Bryan W. Wolf

Safety and tolerance of Lactobacillus reuteri supplementation to a population infected with the human immunodeficiency virus

Probiotic supplementation may provide health benefits, especially for individuals with an underlying disease state that makes them more susceptible to infections. The purpose of this experiment was to evaluate the safety and tolerance of Lactobacillus reuteri ingestion by subjects infected with the human immunodeficiency virus (HIV). Thirty-nine subjects consumed a freeze-dried preparation of L. reuteri or a placebo for 21 days in a double-masked, parallel design experiment. Serum chemistry, haematology, immune profile, urinalysis, physical examination, gastrointestinal tolerance and faecal microbiota data were collected. No clinically significant changes were noted in any of the safety parameters measured. Overall, tolerance was good in both groups. Consumption of L. reuteri tended to increase faecal levels of L. reuteri on days 7, 14 and 21 of treatment feeding (P < 0.06, P < 0.11 and P = 0.05, respectively). However, faecal levels of L. reuteri and total Lactobacillus species were lower than levels previously observed in healthy male adults. Overall, this study documents that L. reuteri may be fed to HIV-positive individuals at 1 x 10(10) colony forming units/day without any clinically significant safety or tolerance problems.

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.

Varying dietary concentrations of fructooligosaccharides affect apparent absorption and balance of minerals in growing rats

Abstract Carbohydrates that bypass digestion in the small intestine and are fermented in the large intestine may affect the absorption of certain minerals. A study was conducted to determine the effect of varying dietary concentrations of fructooligosaccharides (FOS) on the apparent digestibility and balance of certain macro and trace minerals. Forty growing male Sprague-Dawley rats were assigned one of four treatments: 1) purified diet (control); 2) purified diet + 1% FOS; 3) purified diet + 3% FOS, or 4) purified diet + 5% FOS. Rats were acclimated to their metabolic cages for 5 d, after which they were subjected to a 10-d growth period, followed by a 7-d balance period in which diets were restricted to 90% ad libitum intake of the lowest consuming rat. Cecal pH decreased ( P P P P > 0.10) across treatments. The macrominerals (Ca, P, Mg, Na, Cl, K) and trace minerals (Cu, Fe, Mn, Zn) were in a positive balance for all experimental treatments. However, Cu absorption decreased with increasing FOS concentration. This may be explained by an increase in fecal microbial mass which would contain a relatively significant amount of Cu or by an increase in hepatic bile Cu excretion. These results suggest that dietary FOS alters acute Cu metabolism in growing rats.

Apparent digestibility and glycaemic responses to an experimental induced viscosity dietary fibre incorporated into an enteral formula fed to dogs cannulated in the ileum.

The purpose of this study was to evaluate the apparent digestibility and postprandial glycaemic responses of ileal-cannulated dogs when fed an experimental induced viscosity dietary fibre (IVF) incorporated into a liquid enteral formula. Dietary treatments were: (1) control; (2) Glucerna; (3) Glytrol; (4) IVF; and (5) Jevity. Diets varied in concentrations of crude protein (CP), fat, starch and total dietary fibre (TDF). Dry matter and starch intakes by dogs fed the Glucerna and Glytrol treatments were lower (P<0.05) than for those consuming the other diets. However, daily intakes of CP and fat followed a reverse trend. Digestibility of nutrients at the ileum was high (>80%) for all dietary treatments. Mineral absorption proximal to the ileum and from the total tract was not significantly different among treatments. Mean incremental area under the serum glucose response curves for dogs fed Glytrol, Glucerna, and IVF treatments were lower (P<0.05) than the control treatment. Induced viscosity fibre appears to have no negative effects on nutrient digestion throughout the gastrointestinal tract. Its ability to moderate serum glucose concentrations would make it a potentially good choice for a diabetic liquid formula.

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.

Glycemic response to a rapidly digested starch is not affected by the addition of an indigestible dextrin in humans

To evaluate the effect of supplemental indigestible dextrin on the glycemic response to a rapidly digested starch, 30 healthy nondiabetic adult subjects were studied in a double-blind crossover design. After an overnight fast, subjects consumed a product containing either 67.5 g of corn syrup solids or the same plus 16 g of indigestible dextrin. Finger-prick capillary blood was obtained at baseline, 15, 30, 45, 60, 90, and 120 min postprandial for glucose measurement. The postprandial incremental change from baseline did not differ (P > 0.10) between treatments across all time points. Mean peak incremental change from baseline and net incremental area under the curve did not differ (P > 0.10) between treatments. Minimal effects on gastrointestinal symptoms (intensity and frequency of nausea, cramping, distention, and flatulence) were noted for both products, with no clinically significant difference between products. In conclusion, an acute challenge of 16 g supplemental indigestible dextrin did not affect the postprandial glycemic response to a rapidly digested starch and was well tolerated by fasting healthy adult subjects.

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.