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Barley b-glucan (BG) has been shown to reduce glycaemic response (GR) in some studies. It is hypothesised that this reduction may be a function of its physical properties that delay gastric emptying (GE). The effect of these changes in GR and GE on diet-induced thermogenesis (DIT) is not known. The aim of the present study was to assess the effect of BG of different molecular weights and purities on GR, GE and DIT in healthy subjects. This was a randomised, single-blind, repeated-measures design where fifteen healthy subjects were tested on three occasions following an overnight fast. Following the baseline measurements, the volunteers were fed a soup containing high-molecular-weight BG (HBG), a soup containing low-molecular-weight BG (LBG) or a control soup with no BG (CHO). Following the consumption of the breakfast, GR was measured using finger-prick blood samples, GE was determined using the 13 C-octanoic acid breath test and DIT was measured using indirect calorimetry. There was a difference in GR AUC between the soups after 60 min but not after 120 min. The CHO and LBG meals had a greater GR than the HBG meal. There were differences in all GE time points, with the HBG meal having the slowest GE time. There was a correlation between the GR and the initial GE times. There were differences in total DIT between the three test meals with the HBG meal having the lowest DIT. The present study indicates that HBG has the ability to delay GE due to increased viscosity, resulting in a decreased GR and DIT.Key words: Barley b-glucan: Glycaemic responses: Diet-induced thermogenesis: Gastric emptying A worldwide increase in type 2 diabetes along with the prevalence of obesity has prompted the development of nutritional and lifestyle interventions to improve glycaemia and increase energy expenditure. Soluble dietary fibres may have beneficial effects on glycaemic and insulin responses and cholesterol levels as well as body weight maintenance (1 -3) . Barley b-glucan (BG) is one such fibre that forms a highly viscous solution in the stomach and small intestine, which entraps glucose molecules and slows down their intestinal absorption (4) . However, barley BG in foods has not always been effective in lowering glycaemic response (GR) (5 -8) due to variations in its physical properties such as molecular weight and viscosity. Soluble fibres in foods may increase gastric distension, delay gastric emptying (GE) and alter the levels of gut hormones involved in appetite and satiety (9,10) . However, the effect of BG on GE has shown variation with meal consistency and is not always correlated with GR (11) . On the other hand, delayed GE has been reported irrespective of any difference in GR or satiety (12) . Juvonen et al. (13) reported changes in glycaemia, insulinaemia and GE after reducing the viscosity of oat BG in a liquid meal. Elsewhere, the reduced GR could not be associated with a delayed GE rate (14) . Hence, it is evident that the variable effect of BG on GE is not fully understood.Low-glycaemic index foods h...

β-Glucans are believed to lower postprandial glycemia due to their ability to increase viscosity and slow down gastric emptying. The effect of high-purity barley β-glucan (Glucagel) was tested on in vitro starch digestibility and glycemic response of chapattis. In a randomized controlled crossover trial, 10 healthy human subjects consumed chapattis containing 0, 4 and 8% β-glucan on different occasions. Capillary blood samples were collected before and at 0, 15, 30, 45, 60, 90 and 120 min after consuming the chapattis. There was no significant difference either in the amount of glucose released after in vitro digestion or in the glycemic response to chapattis with 0, 4 and 8% β-glucan (P>0.05). It may be concluded that low molecular weight barley β-glucan, although of 75% purity, was not effective in lowering glycemic response possibly due to its inability to influence starch digestion and particle breakdown during in vitro digestion.

Background There are many benefits of maintaining healthy blood glucose levels, and studies have shown that lifestyle changes such as changes to diet can successfully restore normoglycaemia in participants with dysglycaemia. Significant health-related lifestyle changes are often difficult to implement and functional ingredients that can reduce glycaemic and insulaemic responses may help at risk populations. The aim of this study was to investigate whether a mulberry leaf extract could lower the glycaemic and insulinaemic responses to 75 g sucrose in healthy individuals. Methods A double-blind, randomised, placebo-controlled, crossover design trial was conducted by the Oxford Brookes Centre for Nutrition and Health. Thirty-eight participants were recruited into the trial and, after an overnight fast, were given 75 g sucrose + white mulberry leaf extract, or 75 g sucrose alone. Capillary blood samples were collected at 15-min intervals in the first hour and at 30-min intervals over the second hour to determine glucose and plasma insulin levels. Data analysis was conducted using a paired samples T test or a Wilcoxon signed rank test. Results The addition of mulberry leaf extract to sucrose resulted in a significantly lower glycaemic response and insulinaemic response compared to a matched placebo (sucrose alone). The change in blood glucose measurements were significantly lower at 15 min (p < 0.001), 30 min (p < 0.001), 45 min (p = 0.008), and 120 min (p < 0.001) and plasma insulin measurements were significantly lower at 15 min (p < 0.001), 30 min (p < 0.001), 45 min (p < 0.001), 60 min (p = 0.001) and 120 min (p < 0.001). The glucose iAUC (− 42%, p = 0.001), insulin iAUC (− 40%, p < 0.001), peak glucose (− 40.0%, p < 0.001) and peak insulin (− 41%, p < 0.001) from baseline were significantly lower for white mulberry leaf extract compared with the placebo. White mulberry leaf extract was well tolerated and there were no reported adverse events. Conclusions Mulberry leaf extract can be used as part of lifestyle changes that may lead to healthy blood glucose levels. Trial registration: ISRCTN99601810 (23 October 2020, retrospectively registered)

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