The antimicrobial activity of the three commercially available intense sweeteners against common periodontal pathogens: an in vitro study

Insight into the evolution of microbial communities and resistance genes induced by sucralose in partial nitrification system with triclosan pre-exposure

Sucralose (SUC), an artificial sweetener widely used in food, beverages and pharmaceuticals, is frequently detected in various environmental matrices. Triclosan (TCS) is commonly used as a disinfectant and often co-exists with SUC in sewage environments. This study investigated the effects of SUC (0.1-10 mg/L) on the transmission of intracellular and extracellular antibiotic resistance genes (ARGs) in the partial nitrification systems with and without TCS pre-exposure. The reactors operated for 150 days, and SUC did not affect ammonia oxidation performance, while TCS led to the maintenance of partial nitrification. The types and abundances of extracellular ARGs in sludge and free ARGs in water increased significantly after TCS pre-exposure when faced SUC stress, which might be caused by a decrease in α-Helix/(β-Sheet + Random coil). SUC was more easily to enrich ARGs in partial nitrification systems with TCS pre-exposure, exacerbating the risk of ARGs transmission. The microbial community showed stronger relationships to cope with the direct stress of SUC, and the functional bacteria (Thauera and Nitrosomonas) in TCS pre-exposure system might be potential hosts of ARGs. This study might provide insights for better understanding the fates of SUC in partial nitrification systems and the ecological risks in wastewater containing TCS and SUC. ENVIRONMENTAL IMPLICATION: Sucralose (SUC) is often detected in the environment and considered as an emerging contaminant due to its soaring consumption and environmental persistence. Triclosan (TCS) is an antibacterial agent that often co-exists with SUC in personal care products and sewage environments. During 150 d, two partial nitrification reactors with and without TCS pre-exposure were established to study the effects of SUC on nitrification performance, antibiotic resistance genes (ARGs) and microbial communities. This study showed the refractory nature of SUC, and SUC led to the transmission of extracellular ARGs in partial nitrification system with TCS pre-exposure, exacerbating the risk of ARGs dissemination.

Consuming artificial sweeteners may alter the structure and function of duodenal microbial communities

Studies using stool samples suggest that non-sugar sweetener (NSS) consumption affects gut microbiome composition. However, stool does not represent the entire gut. We analyzed the duodenal luminal microbiome in subjects consuming non-aspartame non-sugar sweeteners (NANS, N = 35), aspartame only (ASP, N = 9), and controls (CON, N = 55) and the stool microbiome in a subset (N = 40). Duodenal alpha diversity was decreased in NANS vs. CON. Duodenal relative abundance (RA) of Escherichia, Klebsiella, and Salmonella (all phylum Proteobacteria) was lower in both NANS and ASP vs. CON, whereas stool RA of Escherichia, Klebsiella, and Salmonella was increased in both NANS and ASP vs. CON. Predicted duodenal microbial metabolic pathways altered in NANS vs. CON included polysaccharides biosynthesis and D-galactose degradation, whereas cylindrospermopsin biosynthesis was significantly enriched in ASP vs. CON. These findings suggest that consuming non-sugar sweeteners may significantly alter microbiome composition and function in the metabolically active small bowel, with different alterations seen in stool.

Non-caloric artificial sweeteners modulate conjugative transfer of multi-drug resistance plasmid in the gut microbiota

Non-caloric artificial sweeteners have been widely permitted as table sugar substitutes with high intensities of sweetness. They can pass through the intestinal tract without significant metabolization and frequently encounter the gut microbiome, which is composed of diverse bacterial species and is a pool of antibiotic resistance genes (ARGs). However, little is known about whether these sweeteners could accelerate the spread of ARGs in the gut microbiome. Here, we established an in vitro conjugation model by using Escherichia coli that carries chromosome-inserted Tn7 lacI^q-pLpp-mCherry and plasmid-encoded gfpmut3b gene as the donor and murine fecal bacteria as the recipient. We found that four commonly used artificial sweeteners (saccharin, sucralose, aspartame, and acesulfame potassium) can increase reactive oxygen species (ROS) production and promote plasmid-mediated conjugative transfer to the gut microbiome. Cell sorting and 16S rRNA gene amplicon sequencing analysis of fecal samples reveal that the tested sweeteners can promote the broad-host-range plasmid permissiveness to both Gram-negative and Gram-positive gut bacteria. The increased plasmid permissiveness was also validated with a human pathogen Klebsiella pneumoniae. Collectively, our study demonstrates that non-caloric artificial sweeteners can induce oxidative stress and boost the plasmid-mediated conjugative transfer of ARGs among the gut microbiota and a human pathogen. Considering the soaring consumption of these sweeteners and the abundance of mobile ARGs in the human gut, our results highlight the necessity of performing a thorough risk assessment of antibiotic resistance associated with the usage of artificial sweeteners as food additives.

Personalized microbiome-driven effects of non-nutritive sweeteners on human glucose tolerance

Non-nutritive sweeteners (NNS) are commonly integrated into human diet and presumed to be inert; however, animal studies suggest that they may impact the microbiome and downstream glycemic responses. We causally assessed NNS impacts in humans and their microbiomes in a randomized-controlled trial encompassing 120 healthy adults, administered saccharin, sucralose, aspartame, and stevia sachets for 2 weeks in doses lower than the acceptable daily intake, compared with controls receiving sachet-contained vehicle glucose or no supplement. As groups, each administered NNS distinctly altered stool and oral microbiome and plasma metabolome, whereas saccharin and sucralose significantly impaired glycemic responses. Importantly, gnotobiotic mice conventionalized with microbiomes from multiple top and bottom responders of each of the four NNS-supplemented groups featured glycemic responses largely reflecting those noted in respective human donors, which were preempted by distinct microbial signals, as exemplified by sucralose. Collectively, human NNS consumption may induce person-specific, microbiome-dependent glycemic alterations, necessitating future assessment of clinical implications.

Analysis of the Effects of Food Additives on Porphyromonas gingivalis

This study aims to investigate six food additives (octanoic acid, decanoic acid, acesulfame K, aspartame, saccharin, and sucralose) used in foods for the elderly or people with dysphagia because of the effect of these food additives on Porphyromonas gingivalis (P. gingivalis), which is a keystone pathogen of periodontal diseases. The growth of P. gingivalis was inhibited by 5 mM octanoic acid, 1.25 mM decanoic acid, 1.25% acesulfame K, 0.0625% aspartame, 0.03125% saccharin, and 0.625% sucralose. In addition, these food additives showed bactericidal activity for planktonic P. gingivalis (5 mM octanoic acid, 5 mM decanoic acid, 0.25% aspartame, 0.25% saccharin, and 5% sucralose). Moreover, biofilm formation was inhibited by 10 mM octanoic acid, 10 mM decanoic acid, 10% acesulfame K, 0.35% aspartame, 0.5% saccharin, and 7.5% sucralose. Moreover, the same concentration of these food additives without aspartame killed P. gingivalis in the biofilm. Aspartame and sucralose did not show cytotoxicity to human cell lines at concentrations that affected P. gingivalis. These findings may be useful in clarifying the effects of food additives on periodontopathogenic bacteria.

Artificial sweeteners stimulate horizontal transfer of extracellular antibiotic resistance genes through natural transformation

Antimicrobial resistance has emerged as a global threat to human health. Natural transformation is an important pathway for horizontal gene transfer, which facilitates the dissemination of antibiotic resistance genes (ARGs) among bacteria. Although it is suspected that artificial sweeteners could exert antimicrobial effects, little is known whether artificial sweeteners would also affect horizontal transfer of ARGs via transformation. Here we demonstrate that four commonly used artificial sweeteners (saccharin, sucralose, aspartame, and acesulfame potassium) promote transfer of ARGs via natural transformation in Acinetobacter baylyi ADP1, a model organism for studying competence and transformation. Such phenomenon was also found in a Gram-positive human pathogen Bacillus subtilis and mice faecal microbiome. We reveal that exposure to these sweeteners increases cell envelope permeability and results in an upregulation of genes encoding DNA uptake and translocation (Com) machinery. In addition, we find that artificial sweeteners induce an increase in plasmid persistence in transformants. We propose a mathematical model established to predict the long-term effects on transformation dynamics under exposure to these sweeteners. Collectively, our findings offer insights into natural transformation promoted by artificial sweeteners and highlight the need to evaluate these environmental contaminants for their antibiotic-like side effects.

Sucralose and Cardiometabolic Health: Current Understanding from Receptors to Clinical Investigations

The excess consumption of added sugar is consistently found to be associated with weight gain, and a higher risk of type 2 diabetes mellitus, coronary heart disease, and stroke. In an effort to reduce the risk of cardiometabolic disease, sugar is frequently replaced by low- and null-calorie sweeteners (LCSs). Alarmingly, though, emerging evidence indicates that the consumption of LCSs is associated with an increase in cardiovascular mortality risk that is amplified in those who are overweight or obese. Sucralose, a null-caloric high-intensity sweetener, is the most commonly used LCS worldwide, which is regularly consumed by healthy individuals and patients with metabolic disease. To explore a potential causal role for sucralose in increased cardiovascular risk, this present review summarizes the preclinical and clinical data from current research detailing the effects of sucralose on systems controlling food intake, glucose homeostasis, and gut microbiota.

To a Question on the Mechanism of the Antimicrobial Action of Ortho-Benzoic Sulfimide

The article summarizes and compares data on the properties and biological activity of o-benzoic sulfimide and sulfanilamide compounds. Attention is given to the biochemical conditions under which o-benzoic sulfimide and sulfanilamides have similar activity groups. The results of the experimental and theoretical studies aimed at understanding the molecular organization and biological activity of folic acid and its homologous complexes are analyzed. A hypothesis about the possible mechanisms of the formation of such complexes with the participation of o-benzoic sulfimide is presented. The perspectives for the use of o-benzoic sulfimide and its homologues in biomedicine are evaluated.

Metabolic networks of the human gut microbiota

The human gut microbiota controls factors that relate to human metabolism with a reach far greater than originally expected. Microbial communities and human (or animal) hosts entertain reciprocal exchanges between various inputs that are largely controlled by the host via its genetic make-up, nutrition and lifestyle. The composition of these microbial communities is fundamental to supply metabolic capabilities beyond those encoded in the host genome, and contributes to hormone and cellular signalling that support the dynamic adaptation to changes in food availability, environment and organismal development. Poor functional exchange between the microbial communities and their human host is associated with dysbiosis, metabolic dysfunction and disease. This review examines the biology of the dynamic relationship between the reciprocal metabolic state of the microbiota-host entity in balance with its environment (i.e. in healthy states), the enzymatic and metabolic changes associated with its imbalance in three well-studied diseases states such as obesity, diabetes and atherosclerosis, and the effects of bariatric surgery and exercise.

Consumption of non-nutritive sweeteners during pregnancy

In an effort to reduce sugar consumption to prevent diabetes mellitus and cardiovascular diseases, "sugar-free" or "no added sugar" products that substitute sugar with non-nutritive sweeteners (NNSs) (eg, Splenda, Sweet'N Low, and Stevia) have become increasingly popular. The use of these products during pregnancy has also increased, with approximately 30% of pregnant women reporting intentional NNS consumption. In clinical studies with nonpregnant participants and animal models, NNSs were shown to alter gut hormonal secretion, glucose absorption, appetite, kidney function, in vitro insulin secretion, adipogenesis, and microbiome dysbiosis of gut bacteria. In pregnant animal models, NNS consumption has been associated with altered sweet taste preference later in life and metabolic dysregulations in the offspring (eg, elevated body mass index, increased risk of obesity, microbiome dysbiosis, and abnormal liver function tests). Despite the accumulating evidence, no specific guidelines for NNS consumption are available for pregnant women. Furthermore, there are limited clinical studies on the effects of NNS consumption during pregnancy and postpartum and long-term outcomes in the offspring.

Nonalcoholic fatty liver disease, insulin resistance, and sweeteners: a literature review

Introduction: Sweeteners are substances used to replace sugar. They can either be chemically produced (artificial sweeteners) or extracted from plants (natural sweeteners). In the last two decades, there is an increased popularity in their role as sugar substitutes in individuals to promote weight loss or maintain glycemic control. However, despite their favorable effects, there is concern regarding their side effects and especially their influence in the development of nonalcoholic fatty liver disease (NAFLD).Areas covered: A comprehensive literature search was conducted on Medline including systematic reviews, longitudinal controlled studies, and retrospective cohort studies. We present an up-to-date systematic review of the current literature regarding the safety in artificial and natural sweeteners use as a means of weight loss or diabetes control.Expert opinion: Natural sweeteners have not been associated directly with NAFLD, and on the contrary, some, such as stevia, and trehalose, may have a protective effect. Rare sugars and polyols can be used safely and have significant benefits that include anti-oxidant effect and optimal glycemic control. Artificial sweeteners, due to their effect on NAFLD development and insulin resistance, are not indicated in patients with obesity or diabetes. Further studies in human subjects are required to verify the above findings.

Revisited: Assessing the in vivo data on low/no-calorie sweeteners and the gut microbiota

Over the last two decades, safety concerns about low/no-calorie sweeteners (LNCS) have been described in the archival scientific literature including elevated risk of metabolic syndrome, type 2 diabetes, excessive weight gain, cardiovascular disease, safety, and disruption of the gut microbiome. A recent review by Lobach, Roberts, and Roland in Food and Chemical Toxicology examined 17 research articles on modulation of gut bacteria by LNCS along with other selected publications. In the conclusions of their paper, they claim that LNCS 1) do not affect gut microbiota at use levels and 2) are safe at levels approved by regulatory agencies. Both of these claims are incorrect. The scientific literature on LNCS clearly indicates that it is inappropriate to draw generalized conclusions regarding effects on gut microbiota and safety issues for compounds that vary widely chemical structure and pharmacokinetics. Scientific studies on the sweetener sucralose, used here as a representative LNCS, indicate that this organochlorine compound unequivocally and irrefutably disrupts the gut microbiome at doses relevant to human use. Results of dozens of additional research publications added and reviewed here also raise significant and extensive concerns about the safety of sucralose for the human food supply.

A Personalised Dietary Approach-A Way Forward to Manage Nutrient Deficiency, Effects of the Western Diet, and Food Intolerances in Inflammatory Bowel Disease

This review discusses the personalised dietary approach with respect to inflammatory bowel disease (IBD). It identifies gene–nutrient interactions associated with the nutritional deficiencies that people with IBD commonly experience, and the role of the Western diet in influencing these. It also discusses food intolerances and how particular genotypes can affect these. It is well established that with respect to food there is no “one size fits all” diet for those with IBD. Gene–nutrient interactions may help explain this variability in response to food that is associated with IBD. Nutrigenomic research, which examines the effects of food and its constituents on gene expression, shows that—like a number of pharmaceutical products—food can have beneficial effects or have adverse (side) effects depending on a person’s genotype. Pharmacogenetic research is identifying gene variants with adverse reactions to drugs, and this is modifying clinical practice and allowing individualised treatment. Nutrigenomic research could enable individualised treatment in persons with IBD and enable more accurate tailoring of food intake, to avoid exacerbating malnutrition and to counter some of the adverse effects of the Western diet. It may also help to establish the dietary pattern that is most protective against IBD.

Maternal Exposure to Non-nutritive Sweeteners Impacts Progeny's Metabolism and Microbiome

Non-nutritive sweeteners (NNS) are marketed as sugar alternatives providing sweet taste with few or no calories. Yet their consumption has been linked to metabolic dysfunction and changes in the gut microbiome. NNS exposure mostly originates from diet beverages and sweetener packages in adults or breastmilk in infants. Consequences of early life exposure remain largely unknown. We exposed pregnant and lactating mice to NNS (sucralose, acesulfame-K) at doses relevant for human consumption. While the pups' exposure was low, metabolic changes were drastic, indicating extensive downregulation of hepatic detoxification mechanisms and changes in bacterial metabolites. Microbiome profiling confirmed a significant increase in firmicutes and a striking decrease of Akkermansia muciniphila. Similar microbiome alterations in humans have been linked to metabolic disease and obesity. While our findings need to be reproduced in humans, they suggest that NNS consumption during pregnancy and lactation may have adverse effects on infant metabolism.

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.

Non-nutritive sweeteners possess a bacteriostatic effect and alter gut microbiota in mice

Non-nutritive sweeteners (NNSs) are widely used in various food products and soft drinks. There is growing evidence that NNSs contribute to metabolic dysfunction and can affect body weight, glucose tolerance, appetite, and taste sensitivity. Several NNSs have also been shown to have major impacts on bacterial growth both in vitro and in vivo. Here we studied the effects of various NNSs on the growth of the intestinal bacterium, E. coli, as well as the gut bacterial phyla Bacteroidetes and Firmicutes, the balance between which is associated with gut health. We found that the synthetic sweeteners acesulfame potassium, saccharin and sucralose all exerted strong bacteriostatic effects. We found that rebaudioside A, the active ingredient in the natural NNS stevia, also had similar bacteriostatic properties, and the bacteriostatic effects of NNSs varied among different Escherichia coli strains. In mice fed a chow diet, sucralose increased Firmicutes, and we observed a synergistic effect on Firmicutes when sucralose was provided in the context of a high-fat diet. In summary, our data show that NNSs have direct bacteriostatic effects and can change the intestinal microbiota in vivo.

How Non-nutritive Sweeteners Influence Hormones and Health

Non-nutritive sweeteners (NNSs) elicit a multitude of endocrine effects in vitro, in animal models, and in humans. The best-characterized consequences of NNS exposure are metabolic changes, which may be mediated by activation of sweet taste receptors in oral and extraoral tissues (e.g., intestine, pancreatic β cells, and brain), and alterations of the gut microbiome. These mechanisms are likely synergistic and may differ across species and chemically distinct NNSs. However, the extent to which these hormonal effects are clinically relevant in the context of human consumption is unclear. Further investigation following prolonged exposure is required to better understand the role of NNSs in human health, with careful consideration of genetic, dietary, anthropometric, and other interindividual differences.

Nonnutritive Sweeteners in Weight Management and Chronic Disease: A Review

OBJECTIVE

The objective of this review was to critically review findings from recent studies evaluating the effects of nonnutritive sweeteners (NNSs) on metabolism, weight, and obesity-related chronic diseases. Biologic mechanisms that may explain NNS effects will also be addressed.

METHODS

A comprehensive review of the relevant scientific literature was conducted.

RESULTS

Most cross-sectional and prospective cohort studies report positive associations between NNS consumption, body weight, and health conditions, including type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease. Although findings in cellular and rodent models suggest that NNSs have harmful effects on metabolic health, most randomized controlled trials in humans demonstrate marginal benefits of NNS use on body weight, with little data available on other metabolic outcomes.

CONCLUSIONS

NNS consumption is associated with higher body weight and metabolic disease in observational studies. In contrast, randomized controlled trials demonstrate that NNSs may support weight loss, particularly when used alongside behavioral weight loss support. Additional long-term, well-controlled intervention studies in humans are needed to determine the effects of NNSs on weight, adiposity, and chronic disease under free-living conditions.

Revisiting the safety of aspartame

Aspartame is a synthetic dipeptide artificial sweetener, frequently used in foods, medications, and beverages, notably carbonated and powdered soft drinks. Since 1981, when aspartame was first approved by the US Food and Drug Administration, researchers have debated both its recommended safe dosage (40 mg/kg/d) and its general safety to organ systems. This review examines papers published between 2000 and 2016 on both the safe dosage and higher-than-recommended dosages and presents a concise synthesis of current trends. Data on the safe aspartame dosage are controversial, and the literature suggests there are potential side effects associated with aspartame consumption. Since aspartame consumption is on the rise, the safety of this sweetener should be revisited. Most of the literature available on the safety of aspartame is included in this review. Safety studies are based primarily on animal models, as data from human studies are limited. The existing animal studies and the limited human studies suggest that aspartame and its metabolites, whether consumed in quantities significantly higher than the recommended safe dosage or within recommended safe levels, may disrupt the oxidant/antioxidant balance, induce oxidative stress, and damage cell membrane integrity, potentially affecting a variety of cells and tissues and causing a deregulation of cellular function, ultimately leading to systemic inflammation.

Drug loaded poly(glycerol sebacate) as a local drug delivery system for the treatment of periodontal disease

A simple, cost-efficient method to load drugs into poly(glycerol sebacate) polymer. Drugs were able to sustained release for up to 60 days. The drugs loaded polymer showed cytocompatibility and antimicrobial activities.

Metabolic effects of non-nutritive sweeteners

Until recently, the general belief was that non-nutritive sweeteners (NNSs) were healthy sugar substitutes because they provide sweet taste without calories or glycemic effects. However, data from several epidemiological studies have found that consumption of NNSs, mainly in diet sodas, is associated with increased risk to develop obesity, metabolic syndrome, and type 2 diabetes. The main purpose of this article is to review recent scientific evidence supporting potential mechanisms that explain how "metabolically inactive" NNSs, which have few, if any, calories, might promote metabolic dysregulation. Three potential mechanisms, which are not mutually exclusive, are presented: 1) NNSs interfere with learned responses that contribute to control glucose and energy homeostasis, 2) NNSs interfere with gut microbiota and induce glucose intolerance, and 3) NNSs interact with sweet-taste receptors expressed throughout the digestive system that play a role in glucose absorption and trigger insulin secretion. In addition, recent findings from our laboratory showing an association between individual taste sensitivity to detect sucralose and sucralose's acute effects on metabolic response to an oral glucose load are reported. Taken as a whole, data support the notion that NNSs have metabolic effects. More research is needed to elucidate the mechanisms by which NNSs may drive metabolic dysregulation and better understand potential effects of these commonly used food additives.

Sucralose, a synthetic organochlorine sweetener: overview of biological issues

Sucralose is a synthetic organochlorine sweetener (OC) that is a common ingredient in the world's food supply. Sucralose interacts with chemosensors in the alimentary tract that play a role in sweet taste sensation and hormone secretion. In rats, sucralose ingestion was shown to increase the expression of the efflux transporter P-glycoprotein (P-gp) and two cytochrome P-450 (CYP) isozymes in the intestine. P-gp and CYP are key components of the presystemic detoxification system involved in first-pass drug metabolism. The effect of sucralose on first-pass drug metabolism in humans, however, has not yet been determined. In rats, sucralose alters the microbial composition in the gastrointestinal tract (GIT), with relatively greater reduction in beneficial bacteria. Although early studies asserted that sucralose passes through the GIT unchanged, subsequent analysis suggested that some of the ingested sweetener is metabolized in the GIT, as indicated by multiple peaks found in thin-layer radiochromatographic profiles of methanolic fecal extracts after oral sucralose administration. The identity and safety profile of these putative sucralose metabolites are not known at this time. Sucralose and one of its hydrolysis products were found to be mutagenic at elevated concentrations in several testing methods. Cooking with sucralose at high temperatures was reported to generate chloropropanols, a potentially toxic class of compounds. Both human and rodent studies demonstrated that sucralose may alter glucose, insulin, and glucagon-like peptide 1 (GLP-1) levels. Taken together, these findings indicate that sucralose is not a biologically inert compound.