Postprandial glycaemia is a key determinant of overall glycaemic control. One mechanism by which dietary strategies can reduce postprandial glycaemic excursions is by slowing gastric emptying. This study aimed to evaluate the acute effect of ingesting riceberry rice (RR) compared with that of ingesting white rice (WR) on gastric emptying rate (GER), plasma glucose and glucose-regulating hormones, including insulin, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1), in healthy subjects. A randomised, open-label, within-subject, crossover study was performed in six healthy men. GER was measured by scintigraphy over 240 min, and plasma concentrations of glucose, insulin, GLP-1 and GIP were measured at multiple time points over 180 min. This study revealed that RR slows GER with a reduction in postprandial plasma glucose concentrations compared with WR. Plasma insulin and GLP-1 concentrations did not differ between RR and WR. However, plasma GIP concentrations were markedly increased after WR ingesting v. after RR ingestion. We conclude that RR attenuates postprandial glycaemia by slowing GER without altering plasma insulin or GLP-1. Plasma GIP concentrations are likely related to differences in GER and carbohydrate absorption. We propose that dietary fibre-enriched foods, including RR, could contribute to improvement in postprandial glycaemia via delayed gastric emptying.

This study examined the effects of post-resistance exercise protein ingestion timing on the rate of gastric emptying (GE) and blood glucose (BG) and plasma branched-chain amino acid (BCAA) responses. In all, eleven healthy participants randomly ingested 400 ml of a nutrient-rich drink containing 12 g carbohydrates and 20 g protein at rest (Con), at 5 min (post-exercise (PE)-5) or at 30 min (PE-30) after a single bout of strenuous resistance exercises. The first and second sets comprised ten repetitions at 50 % of each participant’s one-repetition maximum (1RM). The third, fourth and fifth sets comprised ten repetitions at 75 % of 1RM, and the sixth set involved repeated repetitions until exhaustion. Following ingestion of the nutrient-rich drink, we assessed the GE rate using 13C-sodium acetate breath test and evaluated two parameters according to the Tmax-calc (time when the recovery per hour is maximised), which is a standard analytical method, and T1/2 (time when the total cumulative dose of [13CO2] reaches one-half). Tmax-calc and T1/2 were slower for the PE-5 condition than for either the PE-30 or Con condition (Tmax-calc; Con: 53 (sd 7) min, PE-5: 83 (sd 16) min, PE-30: 62 (sd 9) min, T1/2; Con: 91 (sd 7) min, PE-5: 113 (sd 21) min, PE-30: 91 (sd 11) min, P<0·05). BG and BCAA responses were also slower for the PE-5 condition than for either the PE-30 or Con condition. Ingesting nutrients immediately after strenuous resistance exercise acutely delayed GE, which affected BG and plasma BCAA levels in blood circulation.

The short-term effect of soya protein, polydextrose and their combination on energy intake (EI) was investigated in Chinese. In total, twenty-seven healthy, normotensive and lean Chinese men aged 21–40 years were given four different soyabean curd preloads with or without polydextrose. The study was a repeated-measure, randomised, cross-over design. The consumption of high-protein soyabean curd alone or in addition with polydextrose as a preload led to greater reduction in EI at a subsequent meal. A similar observation was also found after intake of low-protein soyabean curd with polydextrose. The gut hormone responses mirrored the reduction in food intake. It appears that incorporation of polydextrose either with low- or high-protein soyabean curd could be a potential strategy to reduce EI and assist with weight management. The popular consumption of soyabean curd in Chinese makes it an ideal vehicle for incorporation of polydextrose. This evidence-based dietary approach can serve as a guideline for developing functional foods for weight reduction and weight maintenance.

The role of carbohydrates in health and disease has received a high profile in recent years, in particular the glycaemic index (GI) as a physiological classification of carbohydrate foods. A common carbohydrate source in the UK is white bread, which is considered to have a high GI value and low satiety value. In the present study, the possibility of favourably altering the GI of white bread by manipulating bread structure (loaf form) was investigated. In a randomised repeated-measures design, ten subjects were tested for glycaemic and satiety responses to four loaves of varying volume, but of consistent macronutrient content. Peak plasma glucose levels and GI values were shown to be significantly reduced by lowering loaf volume (P=0·007, P<0·001 respectively). In addition, a greater satiety index (SI) was seen with decreased loaf volume (P<0·001). In conclusion, the present study demonstrates that reducing the volume of white bread, which is generally considered to be high-GI and low-SI, can favourably alter metabolic and appetite responses. Relatively small differences in the GI of regularly consumed starch foods have been shown to have beneficial effects on health.

Longitudinal studies indicate that milk and fermented milk products lower basal plasma cholesterol concentrations, despite their high content of saturated fat, and therefore have favourable health effects. However, there have been few studies on the postprandial effects of milk products. The present study compared the effect of whole milk with a fermented milk, A-38, on postprandial carbohydrate and lipid metabolism, gastric emptying and appetite. Eight healthy young men participated. On the two test days, they arrived fasting for collection of baseline values before consuming the meals, which for a 75 kg subject consisted of 1·4 litre milk or fermented milk, plus 165 mg [13C]acetate (for later determination of gastric emptying by a [13C]acetate breath test). Lactose (15 g) was added to the A-38 meal to equalize the lactose content. Postprandially the A-38 meal resulted in a slower gastric emptying rate than milk (P>0·001). Furthermore, the A-38 meal resulted in a greater increase and a quicker decrease of the triacylglycerol content in all lipoprotein fractions (LDL-fraction, P>0·05; other fractions, P>0·001) and of the gastrointestinal hormones (cholecystokinin and peptide YY, P>0·05; gastric inhibitory polypeptide and glucagon-like polypeptide-1, P>0·001). There were no significant differences in appetite sensations (measured by visual analogue scale) or in the glucose and insulin response (P<0·10). The slower emptying rate of the liquid phase after the A-38 meal is probably due to the higher viscosity of A-38. The lower and more prolonged triacylglycerol response after the milk meal might be caused by coagulation of milk in the stomach.