Mechanistic Understanding of the Effects of Pectin on In Vivo Starch Digestion: A Review.

Obesity and type II diabetes are closely related to the rapid digestion of starch. Starch is the major food-energy source for most humans, and thus knowledge about the regulation of starch digestion can contribute to prevention and improved treatment of carbohydrate metabolic disorders such as diabetes. Pectins are plant polysaccharides with complex molecular structures and ubiquitous presence in food, and have diverse effects on starch digestion. Pectins can favorably regulate in vivo starch digestion and blood glucose level responses, and these effects are attributed to several reasons: increasing the viscosity of digesta, inhibiting amylase activity, and regulating some in vivo physiological responses. Pectins can influence starch digestion via multiple mechanisms simultaneously, in ways that are highly structure-dependent. Utilizing the multi-functionalities of pectin could provide more ways to design low glycemic-response food and while avoiding the unpalatable high viscosity in food by which is commonly caused by many other dietary fibers.

Effect of Different Nutritional Supplements on Glucose Response of Complete Meals in Two Crossover Studies.

Postprandial hyperglycemia is an important risk factor in the development and progression of type-2 diabetes and cardiometabolic diseases. Therefore, maintaining a low postprandial glucose response is key in preventing these diseases. Carbohydrate-rich meals are the main drivers of excessive glycemic excursions during the day. The consumption of whey protein premeals or mulberry leaf extract was reported to reduce postprandial glycemia through different mechanisms of action. The efficacy of these interventions was shown to be affected by the timing of the consumption or product characteristics. Two randomised crossover studies were performed, aiming to identify the optimal conditions to improve the efficacy of these nutritional supplements in reducing a glycemic response. The acute postprandial glycemic response was monitored with a continuous glucose monitoring device. The first study revealed that a preparation featuring 10 g of whey protein microgel reduced the postprandial glucose response by up to 30% (p = 0.001) and was more efficient than the whey protein isolates, independently of whether the preparation was ingested 30 or 10 min before a complete 320 kcal breakfast. The second study revealed that a preparation featuring 250 mg mulberry leaf extract was more efficient if it was taken together with a complete 510 kcal meal (−34%, p < 0.001) rather than ingested 5 min before (−26%, p = 0.002). These findings demonstrate that the efficacy of whey proteins premeal and mulberry leaf extracts can be optimised to provide potential nutritional solutions to lower the risk of type-2 diabetes or its complications.

Profile of blood pressure and glycemic responses after interval exercise in older women attending (in) a public health physical activity program.

BACKGROUND: and purpose: Interval exercise causes a positive impact on health status. Our aim was to evaluate the effects of a feasible and low-cost interval exercise on blood pressure and glycemic responses in people with controlled systemic arterial hypertension. METHODS: Thirteen women with hypertension (HG; age: 60.2 ± 2.8 years) and 11 without hypertension (CG; age: 54.4 ± 3.8 years) were recruited. Groups performed one session of interval exercise with elastic resistance (10 series of 1:1 min/effort:rest). RESULTS: There were slight reductions of absolute systolic blood pressure values for HG at 10, 30, and 60 min (4, 9, and 8 mmHg, respectively) at post-compared to pre-exercise. Glycemia was reduced (respectively, 17.6%, 17.6%, 19.4%, and 23.1%; p < 0.05) at pre-exercise vs. 0 min and 10, 30, and 60 min post-exercise for the HG. CONCLUSION: A single session of a feasible and low-cost interval exercise modifies and promotes significant clinical effects in blood pressure and glycemic levels in female older adults with and without hypertension.

Deep Dive Into the Effects of Food Processing on Limiting Starch Digestibility and Lowering the Glycemic Response.

During processing of cereal-based food products, starch undergoes dramatic changes. The objective of this work was to evaluate the impact of food processing on the starch digestibility profile of cereal-based foods using advanced imaging techniques, and to determine the effect of preserving starch in its native, slowly digestible form on its in vivo metabolic fate. Four different food products using different processing technologies were evaluated: extruded products, rusks, soft-baked cakes, and rotary-molded biscuits. Imaging techniques (X-ray diffraction, micro-X-ray microtomography, and electronic microscopy) were used to investigate changes in slowly digestible starch (SDS) structure that occurred during these different food processing technologies. For in vivo evaluation, International Standards for glycemic index (GI) methodology were applied on 12 healthy subjects. Rotary molding preserved starch in its intact form and resulted in the highest SDS content (28 g/100 g) and a significantly lower glycemic and insulinemic response, while the three other technologies resulted in SDS contents below 3 g/100 g. These low SDS values were due to greater disruption of the starch structure, which translated to a shift from a crystalline structure to an amorphous one. Modulation of postprandial glycemia, through starch digestibility modulation, is a meaningful target for the prevention of metabolic diseases.

Potato Preload Mitigated Postprandial Glycemic Excursion in Healthy Subjects: An Acute Randomized Trial.

This study investigated the preload effect of the medium and high glycemic index (GI) potato, as well as the combination of partially hydrolyzed guar gum (HG) and potato, when ingested prior to a rice meal, on the iso-carbohydrate basis. In a randomized crossover trial, 17 healthy female subjects consumed (1) rice; (2) co-ingestion of highly cooked potato (HP), and rice (HP + R); (3) co-ingestion of minimally cooked potato (MP) and rice (MP + R); (4) preload HP prior to rice meal (PHP + R); (5) preload MP prior to rice meal (PMP + R); (6) co-ingestion of partially hydrolyzed guar gum (HG), HP and rice (HG + HP + R); (7) preload HG prior to co-ingestion of HP and rice (PHG + HP + R); (8) co-preload of HG and HP prior to rice (PHG + PHP + R); and (9) preload of HP prior to co-ingestion of HG and rice (PHP + HG + R). Postprandial glycemic response (GR) tests and subjective satiety tests were conducted for each test food. Cooked potato as a preload to a rice meal could significantly cut the acute postprandial glycemic excursion by around 1.0 mmol/L, irrespective of the GI of the preload. Co-preload of partial hydrolyzed guar gum and highly cooked potato (PHG + PHP + R) resulted in improved acute GR in terms of peak glucose value and glycemic excursion compared with either HG preload or HP preload. All the meals with preload showed comparable or improved self-reported satiety. Within an equicarbohydrate exchange framework, both high-GI and medium-GI potato preload decreased the postprandial glycemic excursion in young healthy female subjects. The combination of HG and HP as double preload resulted in better GR than both single HG or HP preload did.

Modulating Phenolic Bioaccessibility and Glycemic Response of Starch-Based Foods in Wistar Rats by Physical Complexation between Starch and Phenolic Acid.

This study assessed the impact of caffeic and ferulic acid complexation with maize amylopectin or potato starch on glycemic parameters. In comparison to starch-phenolic mixtures, starch-phenolic complexes resulted in significant modification of phenolic bioaccessibility and cellular uptake (p < 0.05). In addition, glucose release from in vitro digestion of starch was modestly reduced in the complexes compared to native starch alone (21.2-26.8 versus 29.8-30.5 mM). Furthermore, intestinal glucose transport, assessed in Caco-2 cell monolayers, was not affected by the presence of complexes (82.4-124 versus 100% at 90 min). However, a reduced glycemic response was evident in a Wistar rat model, with significant reduction in 240 min of blood glucose area under the curve following oral administration of the potato starch-ferulic acid complex compared to native potato starch (26 170 ± 556 versus 28 951 ± 486 mg min dL-1; p < 0.001). These alterations were attributed to complexation-induced resistant starch formation and phenolic entrapment, providing an alternative mechanistic approach to modulate glycemic properties of starch-based foods.

The effect of 8 plant extracts and combinations on post-prandial blood glucose and insulin responses in healthy adults: a randomized controlled trial.

BACKGROUND: Lower post-prandial glucose (PPG) and insulin (PPI) responses to foods are associated with reduced diabetes risk and progression. Several plant extracts have been proposed to reduce PPG or PPI by inhibiting enzymes or transporters involved in carbohydrate digestion and uptake. This study evaluates a range of such extracts, consumed with a carbohydrate load, for their effects on PPG, PPI and indicators of (gastrointestinal) tolerance. METHODS: Interventions were extracts of mulberry fruit (MFE, 1.5 g), mulberry leaf (MLE, 1.0 g), white bean (WBE, 3.0 g), apple (AE, 2.0 g), elderberry (EE, 2.0 g), turmeric (TE, 0.18 g), AE + TE, and EE + TE. Each of these 8 individual extracts or combinations were added to a rice porridge containing ~ 50 g available carbohydrate (control). In a within-subject (randomised, balanced incomplete block) design, individual subjects received the control and a subset of 4 of the 8 extracts or combinations. Participants were 72 apparently healthy adults (mean [SD] age 31.2 [5.5] yr, body mass index 22.1 [2.0] kg/m2). The primary outcome was the percentage change in 2-h PPG (positive incremental area under the curve) relative to control. Secondary measures were the 2-h PPI response, 7-h breath hydrogen, measures of gastrointestinal discomfort, and urine glucose. RESULTS: In the 65 subjects who completed the control and at least one intervention treatment, additions of AE, MFE and MLE produced statistically significant reductions in PPG vs control (p < 0.05; mean effect - 24.1 to - 38.1%). All extracts and combinations except TE and WBE significantly reduced PPI (p < 0.01; mean effect - 17.3% to - 30.4%). Rises in breath hydrogen > 10 ppm were infrequent, but statistically more frequent than control only for MLE (p = 0.02). Scores for gastrointestinal discomfort were extremely low and not different from control for any treatment, and no glucosuria was observed. CONCLUSIONS: Additions of AE, MFE and MLE to rice robustly reduced PPG and PPI. EE significantly reduced only PPI, while TE and WBE showed no significant efficacy for PPG or PPI. Breath hydrogen responses to MLE suggest possible carbohydrate malabsorption at the dose used, but there were no explicit indications of intolerance to any of the extracts. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT04258501. Registered 6 February 2020 - Retrospectively registered.

Suppression of Oral Sweet Sensations during Consumption of Sweet Food in Humans: Effects on Gastric Emptying Rate, Glycemic Response, Appetite, Food Satisfaction and Desire for Basic Tastes.

Suppression of oral sweet sensation (OSS) acutely reduces intake of sweet-tasting food due to lower liking. However, little is known about other physiological responses during both the prandial and postprandial phase. Here, we explored the effects of Gymnema sylvestre (GS)-based suppression of OSS of several types of sweet-tasting food (muffin, sweet yogurt, banana) on gastric emptying, blood glucose (BG), plasma insulin (PI), appetite indices (hunger, fullness and prospective consumption), satisfaction and desire for tastes. Fifteen healthy subjects (22 ± 3 years, 9 women) took part in the study. Subjects rinsed their mouth with either GS solution or distilled water before eating the sweet-tasting food. Subjects felt decreased sweet taste intensity and reduced taste liking associated with GS rinsing after consuming each food, compared with rinsing with distilled water (p < 0.05). Gastric emptying, BG, PI and appetite indices during and after the prandial phase did not significantly change with GS rinsing compared to rinsing with distilled water (p > 0.05). Higher desire for sweet taste as well as lower satisfaction (p < 0.05) in the postprandial phase were observed with GS rinsing. These results suggest that the suppression of OSS does not affect gastric emptying, glycemic response and appetite during and after consumption of sweet-tasting food.

Inhibitory effect of black tea, lemon juice, and other beverages on salivary and pancreatic amylases: What impact on bread starch digestion? A dynamic in vitro study.

Certain food properties (ex.: pH, polyphenolic composition) can inhibitdigestive amylases and thereby slow down starch digestion. Our aim was twofold. (1) To determine the impact of21 beverages and condiments (coffees, teas, wines, vinegars and lemon juice)on salivary and pancreatic amylolysis: inhibition ranged from 10% to 100%in our experimental conditions. (2) To investigate the effect of one black tea and lemon juice (selected for their strong inhibitory capacity) on starch hydrolysis during dynamicoro-gastro-intestinal digestion of bread. Compared to water (control), the effect of black tea was limited to a ≈20% reduction of released oligosaccharides during the intestinal phase. Lemon juice had a remarkable effect, completely interrupting gastric amylolysis by salivary amylase via a preliminary acidification of gastric contents. These results provide a strong biochemical rationale for the development of dietary strategies to improve the glycaemic impact of starch-rich meals which could be tested in vivo.

Effect of potatoes and other carbohydrate-containing foods on cognitive performance, glycemic response, and satiety in children.

Dietary carbohydrates have been shown to influence cognitive performance and satiety in children. However, it remains unclear whether the carbohydrate source is a primary determinant of cognitive performance and satiety. The objective was to compare the effects of white potatoes and other carbohydrate-containing foods on cognitive performance, glycemic response, and satiety in children. On 6 separate mornings, in random order, children (n = 22) consumed 50 g of available carbohydrates from microwaved mashed potatoes (prepared from fresh potatoes then frozen), deep-fried potato strips (French fries), hash browns, white rice, white beans, or skipped a meal. Cognitive performance, glycemic response, and satiety were measured over 180 min. Cognitive performance was measured using a battery of tests assessing verbal declarative memory, spatial memory, short-term memory, working memory, and information processing speed. Although cognitive performance after the treatment meals did not differ from meal skipping, children recalled more words after French fries (9.1 ± 0.4 words) compared with mashed potatoes (8.2 ± 0.3 words; p = 0.001) and white rice (8.4 ± 0.3 words; p = 0.04) on the verbal declarative memory test. Blood glucose concentrations were higher after white rice compared with white beans, mashed potatoes, and hash browns (p < 0.05). Change from baseline subjective average appetite (mm/kcal) was lower after mashed potatoes compared with all other treatment meals (p < 0.05). In conclusion, verbal declarative memory was higher after French fries and subjective average appetite was lower after mashed potatoes. Future longitudinal studies are needed to confirm these short-term findings and to elucidate the mechanism of action.

Effects of blueberry and cranberry consumption on type 2 diabetes glycemic control: A systematic review.

The metabolic effects of cranberry and blueberry consumption on glycemic control have been evaluated in vitro and in animal models as well as in human studies, although findings have not been systematically reviewed yet. Therefore, a systematic review was carried out of relevant randomized clinical trials (RCTs) in order to assess the effect of berries (blueberry and cranberry) consumption on type 2 diabetes (T2DM) glycemic control. Some evidences were also discussed on the anti-diabetic mechanisms exerted by berries polyphenols. Studies were identified by searching electronic databases: LILACS, PubMed/MEDLINE, Scopus, The Cochrane Library and Web of Science. Three authors independently searched and extracted RCTs in which the effect of berries (cranberry or blueberry) consumption on T2DM glycemic control was assessed. A total of 7 RCTs, involving 270 adults with type 2 diabetes were included. Despite the heterogeneity of the administration forms (in natura, dried, extract, preparations - juice), dosage, duration of the intervention and type of population of the studies involving these two berries some studies highlight the potential benefit of berries, especially of blueberry, on glucose metabolism in T2DM subjects. Daily cranberry juice (240 mL) consumption for 12 weeks and blueberry extract or powder supplementation (9.1 to 9.8 mg of anthocyanins, respectively) for 8 to 12 weeks showed a beneficial effect on glucose control in T2DM subjects. Those results indicate a promising use of these berries in T2DM management; although more studies are required to better understand the mechanisms involved.

Co-Ingestion of Rice Bran Soymilk or Plain Soymilk with White Bread: Effects on the Glycemic and Insulinemic Response.

The regular consumption of soy products is associated with inverse incidence of type 2 diabetes, and there has been an increasing interest in the glycemia reducing potential of rice bran and its components. In this study, we investigated whether consuming soymilk with the addition of rice bran (fiber) can reduce the glycemic response of a carbohydrate meal. Seventeen healthy Asian men (BMI: 18.5-29 kg/m²) participated in this randomized crossover trial. On four occasions, they consumed white bread (two times) and white bread with two different soymilks differing in protein and rice bran content. Blood samples were taken to measure glucose and insulin response over a period of 3 hours. Taking the glycemic index (GI) value of white bread as a reference value of 100, the GI of white bread when co-ingested with rice bran soymilk (RBS) was 83.1 (±7.7) and sugar-free soymilk (SFS) was 77.5 (±10.1), both were lower than white bread (p < 0.05). The insulin response of both soymilk treatments was similar to white bread (p > 0.05). The glucose/insulin ratio of RBS and SFS were respectively 43.1 (± 6.1) and 60.0 (± 17.0) and were lower (p < 0.05) than white bread (123.5 ± 21.1) during the first 30 min. In conclusion, co-ingestion of low amounts of soy protein with a carbohydrate meal stimulated early-phase insulin secretion and thereby increased blood glucose clearance effectiveness. Furthermore, rice bran-fortified soymilk reduced the glycemic response similarly to soymilk with a greater dose of soy protein. Rice bran and its components offer therapeutic potential for glycemic and insulinemic control.

Potato phenolics impact starch digestion and glucose transport in model systems but translation to phenolic rich potato chips results in only modest modification of glycemic response in humans.

Beneficial effects of some phenolic compounds in modulation of carbohydrate digestion and glycemic response have been reported, however effects of phenolics from processed potato products on these endpoints are not well known. The aims of this study were to characterize phenolic profiles of fresh potatoes (purple, red, or white fleshed; 2 varieties each) and chips, and to examine the potential for potato phenolic extracts (PPE) to modulate starch digestion and intestinal glucose transport in model systems. Following in vitro assessment, a pilot clinical study (n=11) assessed differences in glycemic response and gastric emptying between chips from pigmented and white potatoes. We hypothesized that phenolics from pigmented potato chips would be recovered through processing and result in a reduced acute glycemic response in humans relative to chips made from white potatoes. PPEs were rich in anthocyanins (~98, 11 and ND mg/100 g dw) and chlorogenic acids (~519, 425 and 157 mg/100 g dw) for purple, red and white varieties respectively. While no significant effects were observed on starch digestion by α-amylase and the α-glucosidases, PPEs significantly (p<0.05) decreased the rate of glucose transport, measured following transport of 1,2,3,4,5,6,6-d7 -glucose (d7-glu) across Caco-2 human intestinal cell monolayers, by 4.5-83.9%. Consistent with in vitro results, consumption of purple potato chips modestly but significantly (p<0.05) decreased blood glucose at 30 and 60 minutes post consumption compared to white chips without impacting gastric emptying. These results suggest that potato phenolics may play a modest role in modulation of glycemic response and these effects may result in subtle differences between consumer products.

Prior ingestion of exogenous ketone monoester attenuates the glycaemic response to an oral glucose tolerance test in healthy young individuals.

KEY POINTS: The recent development of exogenous ketone supplements allows direct testing of the metabolic effects of elevated blood ketones without the confounding influence of widespread changes experienced with ketogenic diets or prolonged fasting. In the present study, we determined the effect of (R)-3-hydroxybutyl (R)-3-hydroxybutyrate ketone monoester on the glycaemic response and insulin sensitivity index during a 2 h oral glucose tolerance test (OGTT) in humans. The results obtained show that consuming a ketone monoester supplement 30 min prior to an OGTT reduced the glycaemic response and markers of insulin sensitivity without affecting insulin secretion. The findings of the present study provides evidence that ketone supplements could have therapeutic potential for future application as a glucose-lowering nutritional supplement. ABSTRACT: The main objectives of the present study were: (i) to determine whether acute ingestion of ketone monoester (Kme ); (R)-3-hydroxybutyl (R)-3-hydroxybutyrate impacts plasma glucose levels during a standardized oral glucose tolerance test (OGTT) and (ii) to compare changes in insulin concentrations and estimates of insulin sensitivity after acute Kme supplementation. Twenty healthy participants (n = 10 males/females) aged between 18 and 35 years took part in a randomized cross-over study. After an overnight fast, participants consumed a Kme supplement (ΔG®; TΔS Ltd, UK, Oxford, UK; 0.45 ml kg-1 body weight) or placebo (water) 30 min before completing a 75 g OGTT. Blood samples were collected every 15-30 min over 2.5 h. The participants and study personnel performing the laboratory analyses were blinded to the study condition. Kme acutely raised blood d-beta-hydroxybutyrate (ß-OHB) to 3.2 ± 0.6 mm within 30 min with levels remaining elevated throughout the entire OGTT. Compared to placebo, Kme significantly decreased the glucose area under the curve (AUC; -17%, P = 0.001), non-esterified fatty acid AUC (-44%, P < 0.001) and C-peptide incremental AUC (P = 0.005), at the same time as improving oral glucose insulin sensitivity index by ∼11% (P = 0.001). In conclusion, a Kme supplement that acutely increased ß-OHB levels up to ∼3 mm attenuated the glycaemic response to an OGTT in healthy humans. The reduction in glycaemic response did not appear to be driven by an increase in insulin secretion, although it was accompanied by improved markers of insulin sensitivity. These results suggest that ketone monoester supplements could have therapeutic potential in the management and prevention of metabolic diseases.

The Effects of Carbohydrates, in Isolation and Combined with Caffeine, on Cognitive Performance and Mood-Current Evidence and Future Directions.

This review examines the effects of carbohydrates, delivered individually and in combination with caffeine, on a range of cognitive domains and subjective mood. There is evidence for beneficial effects of glucose at a dose of 25 g on episodic memory, but exploration of dose effects has not been systematic and the effects on other cognitive domains is not known. Factors contributing to the differential sensitivity to glucose facilitation include age, task difficulty/demand, task domain, and glucoregulatory control. There is modest evidence to suggest modulating glycemic response may impact cognitive function. The evidence presented in this review identifies dose ranges of glucose and caffeine which improve cognition, but fails to find convincing consistent synergistic effects of combining caffeine and glucose. Whilst combining glucose and caffeine has been shown to facilitate cognitive performance and mood compared to placebo or glucose alone, the relative contribution of caffeine and glucose to the observed effects is difficult to ascertain, due to the paucity of studies that have appropriately compared the effects of these ingredients combined and in isolation. This review identifies a number of methodological challenges which need to be considered in the design of future hypothesis driven research in this area.

The Effect of Isomaltulose Together with Green Tea on Glycemic Response and Antioxidant Capacity: A Single-Blind, Crossover Study in Healthy Subjects.

Isomaltulose, a naturally-occurring isomer of sucrose, is commonly used as an alternative sweetener in foods and beverages. The goal of this study was to determine the effect of isomaltulose together with green tea on postprandial plasma glucose and insulin concentration, as well as antioxidant capacity in healthy subjects. In a randomized, single-blind, crossover study, 15 healthy subjects (eight women and seven men; ages 23.5 ± 0.7 years; with body mass index of 22.6 ± 0.4 kg/m²) consumed five beverages: (1) 50 g sucrose in 400 mL water; (2) 50 g isomaltulose in 400 mL of water; (3) 400 mL of green tea; (4) 50 g sucrose in 400 mL of green tea; and (5) 50 g isomaltulose in 400 mL of green tea. Incremental area under postprandial plasma glucose, insulin, ferric reducing ability of plasma (FRAP) and malondialdehyde (MDA) concentration were determined during 120 min of administration. Following the consumption of isomaltulose, the incremental 2-h area under the curve (AUC0-2 h) indicated a higher reduction of postprandial glucose (43.4%) and insulin concentration (42.0%) than the consumption of sucrose. The addition of green tea to isomaltulose produced a greater suppression of postprandial plasma glucose (20.9%) and insulin concentration (37.7%). In accordance with antioxidant capacity, consumption of sucrose (40.0%) and isomaltulose (28.7%) caused the reduction of green tea-induced postprandial increases in FRAP. A reduction in postprandial MDA after drinking green tea was attenuated when consumed with sucrose (34.7%) and isomaltulose (17.2%). In conclusion, green tea could enhance the reduction of postprandial glucose and insulin concentration when consumed with isomaltulose. In comparison with sucrose, isomaltulose demonstrated less alteration of plasma antioxidant capacity after being consumed with green tea.

Leucine supplementation at the onset of high-fat feeding does not prevent weight gain or improve glycemic regulation in male Sprague-Dawley rats.

Obesity is a major public health concern and it is essential to identify effective treatments and preventative strategies to stop continued increases in obesity rates. The potential functional roles of the branched chain amino acid leucine make this amino acid an attractive candidate for the treatment and/or prevention of obesity. The objective of this study was to determine if long-term leucine supplementation could prevent the development of obesity and reduce the risk factors for chronic disease in rats fed a high-fat (60 % fat) diet. Male Sprague-Dawley rats (n = 30 per dietary treatment) were meal-fed (3 meals/day) either a control, low-fat diet (LF), control + leucine (LFL), high-fat (HF), or high-fat + leucine (HFL) for 42 days. On day 42, rats were sacrificed at 0, 30, or 90 min postprandial. Animals fed the HF and HFL diets had higher (P < 0.05) final body weights and weight gain compared to animals fed the LF and LFL diets. Leucine supplementation increased epididymal fat mass (P < 0.05) and decreased muscle mass (P < 0.05). There was no effect of leucine supplementation on postprandial glucose or insulin response. However, there was a significant effect (P < 0.05) of diet and time on free fatty acid concentrations. There was no effect of leucine on muscle markers of protein synthesis (4E-BP1, p70S6K) or energy metabolism (Akt, AMPK). Leucine supplementation decreased (P < 0.05) PGC1α expression and increased (P < 0.05) PPARγ expression in skeletal muscle. In conclusion, long-term leucine supplementation does not prevent weight gain, improve body composition, or improve glycemic control in rats fed a high-fat diet.

Reduction of postprandial blood glucose in healthy subjects by buns and flatbreads incorporated with fenugreek seed powder.

PURPOSE: This study aimed to determine whether fenugreek seed powder could reduce the glycemic response and glycemic index (GI) when added to buns and flatbreads. METHODS: In a randomised, controlled crossover trial, ten healthy human subjects (five men, five women) were given 50 g glucose (reference food, twice); buns (0 and 10 % fenugreek seed powder); and flatbreads (0 and 10 % fenugreek seed powder) on six different occasions. Finger prick capillary blood samples were collected at 0, 15, 30, 45, 60, 90 and 120 min after the start of the meal. The palatability of the test meals was scored using Likert scales. RESULTS: The incremental areas under the glucose curve value of buns and flatbreads with 10 % fenugreek (138 ± 17 mmol × min/L; 121 ± 16 mmol × min/L) were significantly lower than those of 0 % fenugreek bun and flatbreads (227 ± 15 mmol × min/L; 174 ± 14 mmol × min/L, P = <0.01). Adding 10 % fenugreek seed powder reduced the GI of buns from 82 ± 5 to 51 ± 7 (P < 0.01) and to the GI of flatbread from 63 ± 4 to 43 ± 5 (P < 0.01). CONCLUSIONS: These results suggest that replacing 10 % of refined wheat flour with fenugreek seed powder significantly reduces the glycemic response and the GI of buns and flatbreads. Thus, fenugreek powder may be a useful functional ingredient to reduce postprandial glycemia.

White bread enriched with polyphenol extracts shows no effect on glycemic response or satiety, yet may increase postprandial insulin economy in healthy participants.

Extracts from different plant sources have been shown to modify starch digestion from carbohydrate-rich foods and lower resulting glycemia. It was hypothesized that extracts rich in polyphenols, added to white bread, would improve the glycemic response and insulin response and increase satiety in healthy participants. An in vitro dose-response analysis was performed to determine the optimal dose of a variety of extracts (baobab fruit extract, green tea extract, grape seed extract, and resveratrol) for reducing rapidly digestible starch in white bread. The 2 extracts with the greatest sugar reducing potential were then used for the human study in which 13 volunteers (9 female and 4 male) were recruited for a crossover trial of 3 different meals. On separate days, participants consumed a control white bread, white bread with green tea extract (0.4%), and white bread with baobab fruit extract (1.88%). Glycemic response, insulin response, and satiety were measured 3 hours postprandially. Although enriched breads did not reduce glycemic response or hunger, white bread with added baobab fruit extract significantly (P < .05) reduced the total (0-180 minutes) and segmental insulin area under the curve at 0 to 90, 0 to 120, and 0 to 150 minutes, and therefore reduced the amount of insulin needed for a given blood glucose response. This preliminary research suggests that there is potential for baobab fruit extract added into white bread to improve insulin economy in healthy adults.

The Glycemic Potential of White and Red Rice Affected by Oil Type and Time of Addition.

UNLABELLED: Limited research exists on how different oil types and time of addition affect starch digestibility of rice. This study aimed to assess the starch digestibility of white and red rice prepared with 2 oil types: vegetable oil (unsaturated fat) and ghee (clarified butter, saturated fat) added at 3 different time points during the cooking process ("before": frying raw rice in oil before boiling, "during": adding oil during boiling, and "after": stir-frying cooked rice in oil). Red rice produced a slower digestion rate than white rice. White rice digestibility was not affected by oil type, but was affected by addition time of oil. Adding oil "after" (stir-frying) to white or red rice resulted in higher slowly digestible starch. Red rice cooked using ghee showed the lowest amount of glucose release during in vitro digestion. The addition of ghee "during" (that is boiling with ghee) or "before" (that is frying rice raw with ghee then boiling) cooking showed potential for attenuating the postprandial glycemic response and increasing resistant starch content. This is the first report to show healthier ways of preparing rice. White rice with oil added "after" (stir-fried) may provide a source of sustained glucose and stabilize blood glucose levels. Boiling red rice with ghee or cooking red rice with ghee pilaf-style may provide beneficial effects on postprandial blood glucose and insulin concentrations, and improve colonic health. The encouraging results of the present study justify extending it to an in vivo investigation to conclusively determine the effect of time of addition of fat when rice is cooked on blood glucose homeostasis. PRACTICAL APPLICATION: Rice is a predominant source of energy in most of Asia with excessive consumption of rice being implicated in the rise of type 2 diabetes. Stir-frying white rice can be a source of sustained glucose and provide a stabilizing effect on blood glucose levels. Boiling red rice with ghee or cooking red rice with ghee pilaf-style may provide beneficial effects on postprandial blood glucose and insulin concentrations. This suggests how a single technique of adding fat in the cooking of rice at certain time points may be a useful method in providing taste and lowering glycemia.