The role of low-calorie sweeteners in the prevention and management of overweight and obesity: evidence v. conjecture

Does sweetness exposure drive 'sweet tooth'?

It is widely believed that exposure to sweetened foods and beverages stimulates the liking and desire for sweetness. Here we provide an updated review of the empirical evidence from human research examining whether exposure to sweet foods or beverages influences subsequent general liking for sweetness (‘sweet tooth’), based on the conclusions of existing systematic reviews and more recent research identified from a structured search of literature. Prior reviews have concluded that the evidence for a relationship between sweet taste exposure and measures of sweet taste liking is equivocal, and more recent primary research generally does not support the view that exposure drives increased liking for sweetness, in adults or children. In intervention trials using a range of designs, acute exposure to sweetness usually has the opposite effect (reducing subsequent liking and desire for sweet taste), while sustained exposures have no significant effects or inconsistent effects. Recent longitudinal observational studies in infants and children also report no significant associations between exposures to sweet foods and beverages with measures of sweet taste preferences. Overall, while it is widely assumed that exposure to sweetness stimulates a greater liking and desire for sweetness, this is not borne out by the balance of empirical evidence. While new research may provide a more robust evidence base, there are also a number of methodological, biological and behavioural considerations that may underpin the apparent absence of a positive relationship between sweetness exposure and liking.

Ultraprocessed Foods and Obesity Risk: A Critical Review of Reported Mechanisms

Epidemiologic evidence supports a positive association between ultraprocessed food (UPF) consumption and body mass index. This has led to recommendations to avoid UPFs despite very limited evidence establishing causality. Many mechanisms have been proposed, and this review critically aimed to evaluate selected possibilities for specificity, clarity, and consistency related to food choice (i.e., low cost, shelf-life, food packaging, hyperpalatability, and stimulation of hunger/suppression of fullness); food composition (i.e., macronutrients, food texture, added sugar, fat and salt, energy density, low-calorie sweeteners, and additives); and digestive processes (i.e., oral processing/eating rate, gastric emptying time, gastrointestinal transit time, and microbiome). For some purported mechanisms (e.g., fiber content, texture, gastric emptying, and intestinal transit time), data directly contrasting the effects of UPF and non-UPF intake on the indices of appetite, food intake, and adiposity are available and do not support a unique contribution of UPFs. In other instances, data are not available (e.g., microbiome and food additives) or are insufficient (e.g., packaging, food cost, shelf-life, macronutrient intake, and appetite stimulation) to judge the benefits versus the risks of UPF avoidance. There are yet other evoked mechanisms in which the preponderance of evidence indicates ingredients in UPFs actually moderate body weight (e.g., low-calorie sweetener use for weight management; beverage consumption as it dilutes energy density; and higher fat content because it reduces glycemic responses). Because avoidance of UPFs holds potential adverse effects (e.g., reduced diet quality, increased risk of food poisoning, and food wastage), it is imprudent to make recommendations regarding their role in diets before causality and plausible mechanisms have been verified.

Conditioned preference and avoidance induced in mice by the rare sugars isomaltulose and allulose

Isomaltulose, a slowly digested isocaloric analog of sucrose, and allulose, a noncaloric fructose analog, are promoted as "healthful" sugar alternatives in human food products. Here we investigated the appetite and preference conditioning actions of these sugar analogs in inbred mouse strains. In brief-access lick tests (Experiment 1), C57BL/6 (B6) mice showed similar concentration dependent increases in licking for allulose and fructose, but less pronounced concentration-dependent increases in licking for isomaltulose than sucrose. In Experiment 2, B6 male were given one-bottle training with a CS+ flavor (e.g., grape) mixed with 8% isomaltulose or allulose and a CS- flavor (e.g., cherry) mixed in water followed by two-bottle CS flavor tests. The isomaltulose mice showed only a weak CS+ flavor preference but a strong preference for the sugar over water. The allulose mice strongly preferred the CS- flavor and water over the sugar. The allulose avoidance may be due to gut discomfort as reported in humans consuming high amounts of the sugar. Experiment 3 found that the preference for 8% sucrose over 8% isomaltulose could be reversed or blocked by adding different concentrations of a noncaloric sweetener mixture (sucralose + saccharin, SS) to the isomaltulose. Experiment 4 revealed that the preference of B6 or FVB/N mice for isomaltulose+0.01%SS or sucrose over 0.1%SS increased after separate experience with the sugars and SS. This indicates that isomaltulose, like sucrose, has postoral appetition effects that enhances the appetite for the sugar. In Experiments 5 and 6, the appetition actions of the two sugars were directly compared by giving mice isomaltulose+0.05%SS vs. sucrose choice tests before and after separate experience with the two sugars. In general, the initial preference the mice displayed for isomaltulose+0.05%SS was reduced or reversed after separate experience with the two sugars although some strain and sex differences were obtained. This indicates that isomaltulose has weaker postoral appetition effects than sucrose.

Isomerization of Galactose to Tagatose: Recent Advances in Non-enzymatic Isomerization

The valorization of galactose derived from acid whey to low-calorie tagatose has gained increasing attention. Enzymatic isomerization is of great interest but faces several challenges, such as poor thermal stability of enzymes and a long processing time. In this work, non-enzymatic (supercritical fluids, triethylamine, arginine, boronate affinity, hydrotalcite, Sn-β zeolite, and calcium hydroxide) pathways for galactose to tagatose isomerization were critically discussed. Unfortunately, most of these chemicals showed poor tagatose yields (<30%), except for calcium hydroxide (>70%). The latter is able to form a tagatose-calcium hydroxide-water complex, which stimulates the equilibrium toward tagatose and prevents sugar degradation. Nevertheless, the excessive use of calcium hydroxide may pose challenges in terms of economic and environmental feasibility. Moreover, the proposed mechanisms for the base (enediol intermediate) and Lewis acid (hydride shift between C-2 and C-1) catalysis of galactose were elucidated. Overall, it is crucial to explore novel and effective catalysts as well as integrated systems for isomerizing of galactose to tagatose.

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.

Consumption of low-calorie sweetened drinks is associated with 'sweet satiation', but not with 'sweet-taste confusion': A virtual study

Originating from studies on rats, the 'taste confusion' hypothesis predicts that exposure to low-calorie sweeteners (LCS) will impair compensatory responses to sugar intake, resulting in increased overall calorie intake. We conducted a virtual study in which young adult human participants (n = 332), who differed in their history of exposure to sweet drinks (e.g., drank 'diet' (LCS) soft drinks or 'regular' (sugar-sweetened) soft drinks), imagined consuming a cheese sandwich and two-thirds of a 500 ml drink (still water, sparkling water, diet Coca Cola, regular Coca Cola, or semi-skimmed milk), or no drink, as a hypothetical lunch-time meal. They then used a screen-based tool to select the amount of a sweet snack (chocolate M&M's) or savoury snack (salted peanuts) that they would eat immediately with the remaining third of their drink (i.e., a total of 12 drink and snack combinations per participant). The results were inconsistent with the predictions of the taste confusion hypothesis; specifically, the extent to which consumption of sugar cola compared with water (still or sparkling) reduced snack intake did not differ between habitual diet (LCS) and habitual sugar soft-drink consumers. Other results showed a 'sweet satiation' effect (i.e., lower sweet versus savoury snack intake when the drink accompanying the meal was sweet compared with when it was water), and negligible compensation in snack food intake for the difference in the energy content of diet versus sugar cola.

Is a Non-Caloric Sweetener-Free Diet Good to Treat Functional Gastrointestinal Disorder Symptoms? A Randomized Controlled Trial

Background: A diet containing non-caloric sweeteners (NCS) could reduce calorie intake; conversely, some animal studies suggest that NCS consumption may increase functional gastrointestinal disorder symptoms (FGDs). This study aimed to compare the effect of consuming a diet containing NCS (c-NCS) versus a non-caloric sweetener-free diet (NCS-f) on FGDs. Methods: We conducted a randomized, controlled, parallel-group study using two different diets for five weeks: the c-NCS diet contained 50−100 mg/day NCS, whereas the NCS-f diet had less than 10 mg/day NCS. At the beginning of the study (PreTx) and at the end (PostTx), we assessed FGDs, dietary intake, and NCS consumption. Results: The percentage of participants with diarrhea (PreTx = 19% vs. PstTx = 56%; p = 0.02), post-prandial discomfort (PreTx = 9% vs. PstTx = 39%; p = 0.02), constipation (PreTx = 30% vs. PostTx = 56%; p < 0.01), and burning (PreTx = 13% vs. PostTx = 33%; p < 0.01) increased in the c-NCS diet group. Conversely, abdominal pain (PreTx = 15% vs. PostTx = 3%; p = 0.04), post-prandial discomfort (PreTx = 26% vs. PostTx = 6%; p = 0.02), burning (PreTx = 15% vs. PostTx = 0%; p = 0.02), early satiety (PreTx = 18% vs. PostTx = 3%; p < 0.01), and epigastric pain (PreTx = 38% vs. PostTx = 3%; p < 0.01) decreased in the NCS-f diet group. Conclusion: A c-NCS diet is associated with increased FGDs, including diarrhea, post-prandial discomfort, constipation, and burning or retrosternal pain. The NCS-f diet also decreased FGDs, as well as abdominal pain, post-prandial discomfort, burning or retrosternal pain, early satiety, and epigastric pain.

Varied Effects of COVID-19 Chemosensory Loss and Distortion on Appetite: Implications for Understanding Motives for Eating and Drinking

A common symptom of COVID-19 is altered smell and taste. This qualitative study sought to further characterise this altered chemosensory perception and its effects on appetite for food and drink. Eighteen women and two men who had experienced chemosensory loss associated with COVID-19 participated in semi-structured interviews. Thematic analysis of the interview transcripts revealed five major themes. These confirmed that all participants had experienced an altered sense of smell (anosmia, and less frequently parosmia and phantosmia) of variable duration. Loss of taste (ability to detect sweetness, saltiness, etc.) was less common. Participants experienced decreased, no change or increased appetite, with six participants reporting weight loss. Consistent with evidence linking diminished appetite with inflammation, for two participants, decreased appetite preceded anosmia onset. Anosmia reduced enjoyment of food and drink. Compensatory strategies included choosing salty, sweet and ‘spicy’ foods, and increased attention to food texture, and there was evidence that the postingestive rewarding effects of food intake were also important for maintaining appetite. Some participants mentioned increased alcohol intake, in part facilitated by reduced intensity of disliked flavours of alcoholic drinks. The narratives also underlined the value placed on the sociability and structuring of time that daily meals provide. This research adds to the record and analysis of lived experiences of altered chemosensory perception resulting from SARS-CoV-2 infection, and it contributes insights concerning the role of smell and flavour in motivating and rewarding food ingestion.

A Metagenomics Investigation of Intergenerational Effects of Non-nutritive Sweeteners on Gut Microbiome

To identify possible mechanisms by which maternal consumption of non-nutritive sweeteners increases obesity risk in offspring, we reconstructed the major alterations in the cecal microbiome of 3-week-old offspring of obese dams consuming high fat/sucrose (HFS) diet with or without aspartame (5-7 mg/kg/day) or stevia (2-3 mg/kg/day) by shotgun metagenomic sequencing (n = 36). High throughput 16S rRNA gene sequencing (n = 105) was performed for dams, 3- and 18-week-old offspring. Maternal consumption of sweeteners altered cecal microbial composition and metabolism of propionate/lactate in their offspring. Offspring daily body weight gain, liver weight and body fat were positively correlated to the relative abundance of key microbes and enzymes involved in succinate/propionate production while negatively correlated to that of lactose degradation and lactate production. The altered propionate/lactate production in the cecum of weanlings from aspartame and stevia consuming dams implicates an altered ratio of dietary carbohydrate digestion, mainly lactose, in the small intestine vs. microbial fermentation in the large intestine. The reconstructed microbiome alterations could explain increased offspring body weight and body fat. This study demonstrates that intense sweet tastants have a lasting and intergenerational effect on gut microbiota, microbial metabolites and host health.

Maternal sucralose exposure induces Paneth cell defects and exacerbates gut dysbiosis of progeny mice

Research has shown that maternal sucralose (MS) exposure alters the gut microbiota of offspring at weaning and predisposes the offspring to developing obesity, non-alcoholic fatty liver disease and metabolic syndrome later in life. However, the underlying mechanism remains unclear. Paneth cells are thought to critically influence the gut microbiota. This study aimed to investigate whether MS exposure induced Paneth cell defects and exacerbated gut dysbiosis of offspring. Female C57BL/6 mice were divided into the MS and control (water) groups during pregnancy and lactation. Progeny mice were fed a normal sucralose-free diet after weaning until adulthood. MS inhibited intestinal development and increased the expression of proinflammatory cytokines in the small intestines of 3-week-old progeny mice. MS increased the proportions of abnormal granule secretion by Paneth cells. The number of Paneth cells and mRNA expression of AMPs such as cryptdins and lysozyme were reduced in the MS group. MS disturbed the gut microbiota composition and diversity in the 3-week-old offspring mice. The relative abundances of pro-inflammatory bacteria, such as Desulfovibrionales, Helicobacter, Pasteurellales and Campylobacterales were significantly increased in the MS group, while anti-inflammatory bacteria, including Clostridium XI, were decreased. This dysbiosis continued into adulthood. These findings showed that MS exposure induced Paneth cell defects and exacerbated gut dysbiosis in offspring mice. Sucralose should be consumed with caution, especially during pregnancy and in early life.

Finding the Sweet Spot: Measurement, Modification, and Application of Sweet Hedonics in Humans

Sweetness is a sensation that contributes to the palatability of foods, which is the primary driver of food choice. Thus, understanding how to measure the appeal (hedonics) of sweetness and how to modify it are key to effecting dietary change for health. Sweet hedonics is multidimensional so can only be captured by multiple approaches including assessment of elements such as liking, preference, and consumption intent. There are both innate and learned components to the appeal of sweet foods and beverages. These are responsive to various behavioral and biological factors, suggesting the opportunity to modify intake. Given the high amount of added sugar intake in the United States and recommendations from many groups to reduce this, further exploration of current hypothesized approaches to moderate sugar intake (e.g., induced hedonic shift, use of low-calorie sweeteners) is warranted.

Low-energy sweeteners and body weight: a citation network analysis

OBJECTIVE

Reviews on the relationship of low-energy sweeteners (LES) with body weight (BW) have reached widely differing conclusions. To assess possible citation bias, citation analysis was used to quantify the relevant characteristics of cited articles, and explore citation patterns in relation to review conclusions.

DESIGN

A systematic search identified reviews published from January 2010 to March 2020. Different characteristics (for example, type of review or research, journal impact factor, conclusions) were extracted from the reviews and cited articles. Logistic regression was used to estimate likelihood of articles with particular characteristics being cited in reviews. A qualitative network analysis linked reviews sub-grouped by conclusions with the types of articles they cited.

MAIN OUTCOME MEASURES

(OR; 95% CI) for likelihood that articles with particular characteristics were cited as evidence in reviews.

RESULTS

From 33 reviews identified, 183 different articles were cited (including other reviews). Narrative reviews were 62% less likely to be cited than systematic reviews with meta-analysis (OR 0.38; 0.16 to 0.86; p=0.03). Likelihood of being cited was higher for evidence on children than adults (OR 2.27; 1.59 to 3.25; p<0.0001), and with increased journal impact factor (OR 1.15; 1.00 to 1.31; p=0.04). No other factors were statistically significant in the main analysis, and few factors were significant in subgroup analyses. Network analysis showed that reviews concluding a beneficial relationship of LES with BW cited mainly randomised controlled trials, whereas reviews concluding an adverse relationship cited mainly observational studies.

CONCLUSIONS

Overall reference to the available evidence across reviews appears largely arbitrary, making citation bias likely. Differences in the conclusions of individual reviews map onto different types of evidence cited. Overall, inconsistent and selective use of the available evidence may account for the diversity of conclusions in reviews on LES and BW.

TRIAL REGISTRATION NUMBER

Prior to data analysis, the protocol was registered with the Open Science Framework (https://osf.io/9ghws).

The effects of low-calorie sweeteners on energy intake and body weight: a systematic review and meta-analyses of sustained intervention studies

Previous meta-analyses of intervention studies have come to different conclusions about effects of consumption of low-calorie sweeteners (LCS) on body weight. The present review included 60 articles reporting 88 parallel-groups and cross-over studies ≥1 week in duration that reported either body weight (BW), BMI and/or energy intake (EI) outcomes. Studies were analysed according to whether they compared (1) LCS with sugar, (2) LCS with water or nothing, or (3) LCS capsules with placebo capsules. Results showed an effect in favour of LCS vs sugar for BW (29 parallel-groups studies, 2267 participants: BW change, -1.06 kg, 95% CI -1.50 to -0.62, I2 = 51%), BMI and EI. Effect on BW change increased with 'dose' of sugar replaced by LCS, whereas there were no differences in study outcome as a function of duration of the intervention or participant blinding. Overall, results showed no difference in effects of LCS vs water/nothing for BW (11 parallel-groups studies, 1068 participants: BW change, 0.10 kg, 95% CI -0.87 to 1.07, I2 = 82%), BMI and EI; and inconsistent effects for LCS consumed in capsules (BW change: -0.28 kg, 95% CI -0.80 to 0.25, I2 = 0%; BMI change: 0.20 kg/m2, 95% CI 0.04 to 0.36, I2 = 0%). Occurrence of adverse events was not affected by the consumption of LCS. The studies available did not permit robust analysis of effects by LCS type. In summary, outcomes were not clearly affected when the treatments differed in sweetness, nor when LCS were consumed in capsules without tasting; however, when treatments differed in energy value (LCS vs sugar), there were consistent effects in favour of LCS. The evidence from human intervention studies supports the use of LCS in weight management, constrained primarily by the amount of added sugar that LCS can displace in the diet.

Intake of Non-Nutritive Sweeteners in Chilean Children after Enforcement of a New Food Labeling Law that Regulates Added Sugar Content in Processed Foods

After enforcement of a new food labeling law in 2016, Chile exhibits a greater offer to reduced sugar products with addition of non-nutritive sweeteners (NNS). Many of these products are consumed by children, who are at greater risk of reaching the acceptable daily intake (ADI) of these food additives. The objective of this study was to evaluate the intake levels of NNS in Chilean schoolchildren after the enactment of the aforementioned law. A total of 250 Chilean children 6-12 years old were surveyed. NNS intake was assessed through a food frequency questionnaire. All children evaluated consumed at least one NNS during the previous month. Sucralose had the highest consumption frequency reaching 99.2%, followed by acesulfame-K (92.8%), stevia (86.0%), and aspartame (85.2%). Aspartame showed the highest median intake, which came mainly from beverages (96%). No children exceeded the ADI of any NNS. Smaller children exhibited a higher body weight-adjusted intake of sucralose, acesulfame-K, stevia, and aspartame (p < 0.05). In Chile, a wide range of processed foods with NNSs is available and all schoolchildren evaluated consumed at least one product containing NNS. However, this consumption does not exceed defined ADIs for any of the six sweeteners authorized for food use in Chile.

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.

Perspective: Standards for Research and Reporting on Low-Energy ("Artificial") Sweeteners

Widely differing views exist among experts, policy makers, and the general public with regard to the potential risks and benefits of reduced- or low-energy sweeteners (LES) in the diet. These views are informed and influenced by different types of research in LES, with differing hypotheses, designs, interpretation, and communication. Given the high level of interest in LES, and the public health relevance of the research evidence base, it is important that all aspects of the research process are framed and reported in an appropriate and balanced manner. In this Perspective, we identify and give examples of a number of issues relating to research and reviews on LES, which may contribute toward apparent inconsistencies in the content and understanding of the totality of evidence. We conclude with a set of recommendations for authors, reviewers and journal editors, as general guidance to improve and better standardize the quality of LES research design, interpretation, and reporting. These focus on clarity of underlying hypotheses, characterization of exposures, and the placement and weighting of new research within the wider context of related prior work.

Influences of non‐nutritive sweeteners on ovarian and uterine expression of T1R2 and T1R3 in peripubertal female guinea pigs

The underlying mechanism of taste receptor type 1 subunit 2 (T1R2) and taste receptor type 1 subunit 3 (T1R3) in the hormonal and reproductive system is still elusive. A low or a high dose of sweetness equivalent to that sodium saccharin (SS, 1.5 or 7.5 mM) and rebaudioside A (RA, 0.5 or 2.5 mM) was administered to young female guinea pigs for 28 consecutive days from the age of 28 days. Our results indicated that the sweet taste receptor subunit T1R2 was markedly expressed in the ovary and uterus of guinea pigs, whereas the T1R3 protein was expressed at a lower level. We elucidated that low-dose (1.5 mM) SS increased body and ovary weight associated with elevated ovarian expression of T1R2 in guinea pigs, unlike the high-dose (7.5 mM) SS, which suppressed the ovarian expression of T1R2 and resulted in certain adverse effects on ovarian and uterine morphology. Furthermore, high-dose (2.5 mM) RA increased the number of corpus luteum and elevated uterine expression of T1R2, whereas low-dose (0.5 mM) RA induced increased secretion of serum progesterone. Therefore, our findings suggest that we should pay more attention to the potential adverse effects, including increases in ovary weight, morphology changes, and increased progesterone that result from the dose-dependent regulation of T1R2 by non-nutritive sweeteners (NNS) in the ovaries and uteri of peripubertal females.

Sweet satiation: Acute effects of consumption of sweet drinks on appetite for and intake of sweet and non-sweet foods

Sensory-specific satiety (SSS) describes a reduction in the pleasantness of the taste of (momentary liking) and desire to consume a food that occurs with eating, compared with the relative preservation of liking and desire for uneaten foods. We conducted three studies in healthy female and male participants to test whether SSS generalises from sweet drinks to sweet foods. Studies 1 (n = 40) and 2 (n = 64) used a two-condition cross-over design. Participants consumed non-carbonated, fruit squash drinks sweetened with low-calorie sweeteners (LCS) versus water and evaluated various food and drink samples (stimuli). Generalisation of SSS was evident across all sweet stimuli, without having an effect on non-sweet (savoury) stimuli. These SSS effects were present when measured shortly after consumption of the sweet drink, but not 2 h later. There was no evidence of a 'rebound' increase above baseline in liking or desire to consume sweet foods 2 h after the sweet drink versus water. In study 3, 51 participants consumed labelled and branded 500 ml cola and water drinks (4 conditions, cross-over design) immediately before and during ad libitum consumption of sweet and non-sweet snack foods. Compared with still water, 'diet' (LCS-sweetened) cola reduced sweet food intake, but not total ad libitum intake. Carbonated water decreased hunger and increased fullness compared with still water, without differentially affecting thirst. Energy compensation from the ad libitum snacks for consumption of sugar-containing cola averaged only 20%. Together, these results demonstrate that consumption of LCS drinks acutely decreases desire for sweet foods, which supports their use in place of sugar-sweetened drinks. Further studies on the effects of carbonation of appetite are warranted.

Using Sensory Cues to Optimise the Satiety Value of a Reduced-Calorie Product Labelled 'Healthier Choice'

Reformulation strategies to reduce the energy density of commonly consumed foods and beverages are intended to support weight management, but expectations generated by labelling these as 'healthier' alternatives can have unintended effects on the product's sensory evaluations and consumption behaviours. We compared the impact of four different strategies for presenting a lower-calorie beverage to consumers on product perceptions, short-term appetite and energy intake. Participants (N = 112) consumed higher- (211 kcal/portion) and lower-calorie (98 kcal/portion) fixed-portion soymilks in the morning across two test days, with the lower-calorie version presented in one of four contexts varying in label information and sensory quality: (1) sensory-matched/unlabelled, (2) sensory-matched/labelled, (3) sensory-reduced (less sweet and creamy)/labelled, and (4) sensory-enhanced (sweeter and creamier)/labelled. The label was Singapore's Healthier Choice Symbol, which also highlighted that the soymilk was lower calorie. Changes in reported appetite, ad libitum lunch intake, and self-reported intake for the rest of the text day were recorded. Results indicated that total energy intake was consistently lower on the days the lower calorie beverages were consumed, regardless of how they were presented. However, the 'healthier choice' label increased hunger prior to lunch and reduced the soymilks' perceived thickness and sweetness compared to the same unlabelled version. Increasing the product's sensory intensity successfully maintained liking, experienced sensory quality and appetite. Results suggest that food companies wanting to explicitly label product reformulations could combine messages of 'lower calorie' and 'healthier choice' with appropriate taste and texture enhancements to maintain acceptance and avoid negative effects on appetite.

Biomarker approaches to assessing intakes and health impacts of sweeteners: challenges and opportunities

The term 'sweeteners' encompasses both nutritive and non-nutritive sweeteners, which when added to food/beverages, can enhance the flavour and other functional properties of food/beverage products. This review considers how dietary biomarker approaches may enhance current understanding of nutritive sweetener (namely free sugars) and non-nutritive or low-energy sweetener (LES) intakes and how these may impact health. Recent public health strategies to reduce free sugar consumption will help contribute to challenging sugar intake targets. Robust evaluation is needed to determine the effectiveness of these approaches to reducing free sugar consumption. LES provides a sweet taste without the addition of appreciable energy and can help maintain the palatability of reformulated products. All LES undergo rigorous safety evaluations prior to approval for use. Whilst intervention data suggest LES can be beneficial for health (relating to weight status and glycaemic control), debate persists on their use and findings from population-based research are mixed, in part because of potential contributing factors such as reverse causality. Additionally, assessments often consider only certain sources of LES (e.g. LES-beverages) and/or LES as a homogeneous group despite differing biological fates, thus not adequately capturing intakes of individual LES or allowing for reliable estimation of overall intakes. Urinary biomarker approaches developed/investigated for sweetener consumption have the potential to overcome existing limitations of dietary data by providing more objective intake data, thereby enhancing population-based research. In conclusion, such biomarker approaches to the concomitant study of free sugars and LES intakes are timely and represent interesting developments in an area of significant public health interest.

Combating Excessive Eating: A Role for Four Evidence-Based Remedies

OBJECTIVE

The aim of this study is to review the control of energy balance and outline some causes of and remedies for excessive energy intake.

METHODS

A narrative review was conducted.

RESULTS

There is negative feedback control of energy intake and body weight, but, nonetheless, energy intake is only loosely coupled with energy expenditure. Consequently, we are vulnerable to eating in excess of energy requirements. In this context, energy density, portion size, and habitual meal patterns have strong influences on energy intake and, accordingly, can be targeted to reduce energy intake. For example, energy density can be reduced without much affecting food reward (approximately the pleasure gained from eating) because their relationship is such that reward value is affected relatively little by increments in energy density above 1.5 kcal/g. This and other strategies that increase reward per calorie eaten may be superior to increasing the satiety effect of products because fullness is not inherently rewarding. Low-calorie sweeteners provide a means to reduce energy density while largely preserving food or beverage reward value. Consistent with this, consumption of low-calorie sweeteners compared with consumption of sugars has been found to reduce energy intake and body weight.

CONCLUSIONS

Understanding what causes excessive eating also provides insights into how to combat this problem.

Oral Post-Oral Actions of Low-Calorie Sweeteners: A Tale of Contradictions and Controversies

OBJECTIVE

Many scientists and laypeople alike have concerns about low-calorie sweeteners (LCSs). These concerns stem from both a dissatisfaction with the taste of LCSs and reports that they cause metabolic disruptions (e.g., weight gain, glucose intolerance).

METHODS

This article provides a critical review of the literature on LCSs from the standpoint of their taste, gastrointestinal, and metabolic effects; biological fate in the body; and impact on ingestion and glucose homeostasis.

RESULTS AND CONCLUSIONS

Mammals can readily discriminate between LCSs and sugars because both types of sweetener activate distinct oral and post-oral sensory pathways. LCSs differ in their ability to access post-oral tissues, but few studies have incorporated this observation into their design. It is difficult to extrapolate results between mice, rats, and humans because of interspecies differences in the taste and post-oral actions of LCSs and the fact that investigators often use different response measures in rodents and humans. There is confounding in the experimental design of some of the most widely cited studies of LCS-induced metabolic disruptions. The uncritical acceptance of these studies has generated considerable controversy. More work is needed to obtain a clearer understanding of the metabolic effects of LCSs.

Ibero⁻American Consensus on Low- and No-Calorie Sweeteners: Safety, Nutritional Aspects and Benefits in Food and Beverages

International scientific experts in food, nutrition, dietetics, endocrinology, physical activity, paediatrics, nursing, toxicology and public health met in Lisbon on 2⁻4 July 2017 to develop a Consensus on the use of low- and no-calorie sweeteners (LNCS) as substitutes for sugars and other caloric sweeteners. LNCS are food additives that are broadly used as sugar substitutes to sweeten foods and beverages with the addition of fewer or no calories. They are also used in medicines, health-care products, such as toothpaste, and food supplements. The goal of this Consensus was to provide a useful, evidence-based, point of reference to assist in efforts to reduce free sugars consumption in line with current international public health recommendations. Participating experts in the Lisbon Consensus analysed and evaluated the evidence in relation to the role of LNCS in food safety, their regulation and the nutritional and dietary aspects of their use in foods and beverages. The conclusions of this Consensus were: (1) LNCS are some of the most extensively evaluated dietary constituents, and their safety has been reviewed and confirmed by regulatory bodies globally including the World Health Organisation, the US Food and Drug Administration and the European Food Safety Authority; (2) Consumer education, which is based on the most robust scientific evidence and regulatory processes, on the use of products containing LNCS should be strengthened in a comprehensive and objective way; (3) The use of LNCS in weight reduction programmes that involve replacing caloric sweeteners with LNCS in the context of structured diet plans may favour sustainable weight reduction. Furthermore, their use in diabetes management programmes may contribute to a better glycaemic control in patients, albeit with modest results. LNCS also provide dental health benefits when used in place of free sugars; (4) It is proposed that foods and beverages with LNCS could be included in dietary guidelines as alternative options to products sweetened with free sugars; (5) Continued education of health professionals is required, since they are a key source of information on issues related to food and health for both the general population and patients. With this in mind, the publication of position statements and consensus documents in the academic literature are extremely desirable.

Effects of Consuming Preloads with Different Energy Density and Taste Quality on Energy Intake and Postprandial Blood Glucose

Consumption of reduced energy dense foods and drink has the potential to reduce energy intake and postprandial blood glucose concentrations. In addition, the taste quality of a meal (e.g., sweet or savoury) may play a role in satiation and food intake. The objective of this randomised crossover study was to examine whether energy density and taste quality has an impact on energy intake and postprandial blood glucose response. Using a preload design, participants were asked to consume a sweet ("Cheng Teng") or a savoury (broth) preload soup in high energy density (HED; around 0.50 kcal/g; 250 kcal) or low energy density (LED; around 0.12 kcal/g; 50 kcal) in mid-morning and an ad libitum lunch was provided an hour after the preload. Participants recorded their food intake for the rest of the day after they left the study site. Energy compensation and postprandial blood glucose response were measured in 32 healthy lean males (mean age = 28.9 years, mean BMI = 22.1 kg/m²). There was a significant difference in ad libitum lunch intake between treatments (p = 0.012), with higher intake in sweet LED and savoury LED compared to sweet HED and savoury HED. Energy intake at subsequent meals and total daily energy intake did not differ between the four treatments (both p ≥ 0.214). Consumption of HED preloads resulted in a larger spike in postprandial blood glucose response compared with LED preloads, irrespective of taste quality (p < 0.001). Energy density rather than taste quality plays an important role in energy compensation and postprandial blood glucose response. This suggests that regular consumption of low energy-dense foods has the potential to reduce overall energy intake and to improve glycemic control.