Diet low in advanced glycation end products increases insulin sensitivity in healthy overweight individuals: a double-blind, randomized, crossover trial

Plant foods, healthy plant-based diets, and type 2 diabetes: a review of the evidence

Type 2 diabetes (T2D) is a metabolic chronic disease in which insulin resistance and insufficient insulin production lead to elevated blood glucose levels. The prevalence of T2D is growing worldwide, mainly due to obesity and the adoption of Western diets. Replacing animal foods with healthy plant foods is associated with a lower risk of T2D in prospective studies. In randomized controlled trials, the consumption of healthy plant foods in place of animal foods led to cardiometabolic improvements in patients with T2D or who were at high risk of the disease. Dietary patterns that limit or exclude animal foods and focus on healthy plant foods (eg, fruits, vegetables, whole grains, nuts, legumes), known as healthy, plant-based diets, are consistently associated with a lower risk of T2D in cohort studies. The aim of this review is to examine the differential effects of plant foods and animal foods on T2D risk and to describe the existing literature about the role of healthy, plant-based diets, particularly healthy vegan diets, in T2D prevention and management. The evidence from cohort studies and randomized controlled trials will be reported, in addition to the potential biological mechanisms that seem to be involved.

The inhibitory effects of endophytic metabolites on glycated proteins under non-communicable disease conditions: A review

Protein glycation in human body is closely linked to the onset/progression of diabetes associated complications. These glycated proteins are commonly known as advanced glycation end products (AGEs). Recent literature has also highlighted the involvement of AGEs in other non-communicable diseases (NCDs) such as cardiovascular, cancer, and Alzheimer's diseases and explored the impact of plant metabolites on AGEs formation. However, the significance of endophytic metabolites against AGEs has recently garnered attention but has not been thoroughly summarized thus far. Therefore, the objective of this review is to provide a comprehensive overview of the importance of endophytic metabolites in combating AGEs under NCDs conditions. Additionally, this review aims to elucidate the processes of AGEs formation, absorption, metabolism, and their harmful effects. Collectively, endophytic metabolites play a crucial role in modulating signaling pathways and enhancing the digestibility properties of gut microbiota (GM) by targeting on AGEs/RAGE (receptor for AGEs) axis. Furthermore, these metabolites exhibit anti-AGEs activities similar to those derived from host plants, but at a lower cost and higher production rate. The use of endophytes as a source of such metabolites offers a risk-free and sustainable approach that holds substantial potential for the treatment and management of NCDs.

Evaluation of the effects of dietary advanced glycation end products on inflammation

Advanced glycation end products (AGEs) are a large number of heterogeneous compounds formed by the glycation of proteins, fats or nucleic acids. Endogenous AGEs have been associated with various health problems such as obesity, type 2 diabetes mellitus and cardiovascular disease. Inflammation is thought to be one of the main mechanisms in the development of these disorders. Although AGEs are produced endogenously in the body, exogenous sources such as smoking and diet also contribute to the body pool. Therefore, when the AGE pool in the body rises above physiological levels, different pathological conditions may occur through various mechanisms, especially inflammation. While the effects of endogenous AGEs on the development of inflammation have been studied relatively extensively, and current evidence indicates that dietary AGEs (dAGEs) contribute to the body's AGE pool, it is not yet known whether dAGEs have the same effect on the development of inflammation as endogenous AGEs. Therefore, this review aimed to evaluate the results of cross-sectional and intervention studies to understand whether dAGEs are associated with inflammation and, if there is an effect on inflammation, through which mechanisms this effect might occur.

The RAGE/DIAPH1 axis: mediator of obesity and proposed biomarker of human cardiometabolic disease

Overweight and obesity are leading causes of cardiometabolic dysfunction. Despite extensive investigation, the mechanisms mediating the increase in these conditions are yet to be fully understood. Beyond the endogenous formation of advanced glycation endproducts (AGEs) in overweight and obesity, exogenous sources of AGEs accrue through the heating, production, and consumption of highly processed foods. Evidence from cellular and mouse model systems indicates that the interaction of AGEs with their central cell surface receptor for AGE (RAGE) in adipocytes suppresses energy expenditure and that AGE/RAGE contributes to increased adipose inflammation and processes linked to insulin resistance. In human subjects, the circulating soluble forms of RAGE, which are mutable, may serve as biomarkers of obesity and weight loss. Antagonists of RAGE signalling, through blockade of the interaction of the RAGE cytoplasmic domain with the formin, Diaphanous-1 (DIAPH1), target aberrant RAGE activities in metabolic tissues. This review focuses on the potential roles for AGEs and other RAGE ligands and RAGE/DIAPH1 in the pathogenesis of overweight and obesity and their metabolic consequences.

Carnosine supplementation improves glucose control in adults with pre-diabetes and type 2 diabetes: A randomised controlled trial

BACKGROUND AND AIMS

Type 2 diabetes (T2DM) is a major cause of morbidity and mortality globally. Carnosine, a naturally occurring dipeptide, has anti-inflammatory, antioxidant, and anti-glycating effects, with preliminary evidence suggesting it may improve important chronic disease risk factors in adults with cardiometabolic conditions.

METHODS AND RESULTS

In this randomised controlled trial, 43 adults (30%F) living with prediabetes or T2DM consumed carnosine (2 g) or a matching placebo daily for 14 weeks to evaluate its effect on glucose metabolism assessed via a 2-h 75 g oral glucose tolerance test. Secondary outcomes included body composition analysis by dual energy x-ray absorptiometry (DEXA), calf muscle density by pQCT, and anthropometry. Carnosine supplementation decreased blood glucose at 90 min (-1.31 mmol/L; p = 0.02) and 120 min (-1.60 mmol/L, p = 0.02) and total glucose area under the curve (-3.30 mmol/L; p = 0.04) following an oral glucose tolerance test. There were no additional changes in secondary outcomes. The carnosine group results remained significant before and after adjustment for age, sex, and change in weight (all>0.05), and in further sensitivity analyses accounting for missing data. There were no significant changes in insulin levels.

CONCLUSION

This study provides preliminary support for larger trials evaluating carnosine as a potential treatment for prediabetes and the initial stages of T2DM. Likely mechanisms may include changes to hepatic glucose output explaining the observed reduction in blood glucose without changes in insulin secretion following carnosine supplementation.

Reduction of circulating methylglyoxal levels by a Mediterranean diet is associated with preserved kidney function in patients with type 2 diabetes and coronary heart disease: From the CORDIOPREV randomized controlled trial

AIM

Advanced glycation end products (AGEs) play a role in kidney disease in type 2 diabetes mellitus (T2DM). However, there have been no prior controlled clinical trials examining the effects of specific diets on AGE metabolism and their impact on kidney function. Our aim was to assess whether modulating AGE metabolism resulting in reduced AGEs levels, after consumption of two healthy diets, could delay kidney function decline in patients with T2DM and coronary heart disease (CHD).

METHODS

T2DM patients (540 out of 1002 patients from the CORDIOPREV study), with estimated glomerular filtration rate (eGFR) ≥ 30 ml/min/1.73 m2, were classified based on their baseline kidney function: normal eGFR (≥ 90 ml/min/1.73 m2), mildly decreased eGFR (60- < 90 ml/min/1.73 m2) and moderately decreased eGFR (<60 ml/min/1.73 m2). Serum AGE levels, methylglyoxal (MG) and N-carboximethyllysine (CML), and gene expression related to AGE metabolism (AGER1, RAGE, and GloxI mRNA) were measured before and after 5-years of dietary intervention (a Mediterranean diet or a low-fat diet).

RESULTS

Mediterranean diet produced a lower declined of eGFR compared to the low-fat diet only in patients with mildly decreased eGFR (P = 0.035). Moreover, Mediterranean diet was able to decrease MG levels and increase GloxI expression in normal and mildly decreased eGFR patients (all P < 0.05). One standard deviation increment of MG levels after dietary intervention resulted in a 6.8-fold (95 % CI 0.039;0.554) higher probability of eGFR decline.

CONCLUSION

Our study showed that lowering circulating AGE levels, specifically MG, after following a Mediterranean diet, might be linked to the preservation of kidney function, evidenced by a decreased decline of eGFR in T2DM patients with CHD. Patients with mildly decreased eGFR could potentially benefit more from AGE reduction in maintaining kidney function.

AGEs accumulation with vascular complications, glycemic control and metabolic syndrome: A narrative review

BACKGROUND

Multiple pathogenetic mechanisms are involved in the genesis of various microvascular and macrovascular complications of diabetes mellitus. Of all these, advanced glycation end products (AGEs) have been strongly implicated.

OBJECTIVES

The present narrative review aims to summarize the available literature on the genesis of AGEs and their potential role in the causation of both micro- and macrovascular complications of diabetes mellitus.

RESULTS

Uncontrolled hyperglycemia triggers the formation of AGEs through non-enzymatic glycation reactions between reducing sugars and proteins, lipids, or nucleic acids. AGEs accumulate in bloodstream and bodily tissues under chronic hyperglycemia. AGEs create irreversible cross-linkages of various intra- and extracellular molecules and activate the receptor for advanced glycation end products (RAGE), which stimulates downstream signaling pathways that generate reactive oxygen species (ROS) and contribute to oxidative stress. Additionally, intracellular glycation of mitochondrial respiratory chain proteins by AGEs contributes to the further generation of ROS, which, in turn, sets a vicious cycle that further promotes the production of endogenous AGEs. Through these pathways, AGEs play a principal role in the pathogenesis of various diabetic complications, including diabetic retinopathy, nephropathy, neuropathy, bone disease, atherosclerosis and non-alcoholic fatty liver disease. Multiple clinical studies and meta-analyses have revealed a positive association between tissue or circulating levels of AGEs and development of various diabetic complications. Besides, exogenous AGEs, primarily those derived from diets, promote insulin resistance, obesity, and metabolic syndrome.

CONCLUSIONS

AGEs, triggered by chronic hyperglycemia, play a pivotal role in the pathogenesis of various complications of diabetes mellitus.

Dietary Advanced Glycation End Products: Their Role in the Insulin Resistance of Aging

Insulin resistance (IR) is commonly observed during aging and is at the root of many of the chronic nontransmissible diseases experienced as people grow older. Many factors may play a role in causing IR, but diet is undoubtedly an important one. Whether it is total caloric intake or specific components of the diet, the factors responsible remain to be confirmed. Of the many dietary influences that may play a role in aging-related decreased insulin sensitivity, advanced glycation end products (AGEs) appear particularly important. Herein, we have reviewed in detail in vitro, animal, and human evidence linking dietary AGEs contributing to the bodily burden of AGEs with the development of IR. We conclude that numerous small clinical trials assessing the effect of dietary AGE intake in combination with strong evidence in many animal studies strongly suggest that reducing dietary AGE intake is associated with improved IR in a variety of disease conditions. Reducing AGE content of common foods by simple changes in culinary techniques is a feasible, safe, and easily applicable intervention in both health and disease. Large-scale clinical trials are still needed to provide broader evidence for the deleterious role of dietary AGEs in chronic disease.

Dietary advanced glycation products and their associations with insulin sensitivity and body weight: A 16-week randomized clinical trial

Background

Evidence suggests that changes in advanced glycation end-products (AGEs) may influence body weight. Previous studies have focused on cooking methods as the primary way how to reduce the dietary AGEs but little is known about the effects of a change in diet composition.

Objective

The aim of this study was to assess the effects of a low-fat plant-based diet on dietary AGEs and test the association with body weight, body composition, and insulin sensitivity.

Methods

Participants who were overweight (n = 244) were randomly assigned to an intervention (low-fat plant-based) (n = 122) or control group (n = 122) for 16 weeks. Before and after the intervention period, body composition was measured by dual X-ray absorptiometry. Insulin sensitivity was assessed with the predicted insulin sensitivity index (PREDIM). Three-day diet records were analyzed using the Nutrition Data System for Research software and dietary AGEs were estimated, using a database. Repeated measure ANOVA was used for statistical analysis.

Results

Dietary AGEs decreased in the intervention group by 8768 ku/day on average (95% -9611 to -7925; p < 0.001), compared with the control group (-1608; 95% CI -2709 to -506; p = 0.005; treatment effect -7161 ku/day [95% CI -8540 to -5781]; Gxt, p < 0.001). Body weight decreased by 6.4 kg in the intervention group, compared with 0.5 kg in the control group (treatment effect -5.9 kg [95% CI -6.8 to -5.0]; Gxt, p < 0.001), largely due to a reduction in fat mass, notably visceral fat. PREDIM increased in the intervention group (treatment effect +0.9 [95% CI + 0.5 to +1.2]; p < 0.001). Changes in dietary AGEs correlated with changes in body weight (r = +0.41; p < 0.001), fat mass (r = +0.38; p < 0.001), visceral fat (r = +0.23; p < 0.001), and PREDIM (r = -0.28; p < 0.001), and remained significant even after adjustment for changes in energy intake (r = +0.35; p < 0.001 for body weight; r = +0.34; p < 0.001 for fat mass; r = +0.15; p = 0.03 for visceral fat; and r = -0.24; p < 0.001 for PREDIM).

Conclusions

Dietary AGEs decreased on a low-fat plant-based diet, and this decrease was associated with changes in body weight, body composition, and insulin sensitivity, independent of energy intake. These findings demonstrate positive effects of qualitative dietary changes on dietary AGEs and cardiometabolic outcomes.

Clinical Trial Registry Number

NCT02939638.

Habitual intake of advanced glycation endproducts is not associated with worse insulin sensitivity, worse beta cell function, or presence of prediabetes or type 2 diabetes: The Maastricht Study

BACKGROUND & AIMS

A diet high in advanced glycation endproducts (AGEs) is a potential risk factor for insulin resistance, beta cell dysfunction, and ultimately type 2 diabetes. We investigated associations between habitual intake of dietary AGEs and glucose metabolism in a population-based setting.

METHODS

In 6275 participants of The Maastricht Study (mean ± SD age: 60 ± 9, 15.1% prediabetes and 23.2% type 2 diabetes), we estimated habitual intake of dietary AGEs N^ε-(carboxymethyl)lysine (CML), N^ε-(1-carboxyethyl)lysine (CEL), and N^δ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) by combining a validated food frequency questionnaire (FFQ) with our mass-spectrometry dietary AGE database. We determined insulin sensitivity (Matsuda- and HOMA-IR index), beta cell function (C-peptidogenic index, glucose sensitivity, potentiation factor, and rate sensitivity), glucose metabolism status, fasting glucose, HbA1c, post-OGTT glucose, and OGTT glucose incremental area under the curve. Cross-sectional associations between habitual AGE intake and these outcomes were investigated using a combination of multiple linear regression and multinomial logistic regression adjusting for several potential confounders (demographic, cardiovascular, and lifestyle factors).

RESULTS

Generally, higher habitual intake of AGEs was not associated with worse indices of glucose metabolism, nor with increased presence of prediabetes or type 2 diabetes. Higher dietary MG-H1 was associated with better beta cell glucose sensitivity.

CONCLUSIONS

The present study does not support an association of dietary AGEs with impaired glucose metabolism. Whether higher intake of dietary AGEs translates to increased incidence of prediabetes or type 2 diabetes on the long term should be investigated in large prospective cohort studies.

Blood and Tissue Advanced Glycation End Products as Determinants of Cardiometabolic Disorders Focusing on Human Studies

Cardiometabolic disorders are characterised by a cluster of interactive risk determinants such as increases in blood glucose, lipids and body weight, as well as elevated inflammation and oxidative stress and gut microbiome changes. These disorders are associated with onset of type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). T2DM is strongly associated with CVD. Dietary advanced glycation end products (dAGEs) attributable from modern diets high in sugar and/or fat, highly processed foods and high heat-treated foods can contribute to metabolic etiologies of cardiometabolic disorders. This mini review aims to determine whether blood dAGEs levels and tissue dAGEs levels are determinants of the prevalence of cardiometabolic disorders through recent human studies. ELISA (enzyme-linked immunosorbent assay), high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) for blood dAGEs measurement and skin auto fluorescence (SAF) for skin AGEs measurement can be used. Recent human studies support that a diet high in AGEs can negatively influence glucose control, body weight, blood lipid levels and vascular health through the elevated oxidative stress, inflammation, blood pressure and endothelial dysfunction compared with a diet low in AGEs. Limited human studies suggested a diet high in AGEs could negatively alter gut microbiota. SAF could be considered as one of the predictors affecting risks for cardiometabolic disorders. More intervention studies are needed to determine how dAGEs are associated with the prevalence of cardiometabolic disorders through gut microbiota changes. Further human studies are conducted to find the association between CVD events, CVD mortality and total mortality through SAF measurement, and a consensus on whether tissue dAGEs act as a predictor of CVD is required.

Dietary advanced glycation end-products and postmenopausal hot flashes: A post-hoc analysis of a 12-week randomized clinical trial

OBJECTIVE

Postmenopausal hot flashes are associated with an increased risk of cardiovascular disease and diabetes. Because dietary advanced glycation end-products (AGEs) may act as endocrine disruptors, this study examined the potential association of modifications to the intake of dietary AGEs with the frequency and severity of postmenopausal hot flashes.

METHODS

Postmenopausal women (n = 84) reporting ≥2 moderate-to-severe hot flashes daily were randomly assigned to either the intervention group or the control group. The former were asked to follow a low-fat, vegan diet, including cooked soybeans (1/2 cup [86 g]/day) for 12 weeks, and the latter continued their usual diets for 12 weeks. Frequency and severity of hot flashes were recorded with a mobile application. Three-day diet records were analyzed using the Nutrition Data System for Research software and dietary AGEs were estimated, using a database. Seventy-one participants completed the whole study and 63 provided complete hot flash and dietary data for the AGEs analysis (n = 31 in the intervention and n = 24 in the control group). Pearson correlations were used to assess the association between changes in hot flashes and dietary AGEs.

RESULTS

Dietary AGEs decreased in the intervention group by 73 %, that is by 5509 ku/day on average (95 % -7009 to -4009; p < 0.001), compared with the control group (+458; 95 % CI -835 to +1751; p = 0.47; treatment effect -5968 ku/day [95 % CI -7945 to -3991]; Gxt, p < 0.001). Severe hot flashes decreased by 92 % (p < 0.001) and moderate-to-severe hot flashes decreased by 88 % in the intervention group (p < 0.001). Changes in dietary AGEs correlated with changes in severe (r = +0.39; p = 0.002) and moderate hot flashes (r = +0.34; p = 0.009) and remained significant after adjustment for changes in energy intake (r = +0.45; p < 0.001; and r = +0.37; p = 0.004, respectively) and changes in body mass index (r = +0.37; p = 0.004; and r = +0.27; p = 0.04, respectively). The reduction in dietary AGEs required to achieve a predicted reduction in hot flashes by 1/day was 6933 ku/day for severe and 4366 ku/day for moderate-to-severe hot flashes.

CONCLUSIONS

The reduction in dietary AGEs with a low-fat plant-based diet was associated with a significant reduction in the frequency of severe and moderate-to-severe postmenopausal hot flashes, independent of changes in energy intake and weight loss. Plant-based diets could be used not only to alleviate vasomotor symptoms in postmenopausal women, but also to reduce other health risks associated with AGEs.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04587154.

Understanding the role of glycation in the pathology of various non-communicable diseases along with novel therapeutic strategies

Glycation refers to carbonyl group condensation of the reducing sugar with the free amino group of protein, which forms Amadori products and advanced glycation end products (AGEs). These AGEs alter protein structure and function by configuring a negative charge on the positively charged arginine and lysine residues. Glycation plays a vital role in the pathogenesis of metabolic diseases, brain disorders, aging, and gut microbiome dysregulation with the aid of 3 mechanisms: (i) formation of highly reactive metabolic pathway-derived intermediates, which directly affect protein function in cells, (ii) the interaction of AGEs with its associated receptors to create oxidative stress causing the activation of transcription factor NF-κB, and (iii) production of extracellular AGEs hinders interactions between cellular and matrix molecules affecting vascular and neural genesis. Therapeutic strategies are thus required to inhibit glycation at different steps, such as blocking amino and carbonyl groups, Amadori products, AGEs-RAGE interactions, chelating transition metals, scavenging free radicals, and breaking crosslinks formed by AGEs. The present review focused on explicitly elaborating the impact of glycation-influenced molecular mechanisms in developing and treating noncommunicable diseases.

Advanced Glycation End Products and Inflammation in Type 1 Diabetes Development

Type 1 diabetes (T1D) is an autoimmune disease in which the β-cells of the pancreas are attacked by the host's immune system, ultimately resulting in hyperglycemia. It is a complex multifactorial disease postulated to result from a combination of genetic and environmental factors. In parallel with increasing prevalence of T1D in genetically stable populations, highlighting an environmental component, consumption of advanced glycation end products (AGEs) commonly found in in Western diets has increased significantly over the past decades. AGEs can bind to cell surface receptors including the receptor for advanced glycation end products (RAGE). RAGE has proinflammatory roles including in host-pathogen defense, thereby influencing immune cell behavior and can activate and cause proliferation of immune cells such as islet infiltrating CD8+ and CD4+ T cells and suppress the activity of T regulatory cells, contributing to β-cell injury and hyperglycemia. Insights from studies of individuals at risk of T1D have demonstrated that progression to symptomatic onset and diagnosis can vary, ranging from months to years, providing a window of opportunity for prevention strategies. Interaction between AGEs and RAGE is believed to be a major environmental risk factor for T1D and targeting the AGE-RAGE axis may act as a potential therapeutic strategy for T1D prevention.

Receptor of advanced glycation end-products axis and gallbladder cancer: A forgotten connection that we should reconsider

Compelling evidence derived from clinical and experimental research has demonstrated the crucial contribution of chronic inflammation in the development of neoplasms, including gallbladder cancer. In this regard, data derived from clinical and experimental studies have demonstrated that the receptor of advanced glycation end-products (RAGE)/AGEs axis plays an important role in the onset of a crucial and long-lasting inflammatory milieu, thus supporting tumor growth and development. AGEs are formed in biological systems or foods, and food-derived AGEs, also known as dietary AGEs are known to contribute to the systemic pool of AGEs. Once they bind to RAGE, the activation of multiple and crucial signaling pathways are triggered, thus favoring the secretion of several proinflammatory cytokines also involved in the promotion of gallbladder cancer invasion and migration. In the present review, we aimed to highlight the relevance of the association between high dietary AGEs intakes and high risk for gallbladder cancer, and emerging data supporting that dietary intervention to reduce gallbladder cancer risk is a very attractive approach that deserves much more research efforts.

High Molecular Weight Fucoidan Restores Intestinal Integrity by Regulating Inflammation and Tight Junction Loss Induced by Methylglyoxal-Derived Hydroimidazolone-1

Fucoidan from brown seaweeds has several biological effects, including preserving intestinal integrity. To investigate the intestinal protective properties of high molecular weight fucoidan (HMWF) from Undaria pinnatifida on intestinal integrity dysfunction caused by methylglyoxal-derived hydroimidazolone-1 (MG-H1), one of the dietary advanced-glycation end products (dAGEs) in the human-colon carcinoma-cell line (Caco-2) cells and ICR mice. According to research, dAGEs may damage the intestinal barrier by increasing gut permeability. The findings of the study showed that HMWF + MG-H1 treatment reduced by 16.8% the amount of reactive oxygen species generated by MG-H1 treatment alone. Furthermore, HMWF + MGH-1 treatment reduced MG-H1-induced monolayer integrity disruption, as measured by alterations in transepithelial electrical resistance (135% vs. 75.5%) and fluorescein isothiocyanate incorporation (1.40 × 10^-6 cm/s vs. 3.80 cm/s). HMWF treatment prevented the MG-H1-induced expression of tight junction markers, including zonula occludens-1, occludin, and claudin-1 in Caco-2 cells and mouse colon tissues at the mRNA and protein level. Also, in Caco-2 and MG-H1-treated mice, HMWF plays an important role in preventing receptor for AGEs (RAGE)-mediated intestinal damage. In addition, HMWF inhibited the nuclear factor kappa B activation and its target genes leading to intestinal inflammation. These findings suggest that HMWF with price competitiveness could play an important role in preventing AGEs-induced intestinal barrier dysfunction.

Contribution of Advanced Glycation End Products to PCOS Key Elements: A Narrative Review

In the last decade, data has suggested that dietary advanced glycation end products (AGEs) play an important role in both reproductive and metabolic dysfunctions associated with polycystic ovary syndrome (PCOS). AGEs are highly reactive molecules that are formed by the non-enzymatic glycation process between reducing sugars and proteins, lipids, or nucleic acids. They can be formed endogenously under normal metabolic conditions or under abnormal situations such as diabetes, renal disease, and other inflammatory disorders. Bodily AGEs can also accumulate from exogenous dietary sources particularly when ingested food is cooked and processed under high-temperature conditions, such as frying, baking, or grilling. Women with PCOS have elevated levels of serum AGEs that are associated with insulin resistance and obesity and that leads to a high deposition of AGEs in the ovarian tissue causing anovulation and hyperandrogenism. This review will describe new data relevant to the role of AGEs in several key elements of PCOS phenotype and pathophysiology. Those elements include ovarian dysfunction, hyperandrogenemia, insulin resistance, and obesity. The literature findings to date suggest that targeting AGEs and their cellular actions could represent a novel approach to treating PCOS symptoms.

Advanced Glycation End Products (AGEs) and Chronic Kidney Disease: Does the Modern Diet AGE the Kidney?

Since the 1980s, chronic kidney disease (CKD) affecting all ages has increased by almost 25%. This increase may be partially attributable to lifestyle changes and increased global consumption of a “western” diet, which is typically energy dense, low in fruits and vegetables, and high in animal protein and ultra-processed foods. These modern food trends have led to an increase in the consumption of advanced glycation end products (AGEs) in conjunction with increased metabolic dysfunction, obesity and diabetes, which facilitates production of endogenous AGEs within the body. When in excess, AGEs can be pathological via both receptor-mediated and non-receptor-mediated pathways. The kidney, as a major site for AGE clearance, is particularly vulnerable to AGE-mediated damage and increases in circulating AGEs align with risk of CKD and all-cause mortality. Furthermore, individuals with significant loss of renal function show increased AGE burden, particularly with uraemia, and there is some evidence that AGE lowering via diet or pharmacological inhibition may be beneficial for CKD. This review discusses the pathways that drive AGE formation and regulation within the body. This includes AGE receptor interactions and pathways of AGE-mediated pathology with a focus on the contribution of diet on endogenous AGE production and dietary AGE consumption to these processes. We then analyse the contribution of AGEs to kidney disease, the evidence for dietary AGEs and endogenously produced AGEs in driving pathogenesis in diabetic and non-diabetic kidney disease and the potential for AGE targeted therapies in kidney disease.

A 4-Week Diet Low or High in Advanced Glycation Endproducts Has Limited Impact on Gut Microbial Composition in Abdominally Obese Individuals: The deAGEing Trial

Dietary advanced glycation endproducts (AGEs), abundantly present in Westernized diets, are linked to negative health outcomes, but their impact on the gut microbiota has not yet been well investigated in humans. We investigated the effects of a 4-week isocaloric and macronutrient-matched diet low or high in AGEs on the gut microbial composition of 70 abdominally obese individuals in a double-blind parallel-design randomized controlled trial (NCT03866343). Additionally, we investigated the cross-sectional associations between the habitual intake of dietary dicarbonyls, reactive precursors to AGEs, and the gut microbial composition, as assessed by 16S rRNA amplicon-based sequencing. Despite a marked percentage difference in AGE intake, we observed no differences in microbial richness and the general community structure. Only the Anaerostipes spp. had a relative abundance >0.5% and showed differential abundance (0.5 versus 1.11%; p = 0.028, after low- or high-AGE diet, respectively). While the habitual intake of dicarbonyls was not associated with microbial richness or a general community structure, the intake of 3-deoxyglucosone was especially associated with an abundance of several genera. Thus, a 4-week diet low or high in AGEs has a limited impact on the gut microbial composition of abdominally obese humans, paralleling its previously observed limited biological consequences. The effects of dietary dicarbonyls on the gut microbiota composition deserve further investigation.

Plasma Levels of Free NƐ-Carboxymethyllysine (CML) after Different Oral Doses of CML in Rats and after the Intake of Different Breakfasts in Humans: Postprandial Plasma Level of sRAGE in Humans

N-carboxymethyl-lysine (CML) and other dietary advanced glycation end-products (AGEs) are chemically modified amino acids with potential toxicological effects putatively related to their affinity with the receptor for AGEs (RAGE). The goal of this study was to determine the postprandial kinetics of CML in both rodents and humans and, in the latter, to evaluate their relationship with the soluble RAGE isoforms (sRAGE). Four gavage solutions containing different forms of CML were given to rats, and blood was collected over 8 h. Three different breakfasts containing dietary CML (dCML) were administered to 20 healthy volunteers, and blood was collected over 2 h. Concentrations of CML, CEL, and lysine were quantified in plasma and human meals by LC-MS/MS, and sRAGE was determined in human plasma by ELISA. The results showed that dCML did not affect the concentrations of circulating protein-bound CML and that only free CML increased in plasma, with a postprandial peak at 90 to 120 min. In humans, the postprandial plasmatic sRAGE concentration decreased independently of the dAGE content of the breakfasts. This study confirms reports of the inverse postprandial relationship between plasmatic free CML and sRAGE, though this requires further investigation for causality to be established.

Differences in kinetics and dynamics of endogenous versus exogenous advanced glycation end products (AGEs) and their precursors

Advanced glycation end products (AGEs) and their precursors, referred to as glycation products, are a heterogenous group of compounds being associated with adverse health effects. They are formed endogenously and in exogenous sources including food. This review investigates the roles of endogenously versus exogenously formed glycation products in the potential induction of adverse health effects, focusing on differences in toxicokinetics and toxicodynamics, which appeared to differ depending on the molecular mass of the glycation product. Based on the available data, exogenous low molecular mass (LMM) glycation products seem to be bioavailable and to contribute to dicarbonyl stress and protein cross-linking resulting in formation of endogenous AGEs. Bioavailability of exogenous high molecular mass (HMM) glycation products appears limited, while these bind to the AGE receptor (RAGE), initiating adverse health effects. Together, this suggests that RAGE-binding in relevant tissues will more likely result from endogenously formed glycation products. Effects on gut microbiota induced by glycation products is proposed as a third mode of action. Overall, studies which better discriminate between LMM and HMM glycation products and between endogenous and exogenous formation are needed to further elucidate the contributions of these different types and sources of glycation products to the ultimate biological effects.

A 4-week high-AGE diet does not impair glucose metabolism and vascular function in obese individuals

BACKGROUND

Accumulation of advanced glycation endproducts (AGEs) may contribute to the pathophysiology of type 2 diabetes and its vascular complications. AGEs are widely present in food, but whether restricting AGE intake improves risk factors for type 2 diabetes and vascular dysfunction is controversial.

METHODS

Abdominally obese but otherwise healthy individuals were randomly assigned to a specifically designed 4-week diet low or high in AGEs in a double-blind, parallel design. Insulin sensitivity, secretion, and clearance were assessed by a combined hyperinsulinemic-euglycemic and hyperglycemic clamp. Micro- and macrovascular function, inflammation, and lipid profiles were assessed by state-of-the-art in vivo measurements and biomarkers. Specific urinary and plasma AGEs N^ε-(carboxymethyl)lysine (CML), N^ε-(1-carboxyethyl)lysine (CEL), and N^δ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) were assessed by mass spectrometry.

RESULTS

In 73 individuals (22 males, mean ± SD age and BMI 52 ± 14 years, 30.6 ± 4.0 kg/m²), intake of CML, CEL, and MG-H1 differed 2.7-, 5.3-, and 3.7-fold between the low- and high-AGE diets, leading to corresponding changes of these AGEs in urine and plasma. Despite this, there was no difference in insulin sensitivity, secretion, or clearance; micro- and macrovascular function; overall inflammation; or lipid profile between the low and high dietary AGE groups (for all treatment effects, P > 0.05).

CONCLUSION

This comprehensive RCT demonstrates very limited biological consequences of a 4-week diet low or high in AGEs in abdominally obese individuals.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT03866343; trialregister.nl, NTR7594.

FUNDING

Diabetesfonds and ZonMw.

The impact of a modified carbohydrate formula, and its constituents, on glycaemic control and inflammatory markers: A nested mechanistic sub-study

BACKGROUND

Hyperglycaemia occurs frequently in the critically ill. Dietary intake of advanced glycation end-products (AGEs), specifically Nε-(carboxymethyl)lysine (CML), may exacerbate hyperglycaemia through perturbation of insulin sensitivity. The present study aimed to determine whether the use of nutritional formulae, with varying AGE loads, affects the amount of insulin administered and inflammation.

METHODS

Exclusively tube fed patients (n = 35) were randomised to receive Nutrison Protein Plus Multifibre®, Diason® or Glucerna Select®. Insulin administration was standardised according to protocol based on blood glucose (<10 mmol L^-1 ). Samples were obtained at randomisation and 48 h later. AGEs in nutritional formula, plasma and urine were measured using mass spectrometry. Plasma inflammatory markers were measured using an enzyme-linked immunosorbent assay and multiplex bead-based assays.

RESULTS

AGE concentrations of CML in nutritional formulae were greatest with delivery of Nutrison Protein Plus® (mean [SD]; 6335 pmol mol^-1 [2436]) compared to Diason® (4836 pmol mol^-1 [1849]) and Glucerna Select® (4493 pmol mol^-1 [1829 pmol mol^-1 ]) despite patients receiving similar amounts of energy (median [interquartile range]; 12 MJ [8.2-13.7 MJ], 11.5 MJ [8.3-14.5 MJ], 11.5 MJ [8.3-14.5 MJ]). More insulin was administered with Nutrison Protein Plus® (2.47 units h^-1 [95% confidence interval (CI) = 1.57-3.37 units h^-1 ]) compared to Diason® (1.06 units h^-1 [95% CI = 0.24-1.89 units h^-1 ]) or Glucerna Select® (1.11 units h^-1 [95% CI = 0.25-1.97 units h^-1 ]; p = 0.04). Blood glucose concentrations were similar. There were associations between greater insulin administration and reductions in circulating interleukin-6 (r = -0.46, p < 0.01), tumour necrosis factor-α (r = -0.44, p < 0.05), high sensitivity C-reactive protein (r = -0.42, p < 0.05) and soluble receptor for advanced glycation end-products (r = -0.45, p < 0.01) concentrations.

CONCLUSIONS

The administration of greater AGE load in nutritional formula potentially increases the amount of insulin required to maintain blood glucose within a normal range during critical illness. There was an inverse relationship between exogenous insulin and plasma inflammatory markers.

Metabolic Disease Programming: From Mitochondria to Epigenetics, Glucocorticoid Signalling and Beyond

Embryonic and foetal development are critical periods of development in which several environmental cues determine health and disease in adulthood. Maternal conditions and an unfavourable intrauterine environment impact foetal development and may programme the offspring for increased predisposition to metabolic diseases and other chronic pathologic conditions throughout adult life. Previously, non-communicable chronic diseases were only associated with genetics and lifestyle. Now the origins of non-communicable chronic diseases are associated with early-life adaptations that produce long-term dysfunction. Early-life environment sets the long-term health and disease risk and can span through multiple generations. Recent research in developmental programming aims at identifying the molecular mechanisms responsible for developmental programming outcomes that impact cellular physiology and trigger adulthood disease. The identification of new therapeutic targets can improve offspring's health management and prevent or overcome adverse consequences of foetal programming. This review summarizes recent biomedical discoveries in the Developmental Origins of Health and Disease (DOHaD) hypothesis and highlight possible developmental programming mechanisms, including prenatal structural defects, metabolic (mitochondrial dysfunction, oxidative stress, protein modification), epigenetic and glucocorticoid signalling-related mechanisms suggesting molecular clues for the causes and consequences of programming of increased susceptibility of offspring to metabolic disease after birth. Identifying mechanisms involved in DOHaD can contribute to early interventions in pregnancy or early childhood, to re-set the metabolic homeostasis and break the chain of subsequent events that could lead to the development of disease.

Habitual intake of dietary advanced glycation end products is not associated with generalized microvascular function-the Maastricht Study

BACKGROUND

Endogenously formed advanced glycation end products (AGEs) may be important drivers of microvascular dysfunction and the microvascular complications of diabetes. AGEs are also formed in food products, especially during preparation methods involving dry heat.

OBJECTIVES

We aimed to assess cross-sectional associations between dietary AGE intake and generalized microvascular function in a population-based cohort.

METHODS

In 3144 participants of the Maastricht Study (mean ± SD age: 60 ± 8 y, 51% men) the dietary AGEs Nε-(carboxymethyl)lysine (CML), Nε-(1-carboxyethyl)lysine (CEL), and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) were estimated using the combination of our ultra-performance LC-tandem MS dietary AGE database and an FFQ. Microvascular function was determined in the retina as flicker light-induced arteriolar and venular dilation and as central retinal arteriolar and venular equivalents, in plasma as a z score of endothelial dysfunction biomarkers (soluble vascular adhesion molecule 1 and soluble intracellular adhesion molecule 1, soluble E-selectin, and von Willebrand factor), in skin as the heat-induced skin hyperemic response, and in urine as 24-h albuminuria. Associations were evaluated using multiple linear regression adjusting for demographic, cardiovascular, lifestyle, and dietary factors.

RESULTS

Overall, intakes of CML, CEL, and MG-H1 were not associated with the microvascular outcomes. Although higher intake of CEL was associated with higher flicker light-induced venular dilation (β percentage change over baseline: 0.14; 95% CI: 0.02, 0.26) and lower plasma biomarker z score (β: -0.04 SD; 95% CI: -0.08, -0.00 SD), the effect sizes were small and their biological relevance can be questioned.

CONCLUSIONS

We did not show any strong association between habitual intake of dietary AGEs and generalized microvascular function. The contribution of dietary AGEs to generalized microvascular function should be further assessed in randomized controlled trials using specifically designed dietary interventions.

Deletion of RAGE fails to prevent hepatosteatosis in obese mice due to impairment of other AGEs receptors and detoxifying systems

Advanced glycation endproducts (AGEs) are involved in several diseases, including NAFLD and NASH. RAGE is the main receptor mediating the pro-inflammatory signalling induced by AGEs. Therefore, targeting of RAGE has been proposed for prevention of chronic inflammatory diseases. However, the role of RAGE in the development of NAFLD and NASH remains poorly understood. We thus aimed to analyse the effect of obesity on AGEs accumulation, AGE-receptors and AGE-detoxification, and whether the absence of RAGE might improve hepatosteatosis and inflammation, by comparing the liver of lean control, obese (LeptrDb-/-) and obese RAGE-deficient (RAGE-/- LeptrDb-/-) mice. Obesity induced AGEs accumulation and RAGE expression with hepatosteatosis and inflammation in LeptrDb-/-, compared to lean controls. Despite the genetic deletion of RAGE in the LeptrDb-/- mice, high levels of intrahepatic AGEs were maintained accompanied by decreased expression of the protective AGE-receptor-1, impaired AGE-detoxifying system glyoxalase-1, and increased expression of the alternative AGE-receptor galectin-3. We also found sustained hepatosteatosis and inflammation as determined by persistent activation of the lipogenic SREBP1c and proinflammatory NLRP3 signalling pathways. Thus, RAGE targeting is not effective in the prevention of NAFLD in conditions of obesity, likely due to the direct liver specific crosstalk of RAGE with other AGE-receptors and AGE-detoxifying systems.

Short Duration Alagebrium Chloride Therapy Prediabetes Does Not Inhibit Progression to Autoimmune Diabetes in an Experimental Model

Mechanisms by which advanced glycation end products (AGEs) contribute to type 1 diabetes (T1D) pathogenesis are poorly understood. Since life-long pharmacotherapy with alagebrium chloride (ALT) slows progression to experimental T1D, we hypothesized that acute ALT therapy delivered prediabetes, may be effective. However, in female, non-obese diabetic (NODShiLt) mice, ALT administered prediabetes (day 50-100) did not protect against experimental T1D. ALT did not decrease circulating AGEs or their precursors. Despite this, pancreatic β-cell function was improved, and insulitis and pancreatic CD45.1+ cell infiltration was reduced. Lymphoid tissues were unaffected. ALT pre-treatment, prior to transfer of primed GC98 CD8+ T cell receptor transgenic T cells, reduced blood glucose concentrations and delayed diabetes, suggesting islet effects rather than immune modulation by ALT. Indeed, ALT did not reduce interferon-γ production by leukocytes from ovalbumin-pre-immunised NODShiLt mice and NODscid recipients given diabetogenic ALT treated NOD splenocytes were not protected against T1D. To elucidate β-cell effects, NOD-derived MIN6N8 β-cell major histocompatibility complex (MHC) Class Ia surface antigens were examined using immunopeptidomics. Overall, no major changes in the immunopeptidome were observed during the various treatments with all peptides exhibiting allele specific consensus binding motifs. As expected, longer MHC Class Ia peptides were captured bound to H-2Db than H-2Kb under all conditions. Moreover, more 10-12 mer peptides were isolated from H-2Db after AGE modified bovine serum albumin (AGE-BSA) treatment, compared with bovine serum albumin (BSA) or AGE-BSA+ALT treatment. Proteomics of MIN6N8 cells showed enrichment of processes associated with catabolism, the immune system, cell cycling and presynaptic endocytosis with AGE-BSA compared with BSA treatments. These data show that short-term ALT intervention, given prediabetes, does not arrest experimental T1D but transiently impacts β-cell function.

Dietary advanced glycation endproducts (AGEs) increase their concentration in plasma and tissues, result in inflammation and modulate gut microbial composition in mice; evidence for reversibility

SCOPE

Dietary advanced glycation endproducts (AGEs) are associated with negative biological effects, possibly due to accumulation in plasma and tissues and through modulation of inflammation and gut microbiota. Whether these biological consequences are reversible by limiting dietary AGE intake is unknown.

METHODS AND RESULTS

Young healthy C57BL/6 mice were fed a standard chow (n = 10) or a baked chow high AGE-diet (n = 10) (~1.8-6.9 fold increased protein-bound Nε-(carboxymethyl)lysine (CML), Nε-(1-carboxyethyl)lysine (CEL), and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1)) for 10 weeks or a switch diet with baked chow for 5 weeks followed by 5 weeks of standard chow (n = 10). We assessed accumulation of AGEs in plasma, kidney, and liver and measured inflammatory markers and gut microbial composition. After 10 weeks of baked chow, a substantial panel of AGEs were increased in plasma, liver, and kidney. These increases were normalized after the switch diet. The inflammatory z-score increased after the baked chow diet. Gut microbial composition differed significantly between groups, with enriched Dubosiella spp. dominating these alterations.

CONCLUSION

A high AGE-diet led to an increase of AGEs in plasma, kidney, and liver and to more inflammation and modification of the gut microbiota. These effects were reversed or discontinued by a diet lower in AGEs.

Early AGEing and metabolic diseases: is perinatal exposure to glycotoxins programming for adult-life metabolic syndrome?

Perinatal early nutritional disorders are critical for the developmental origins of health and disease. Glycotoxins, or advanced glycation end-products, and their precursors such as the methylglyoxal, which are formed endogenously and commonly found in processed foods and infant formulas, may be associated with acute and long-term metabolic disorders. Besides general aspects of glycotoxins, such as their endogenous production, exogenous sources, and their role in the development of metabolic syndrome, we discuss in this review the sources of perinatal exposure to glycotoxins and their involvement in metabolic programming mechanisms. The role of perinatal glycotoxin exposure in the onset of insulin resistance, central nervous system development, cardiovascular diseases, and early aging also are discussed, as are possible interventions that may prevent or reduce such effects.

From diabetes to renal aging: the therapeutic potential of adiponectin

Nowadays, the complications related to diabetes, such as nephropathy, cardiovascular problems, and aging, are highly being considered. Renal cell aging is affected by various mechanisms of inflammation, oxidative stress, and basement membrane thickening, which are significant causes of renal dysfunction in diabetes. Due to recent studies, adiponectin plays a key role in diabetes-related kidney diseases as a fat-derived hormone. In diabetes, reduced adiponectin levels are associated to renal cell aging. Oxidative stress and related signaling pathways are the main routes in which adiponectin may be effective to decline diabetes-associated aging. Therefore, adiponectin signaling in target tissues becomes one of the research areas of interest in metabolism and clinical medicine. Studies on adiponectin signaling will increase our understanding of adiponectin role in diabetes-linked diseases as well as shortening life span conditions which may guide the design of antidiabetic and anti-aging drugs.

Impact of ultra-processed food consumption on metabolic health

PURPOSE OF REVIEW

Ultra-processed foods (UPF) have been associated with poor diet quality and adverse health outcomes. Our aim in this review is to summarize recent research assessing the impact of UPF consumption, classified according to the NOVA system, on outcomes related to metabolic health.

RECENT FINDINGS

Thirty recent studies with different design, quality and target population have investigated the impact of UPF consumption on parameters related to metabolic health, which were organized into: metabolic syndrome; body weight change and obesity indicators; blood pressure and hypertension; glucose profile, insulin resistance and type 2 diabetes; other metabolic risks and cardiovascular diseases and mortality. Most of the studies demonstrated adverse associations between high UPF consumption and metabolic health, mainly those with robust design and involving adults.

SUMMARY

Most of the latest findings have revealed an adverse impact of high UPF consumption on metabolic health, including cardiovascular diseases and mortality. Scientific evidence is accumulating towards the necessity of curbing UPF consumption worldwide at different life stages. Nevertheless, other studies are needed to confirm the causality between UPF consumption and metabolic health in diverse scenarios and to better elucidate all likely mechanisms involved in this relationship.

Risk and Benefit of Natural and Commercial Dark Brown Sugars as Evidenced by Phenolic and Maillard Reaction Product Contents

Products of dark brown sugar (DBS) from different production processes and raw materials may bring different risks and benefits to human health. Therefore, this study was aimed to evaluate the quality of natural and commercial DBS products. Results showed that physicochemical properties, including pH value, turbidity, and browning degree have no significant difference between natural and commercial DBS products. Total flavonoid content of natural DBS was found to be significantly higher than that of commercial DBS (p < 0.05). Notably, the levels of harmful Maillard reaction products in natural DBS were significantly lower than that in commercial DBS as evidenced by analyses of methylglyoxal and fluorescent advanced glycation end products (p < 0.05). However, the amount of acrylamide in natural DBS was significantly higher than that in commercial DBS. In conclusion, this study provides useful information for risk-benefit assessment of DBS products, which is helpful for food safety management.

The impact of low advanced glycation end products diet on obesity and related hormones: a systematic review and meta-analysis

Several randomized clinical trials (RCTs) have investigated the effect of dietary advanced glycation end products (AGE) on obesity factors and related hormones in adults; results were conflicting. Therefore, a study was performed to assess the effect of low advanced glycation end products diet on obesity and related hormones. A comprehensive literature search without any limitation on language was conducted using the following bibliographical databases: Web of Science, Scopus, Ovid MEDLINE, Cochrane, and Embase up to October, 2019. From the eligible trials, 13 articles were selected for the systematic review and meta-analysis. Our systematic reviews and meta-analyses have shown a significant decrease in BMI (WMD: − 0.3 kg/m²; 95% CI: − 0.52, − 0.09, p = 0.005; I² = 55.8%), weight (WMD: − 0.83 kg; 95% CI: − 1.55, − 0.10, p = 0.026; I² = 67.0%), and leptin (WMD: − 19.85 ng/ml; 95% CI: − 29.88, − 9.82, p < 0.001; I² = 81.8%) and an increase in adiponectin (WMD: 5.50 µg/ml; 95% CI: 1.33, 9.67, p = 0.010; I² = 90.6%) levels after consumption of the low AGE diets compared to the high AGE diets. Also, the effect of intake of low AGE compared to high AGE diets was more pronounced in subgroup with duration > 8 weeks for the BMI and weight. Overall, according to our results, although low AGE diets appeared to be statistically significant in reducing the prevalence of obesity and chronic diseases compared to high consumption of dietary AGEs. But, no clinical significance was observed. Therefore, to confirm these results clinically, further prospective studies should be conducted in this regard. The study protocol was registered in the in International prospective register of systematic reviews (PROSPERO) database as CRD42020203734.

The potential role of dietary advanced glycation endproducts in the development of chronic non-infectious diseases: a narrative review

Increasing clinical and experimental evidence accumulated during the past few decades supports an important role for dietary advanced glycation endproducts (AGE) in the pathogenesis of many chronic non-infectious diseases, such as type 2 diabetes, CVD and others, that are reaching epidemic proportions in the Western world. Although AGE are compounds widely recognised as generated in excess in the body in diabetic patients, the potential importance of exogenous AGE, mostly of dietary origin, has been largely ignored in the general nutrition audience. In the present review we aim to describe dietary AGE, their mechanisms of formation and absorption into the body as well as their main mechanisms of action. We will present in detail current evidence of their potential role in the development of several chronic non-infectious clinical conditions, some general suggestions on how to restrict them in the diet and evidence regarding the potential benefits of lowering their consumption.

The Impact of Low Advanced Glycation End Products Diet on Metabolic Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Several randomized clinical trials have investigated the effect of dietary advanced glycation end products (AGEs) on metabolic syndrome risk factors in adults. However, the results of these studies were conflicting. Therefore, our aim was to assess the effect of dietary AGEs on metabolic syndrome risk factors. We searched the PubMed-MEDLINE, Scopus, Cochrane Databases, Google Scholar, Web of Science, and Embase databases for papers published up to October 2019 that investigated the effect of dietary AGEs on metabolic syndrome risk factors. From the eligible trials, 13 articles were selected for inclusion in this systematic review and meta-analysis. The meta-analysis was performed using a random-effects model. Heterogeneity was determined by I2 statistics and Cochrane Q test. Pooled results from the random-effects model showed a significant reduction for insulin resistance [weighted mean difference (WMD): -1.204; 95% CI: -2.057, -0.358; P = 0.006], fasting insulin (WMD: -5.472 μU/mL; 95% CI: -9.718, -1.234 μU/mL; P = 0.011), total cholesterol (WMD: -5.486 mg/dL; 95% CI: -10.222, -0.747 mg/dL; P = 0.023), and LDL (WMD: -6.263 mg/dL; 95% CI: -11.659, -0.866 mg/dL; P = 0.023) in the low-AGEs groups compared with the high-AGEs groups. There were no changes in the other components of the metabolic syndrome. The results of this review suggest that a diet with a low AGEs content has beneficial effects on insulin resistance, fasting insulin, total cholesterol, and LDL. Moreover, following a diet low in AGEs may be a helpful strategy to decrease the burden of metabolic syndrome risk factors in adults and particularly in patients with diabetes.

Lifestyle interventions for the prevention and treatment of hypertension

Hypertension affects approximately one third of the world's adult population and is a major cause of premature death despite considerable advances in pharmacological treatments. Growing evidence supports the use of lifestyle interventions for the prevention and adjuvant treatment of hypertension. In this Review, we provide a summary of the epidemiological research supporting the preventive and antihypertensive effects of major lifestyle interventions (regular physical exercise, body weight management and healthy dietary patterns), as well as other less traditional recommendations such as stress management and the promotion of adequate sleep patterns coupled with circadian entrainment. We also discuss the physiological mechanisms underlying the beneficial effects of these lifestyle interventions on hypertension, which include not only the prevention of traditional risk factors (such as obesity and insulin resistance) and improvements in vascular health through an improved redox and inflammatory status, but also reduced sympathetic overactivation and non-traditional mechanisms such as increased secretion of myokines.

Dietary intake of advanced glycation end products (AGEs) and changes in body weight in European adults

PURPOSE

Advanced glycation end products (AGEs) can be formed in foods by the reaction of reducing sugars with proteins, and have been shown to induce insulin resistance and obesity in experimental studies. We examined the association between dietary AGEs intake and changes in body weight in adults over an average of 5 years of follow-up.

METHODS

A total of 255,170 participants aged 25-70 years were recruited in ten European countries (1992-2000) in the PANACEA study (Physical Activity, Nutrition, Alcohol, Cessation of smoking, Eating out of home in relation to Anthropometry), a sub-cohort of the EPIC (European Prospective Investigation into Cancer and Nutrition). Body weight was measured at recruitment and self-reported between 2 and 11 years later depending on the study center. A reference database for AGEs was used containing UPLC-MS/MS-measured Nε-(carboxymethyl)-lysine (CML), Nε-(1-carboxyethyl)-lysine (CEL), and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) in 200 common European foods. This reference database was matched to foods and decomposed recipes obtained from country-specific validated dietary questionnaires in EPIC and intake levels of CEL, CML, and MG-H1 were estimated. Associations between dietary AGEs intake and body weight change were estimated separately for each of the three AGEs using multilevel mixed linear regression models with center as random effect and dietary AGEs intake and relevant confounders as fixed effects.

RESULTS

A one-SD increment in CEL intake was associated with 0.111 kg (95% CI 0.087-0.135) additional weight gain over 5 years. The corresponding additional weight gain for CML and MG-H1 was 0.065 kg (0.041-0.089) and 0.034 kg (0.012, 0.057), respectively. The top six food groups contributing to AGEs intake, with varying proportions across the AGEs, were cereals/cereal products, meat/processed meat, cakes/biscuits, dairy, sugar and confectionary, and fish/shellfish.

CONCLUSION

In this study of European adults, higher intakes of AGEs were associated with marginally greater weight gain over an average of 5 years of follow-up.

Circulating Levels of the Soluble Receptor for AGE (sRAGE) during Escalating Oral Glucose Dosages and Corresponding Isoglycaemic i.v. Glucose Infusions in Individuals with and without Type 2 Diabetes

Postprandial glucose excursions are postulated to increase the risk for diabetes complications via the production of advanced glycation end products (AGEs). The soluble receptor of AGEs (sRAGE) likely acts as a decoy receptor, mopping up AGEs, diminishing their capacity for pro-inflammatory and pro-apoptotic signaling. Recent evidence suggests that AGEs and soluble receptor for AGEs (sRAGE) may be altered under postprandial and fasting conditions. Here, we investigated the effects of increasing oral glucose loads during oral glucose tolerance tests (OGTT) and matched isoglycaemic intravenous (i.v.) glucose infusions (IIGI) on circulating concentrations of sRAGE. Samples from eight individuals with type 2 diabetes and eight age-, gender-, and body mass index (BMI)-matched controls, all of whom underwent three differently dosed OGTTs (25 g, 75 g, and 125 g), and three matched IIGIs were utilised (NCT00529048). Serum concentrations of sRAGE were measured over 240 min during each test. For individuals with diabetes, sRAGE area under the curve (AUC_0–240min) declined with increasing i.v. glucose dosages (p < 0.0001 for trend) and was lower during IIGI compared to OGTT at the 125 g dosage (p = 0.004). In control subjects, sRAGE AUC_0–240min was only lower during IIGI compared to OGTT at the 25 g dose (p = 0.0015). sRAGE AUC_0–240min was negatively correlated to AUC_0–240min for the incretin hormone glucagon-like peptide −1 (GLP-1) during the 75 g OGTT and matched IIGI, but only in individuals with type 2 diabetes. These data suggest that gastrointestinal factors may play a role in regulating sRAGE concentrations during postprandial glucose excursions, thus warranting further investigation.

Serum Soluble Receptor for AGE (sRAGE) Levels Are Associated With Unhealthy Lifestyle and Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) has been demonstrated to be positively associated with serum advanced glycation end products (AGEs) and negatively with soluble receptor for AGE (sRAGE) in a few small studies. We aimed to test the association between lifestyle and sRAGE levels and the association between sRAGE levels or AGEs intake and NAFLD, insulin resistance (IR), and elevated alanine aminotransferase (ALT).

Differential Effects of Dietary Patterns on Advanced Glycation end Products: A Randomized Crossover Study

Dietary advanced glycation end products (AGEs) are believed to contribute to pathogenesis of diabetes and cardiovascular disease. The objective of this study was to determine if a diet high in red and processed meat and refined grains (HMD) would elevate plasma concentrations of protein-bound AGEs compared with an energy-matched diet high in whole grain, dairy, nuts and legumes (HWD). We conducted a randomized crossover trial with two 4-week weight-stable dietary interventions in 51 participants without type 2 diabetes (15 men and 36 women aged 35.1 ± 15.6 y; body mass index (BMI), 27.7 ± 6.9 kg/m²). Plasma concentrations of protein-bound Nε-(carboxymethyl) lysine (CML), Nε-(1-carboxyethyl) lysine (CEL) and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) were measured by liquid chromatography–tandem mass spectrometry (LC-MS/MS). The HMD significantly increased plasma concentrations (nmol/mL) of CEL (1.367, 0.78 vs. 1.096, 0.65; p < 0.01; n = 48) compared with the HWD. No differences in CML and MG-H1 between HMD and HWD were observed. HMD increased plasma CEL concentrations compared with HWD in individuals without type 2 diabetes.

Can advanced glycation end-products and their receptors be affected by weight loss? A systematic review

Advanced glycation end products (AGEs) have been implicated in the pathogenesis of most chronic diseases. Therefore, identification of treatments that can attenuate the effects of these compounds and prevent cardiometabolic complications is of extreme public health interest. Recently, body weight management interventions showed positive results on reducing serum AGE concentrations. Moreover, the soluble receptor for advanced glycation end products (sRAGE) is considered to be a novel biomarker to identify patients with obesity most likely to benefit from weight management interventions. This systematic review aimed to critically analyze papers evaluating the effects of weight loss on serum AGEs and its receptors in adults with excess body weight. MEDLINE, Cochrane, Scopus, and Lilacs databases were searched. Three studies evaluating the response of AGEs to energy-restricted diets and six assessing sRAGE as the primary outcome were included. Energy-restricted diets and bariatric surgery reduced serum AGE concentrations, but effects on endogenous secretory RAGE (esRAGE) and sRAGE concentrations are conflicting. These results may be associated with mechanisms related to changes in dietary intake and limiting endogenous AGE formation. Therefore, the role of energy-restricted diets and bariatric surgery on lowering serum AGE concentrations, as well as its effects on AGEs receptors, deserves further investigation.

Combination of Naringenin and Lisinopril Ameliorates Nephropathy in Type-1 Diabetic Rats

BACKGROUND

Diabetes is a metabolic disorder affecting a large percentage of the population worldwide. The chronic hyperglycemic condition leads to the generation of advanced glycation end products, reactive oxygen species and inflammatory cytokines, which worsen the functioning of the kidney. Clinical management of diabetic nephropathy is difficult as it requires a multi-focused approach. Hence, a combination of lisinopril a drug used in clinical practice for nephropathy, and naringenin, a flavonoid reported to have a significant effect in nephropathy, may show additive or synergistic effect with less side effects.

OBJECTIVE

The objective of the present study was to evaluate the effect of a combination of lisinopril with naringenin in diabetic nephropathy.

METHODS

Diabetes was induced in male Sprague Dawley rats by streptozotocin (55 mg/kg, i.p.). After four weeks of diabetes induction animals were treated with naringenin alone and a combination of Lisinopril and naringenin for the next four weeks. At the end of the study, various urine and biochemical parameters were evaluated. Oxidative stress parameters like malondialdehyde, reduced glutathione; catalase and superoxide dismutase for kidney tissues were estimated and histopathology studies of kidneys were carried out.

RESULTS

The combination of lisinopril (10 mg/kg) and naringenin (25 and 50 mg/kg) treatment showed significant improvement in the biochemical and urine parameters. Combination treatment also attenuated renal oxidative stress and renal damage as observed in histopathological studies.

CONCLUSION

Treatment with a combination of lisinopril and naringenin showed a promising effect on diabetic nephropathy in rats.

The Role of Dietary Advanced Glycation End Products in Metabolic Dysfunction

Advanced glycation end products (AGEs) are a heterogeneous group of molecules produced, non-enzymatically, from the interaction between reducing sugars and the free amino groups of proteins, nucleic acids, and lipids. AGEs are formed as a normal consequence of metabolism but can also be absorbed from the diet. They have been widely implicated in the complications of diabetes affecting cardiovascular health, the nervous system, eyes, and kidneys. Increased levels of AGEs are also detrimental to metabolic health and may contribute to the metabolic abnormalities induced by the Western diet, which is high in processed foods and represents a significant source of AGEs. While increased AGE levels are a consequence of diabetic hyperglycaemia, AGEs themselves activate signaling pathways, which compromise insulin signaling and pancreatic β-cell function, thus, contributing to the development of type 2 diabetes mellitus (T2DM). Furthermore, AGEs may also contribute to the obesogenic effects of the Western diet by promoting hypothalamic inflammation and disrupting the central control of energy balance. Here, the role of dietary AGEs in metabolic dysfunction is reviewed with a focus on the mechanisms underpinning their detrimental role in insulin resistance, pancreatic β-cell dysfunction, hypothalamic control of energy balance, and the pathogenesis of T2DM and obesity.

Effect of reducing dietary advanced glycation end products on obesity-associated complications: a systematic review

CONTEXT

Consumption of dietary advanced glycation end products (AGEs) is associated with oxidative stress, inflammation, and other chronic conditions commonly associated with obesity.

OBJECTIVE

To analyze the effects of dietary AGEs on complications associated with obesity.

DATA SOURCES

This systematic review was conducted and reported according to PRISMA guidelines. The PubMed, Cochrane, and Scopus databases were searched, using the terms "advanced glycation end products," "overweight," and "obesity." The last search was performed in October 2018.

DATA EXTRACTION

Six studies that evaluated the effects of low-AGE and high-AGE diets were included in the review. The duration of the studies ranged from 1 day to 12 weeks. A comparison of all the compiled data was conducted by the authors.

DATA ANALYSIS

Circulating and urinary AGE markers, besides soluble receptor for AGEs, were considered as the primary outcomes. The secondary outcomes were cardiometabolic, inflammatory, glycemic, anthropometric, and renal markers.

CONCLUSIONS

AGE-RAGE interactions can activate the NF-κB (nuclear factor kappa B) signaling pathway and inhibit the PI3K-AKT pathway in adipocytes, which may explain their association with chronic diseases. This interaction can be considered as a novel explanation for the pathogenesis of obesity. AGEs can also be used as a biomarker for monitoring responses to dietary interventions in overweight and obese people.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42018082745.

Targeting the receptor for advanced glycation end products (RAGE) in type 1 diabetes

Type 1 diabetes (T1D) is one of the most common chronic diseases manifesting in early life, with the prevalence increasing worldwide at a rate of approximately 3% per annum. The prolonged hyperglycaemia characteristic of T1D upregulates the receptor for advanced glycation end products (RAGE) and accelerates the formation of RAGE ligands, including advanced glycation end products, high-mobility group protein B1, S100 calcium-binding proteins, and amyloid-beta. Interestingly, changes in the expression of RAGE and these ligands are evident in patients before the onset of T1D. RAGE signals via various proinflammatory cascades, resulting in the production of reactive oxygen species and cytokines. A large number of proinflammatory ligands that can signal via RAGE have been implicated in several chronic diseases, including T1D. Therefore, it is unsurprising that RAGE has become a potential therapeutic target for the treatment and prevention of disease. In this review, we will explore how RAGE might be targeted to prevent the development of T1D.

Relationship between minimally and ultra-processed food intake during pregnancy with obesity and gestational diabetes mellitus

This study aimed to investigate the relationship between food intake (considering the nature, extent, and purpose of food processing) during pregnancy and overweight, obesity, and gestational diabetes mellitus conditions. This is a cross-sectional study conducted among 785 adult women in singleton pregnancies (between 24th and 39th weeks of gestation) in Brazil. Usual food intake was estimated by the Multiple Source Method, using two 24-hour dietary recalls. The food groups of interest in this study were the unprocessed or minimally processed foods and ultra-processed foods. The World Health Organization criteria for the diagnosis of gestational diabetes mellitus and the Atalah criteria for excess weight were used. Adjusted multinomial logistic regression models were used to assess the relationship between energy contribution (%E) from foods with overweight and obesity conditions and, adjusted logistic regression models for gestational diabetes mellitus. In total, 32.1% participants were overweight, 24.6% were obese, and 17.7% of women were diagnosed with gestational diabetes mellitus . After adjustments, an inverse association between the highest tertile of %E from the intake of unprocessed or minimally processed foods and obesity was found [0.49 (0.30-0.79)]. Moreover, a positive association between the highest tertile of %E from ultra-processed food intake [3.06 (1.27-3.37)] and obesity was observed. No association between food intake (considering the nature, extent, and purpose of food processing) during pregnancy and overweight or gestational diabetes mellitus was found. The findings suggest a role of food processing in obesity but not in gestational diabetes mellitus. Further research is warranted to provide robust evidence on the relationship between the role of processed foods in obesity and gestational diabetes mellitus.