Not so Sweet Revenge: Unanticipated Consequences of High-Intensity Sweeteners

Sweetener aspartame aggravates atherosclerosis through insulin-triggered inflammation

Consumption of artificial sweeteners (ASWs) in various foods and beverages has been linked to an increased risk of cardiovascular diseases (CVDs). However, molecular mechanisms underlying ASW-associated CVD remain unknown. Here, we show that consumption of 0.15% aspartame (APM) markedly increased insulin secretion in mice and monkeys. Bilateral subdiaphragmatic vagotomy (SDV) obliterated APM-elevated blood insulin levels, demonstrating crucial roles of parasympathetic activation in regulation of insulin secretion. Incessant APM feeding of ApoE-/- mice aggravated atherosclerotic plaque formation and growth via an insulin-dependent mechanism. Implantation of an insulin-slow-release pump in ApoE-/- mice exacerbated atherosclerosis. Whole-genome expression profiling discovered that CX3CL1 chemokine was the most upregulated gene in the insulin-stimulated arterial endothelial cells. Specific deletion of a CX3CL1 receptor, Cx3cr1 gene, in monocytes/macrophages completely abrogated the APM-exacerbated atherosclerosis. Our findings uncover a novel mechanism of APM-associated atherosclerosis and therapeutic targeting of the endothelial CX3CL1-macrophage CX3CR1 signaling axis provides an approach for treating atherosclerotic CVD.

Stevia rebaudiana Bertoni, an American plant used as sweetener: Study of its effects on body mass control and glycemia reduction in Wistar male and female rats

Stevia rebaudiana Bertoni water extracts have been used as a natural sweetener and customary medicine by the indigenous inhabitants of South America for several hundred years. This plant was sent to Europe in the 16th century and was described by Peter Jacob Esteve in Spain. Recently the food industry has started to employ S. rebaudiana as sweetener using its glycosides after purification. Advertisement claims that Stevia glycosides is good for controling body mass and reducing glycemia. This study's objective was to evaluate the effect of S. rebaudiana leaf extract on Wistar rats as animal model to prove its effectiveness on body mass control, glycemia reduction, and other biochemical parameters. Three groups were randomly formed with 24 males and 24 females: A blank group without any sweetener, a control group drinking water with 10% glucose, and the test group ingesting a 0.94% water extract of S. rebaudiana. Body mass measurements as well as food and drink consumption were daily performed. The experiment lasted 120 days after the specimens were weaned and got used to eating solid food. Euthanasia was done and blood serum was collected to evaluate the following biochemical parameters: Glucose, triglycerides, cholesterol, insulin, glucagon, leptin, ghrelin, and glucose-dependent insulinotropic peptide, GIP. Results indicated that only female rats had statistical differences in body mass gain. No relevant effects either positive or negative were found in the biochemical parameters measured. The crude extracts of S. rebaudiana did not show any relevant changes in biochemical and hormonal profiles, changes nor body mass with respect to the blank and control groups of young and healthy rats in the age range of infancy to youth. According to the results obtained, the therapeutic properties that have been associated to S. rebaudiana consumption especially for body mass control and glycemia reduction, did not occur in young and healthy male and female rats in equivalent age to infants, young children, and youths.

Associations of artificially sweetened beverages, sugar-sweetened beverages, and pure fruit/vegetable juice with visceral adipose tissue mass

OBJECTIVE

To test the associations of sugar-sweetened beverage, artificially sweetened beverage, and pure fruit/vegetable juice consumption with visceral adipose tissue (VAT) mass at baseline and follow-up and to determine whether BMI and genetic risk of VAT mass modified the associations.

METHODS

A total of 203,348 participants from UK Biobank with consumption data on three beverages were included. Participants were categorized into nonconsumers and consumers with >0-1, >1-2 and >2 L/week. A sex-specific prediction model was used to calculate VAT mass. A weighted genetic risk score for high VAT mass was calculated.

RESULTS

The participants with a sugar-sweetened beverage and artificially sweetened beverage consumption of >2 L/week had the greatest B values [B (95% CI): 24.02 (16.53, 31.51) and 60.81 (52.08, 69.54) in men, respectively; 10.20 (5.92, 14.48) and 24.72 (20.80, 28.64) in women]. Low and moderate intake of pure fruit/vegetable juices showed a significantly inverse association with VAT mass in men [-10.52 (-15.37, -5.67); -6.46 (-11.27, -1.65)] and women [-6.70 (-8.99, -4.41); -5.93 (-8.33, -3.54)]. Regarding changes in VAT mass, participants who consumed >2 L/week of sugar-sweetened beverages and artificially sweetened beverages had greater changes. BMI but not genetic risk modified the associations between beverage intake and VAT mass, which were strengthened in participants with BMI ≥25 kg/m2 for sugar-sweetened and artificially sweetened beverage consumption.

CONCLUSIONS

Higher consumption of sugar-sweetened beverages or artificially sweetened beverages was associated with greater VAT mass regardless of genetic risk. Mild-to-moderate intake of pure fruit/vegetable juices was linked to lower VAT mass.

Sugar, non-nutritive sweetener intake and obesity risk in college students

OBJECTIVE

The purpose of this study was to investigate the association between sugar and NNS consumption with body fat percentage in young adults.

METHODS

524 college students were asked to complete the Web-based National Institutes of Health (NIH) Diet History Questionnaire II and had their body fat percentage measured using a bioelectrical impedance analysis scale.

RESULT

One-fourth of the participants were classified as overfat/obese and of those overfat or obese, 49% of them were African American. Overfat/obese participants consumed significantly more sugar than the heathy group and the underfat group (p < 0.001). Saccharin consumption was significantly higher in the overfat/obese group compare to the underfat and normal groups (p < 0.001). The odds of becoming overfat/obese increased 1.2 times for excessive total sugar consumption (95% CI: 1.0-1.8, p < 0.05).

CONCLUSION

Excessive sugar and saccharin consumption were associated with higher body fat percentage in young adults.

The role of sugar-sweetened beverages in the global epidemics of obesity and chronic diseases

Sugar-sweetened beverages (SSBs) are a major source of added sugars in the diet. A robust body of evidence has linked habitual intake of SSBs with weight gain and a higher risk (compared with infrequent SSB consumption) of type 2 diabetes mellitus, cardiovascular diseases and some cancers, which makes these beverages a clear target for policy and regulatory actions. This Review provides an update on the evidence linking SSBs to obesity, cardiometabolic outcomes and related cancers, as well as methods to grade the strength of nutritional research. We discuss potential biological mechanisms by which constituent sugars can contribute to these outcomes. We also consider global trends in intake, alternative beverages (including artificially-sweetened beverages) and policy strategies targeting SSBs that have been implemented in different settings. Strong evidence from cohort studies on clinical outcomes and clinical trials assessing cardiometabolic risk factors supports an aetiological role of SSBs in relation to weight gain and cardiometabolic diseases. Many populations show high levels of SSB consumption and in low-income and middle-income countries, increased consumption patterns are associated with urbanization and economic growth. As such, more intensified policy efforts are needed to reduce intake of SSBs and the global burden of obesity and chronic diseases.

Sugar-Sweetened Beverages and Cardiometabolic Health: An Update of the Evidence

Sugar-sweetened beverages (SSBs) have little nutritional value and a robust body of evidence has linked the intake of SSBs to weight gain and risk of type 2 diabetes (T2D), cardiovascular disease (CVD), and some cancers. Metabolic Syndrome (MetSyn) is a clustering of risk factors that precedes the development of T2D and CVD; however, evidence linking SSBs to MetSyn is not clear. To make informed recommendations about SSBs, new evidence needs to be considered against existing literature. This review provides an update on the evidence linking SSBs and cardiometabolic outcomes including MetSyn. Findings from prospective cohort studies support a strong positive association between SSBs and weight gain and risk of T2D and coronary heart disease (CHD), independent of adiposity. Associations with MetSyn are less consistent, and there appears to be a sex difference with stroke with greater risk in women. Findings from short-term trials on metabolic risk factors provide mechanistic support for associations with T2D and CHD. Conclusive evidence from cohort studies and trials on risk factors support an etiologic role of SSB in relation to weight gain and risk of T2D and CHD. Continued efforts to reduce intake of SSB should be encouraged to improve the cardiometabolic health of individuals and populations.

Postmeal Optogenetic Inhibition of Dorsal or Ventral Hippocampal Pyramidal Neurons Increases Future Intake

Memory of a recently eaten meal can serve as a powerful mechanism for controlling future eating behavior because it provides a record of intake that likely outlasts most physiological signals generated by the meal. In support, impairing the encoding of a meal in humans increases the amount ingested at the next eating episode. However, the brain regions that mediate the inhibitory effects of memory on future intake are unknown. In the present study, we tested the hypothesis that dorsal hippocampal (dHC) and ventral hippocampal (vHC) glutamatergic pyramidal neurons play a critical role in the inhibition of energy intake during the postprandial period by optogenetically inhibiting these neurons at specific times relative to a meal. Male Sprague Dawley rats were given viral vectors containing CaMKIIα-eArchT3.0-eYFP or CaMKIIα-GFP and fiber optic probes into dHC of one hemisphere and vHC of the other. Compared to intake on a day in which illumination was not given, inhibition of dHC or vHC glutamatergic neurons after the end of a chow, sucrose, or saccharin meal accelerated the onset of the next meal and increased the amount consumed during that next meal when the neurons were no longer inhibited. Inhibition given during a meal did not affect the amount consumed during that meal or the next one but did hasten meal initiation. These data show that dHC and vHC glutamatergic neuronal activity during the postprandial period is critical for limiting subsequent ingestion and suggest that these neurons inhibit future intake by consolidating the memory of the preceding meal.

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.

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

By virtue of reducing dietary energy density, low-calorie sweeteners (LCS) can be expected to decrease overall energy intake and thereby decrease body weight. Such effects will be limited by the amount of sugar replaced by LCS, and the dynamics of appetite and weight control (e.g., acute compensatory eating, and an increase in appetite and decrease in energy expenditure accompanying weight loss). Consistent with these predictions, short-term intervention studies show incomplete compensation for the consumption of LCS v. sugar, and longer-term intervention studies (from 4 weeks to 40 months duration) show small decreases in energy intake and body weight with LCS v. sugar. Despite this evidence, there are claims that LCS undermine weight management. Three claims are that: (1) LCS disrupt the learned control of energy intake (sweet taste confusion hypothesis); (2) exposure to sweetness increases desire for sweetness (sweet tooth hypothesis); (3) consumers might consciously overcompensate for 'calories saved' when they know they are consuming LCS (conscious overcompensation hypothesis). None of these claims stands up to close examination. In any case, the results of the intervention studies comparing LCS v. sugar indicate that the effect of energy dilution outweighs any tendency LCS might conceivably have to increase energy intake.

The Association Between Artificial Sweeteners and Obesity

PURPOSE OF REVIEW

The purpose of this paper is to review the epidemiology of obesity and the evolution of artificial sweeteners; to examine the latest research on the effects of artificial sweeteners on the host microbiome, the gut-brain axis, glucose homeostasis, and energy consumption; and to discuss how all of these changes ultimately contribute to obesity.

RECENT FINDINGS

Although artificial sweeteners were developed as a sugar substitute to help reduce insulin resistance and obesity, data in both animal models and humans suggest that the effects of artificial sweeteners may contribute to metabolic syndrome and the obesity epidemic. Artificial sweeteners appear to change the host microbiome, lead to decreased satiety, and alter glucose homeostasis, and are associated with increased caloric consumption and weight gain. Artificial sweeteners are marketed as a healthy alternative to sugar and as a tool for weight loss. Data however suggests that the intended effects do not correlate with what is seen in clinical practice. Future research should focus on the newer plant-based sweeteners, incorporate extended study durations to determine the long-term effects of artificial sweetener consumption, and focus on changes in the microbiome, as that seems to be one of the main driving forces behind nutrient absorption and glucose metabolism.

Early maternal separation induces preference for sucrose and aspartame associated with increased blood glucose and hyperactivity

Early life stress and exposure to sweeteners lead to physiological and behavioral alterations in adulthood. Nevertheless, many genetic and environmental factors as well as the neurobiological mechanisms that contribute to the development of these disorders are not fully understood. Similarly, evidence about the long-term metabolic effects of exposure to sweeteners in early life is limited and inconsistent. This study used an animal model of maternal separation during breastfeeding (MS) to analyze the effects of early life stress on consumption of sweeteners, weight gain, blood glucose and locomotion. Rats were housed under a reversed light/dark cycle (lights off at 7:00 h) with ad libitum access to water and food. In the MS protocol, MS pups were separated from the dam for 6 h per day in two periods of 180 minutes (7:00-10:00 and 13:00-16:00 h) during the dark phase of postnatal day (PND) 1 to PND 21. Non-separated (NS) pups served as controls. On PND 22 rats were grouped by sex and treatment. From PND 26 to PND 50 sucrose and aspartame were provided to rats, and sweetener intake, body weight and blood glucose-related measures were scored. On PND 50, both male and female rats were exposed to the open field test to obtain locomotion and anxiety-related measures. Results showed that both early maternal separation and sweetener intake during adolescence resulted in increased blood glucose and hyperactivity in male rats but not in female rats. Data suggest that the combination of early stress and exposure to sucrose and aspartame could be a risk factor for the development of chronic diseases such as diabetes, as well as for behavioral alterations.

Artificial sweeteners and metabolic dysregulation: Lessons learned from agriculture and the laboratory

Escalating rates of obesity and public health messages to reduce excessive sugar intake have fuelled the consumption of artificial sweeteners in a wide range of products from breakfast cereals to snack foods and beverages. Artificial sweeteners impart a sweet taste without the associated energy and have been widely recommended by medical professionals since they are considered safe. However, associations observed in long-term prospective studies raise the concern that regular consumption of artificial sweeteners might actually contribute to development of metabolic derangements that lead to obesity, type 2 diabetes and cardiovascular disease. Obtaining mechanistic data on artificial sweetener use in humans in relation to metabolic dysfunction is difficult due to the long time frames over which dietary factors might exert their effects on health and the large number of confounding variables that need to be considered. Thus, mechanistic data from animal models can be highly useful because they permit greater experimental control. Results from animal studies in both the agricultural sector and the laboratory indicate that artificial sweeteners may not only promote food intake and weight gain but can also induce metabolic alterations in a wide range of animal species. As a result, simple substitution of artificial sweeteners for sugars in humans may not produce the intended consequences. Instead consumption of artificial sweeteners might contribute to increases in risks for obesity or its attendant negative health outcomes. As a result, it is critical that the impacts of artificial sweeteners on health and disease continue to be more thoroughly evaluated in humans.

Sweetening yoghurt with glucose, but not with saccharin, promotes weight gain and increased fat pad mass in rats

The claim that non-nutritive sweeteners accelerate body weight gain by disrupting sweet-calorie associations was tested in two experiments using rats. The experiments were modelled on a key study from a series of experiments reporting greater body weight gain in rats fed yoghurt sweetened with saccharin than with glucose (Swithers & Davidson, 2008). Both of the current experiments likewise compared groups fed saccharin- or glucose-sweetened yoghurt in addition to chow and water, while Experiment 1 included a third group (Control) given unsweetened yoghurt. In Experiment 1, but not in Experiment 2, rats were initially exposed to both saccharin- and glucose-sweetened yoghurts to assess their relative palatability. We also tested whether the provision of an energy-dense sweet biscuit would augment any effects of saccharin on food intake and weight gain, as seemingly predicted by Swithers and Davidson (2008). In Experiment 1 there were no differences in body weight gain or fat pad mass between the Saccharin and Control group, whereas the Glucose group was the heaviest by the final 5 weeks and at cull had the largest fat pads. Greater acceptance of saccharin predicted more weight gain over the whole experiment. Consistent with past reports, fasting blood glucose and insulin measures did not differ between the Saccharin and Control groups, but suggested some impairment of insulin sensitivity in the Glucose group. Experiment 2 found similar effects of glucose on fat mass, but not on body weight gain. In summary, adding saccharin had no detectable effects on body-weight regulation, whereas the effects of glucose on fat pad mass were consistent with previous studies reporting more harmful effects of sugars compared to non-nutritive sweeteners.