Consumption of the Non-Nutritive Sweetener Stevia for 12 Weeks Does Not Alter the Composition of the Human Gut Microbiota.

The use of non-nutritive sweeteners (NNSs) as an alternative to caloric sugars has increased in recent years. Stevia is an NNS that has demonstrated beneficial effects on appetite and energy intake. However, the impact on the gut microbiota is not well understood. Therefore, we investigated how regular consumption of stevia, for up to 12 weeks, impacts the human gut microbiota. Healthy subjects with a normal body mass index participated in our study; the stevia group (n = 14) was asked to consume five drops of stevia twice daily, compared to control participants (n = 13). Faecal samples collected before and after treatment were analysed by 16S rRNA gene sequencing. Stevia did not cause significant changes in the alpha or beta diversity when compared to the control groups. When the relative abundances of taxa were investigated, no clear differences were detected. Conversely, a random forest analysis correctly associated the gut microbiome with the control and stevia groups with an average of 75% accuracy, suggesting that there are intrinsic patterns that could discriminate between control and stevia use. However, large-scale changes in the gut microbiota were not apparent in this study, and, therefore, our data suggest that stevia does not significantly impact the gut microbiota.

Mapping the Homeostatic and Hedonic Brain Responses to Stevia Compared to Caloric Sweeteners and Water: A Double-Blind Randomised Controlled Crossover Trial in Healthy Adults.

Non-nutritive sweeteners have potential effects on brain function. We investigated neural correlates of responses to beverages differing in sweetness and calories. Healthy participants completed 4 randomised sessions: water vs. water with stevia, glucose, or maltodextrin. Blood-oxygenation level-dependent (BOLD) contrast was monitored for 30 min post-ingestion by functional Magnetic Resonance Imaging. A food visual probe task at baseline was repeated at 30 min. A significant interaction of taste-by-calories-by-time was demonstrated mainly in motor, frontal, and insula cortices. Consumption of the stevia-sweetened beverage resulted in greater BOLD decrease, especially in the 20-30 min period, compared to other beverages. There was a significant interaction of taste-by-time in BOLD response in gustatory and reward areas; sweet beverages induced greater reduction in BOLD compared to non-sweet. The interaction calories-by-time showed significantly greater incremental area under the curve in thalamic, visual, frontal, and parietal areas for glucose and maltodextrin 10-20 min post-consumption only, compared to water. In the visual cue task, the water demonstrated an increased response in the visual cortex to food images post-consumption; however, no difference was observed for the three sweet/caloric beverages. In conclusion, both sweet taste and calories exert modulatory effects, but stevia showed a more robust and prolonged effect.

Appetite, the enteroendocrine system, gastrointestinal disease and obesity.

The enteroendocrine system is located in the gastrointestinal (GI) tract, and makes up the largest endocrine system in the human body. Despite that, its roles and functions remain incompletely understood. Gut regulatory peptides are the main products of enteroendocrine cells, and play an integral role in the digestion and absorption of nutrients through their effect on intestinal secretions and gut motility. Several peptides, such as cholecystokinin, polypeptide YY and glucagon-like peptide-1, have traditionally been reported to suppress appetite following food intake, so-called satiety hormones. In this review, we propose that, in the healthy individual, this system to regulate appetite does not play a dominant role in normal food intake regulation, and that there is insufficient evidence to wholly link postprandial endogenous gut peptides with appetite-related behaviours. Instead, or additionally, top-down, hedonic drive and neurocognitive factors may have more of an impact on food intake. In GI disease however, supraphysiological levels of these hormones may have more of an impact on appetite regulation as well as contributing to other unpleasant abdominal symptoms, potentially as part of an innate response to injury. Further work is required to better understand the mechanisms involved in appetite control and unlock the therapeutic potential offered by the enteroendocrine system in GI disease and obesity.

Effects of the Daily Consumption of Stevia on Glucose Homeostasis, Body Weight, and Energy Intake: A Randomised Open-Label 12-Week Trial in Healthy Adults.

Stevia is a non-nutritive sweetener, providing sweet taste with no calories. This randomised, controlled, open-label 2-parallel arm trial examined the effects of daily stevia consumption on glycaemia in healthy adults. Secondary endpoints included body weight (BW) and energy intake (EI). Healthy participants (n = 28; aged 25 ± 5y, body mass index 21.2 ± 1.7 kg/m2) were randomised into either the stevia group (n = 14)-required to consume a stevia extract daily-or to the control group (n = 14). At weeks 0 and 12, the glucose and insulin responses to an oral glucose tolerance test were measured; BW and EI were assessed at weeks 0, 6, and 12. There was no significant difference in the glucose or insulin responses. There was a significant main effect of group on BW change (F(1,26) = 5.56, p = 0.026), as the stevia group maintained their weight as opposed to the control group (mean weight change at week 12: -0.22 kg, 95%CI [-0.96, 0.51] stevia group, +0.89 kg, 95%CI [0.16, 1.63] control group). The energy intake was significantly decreased between week 0 and 12 in the stevia group (p = 0.003), however no change was found in the control group (p = 0.973). Although not placebo-controlled, these results suggest that daily stevia consumption does not affect glycaemia in healthy individuals, but could aid in weight maintenance and the moderation of EI.

Stevia Beverage Consumption prior to Lunch Reduces Appetite and Total Energy Intake without Affecting Glycemia or Attentional Bias to Food Cues: A Double-Blind Randomized Controlled Trial in Healthy Adults.

BACKGROUND: Stevia is a zero-calorie alternative to caloric sugars. Substituting caloric sweeteners with noncaloric sweeteners reduces available energy, but their effects on appetite, subsequent food intake, and neurocognitive responses are still unclear. OBJECTIVE: The aim was to examine whether sweetness with or without calories influences food intake, appetite, blood glucose concentrations, and attentional bias (AB) to food cues. METHODS: This was a randomized, controlled, double-blind crossover study. Healthy participants [n = 20; aged 27 ± 5 y,  55% female; BMI (kg/m2): 21.8 ± 1.5] completed 5 visits, consuming 5 study beverages: 330 mL water (control, no sweet taste, no calories) and either 330 mL water containing 40 g glucose or sucrose (sweet taste; calories, both 160 kcal), maltodextrin (no sweet taste; calories, 160 kcal), or 240 ppm stevia (sweet taste, no calories). Glucose and stevia beverages were matched for sweetness. Subjective appetite ratings and blood glucose were measured at baseline and at 15, 30, and 60 min postprandially. At 15 min participants performed a visual-dot probe task to assess AB to food cues; at 30 min, participants were offered an ad libitum lunch; food intake was measured. RESULTS: Subjective appetite ratings showed that preload sweetness and calorie content both affected appetite. The total AUC for glycemia was significantly higher after the caloric beverages (mean ± SD: maltodextrin, 441 ± 57.6;  glucose, 462 ± 68.1;  sucrose, 425 ± 53.6 mmol × min × L-1 ) compared with both stevia (320 ± 34.2 mmol × min × L-1) and water (304 ± 32.0 mmol × min × L-1) (all P < 0.001). Total energy intake (beverage and meal) was significantly lower after the stevia beverage (727 ± 239 kcal) compared with water (832 ± 198 kcal,  P = 0.013), with no significant difference between the water and caloric beverages (P = 1.00 for water vs. maltodextrin, glucose, and sucrose). However, food-related AB did not differ across conditions (P = 0.140). CONCLUSIONS: This study found a beneficial and specific effect of a stevia beverage consumed prior to a meal on appetite and energy intake in healthy adults. This trial is registered at clinicaltrials.gov as NCT03711084.

Attentional bias to food varies as a function of metabolic state independent of weight status.

Eating behaviour requires that internal metabolic changes are recognized by the central nervous system which regulates brain responses to food cues. This function may be altered in obesity. The aim of this study was to examine potential differences in neurocognitive responses to visual food cues as a function of metabolic state and weight status. A crossover study with two participant groups was conducted, one group with normal-weight (n = 20) and one group with overweight/obesity (n = 22), who completed a novel battery of neurocognitive tests assessing food-cue elicited behavior in both fasted and fed states. The test battery included a visual-dot probe task (VPT), a stimulus-response compatibility task (SRCT) and an implicit association task (IAT). Results from the VPT showed a significant main effect of metabolic state on attentional bias (F(1,40) = 9.90, p = .003, η2p = .198), with participants in the fasted state showing a significantly greater attentional bias for food stimuli than in the fed state. No significant main effect of metabolic state on approach food bias, assessed via the SRCT, or implicit attitudes to food cues, assessed via the IAT, was found and overall, no difference in neurocognitive processing of food cues was demonstrated between participant groups. In the fed state, attentional bias to food cues decreases in both normal-weight controls and participants with overweight/obesity, indicating that changes in current metabolic state can be reflected in attentional processing of visual food cues independently of weight status. Neurocognitive tasks which can effectively and sensitively identify differences in food cue perception according to changes in metabolic status will be useful tools in exploring more complicated interactions between homeostatic and hedonic drives of food intake.

Controlling type-2 diabetes by inclusion of Cr-enriched yeast bread in the daily dietary pattern: a randomized clinical trial.

PURPOSE: Chromium (Cr)-enriched yeast supplementation to whole wheat bread (WWCrB) has been shown to ameliorate postprandial glycemic response in healthy subjects. The present study investigates the long-term benefit of WWCrB consumption for patients with type-2 diabetes mellitus (T2DM). METHODS: Thirty patients with T2DM were randomly assigned to a group receiving WWCrB or the plain whole wheat bread (WWB) group. Plasma glucose, insulin, glycosylated hemoglobin (HbA1c) and insulin resistance were determined, and oral glucose tolerance test (OGTT) was performed at the beginning and the end of the dietary intervention, which lasted for 12 weeks. Biochemical parameters related to the disease, markers of inflammation as well as body weight and energy balance were examined. RESULTS: At the end of the study, subjects of WWCrB group exerted lower levels of glucose, insulin and HbA1c and improved insulin resistance (P < 0.05 against before treatment). Area under the glucose curve attained during OGTT decreased after the intervention (28,117.5 ± 1266.4 vs. 31,588.5 ± 1187.5 mg min/dL before treatment, P < 0.05) with significantly lower values of glucose concentration at 0 and 60 min. A significant reduction in body weight and systolic blood pressure (SBP) was observed (P < 0.05 against before treatment). Markers of inflammation and lipid profiles were not affected by WWCrB consumption. CONCLUSIONS: Inclusion of WWCrB in the daily dietary pattern of diabetic patients resulted in improvement of glucose tolerance and insulin resistance, significant reduction in HbA1c, weight loss and lower SBP. Patients with inadequate glycemic control may benefit from the consumption of WWCrB.

A workshop on 'Dietary Sweetness-Is It an Issue?'

This report summarises a workshop convened by ILSI Europe on 3 and 4 April 2017 to discuss the issue of dietary sweetness. The objectives were to understand the roles of sweetness in the diet, establish whether exposure to sweetness affects diet quality and energy intake, and consider whether sweetness per se affects health. Although there may be evidence for tracking of intake of some sweet components of the diet through childhood, evidence for tracking of whole diet sweetness, or through other stages of maturity are lacking. The evidence to date does not support adverse effects of sweetness on diet quality or energy intake, except where sweet food choices increase intake of free sugars. There is some evidence for improvements in diet quality and reduced energy intake where sweetness without calories replaces sweetness with calories. There is a need to understand the physiological and metabolic relevance of sweet taste receptors on the tongue, in the gut and elsewhere in the body, as well as possible differentiation in the effects of sustained consumption of individual sweeteners. Despite a plethora of studies, there is no consistent evidence for an association of sweetness sensitivity/preference with obesity or type 2 diabetes. A multifaceted integrated approach, characterising nutritive and sensory aspects of the whole diet or dietary patterns, may be more valuable in providing contextual insight. The outcomes of the workshop could be used as a scientific basis to inform the expert community and create more useful dialogue among health care professionals.

Bread making technology influences postprandial glucose response: a review of the clinical evidence.

Lowering postprandial glucose and insulin responses may have significant beneficial implications for prevention and treatment of metabolic disorders. Bread is a staple food consumed worldwide in a daily basis, and the use of different baking technologies may modify the glucose and insulin response. The aim of this review was to critically record the human studies examining the application of different bread making processes on postprandial glucose and insulin response to bread. Literature is rich of results which show that the use of sourdough fermentation instead of leavening with Saccharomyces cerevisiae is able to modulate glucose response to bread, whereas evidence regarding its efficacy on lowering postprandial insulin response is less clear. The presence of organic acids is possibly involved, but the exact mechanism of action is still to be confirmed. The reviewed data also revealed that the alteration of other processing conditions (method of cooking, proofing period, partial baking freezing technology) can effectively decrease postprandial glucose response to bread, by influencing physical structure and retrogradation of starch. The development of healthier bread products that benefit postprandial metabolic responses is crucial and suggested baking conditions can be used by the bread industry for the promotion of public health.

Cr-enriched yeast: beyond fibers for the management of postprandial glycemic response to bread.

PURPOSE: Efforts regarding the amelioration of postprandial glycemic response to bread are mainly focused in the addition of soluble dietary fibers. The current study presents another approach which is based on the supplementation of flour with Cr-enriched yeast. Cr is known for its beneficial effects on improvement of glucose tolerance and enhancement of insulin sensitivity. METHODS: Twelve normoglycemic subjects were provided with white bread (WB, reference food) or whole wheat bread with Cr-enriched yeast (WWCrB, rich in insoluble fibers) or white wheat bread with Cr-enriched yeast (WCrB, poor in fibers) or whole wheat-rye-barley bread enriched with oat beta glucans (BGB, rich in soluble fibers) with 1-week intervals in amounts that yielded 50 g of available carbohydrates. Postprandial glucose, insulin and ghrelin responses as well as glycemic index (GI) were evaluated. RESULTS: Ingestion of WWCrB, WCrB and BGB elicited lower incremental area under the curve (iAUC) for 120-min glycemic response compared to WB (1033.02 ± 282.32, 701.69 ± 330.86 and 748.95 ± 185.42 vs 2070.87 ± 518.44 mg/dL min, respectively, P < 0.05 for WCrB and BGB). The GI was calculated as 62.35 ± 11.78 for WWCrB, 34.22 ± 11.93 for WCrB and 37.90 ± 5.00 for BGB (P < 0.05 vs WB, GI = 100). iAUC for 120-min insulin response to BGB was significantly lower than WB (2780.04 ± 303.26 vs 3915.53 ± 490.57 µU/mL min, P < 0.05), while ghrelin remained suppressed for almost 120 min after the consumption of WWCrB and BGB. CONCLUSIONS: Supplementation of flour with Cr-enriched yeast induces milder postprandial glycemic response to bread without the necessity of high fiber amounts, providing with another strategy for the management of glycemic control.

Evaluation of a high nutritional quality snack based on oat flakes and inulin: effects on postprandial glucose, insulin and ghrelin responses of healthy subjects.

The consumption of high nutritional value snacks may favorably affect the diet quality. Biscuits manufactured with oat flakes and maltitol were assessed for glycemic, insulinemic and ghrelin responses. Enrichment with inulin, a fructooligosachararide (FOS) which acts as soluble fiber, was performed in an attempt to further increase the dietary fiber content and examine potential additional postprandial benefits. Eleven healthy subjects participated in the study and consumed either 80 g oat biscuits (OB) or 81 g oat biscuits with 4% inulin (OBIN) or a solution containing 50 g of glucose (reference food), each yielding 50 g of available carbohydrates. Venous blood samples were collected before consumption and at 15, 30, 45, 60, 90, 120 and 180 min postprandially. The developed products were also evaluated for physicochemical properties, including porosity, density, texture, color, sensory attributes and microstructure (by scanning electron microscopy). Both biscuits demonstrated a low glycemic index (GI), which was found to be 32.82 ± 8.07 for OB and 45.68 ± 9.64 for OBIN. Compared to OB, OBIN demonstrated higher insulin response at 45 and 60 min and higher ghrelin suppression at 60 and 120 min postprandially (P < 0.05). Furthermore, OBIN demonstrated increased hardness and color values, lower porosity, and higher rate of starch granule gelatinization, without significantly altering the sensory attributes. Biscuits formulated with oat flakes and maltitol with or without 4% inulin can be classified as low GI foods. Inulin addition significantly lowered the ghrelin response to OBIN, suggesting an advantage of OBIN in the modulation of satiety; however, no further benefits regarding glucose and insulin responses were observed.

Non-cereal ingredients for the attenuation of glycaemic response to bread: a review of the clinical evidence.

Lowering postprandial blood glucose response remains at the forefront of scientific interest, due to emerging evidence of potential health benefits. Although a large variety of commercial bread products is available, specific postprandial effects of different carbohydrate sources in humans have not been elucidated. The purpose of the present review is to critically record the human studies investigating the efficacy of non-cereal based ingredients on the modulation of glycaemic response to bread. The review of the literature revealed that the substitution of refined flours for legume flours is the main alternative strategy for reducing glycaemic response to bread beyond cereal ingredients. The incorporation of fruit-derived ingredients, specific dietary fibre originating from various sources, and the micronutrient enrichment of bread with trivalent chromium constitute novel and promising strategies for the production of low GI breadstuff. In agreement to the above, bakery industry should focus on technological aspects calculating on the suggested approaches in order to obtain health-promoting bread products based on ingredients originating from non-cereal sources.