Nutritional and Physiological Constraints Contributing to Limitations in Small Intestinal Starch Digestion and Glucose Absorption in Ruminants

Increased efficiency of nutrient utilization can potentially be gained with increased starch digestion in the small intestine in ruminants. However, ruminants have quantitative limits in the extent of starch disappearance in the small intestine. The objective is to explore the nutritional and physiological constraints that contribute to limitations of carbohydrate assimilation in the ruminant small intestine. Altered digesta composition and passage rate in the small intestine, insufficient pancreatic α-amylase and/or small intestinal carbohydrase activity, and reduced glucose absorption could all be potentially limiting factors of intestinal starch assimilation. The absence of intestinal sucrase activity in ruminants may be related to quantitative limits in small intestinal starch hydrolysis. Multiple sequence alignment of the sucrase-isomaltase complex gives insight into potential molecular mechanisms that may be associated with the absence of intestinal sucrase activity, reduced capacity for intestinal starch digestion, and limitations in the efficiency of feed utilization in cattle and sheep. Future research efforts in these areas will aid in our understanding of small intestinal starch digestion and glucose absorption to optimize feeding strategies for increased meat and milk production efficiency.

L-arabinose and D-xylose: sweet pentoses that may reduce postprandial glucose and insulin responses

Background: Diets inducing high fluctuations in plasma glucose levels are linked to type 2 diabetes. L-arabinose and D-xylose have been hypothesized to inhibit intestinal sucrase activity, delay sucrose digestion, and reduce glycaemic and insulinaemic responses. However, few human studies have assessed this using realistic foods. Objective: We investigated the effects of the addition of L-arabinose and D-xylose on glucose homeostasis using a fruit-based drink and the effect of L-arabinose using a muffin. Design: Fifteen males participated in two double-blind, randomized cross-over experiments. In experiment A, three drinks were tested: (1) L-arabinose, (2) D-xylose and (3) control drink. In experiment B, two muffins were tested: (1) L-arabinose and (2) control muffin. All products consisted of ~50 g available carbohydrates, and L-arabinose or D-xylose was added as 10% of sucrose. Pre- and post-ingestive plasma glucose and insulin levels were measured at fixed time points up to 180 min after consumption. Results: Glucose and insulin peaks were lower after the L-arabinose and D-xylose drink than the control drink (P < 0.01). After consumption of the muffin, glucose responses were not significantly different; however, the insulin peak and incremental area under the curve (iAUC) tended to be lower for the L-arabinose muffin. Conclusion: L-arabinose and D-xylose are functional ingredients that can potentially lower the post-ingestive glycaemic and insulinaemic responses when added to realistic foods. However, the efficacy of applying L-arabinose appears to depend on the food matrix. Addition of these compounds needs further testing in other foods and in other populations, such as pre-diabetics.

Optimisation, validation and field applicability of a 13C-sucrose breath test to assess intestinal function in environmental enteropathy among children in resource poor settings: study protocol for a prospective study in Bangladesh, India, Kenya, Jamaica, Peru and Zambia

IntroductionEnvironmental enteropathy (EE) is suspected to be a cause of growth faltering in children with sustained exposure to enteric pathogens, typically in resource-limited settings. A major hindrance to EE research is the lack of sensitive, non-invasive biomarkers. Current biomarkers measure intestinal permeability and inflammation, but not the functional capacity of the gut. Australian researchers have demonstrated proof of concept for an EE breath test based on using naturally 13C-enriched sucrose, derived from maize, to assay intestinal sucrase activity, a digestive enzyme that is impaired in villus blunting. Here, we describe a coordinated research project to optimise, validate and evaluate the usability of a breath test protocol based on highly enriched 13C-sucrose to quantify physiological dysfunction in EE in relevant target populations.Methods and analysisWe use the 13C-sucrose breath test (13C-SBT) to evaluate intestinal sucrase activity in two phases. First, an optimisation and validation phase will (1) confirm that a 13C-SBT using highly enriched sucrose tracers reports similar information to the naturally enriched 13C-SBT; (2) examine the dose–response relationship of the test to an intestinal sucrase inhibitor; (3) validate the 13C-SBT in paediatric coeliac disease (4) validate the highly enriched 13C-SBT against EE defined by biopsy in adults and (5) validate the 13C-SBT against EE defined by the urinary lactulose:rhamnose ratio (LR) among children in Peru. Second, a cross-sectional study will be conducted in six resource-limited countries (Bangladesh, India, Jamaica, Kenya, Peru and Zambia) to test the usability of the optimised 13C-SBT to assess EE among 600 children aged 12–15 months old.Ethics and disseminationEthical approval will be obtained from each participating study site. By working as a consortium, the test, if shown to be informative of EE, will demonstrate strong evidence for utility across diverse, low-income and middle-income country paediatric populations.Trial registration numberNCT04109352; Pre-results.

Aversive responses to L-arabinose in caterpillars of Helicoverpa armigera (Hübner)

ABSTRACTBackgroundOne of the naturally non-nutritive artificial sweeteners, L-arabinose, is widely used in the modern human food industry to combat obesity and diabetes because of its inhibition effect on the intestinal sucrase activity in mammals. However, whether it shows impact on herbivorous insects remains largely unknown. In the present study, we investigated the effects of L-arabinose on the feeding behaviors, gustation, development and intestinal sucrase activity of an herbivorous insect species, the cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae).ResultsThe results show that both the feeding preferences of H. armigera caterpillars for host plants and for phagostimulants were inhibited by L-arabinose in a dose-dependent manner. Gustatory receptor neurons (GRNs) sensitive to L-arabinose were not found in the peripheral gustatory sensilla, but the sensitivities of GRNs sensitive to other plant metabolites were suppressed by L-arabinose. Exposure of dietary L-arabinose to caterpillars resulted in prolonged larval developmental duration, suppressed activity of intestinal sucrase and reduced glucose level in midguts. In vitro, L-arabinose inhibits activity of intestinal sucrase of H. armigera caterpillars in an uncompetitive manner.ConclusionTaken together, these findings demonstrate that L-arabinose is a feeding and physiological inhibitor to caterpillars of H. armigera caterpillars. To our knowledge, this is the first report of a non-nutritive sweetener perceived by an animal as an inhibitor from both peripheral taste coding and feeding decisions, which should provide a physiological and behavioral basis for the future possible application of L-arabinose in controlling the herbivores pests.

Elephant foot yam ameliorates activities of intestinal and renal disaccharidases in streptozotocin induced diabetic rats

Elephant foot yam (Amorphophallus paeoniifolius (Dennst.) Nicolson syn. Amorphophallus campanulatus) is a tuber vegetable used as an ingredient in ayurvedic preparations for various ailments. The present investigation deals with the effect of elephant foot yam extract on intestinal and renal disaccharidases in normal rats and streptozotocin induced diabetic rats. The specific activities of maltase, sucrase and lactase were measured in control and starch fed diabetic (SFD), elephant foot yam extract at 0.1% fed diabetic (YFD0.1), elephant foot yam extract at 0.25% fed diabetic (YFD0.25) and aminoguanidine fed diabetic (AFD) groups at the end of experimental period. Intestinal maltase, sucrase and lactase activities were high in SFD group compared to control, YFD0.1, YFD0.25 and AFD groups. Amelioration of intestinal maltase activities by 18% 26% and 48% was observed in YFD0.1, YFD0.25 and AFD groups respectively when compared to SFD group. Intestinal sucrase activity was ameliorated in YFD0.1, YFD0.25 and AFD groups to about 28%, 45% and 56% respectively. Lactase activity of intestine was improved by 36%, 52% and 64% in YFD0.1, YFD0.25 and AFD groups respectively. On the contrary, specific activities of renal maltase, sucrase and lactase were decreased in SFD group compared to control groups. Supplementation of elephant foot yam extract in diet significantly ameliorated renal disachharidases activities in YFD0.1 and YFD0.25 groups. The results demonstrate the potential use of elephant foot yam for the management of diabetes.