Combination of erythritol and fructose increases gastrointestinal symptoms in healthy adults.

Consumption of a large amount of dietary fructose induces gastrointestinal intolerance, and glucose has been known as an enhancer of fructose absorption. Erythritol is a nonglycemic sugar alcohol, and it has been suggested that erythritol is absorbed paracellularly. It was hypothesized that paracellular absorption of erythritol could also enhance paracellular absorption of fructose in healthy adults. This is one of the proposed pathways for how additional glucose enhances the absorption of fructose. Thirty-seven nondiabetic, healthy adults participated in a randomized, double-masked, controlled crossover study. After an overnight fast, participants consumed beverages containing either 50 g fructose and 50 g glucose, 50 g fructose and 33.3 g erythritol (an equimolar concentration of fructose), or 50 g fructose alone. Breath hydrogen response was determined for 8 hours postprandially. Gastrointestinal intolerance symptoms and the number and consistency of bowel movements were recorded for 24 hours postprandially. The breath hydrogen area under the curve (AUC) of the fructose and erythritol beverage was 2 times the AUC of the fructose beverage and 8.75 times the AUC of the fructose and glucose beverage (P < .001, respectively). Compared with fructose and glucose beverage and fructose alone, frequency of watery stools increased (P < .05) and gastrointestinal tolerance worsened (P < .05) when participants consumed fructose and erythritol. These data suggest that coingestion of equimolar concentrations of fructose and erythritol increased carbohydrate malabsorption.

Gamma-cyclodextrin lowers postprandial glycemia and insulinemia without carbohydrate malabsorption in healthy adults.

OBJECTIVE: Preliminary in vitro and animal studies have shown that gamma-cyclodextrin (GCD) is a slowly and completely digestible carbohydrate. The objective of this study was to determine the glycemic and insulinemic responses to GCD in humans. Breath hydrogen excretion was measured simultaneously to evaluate carbohydrate malabsorption. METHODS: Healthy adult subjects (N = 32) received 50 g of carbohydrate from GCD or a rapidly digested maltodextrin (MD) in a double-masked, randomized, crossover design. Plasma glucose (fingerstick) and serum insulin (venous) concentrations were measured at baseline and at 15, 30, 45, 60, 90, 120, 150, and 180 min postprandially. Breath hydrogen excretion was monitored hourly for 8 h postprandially. The severity of gastrointestinal symptoms (nausea, cramping, distension, flatulence) was rated by the subjects on a ranked scale for two 24-h periods postprandially. RESULTS: The mean baseline-adjusted peak plasma glucose concentration was 47% lower (P < 0.001), and the mean baseline-adjusted peak serum insulin concentration was decreased by 45% (P < 0.001) after subjects consumed GCD compared with MD. Positive incremental area under the curve (0-120 min) was reduced 45% for plasma glucose and 49% for serum insulin by GCD compared with MD (P < 0.001 in each case). There were no differences between GCD and MD in the proportion of positive breath hydrogen tests and both carbohydrates were equally well tolerated. CONCLUSIONS: GCD effectively lowers postprandial glycemia and insulinemia compared with MD, without resulting in appreciable carbohydrate malabsorption or gastrointestinal intolerance.

Pullulans and gamma-cyclodextrin affect apparent digestibility and metabolism in healthy adult ileal cannulated dogs.

Pullulan and gamma-cyclodextrin are incompletely digestible, glucose-based, nonstructural carbohydrates synthesized by microorganisms. To determine their effect when incorporated into a complete liquid diet on ileal and total tract nutrient digestibility, ileal cannulated dogs (n = 8) were used in a repeated 4 x 4 Latin-square design. Twice daily, diets were offered containing 30% (DMB) maltodextrin, high-molecular-weight (MW) pullulan (MW 100,000), low-MW pullulan (MW 6300), or gamma-cyclodextrin. Fecal and ileal samples were collected for the last 4 d of each 10-d period. Dogs consuming high-MW pullulan had lower (P < 0.05) dry matter, organic matter, crude protein, fat, carbohydrate ileal and total tract digestibilities, and fecal DM, and higher (P < 0.05) fecal output and fecal scores (indicating looser stools). To evaluate glycemic and insulinemic responses to pullulans, food-deprived dogs consumed 25 g maltodextrin, high-MW pullulan, or low-MW pullulan in a repeated 3 x 3 Latin-square design. Glucose and insulin responses were determined for 180 min. Consumption of 25 g alpha-, beta-, and gamma-cyclodextrin resulted in regurgitation within 60 min. High-MW pullulan reduced (P < 0.05) blood glucose concentration at 15, 30, 45, and 60 min. Compared with maltodextrin, low-MW pullulan and gamma-cyclodextrin did not alter nutrient digestibilities or fecal characteristics to any extent, and low MW pullulan did not affect glycemic response. Although high MW pullulan decreased glycemic response, consumption of large amounts negatively affected nutrient digestibility and fecal characteristics.

Effects of a nutritional supplement containing Salacia oblonga extract and insulinogenic amino acids on postprandial glycemia, insulinemia, and breath hydrogen responses in healthy adults.

OBJECTIVE: This study evaluated the postprandial glycemic, insulinemic, and breath hydrogen responses to a liquid nutritional product containing Salacia oblonga extract, an herbal alpha-glucosidase inhibitor, and two insulinogenic amino acids. METHODS: In a randomized, double-masked, crossover design, 43 healthy subjects were fed the following meals on separate days after overnight fasting: control (C; 480 mL of a study beverage containing 82 g of carbohydrate, 20 g of protein, and 14 g of fat), control plus 3.5 g each of phenylalanine and leucine (AA), control plus 1000 mg of S. oblonga extract (S), and control plus S and AA (SAA). Postprandially, fingerstick capillary plasma glucose and venous serum insulin levels were measured for 180 min, and breath hydrogen excretion was measured for 480 min. RESULTS: The baseline-adjusted peak glucose response was not different across meals. However, changes in plasma glucose areas under the curve (0 to 120 min and 0 to 180 min, respectively) compared with C were -9% and -11% for AA (P>0.05 each), -27% and -24% for S (P=0.035 and 0.137), and -27% and -29% for SAA (P<0.05 each). Changes in insulin areas under the curve were +5% and +5% for AA (P>0.05 each), -35% and -36% for S (P<0.001 each), and -6% and -7% for SAA (P>0.05 each). Breath hydrogen excretion was 60% greater (P<0.001) in the S-containing meals than in the C- and AA-containing meals and was associated with mild flatulence. CONCLUSIONS: Salacia oblonga extract is a promising nutraceutical ingredient that decreased glycemia in this study. Supplementation with amino acids had no significant additional effect on glycemia.

Effects of a medical food containing an herbal alpha-glucosidase inhibitor on postprandial glycemia and insulinemia in healthy adults.

OBJECTIVE: To determine the effect of different doses of Salacia oblonga extract, an herbal alpha-glucosidase inhibitor, on postprandial glycemic, insulinemic, and breath hydrogen responses in healthy adults. DESIGN: Double-masked, randomized crossover design. INTERVENTION: Subjects, after fasting for 12 hours, consumed four test meals consisting of 480 mL of study beverage (14 g fat, 82 g carbohydrate, and 20 g protein) with 0, 500, 700, or 1,000 mg of S oblonga extract on four separate occasions. Capillary finger-prick plasma glucose and venous serum insulin concentrations were measured at baseline and for 2 hours postprandially. Breath hydrogen excretion was measured at baseline and hourly for 8 hours postprandially. SUBJECTS/SETTING: Thirty-nine healthy, nondiabetic adults (body mass index=23.7+/-0.4, age=25.7+/-0.9 years. STATISTICAL ANALYSES PERFORMED: Repeated-measures analysis of variance was applied to the raw data or data that had been transformed (log, rank) when necessary due to nonnormality. The Tukey-Kramer post hoc test was used for pairwise comparisons. RESULTS: Compared with the control, the 1,000-mg S oblonga extract dose reduced the plasma glucose and serum insulin incremental areas under the curve (0 to 120 minutes postprandial) by 23% ( P =.32) and 29% ( P =.01), respectively. The other doses of S oblonga extract did not impact glycemia or insulinemia. Breath hydrogen excretion increased linearly as the dose of S oblonga extract was advanced. CONCLUSIONS: The presence of S oblonga extract tended to lower postprandial glycemia and significantly reduced the postprandial insulin response. The increase in breath hydrogen excretion suggests a mechanism similar to prescription alpha-glucosidase inhibitors. Future studies of S oblonga extract in patients with diabetes are needed.

Inclusion of guar gum and alginate into a crispy bar improves postprandial glycemia in humans.

A novel induced viscosity fiber (IVF) crispy bar was formulated with the viscous dietary fibers alginate and guar gum. To evaluate the glycemic response and gastrointestinal tolerance to IVF crispy bars, nondiabetic healthy adult subjects (n = 48) were studied in a randomized, double-masked, crossover design. The control crispy bars and IVF crispy bars were identical except for the 2 dietary fibers contained in the experimental (IVF) bars. After an overnight fast, subjects consumed test bars containing 50 g carbohydrate. Their capillary blood glucose response was determined for 180 min postprandially. When subjects consumed IVF, the incremental blood glucose excursions were reduced (P < 0.05) at 15, 30, 45, and 120 min. At 180 min, the subjects' blood glucose concentration was maintained above the basal blood glucose concentration for both bars. Compared with controls, the incremental peak blood glucose concentration was reduced (P < 0.001) 30% when subjects consumed IVF. When subjects consumed IVF, the positive incremental area under the curve for glucose was reduced (P < 0.01) by 33% compared with controls. In the 24-h postprandial period after each treatment, the frequency and intensity of gastrointestinal tolerance symptoms did not differ. In conclusion, compared with a control crispy bar, the IVF crispy bar attenuated the postprandial glycemic excursion without gastrointestinal intolerance in healthy adult subjects.

Estimates of starch digestion in the rat small intestine differ from those obtained using in vitro time-sensitive starch fractionation assays.

The objectives of this study were as follows: 1) to determine the rate and extent of starch disappearance from the small intestine of the rat fed selected starch sources, 2) to determine the ratios of the major starch fractions [rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS)] in those starch sources using two in vitro methods and 3) to compare the two data sets to determine the accuracy of the in vitro methods. Diets were prepared using cornstarch, potato starch, amylomaize, maltodextrin, modified maltodextrin or pullulan. Starch sources and diets were analyzed for starch fractions by two in vitro methods. Diets were fed to rats, intestinal contents were collected and the ethanol-induced precipitate from the contents was analyzed to obtain a digestion curve that was mathematically modeled for comparison to results obtained using the two in vitro methods. Only the cornstarch diet had a defined amount of RDS, SDS and RS. The RDS concentration obtained from the intestinal contents of the rats fed the cornstarch diet differed (P < 0.05) from that determined by one in vitro method but was consistent with the value obtained using the other in vitro method. All other digestible starch values obtained differed (P < 0.05) among methods except for that of amylomaize. Starch fractions in starch sources obtained using in vitro procedures differed (P < 0.05) from values obtained for diets. The rate of disappearance differed (P < 0.05) between in vivo and in vitro procedures. There was minimal agreement between in vitro methods tested, and there was also minimal agreement between in vitro and in vivo results. Classification of starch into RDS and SDS components cannot be accomplished for a variety of starch sources, with cornstarch being the major exception.

Pullulan is a slowly digested carbohydrate in humans.

Pullulan is an extracellular polysaccharide excreted by the fungus Aureobasidium pullulans. To evaluate the glycemic and breath hydrogen responses and gastrointestinal tolerance to pullulan, nondiabetic healthy adult subjects (n = 28) were studied in a randomized, double-masked, crossover design. After an overnight fast, subjects consumed beverages containing 50 g of carbohydrate from either maltodextrin (control) or pullulan. Capillary blood glucose response was determined for 180 min postprandially. Breath hydrogen response was determined for 8 h postprandially. Compared with control, incremental peak blood glucose concentration was reduced (P < 0.01) when subjects consumed pullulan (4.24 +/- 0.35 vs. 1.97 +/- 0.10 mmol/L). In addition, pullulan reduced (P < 0.01) the positive incremental area under the glucose curve by 50%. When subjects consumed pullulan, the incremental blood glucose excursions were reduced (P < 0.01) at 15, 30, 45, 60 and 90 min, but were maintained above basal glucose concentrations at 150 and 180 min. At 180 min, the blood glucose concentration was higher (P < 0.05) when subjects consumed pullulan compared with control, supporting the hypothesis that pullulan is digested slowly. Breath hydrogen concentrations were increased (P < 0.01) at 3, 4, 5, 6, 7 and 8 h postprandially when subjects consumed pullulan. In the first 24-h postprandial period, the frequency and intensity of flatulence was higher (P < 0.05) after subjects consumed pullulan compared with control. In conclusion, pullulan attenuated the postprandial glycemic excursion compared with an equivalent maltodextrin challenge. Pullulan also increased breath hydrogen excretion and the incidence of gastrointestinal intolerance symptoms, indicating that a portion of pullulan was malabsorbed.

Fructooligosaccharides and Lactobacillus acidophilus modify gut microbial populations, total tract nutrient digestibilities and fecal protein catabolite concentrations in healthy adult dogs.

The objective of this research was to determine whether fructooligosaccharides (FOS) and (or) Lactobacillus acidophilus (LAC) affected concentrations of gut microbial populations, fermentative end products and nutrient digestibilities in healthy adult dogs. Two experiments were performed using 40 adult dogs (20 dogs/experiment). Dogs in each experiment were randomly assigned to one of 4 treatments. Twice daily, treatments were given orally via gelatin capsules: 1) 2 g sucrose + 80 mg cellulose; 2) 2 g FOS + 80 mg cellulose; 3) 2 g sucrose + 1 x 10(9) colony forming units (cfu) LAC; or 4) 2 g FOS + 1 x 10(9) cfu LAC. Data were analyzed by the General Linear Models procedure of SAS. In Experiment 1, FOS resulted in lower (P = 0.08) Clostridium perfringens and greater fecal butyrate (P = 0.06) and lactate (P < 0.05) concentrations. In Experiment 2, FOS supplementation increased (P < 0.05) bifidobacteria, increased lactobacilli (P = 0.08), increased fecal lactate (P = 0.06) and butyrate (P < 0.05), and decreased (P < 0.05) fecal ammonia, isobutyrate, isovalerate and total branched-chain fatty acid concentrations. Dogs fed LAC had the highest fecal concentrations of hydrogen sulfide and methanethiol in Experiment 1 and dimethyl sulfide in Experiment 2, whereas dogs fed FOS had the lowest concentrations of these compounds. Overall, FOS appeared to enhance indices of gut health by positively altering gut microbial ecology and fecal protein catabolites, whereas LAC was more effective when fed in combination with FOS rather than fed alone.

Fructooligosaccharides and Lactobacillus acidophilus modify bowel function and protein catabolites excreted by healthy humans.

The objective of this experiment was to determine whether supplementation with fructooligosaccharides (FOS) and (or) Lactobacillus acidophilus (LAC) affected bowel function and fermentative end-product concentrations in feces of healthy humans. Subjects (n = 68) were enrolled in a randomized, double-blind, placebo-controlled, parallel study design. After a 4-wk baseline period, subjects consumed one of the following treatments twice daily for 4 wk: 1) 3 g sucrose + 80 mg cornstarch; 2) 3 g FOS + 80 mg cornstarch; 3) 3 g sucrose + 1 x 10(9) colony-forming units (cfu) LAC; or 4) 3 g FOS + 1 x 10(9) cfu LAC. Subjects completed 7-d bowel function forms and 3-d dietary records before collection of fresh stool samples at wk 4, 6 and 8. Statistical analyses were performed on differences from baseline using the General Linear Models procedure of SAS. Fructooligosaccharides decreased fecal ammonia (P = 0.07) and isovalerate (P = 0.12) concentrations at wk 6. At wk 8, FOS tended (P = 0.11) to increase fecal putrescine concentrations. Lactobacillus decreased fecal organic matter percentage at wk 6 (P < 0.05) and 8 (P = 0.07). At wk 6 and 8, LAC increased (P < 0.05) fecal 2-methylindole, total indole, and total indole and phenol concentrations. At wk 8, LAC decreased fecal agmatine (P = 0.08) and phenylethylamine (P < 0.05) concentrations. In conclusion, FOS and LAC modified several metabolites associated with gut health, with FOS tending to be beneficial (decreased fecal protein catabolites) and LAC being negative (increased fecal protein catabolites).

Fructose prefeeding reduces the glycemic response to a high-glycemic index, starchy food in humans.

The study objective was to determine whether a small dose of fructose administered before or simultaneously with a high glycemic index, starchy food decreases postprandial glycemic response. Nondiabetic healthy adults (n = 31; mean +/- SEM: age, 26 +/- 1 y; weight, 66.1 +/- 2.6 kg; body mass index, 23.3 +/- 0.6 kg/m(2)) were studied in a randomized crossover design. Treatments consisted of 50 g available carbohydrate from instant mashed potatoes fed alone (control) or with 10 g fructose fed 60, 30 or 0 min before the potato meal. Capillary finger-stick blood samples were analyzed for glucose concentration at -60, -30, 0, 15, 30, 45, 60, 90 and 120 min relative to the ingestion of the potato meal. Compared with the control, the positive incremental area under the glucose curve was reduced 25 and 27% (P < 0.01) when fructose was fed either 60 or 30 min before the meal, respectively. In contrast to previous studies demonstrating that immediate administration of a small amount of fructose lowers the glycemic response to a glucose solution, we found that fructose must be consumed before a starchy food to reduce postprandial glycemia.

Glycemic and insulinemic responses of nondiabetic healthy adult subjects to an experimental acid-induced viscosity complex incorporated into a glucose beverage.

OBJECTIVE: An acid-induced-viscosity (I-V) complex containing alginate, citrate, and insoluble calcium was incorporated into a glucose-based beverage. We hypothesized that the acid I-V beverage would become viscous in the stomach (due to the solubilization of calcium and its interaction with alginate and citrate) and would blunt glycemia. METHODS: Thirty subjects were used in a double-masked, placebo-controlled crossover study evaluating the acid I-V complex. The placebo was a glucose-based beverage that had a similar total dietary fiber level and initial viscosity (Control). After a 12-h overnight fast, serum glucose and insulin were monitored over a 3-h postprandial period. RESULTS: The postprandial mean peak incremental change from baseline in serum glucose tended (P < 0.06) to be lower for the acid I-V product. The net incremental area under the curve (AUC) for serum glucose was reduced 75% (P < 0.01) by the acid I-V product, which was due mainly to an increased undershoot. The mean peak incremental change from baseline in serum insulin was higher (P < 0.05) for the acid I-V product. Net incremental AUC for serum insulin did not differ (P > 0.20) between products. CONCLUSIONS: Results of this study suggested that the acid I-V complex may attenuate the postprandial glycemic response to a glucose challenge in healthy subjects.

Supplemental fructose attenuates postprandial glycemia in Zucker fatty fa/fa rats.

Experiments were conducted to evaluate the effects of supplemental fructose on postprandial glycemia. After overnight food deprivation, Zucker fatty fa/fa rats were given a meal glucose tolerance test. Plasma glucose response was determined for 180 min postprandially. At a dose of 0.16 g/kg body, fructose reduced (P < 0.05) the incremental area under the curve (AUC) by 34% when supplemented to a glucose challenge and by 32% when supplemented to a maltodextrin (a rapidly digested starch) challenge. Similarly, sucrose reduced (P = 0.0575) the incremental AUC for plasma glucose when rats were challenged with maltodextrin. Second-meal glycemic response was not affected by fructose supplementation to the first meal, and fructose supplementation to the second meal reduced (P < 0.05) postprandial glycemia when fructose had been supplemented to the first meal. In a dose-response study (0.1, 0.2, and 0.5 g/kg body), supplemental fructose reduced (P < 0.01) the peak rise in plasma glucose (linear and quadratic effects). In the final experiment, a low dose of fructose (0.075 g/kg body) reduced (P < 0.05) the incremental AUC by 18%. These data support the hypothesis that small amounts of oral fructose or sucrose may be useful in lowering the postprandial blood glucose response.