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Manipulation of starch bioaccessibility in wheat endosperm to regulate starch digestion, postprandial glycemia, insulinemia, and gut hormone responses: a randomized controlled trial in healthy ileostomy participants.

Edwards CH, Grundy MM, Grassby T, Vasilopoulou D, Frost GS, Butterworth PJ, Berry SE, Sanderson J, Ellis PR - Am. J. Clin. Nutr. (2015)

Bottom Line: The aims of this study were to compare the effects of 2 porridge meals prepared from wheat endosperm with different degrees of starch bioaccessibility on postprandial metabolism (e.g., glycemia) and to gain insight into the structural and biochemical breakdown of the test meals during gastroileal transit.The structure of the test meal had no effect on the amount or pattern of RS output.The structural integrity of wheat endosperm is largely retained during gastroileal digestion and has a primary role in influencing the rate of starch amylolysis and, consequently, postprandial metabolism.

View Article: PubMed Central - PubMed

Affiliation: Biopolymers Group, Diabetes and Nutritional Sciences Division, King's College London, London, United Kingdom;

ABSTRACT

Background: Cereal crops, particularly wheat, are a major dietary source of starch, and the bioaccessibility of starch has implications for postprandial glycemia. The structure and properties of plant foods have been identified as critical factors in influencing nutrient bioaccessibility; however, the physical and biochemical disassembly of cereal food during digestion has not been widely studied.

Objectives: The aims of this study were to compare the effects of 2 porridge meals prepared from wheat endosperm with different degrees of starch bioaccessibility on postprandial metabolism (e.g., glycemia) and to gain insight into the structural and biochemical breakdown of the test meals during gastroileal transit.

Design: A randomized crossover trial in 9 healthy ileostomy participants was designed to compare the effects of 55 g starch, provided as coarse (2-mm particles) or smooth (<0.2-mm particles) wheat porridge, on postprandial changes in blood glucose, insulin, C-peptide, lipids, and gut hormones and on the resistant starch (RS) content of ileal effluent. Undigested food in the ileal output was examined microscopically to identify cell walls and encapsulated starch.

Results: Blood glucose, insulin, C-peptide, and glucose-dependent insulinotropic polypeptide concentrations were significantly lower (i.e., 33%, 43%, 40%, and 50% lower 120-min incremental AUC, respectively) after consumption of the coarse porridge than after the smooth porridge (P < 0.01). In vitro, starch digestion was slower in the coarse porridge than in the smooth porridge (33% less starch digested at 90 min, P < 0.05, paired t test). In vivo, the structural integrity of coarse particles (∼2 mm) of wheat endosperm was retained during gastroileal transit. Microscopic examination revealed a progressive loss of starch from the periphery toward the particle core. The structure of the test meal had no effect on the amount or pattern of RS output.

Conclusion: The structural integrity of wheat endosperm is largely retained during gastroileal digestion and has a primary role in influencing the rate of starch amylolysis and, consequently, postprandial metabolism. This trial was registered at isrctn.org as ISRCTN40517475.

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Starch digestibility (A) and HI (B) of smooth and coarse porridge endosperm relative to pure starch assessed in vitro. Digestibility curves show percentage of hydrolyzable starch digested for smooth and coarse endosperm and a highly digestible reference (i.e., pure, gelatinized durum wheat starch). In these curves, each experimental point represents the mean value from analysis performed in triplicate with vertical error bars showing SEMs. Digestibility curves of smooth and coarse porridge were significantly different (paired t test for incremental AUC at 60 min, P < 0.001). HI is the percentage of hydrolyzable starch digested at 90 min, and was calculated with the use of the previously described logarithm of slope model (18). HI values were significantly different between smooth and coarse porridge (paired t test, P = 0.03). HI, hydrolysis index; REF, reference.
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fig2: Starch digestibility (A) and HI (B) of smooth and coarse porridge endosperm relative to pure starch assessed in vitro. Digestibility curves show percentage of hydrolyzable starch digested for smooth and coarse endosperm and a highly digestible reference (i.e., pure, gelatinized durum wheat starch). In these curves, each experimental point represents the mean value from analysis performed in triplicate with vertical error bars showing SEMs. Digestibility curves of smooth and coarse porridge were significantly different (paired t test for incremental AUC at 60 min, P < 0.001). HI is the percentage of hydrolyzable starch digested at 90 min, and was calculated with the use of the previously described logarithm of slope model (18). HI values were significantly different between smooth and coarse porridge (paired t test, P = 0.03). HI, hydrolysis index; REF, reference.

Mentions: The cooked particles of wheat endosperm used to make the smooth and coarse porridge meals were found to have contrasting starch amylolysis characteristics (Figure 2). Coarse porridge endosperm (cell wall–encapsulated starch) was digested more slowly and to a lesser extent than smooth porridge endosperm (no encapsulated starch), and both materials were less digestible than the pure starch reference (100% hydrolyzable starch). After 90 min, the amount of hydrolyzable starch digested was 33% lower for coarse porridge (HI = 54) than for smooth porridge (HI = 81) and, on this basis, a comparable difference in magnitude of the blood glucose response (incremental AUC) over 120 min was expected.


Manipulation of starch bioaccessibility in wheat endosperm to regulate starch digestion, postprandial glycemia, insulinemia, and gut hormone responses: a randomized controlled trial in healthy ileostomy participants.

Edwards CH, Grundy MM, Grassby T, Vasilopoulou D, Frost GS, Butterworth PJ, Berry SE, Sanderson J, Ellis PR - Am. J. Clin. Nutr. (2015)

Starch digestibility (A) and HI (B) of smooth and coarse porridge endosperm relative to pure starch assessed in vitro. Digestibility curves show percentage of hydrolyzable starch digested for smooth and coarse endosperm and a highly digestible reference (i.e., pure, gelatinized durum wheat starch). In these curves, each experimental point represents the mean value from analysis performed in triplicate with vertical error bars showing SEMs. Digestibility curves of smooth and coarse porridge were significantly different (paired t test for incremental AUC at 60 min, P < 0.001). HI is the percentage of hydrolyzable starch digested at 90 min, and was calculated with the use of the previously described logarithm of slope model (18). HI values were significantly different between smooth and coarse porridge (paired t test, P = 0.03). HI, hydrolysis index; REF, reference.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4588739&req=5

fig2: Starch digestibility (A) and HI (B) of smooth and coarse porridge endosperm relative to pure starch assessed in vitro. Digestibility curves show percentage of hydrolyzable starch digested for smooth and coarse endosperm and a highly digestible reference (i.e., pure, gelatinized durum wheat starch). In these curves, each experimental point represents the mean value from analysis performed in triplicate with vertical error bars showing SEMs. Digestibility curves of smooth and coarse porridge were significantly different (paired t test for incremental AUC at 60 min, P < 0.001). HI is the percentage of hydrolyzable starch digested at 90 min, and was calculated with the use of the previously described logarithm of slope model (18). HI values were significantly different between smooth and coarse porridge (paired t test, P = 0.03). HI, hydrolysis index; REF, reference.
Mentions: The cooked particles of wheat endosperm used to make the smooth and coarse porridge meals were found to have contrasting starch amylolysis characteristics (Figure 2). Coarse porridge endosperm (cell wall–encapsulated starch) was digested more slowly and to a lesser extent than smooth porridge endosperm (no encapsulated starch), and both materials were less digestible than the pure starch reference (100% hydrolyzable starch). After 90 min, the amount of hydrolyzable starch digested was 33% lower for coarse porridge (HI = 54) than for smooth porridge (HI = 81) and, on this basis, a comparable difference in magnitude of the blood glucose response (incremental AUC) over 120 min was expected.

Bottom Line: The aims of this study were to compare the effects of 2 porridge meals prepared from wheat endosperm with different degrees of starch bioaccessibility on postprandial metabolism (e.g., glycemia) and to gain insight into the structural and biochemical breakdown of the test meals during gastroileal transit.The structure of the test meal had no effect on the amount or pattern of RS output.The structural integrity of wheat endosperm is largely retained during gastroileal digestion and has a primary role in influencing the rate of starch amylolysis and, consequently, postprandial metabolism.

View Article: PubMed Central - PubMed

Affiliation: Biopolymers Group, Diabetes and Nutritional Sciences Division, King's College London, London, United Kingdom;

ABSTRACT

Background: Cereal crops, particularly wheat, are a major dietary source of starch, and the bioaccessibility of starch has implications for postprandial glycemia. The structure and properties of plant foods have been identified as critical factors in influencing nutrient bioaccessibility; however, the physical and biochemical disassembly of cereal food during digestion has not been widely studied.

Objectives: The aims of this study were to compare the effects of 2 porridge meals prepared from wheat endosperm with different degrees of starch bioaccessibility on postprandial metabolism (e.g., glycemia) and to gain insight into the structural and biochemical breakdown of the test meals during gastroileal transit.

Design: A randomized crossover trial in 9 healthy ileostomy participants was designed to compare the effects of 55 g starch, provided as coarse (2-mm particles) or smooth (<0.2-mm particles) wheat porridge, on postprandial changes in blood glucose, insulin, C-peptide, lipids, and gut hormones and on the resistant starch (RS) content of ileal effluent. Undigested food in the ileal output was examined microscopically to identify cell walls and encapsulated starch.

Results: Blood glucose, insulin, C-peptide, and glucose-dependent insulinotropic polypeptide concentrations were significantly lower (i.e., 33%, 43%, 40%, and 50% lower 120-min incremental AUC, respectively) after consumption of the coarse porridge than after the smooth porridge (P < 0.01). In vitro, starch digestion was slower in the coarse porridge than in the smooth porridge (33% less starch digested at 90 min, P < 0.05, paired t test). In vivo, the structural integrity of coarse particles (∼2 mm) of wheat endosperm was retained during gastroileal transit. Microscopic examination revealed a progressive loss of starch from the periphery toward the particle core. The structure of the test meal had no effect on the amount or pattern of RS output.

Conclusion: The structural integrity of wheat endosperm is largely retained during gastroileal digestion and has a primary role in influencing the rate of starch amylolysis and, consequently, postprandial metabolism. This trial was registered at isrctn.org as ISRCTN40517475.

Show MeSH
Related in: MedlinePlus