectal cancer and other cancers, as well as certain gastrointestinal pathologies.…”

“…SDS, which leads to a slower entry of glucose into the blood stream and a lower glycaemic response, is digested completely in the small intestine at a lower rate as compared to RDS, whereas RS is the starch portion that cannot be digested in the small intestine, but is fermented in the large intestine. Experimentally, each starch fraction can be quantified on the basis of the in vitro Englyst method (8,9) : starch digested within 20 min belongs to RDS, whereas SDS represents the digested starch between 20 and 120 min, and the remaining fraction is RS. Bread has a variable proportion of SDS and of RS, according to the variety of grain.…”

In vitro production of short-chain fatty acids from resistant starch by pig faecal inoculum

“…The main end-products of RS fermentation are gases (i.e., H 2 , CO 2 and CH 4 ) and short-chain fatty acids (SCFA) (Englyst et al, 1996). In pigs, SCFA can exert specific physiological effects (Williams et al, 2005).…”