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

Advanced glycation end-product intake predicts insulin resistance in a sex-dependent fashion

PURPOSE

Dietary advanced glycation end products (AGEs) have been implicated in promoting insulin resistance. However, their impact on insulin resistance in a mixed population made up of males and females remains controversial. The aim of this study was to evaluate whether the relationship between dietary AGEs and insulin resistance may be sex-dependent.

METHODS

195 males and 239 females were included in this cross-sectional study. Study participants underwent anthropometric and metabolic assessments. AGE intake was estimated using food frequency questionnaires and databases reporting AGE content in individual food items. The relationship between AGE intake and insulin resistance, estimated using HOMA-IR, was assessed using Pearson correlation test. The predictive power of dietary AGEs towards HOMA-IR was investigated using stepwise linear regression.

RESULTS

AGE intake correlated positively with HOMA-IR in females (p < 0.01) but not in male study participants (p > 0.05). Moreover, AGE intake was able to increase the predictive power of BMI towards insulin resistance in females but not males. Instead, anthropometric variables were the only discriminants able to predict insulin resistance in males.

CONCLUSION

Dietary AGEs exert a sex-dependent effect on insulin resistance as their intake is associated with and able to predict HOMA-IR in females but not males. This suggests that females may be more susceptible to the deleterious impact of these glycotoxins on insulin sensitivity. Nevertheless, considering this study not involving a nutritional intervention to directly elucidate whether the effect of AGEs on insulin resistance is sex-dependent, further studies are warranted to confirm the present findings.

Effect of lutein supplementation on blood lipids and advanced glycation end products in adults with central obesity: a double-blind randomized controlled trial

Central obesity poses a significant health threat. Lutein-rich fruits and vegetables may help manage obesity. Limited evidence suggests that lutein exerts health effects by inhibiting advanced glycation end products (AGEs), but data on its effects in centrally obese individuals are sparse. Thus, we aimed to investigate the effects of lutein supplementation in subjects with central obesity. A double-blind, randomized controlled trial was conducted involving patients with central obesity. Anthropometric indices, dietary intake, metabolic parameters, carotenoid and AGEs levels were compared between those receiving a 32-week intervention of 10 mg d-1 lutein and a placebo group. There were 117 patients randomly assigned in the analysis. Twenty-three patients were lost to follow-up. Both intention-to-treat analysis and the per-protocol analysis showed significant reductions in plasma total cholesterol, low-density lipoprotein cholesterol, apolipoprotein B, and malonaldehyde levels in the lutein supplementation group compared with the placebo group. Significant differences were also observed between the groups in plasma lutein, carboxyethyl lysine (CEL), carboxymethyl lysine (CML), methylglyoxal hydroimidazolone (MG-HI) levels and skin carotenoid index (all P < 0.05). The mean difference and 95% confidence interval were 0.12 [0.08 to 0.16] μg ml-1, -8.76 [-16.60 to -0.89] ng ml-1, -72.3 [-134.0 to -10.9] ng ml-1, -233.9 [-429.0 to -36.8] ng ml-1 and 0.94 [0.56 to 1.31] a.u., respectively. Furthermore, changes in plasma lutein concentration were positively correlated with changes in the skin carotenoid index (r = 0.41, P < 0.001), and negatively correlated with changes in plasma CEL (r = -0.24, P = 0.018), (CML) (r = -0.21, P = 0.051, and MG-H1) (r = -0.25, P = 0.017). In conclusion, regular lutein intake can improve metabolic health in adults with central obesity by increasing plasma lutein concentrations, reducing oxidative stress, lowering plasma TC, LDL-C, and ApoB levels, and downregulating AGEs.

Effect of low vs high dietary-advanced glycation end products on insulin-sensitivity and inflammatory- markers among overweight/obese Asian-Indian adults-A randomised controlled trial

The present study investigated the effect of low vs high-dietary-Advanced Glycation End products-based diets on oral disposition index-(DIo)-a marker of islet β-cell function and cardiometabolic risks factors in 38-overweight and obese Asian Indian-adults (aged 25-45 years with body-mass-index (BMI) ≥23kg/m2) through 12-week isocaloric crossover feeding trial. Biochemical-measures included-glucose tolerance test (GTT), Insulin assay (0,30 and 120 min), lipid-profile, serum-adiponectin, serum-AGE and serum-Thiobarbituric acid reactive substances-(TBARS) assessed both at baseline and end of each intervention. Generalised linear models showed that low-dAGE diet significantly improved in oral disposition index [Least Square Mean (SE), +0.3 (0.1); p = 0.03] compared to high-dAGE diet. The low-dAGE diet also showed a significant reduction in 30-minutes plasmapost-glucose-challenge-value:(-8.1[3.8] (mg/dl) vs 3.8 [3.8] (mg/dl); p = 0.01), serum-AGEs-(-3.2 [0.2] (μg/ml) vs -0.8 [0.2] (μg/ml); p = <0.0001) compared to high-dAGE diet. In summary, low-dAGE diets exhibited improvement in the insulin-sensitivity and reduction in the inflammatory levels compared to high-dAGE diets. Hence, study first time in India revealed that low dAGE diets could be a potential strategy to reduce diabetes risk.

Dietary advanced glycation end products, body composition, and anthropometric measures: A cross-sectional analysis in women with excess body weight

BACKGROUND AND AIMS

To assess the association between dietary advanced glycation end products (dAGEs) versus body composition and anthropometric variables.

METHODS AND RESULTS

Body composition (dual-energy X-ray absorptiometry), anthropometry, and habitual food intake were cross-sectionally evaluated in women with excess body weight and body fat. Mean dAGEs content was estimated using a database containing the Nԑ-(carboxymethyl)lysine (CML) content of 549 foods, which was adjusted by mean energy intake, and categorized into low, medium, and high dAGEs, by the 10th and 50th percentiles of the sample. Associations were tested by linear regression adjusted for age, education, marital status, and physical activity level. Eighty participants had mean ± standard deviation dAGEs 7.85 ± 2.65 AGEs kU/kcal. Compared with high dAGEs, women with low dAGEs ingested more carbohydrate (62% vs. 50% of calories, p < 0.001) and fiber (≈25 g vs. ≈18 g, p = 0.027) and less protein (13% vs. 17% of calories, p = 0.006) and fat (26% vs. 33% of calories, p = 0.011). Women with low dAGEs had waist/hip ratio 0.05 higher than those with high dAGEs (R2 = 0.256, p = 0.005). Low dAGEs relative to medium (p = 0.009) and high (p = 0.002) dAGEs was associated with a ≈5% gynoid fat reduction (R2 = 0.164).

CONCLUSION

Low dAGEs was associated with a higher waist/hip ratio and lower percentage of gynoid fat in women with excess body weight and excess body fat.

REGISTRATION NUMBER

RBR-7z358j.

Increased calcium intake from skimmed milk in energy-restricted diets reduces glycation markers in adults with type 2 diabetes and overweight: A secondary analysis of a randomized clinical trial

The effect of calcium (Ca) on glycation markers is unknown. We hypothesized that increased Ca intake from skimmed milk associated with an energy-restricted diet intake will reduce glycation markers. This reduction will be associated with a greater improvement in markers of metabolic control in adults with type 2 diabetes, overweight, and low habitual Ca intake (<600 mg/d). In this secondary data analysis based on a crossover clinical trial, 14 adults were allocated into 2 groups: high calcium (shake containing 700 mg Ca/day) or low calcium (shake with 6.4 mg Ca/day), for 12 consecutive weeks per session. Energy-restricted diets were also prescribed (-500 kcal/d, 800 mg of dietary Ca/d) to all participants. Advanced glycation end products (AGEs), soluble receptor for AGEs (sRAGE), glycemic control, and lipid profile were assessed at baseline and after 12 weeks. High-calcium serum AGE concentrations and AGE/sRAGE ratio were lower at the end of the study. ΔAGE and ΔAGE/sRAGE ratio were both positively associated with Δtriglycerides, Δtotal cholesterol, Δtriglyceride-glucose index and variations, and Δvisceral adiposity index. ΔAGE/sRAGE was positively associated with Δfructosamine and Δhigh-density lipoprotein-cholesterol, and negatively associated with male sex. Consumption of approximately 1200 mg/day of calcium (3 servings of skim milk) reduced serum AGEs concentrations and the AGE/sRAGE ratio in individuals with diabetes. In general, positive changes in glycation markers are associated with lipid profile, insulin resistance, and adiposity markers worsening. ΔAGEs/ΔsRAGE ratio seems to be a better marker of metabolic status than ΔAGEs and ΔsRAGE alone. Registered in ClinicalTrials.gov (NCT02377076).

Associations of dietary advanced glycation end products with liver steatosis via vibration controlled transient elastography in the United States: a nationwide cross-sectional study

PURPOSE

Large population-based studies for the associations between dietary advanced glycation end products (dAGEs) intake and liver steatosis remain lacking. It is necessary to clarify the relationship of dAGEsintake with liver steatosis through the National Health and Nutrition Survey (NHANES).

METHODS

A total of 5856 participants in the NHANES 2017-2018 were included. The dietary AGEs intake, including ε-(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 ultra-performance LC-tandem MS dietary AGEs database and two 24-h dietary recall interviews. Liver steatosis was assessed by controlled attenuation parameter via transient elastography. Logistic regression model was adopted to explore the relationships between dAGEs intake and hepatic steatosis.

RESULTS

Compared with individuals of total dAGEs, CML, MG-H1 in the lowest tertile, those in the highest tertile had highest risk of hepatic steatosis, and the corresponding odds radios(ORs) (95% confidence interval(CI)) were 1.37 (1.01, 1.84), 1.36 (1.04,1.78) and 1.40 (1.06, 1.85), respectively. Subgroups analysis found that the positive association between dAGEs, CML, CEL and MG-H1 and hepatic steatosis appeared stronger in subjects with obesity and those with abnormal waist circumference (WC).

CONCLUSION

There was a positive correlation between dAGEs, CML, MG-H1, and hepatic steatosis, and this association mainly existed in subjects with obesity and those with abnormal WC. Dietary AGEs restriction might be of high priority for subjects with obesity for the prevention of fatty liver disease. Further longitudinal studies are required to confirm the causal associations and explore the potential mechanisms.

Soluble receptor for advanced glycation end products (sRAGE) is associated with obesity rates: a systematic review and meta-analysis of cross-sectional study

BACKGROUND

Several studies have highlighted the possible positive effects of soluble receptor for advanced glycation end products (sRAGE) against obesity. However, due to their inconsistent results, this systematic review and meta-analysis aimed to quantitatively evaluate and critically review the results of studies evaluating the relationship between sRAGE with obesity among adult population.

METHODS

In the systematic search, the eligibility criteria were as follows: studies conducted with a cross-sectional design, included apparently healthy adults, adults with obesity, or obesity-related disorders, aged over 18 years, and evaluated the association between general or central obesity indices with sRAGE.

RESULTS

Our systematic search in electronic databases, including PubMed, Scopus, and Embase up to 26 October, 2023 yielded a total of 21,612 articles. After removing duplicates, screening the titles and abstracts, and reading the full texts, 13 manuscripts were included in the final meta-analysis. According to our results, those at the highest category of circulating sRAGE concentration with median values of 934.92 pg/ml of sRAGE, had 1.9 kg/m2 lower body mass index (BMI) (WMD: -1.927; CI: -2.868, -0.986; P < 0.001) compared with those at the lowest category of sRAGE concentration with median values of 481.88 pg/ml. Also, being at the highest sRAGE category with the median values of 1302.3 pg/ml sRAGE, was accompanied with near 6 cm lower waist circumference (WC) (WMD: -5.602; CI: -8.820, -2.383; P < 0.001 with 86.4% heterogeneity of I2) compared with those at the lowest category of sRAGE concentration with median values of 500.525 pg/ml. Individuals with obesity had significantly lower circulating sRAGE concentrations (WMD: -135.105; CI: -256.491, -13.72; P = 0.029; with 79.5% heterogeneity of I2). According to the subgrouping and meta-regression results, country and baseline BMI were possible heterogeneity sources. According to Begg's and Egger's tests and funnel plots results, there was no publication bias.

CONCLUSION

According to our results, higher circulating sRAGE concentrations was associated with lower BMI and WC among apparently healthy adults. Further randomized clinical trials are warranted for possible identification of causal associations.

AGER-1 Long Non-Coding RNA Levels Correlate with the Expression of the Advanced Glycosylation End-Product Receptor, a Regulator of the Inflammatory Response in Visceral Adipose Tissue of Women with Obesity and Type 2 Diabetes Mellitus

The advanced glycosylation end-product receptor (AGER) is involved in the development of metabolic inflammation and related complications in type 2 diabetes mellitus (T2DM). Tissue expression of the AGER gene (AGER) is regulated by epigenetic mediators, including a long non-coding RNA AGER-1 (lncAGER-1). This study aimed to investigate whether human obesity and T2DM are associated with an altered expression of AGER and lncAGER-1 in adipose tissue and, if so, whether these changes affect the local inflammatory milieu. The expression of genes encoding AGER, selected adipokines, and lncAGER-1 was assessed using real-time PCR in visceral (VAT) and subcutaneous (SAT) adipose tissue. VAT and SAT samples were obtained from 62 obese (BMI > 40 kg/m2; N = 24 diabetic) and 20 normal weight (BMI = 20-24.9 kg/m2) women, while a further 15 SAT samples were obtained from patients who were 18 to 24 months post-bariatric surgery. Tissue concentrations of adipokines were measured at the protein level using an ELISA-based method. Obesity was associated with increased AGER mRNA levels in SAT compared to normal weight status (p = 0.04) and surgical weight loss led to their significant decrease compared to pre-surgery levels (p = 0.01). Stratification by diabetic status revealed that AGER mRNA levels in VAT were higher in diabetic compared to non-diabetic women (p = 0.018). Elevated AGER mRNA levels in VAT of obese diabetic patients correlated with lncAGER-1 (p = 0.04, rs = 0.487) and with interleukin 1β (p = 0.008, rs = 0.525) and resistin (p = 0.004, rs = 0.6) mRNA concentrations. In conclusion, obesity in women is associated with increased expression of AGER in SAT, while T2DM is associated with increased AGER mRNA levels and pro-inflammatory adipokines in VAT.

Yeast-Hydrolysate-Derived 1-Methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic Acid Inhibits Fat Accumulation during Adipocyte Differentiation

This study aimed to investigate the impact of yeast hydrolysate (YH) on lipogenesis, elucidate its mechanistic action, and identify the active compounds responsible for its anti-adipogenic effects. YH (2 mg/mL) significantly reduced Oil Red O-stained lipids. YH (2 mg/mL) also downregulated C/EBPβ and upregulated KLF2, both of which are early adipogenic factors. Moreover, YH (2 mg/mL) decreased C/EBPα, PPARγ, FABP4, FAS, ACC, and HMGCR mRNA expression. Additionally, YH significantly downregulated SEBP1c and SREBP2 and their target genes, which govern fatty acid and cholesterol metabolism; however, 2 mg/mL YH had a greater suppressive effect on SREBP1c than on SREBP2. YH (2 mg/mL) also significantly reduced the mRNA level of G6PD and malic enzyme, which are enzymes that synthesize NADPH for lipid synthesis, compared with the control. Furthermore, 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA) was identified as the active compound with anti-adipogenic effects using solvent fractionation and chromatographic analysis of YH, and 1.1 μg/mL MTCA significantly downregulated SREBP1c/SREBP2 mRNAs by 47.8% and 69.2%, respectively, along with the target genes FAS, ACC, and HMGCR by 79.0%, 77.0%, and 40.9%, respectively. Collectively, YH effectively suppressed adipogenic lipid storage by downregulating SREBP- and NADPH-synthesizing genes. These findings suggest that YH containing MTCA has the potential to act as an anti-obesity agent.

The Role of Obesity in Breast Cancer Pathogenesis

Research has shown that obesity increases the risk for type 2 diabetes mellitus (Type 2 DM) by promoting insulin resistance, increases serum estrogen levels by the upregulation of aromatase, and promotes the release of reactive oxygen species (ROS) by macrophages. Increased circulating glucose has been shown to activate mammalian target of rapamycin (mTOR), a significant signaling pathway in breast cancer pathogenesis. Estrogen plays an instrumental role in estrogen-receptor-positive breast cancers. The role of ROS in breast cancer warrants continued investigation, in relation to both pathogenesis and treatment of breast cancer. We aim to review the role of obesity in breast cancer pathogenesis and novel therapies mediating obesity-associated breast cancer development. We explore the association between body mass index (BMI) and breast cancer incidence and the mechanisms by which oxidative stress modulates breast cancer pathogenesis. We discuss the role of glutathione, a ubiquitous antioxidant, in breast cancer therapy. Lastly, we review breast cancer therapies targeting mTOR signaling, leptin signaling, blood sugar reduction, and novel immunotherapy targets.

Increased dietary intake of ultraprocessed foods and mitochondrial metabolism alterations in pediatric obesity

The increased intake of ultraprocessed foods (UPFs) in the pediatric age paralleled with the risen prevalence of childhood obesity. The Ultraprocessed Foods in Obesity (UFO) Project aimed at investigating the potential mechanisms for the effects of UPFs in facilitating pediatric obesity, focusing on the direct role of advanced glycation end-products (AGEs) on mitochondrial function, the key regulator of obesity pathophysiology. We comparatively investigated the daily dietary intake of UPFs, energy, nutrients, dietary AGEs [Nε -(carboxymethyl)lysine (CML), Nε -(1-carboxyethyl)lysine (CEL), and Nδ -(5-hydro-5- methyl-4-imidazolon-2-yl)-ornithine (MG-H1)] in 53 obese patients and in 100 healthy controls visiting the Tertiary Center for Pediatric Nutrition of the Department of Translational Medical Science at the University of Naples "Federico II". AGEs skin accumulation and mitochondrial function in peripheral blood mononuclear cells (PBMCs) were also assessed. A higher intake of UPFs and AGEs, energy, protein, fat, and saturated fatty acids was observed in obese patients. Obese children presented significantly higher skin AGEs accumulation and alterations in mitochondrial metabolism. PBMCs from healthy controls exposed to AGEs showed the same mitochondrial alterations observed in patients. These findings support the UPFs role in pediatric obesity, and the need for dietary strategies limiting UPFs exposure for obesity prevention and treatment.

In Vitro Bioactivities of Commonly Consumed Cereal, Vegetable, and Legume Seeds as Related to Their Bioactive Components: An Untargeted Metabolomics Approach Using UHPLC-QTOF-MS2

We conducted a comprehensive evaluation of the antioxidant, anti-obesity, anti-diabetic, and anti-glycation activities associated with the consumption of broccoli, red cabbage, alfalfa, and buckwheat seeds. Additionally, we explored the relationship between these biological activities and the profiles of amino acids, polyphenols, and organic acids identified in the seeds. Our findings demonstrated that red cabbage, broccoli, and buckwheat extracts exhibited significantly higher antioxidant potential compared to the alfalfa extract. Moreover, buckwheat displayed the most significant capacity for inhibiting alpha-glucosidase. Remarkably, broccoli and red cabbage demonstrated substantial anti-glycation and lipase inhibitory potentials. We identified the presence of amino acids, polyphenols, and organic acids in the extracts through untargeted metabolomics analysis. Correlation analysis revealed that pyroglutamic acid positively correlated with all the investigated functional properties. Most polyphenols made positive contributions to the functional properties, with the exception of ferulic acid, which displayed a negative correlation with all tested biological activities. Furthermore, gluconic acid and arabinonic acid among the organic acids identified displayed a positive correlation with all the functional properties. These results strongly support the anti-diabetic, anti-obesity, and anti-glycation potential of red cabbage, broccoli, and buckwheat seeds.

Receptor for the Advanced Glycation End Products (RAGE) Pathway in Adipose Tissue Metabolism

Advanced glycation end products (AGEs) are mediators in the process of cellular dysfunction in response to hyperglycemia. Numerous data indicate that the accumulation of AGEs in the extracellular matrix plays a key role in the development of obesity-related adipose tissue dysfunction. Through binding of their membrane receptor (RAGE), AGEs affect numerous intracellular pathways and impair adipocyte differentiation, metabolism, and secretory activity. Therefore, inhibiting the production and accumulation of AGEs, as well as interfering with the metabolic pathways they activate, may be a promising therapeutic strategy for restoring normal adipose tissue function and, thus, combating obesity-related comorbidities. This narrative review summarizes data on the involvement of the RAGE pathway in adipose tissue dysfunction in obesity and the development of its metabolic complications. The paper begins with a brief review of AGE synthesis and the RAGE signaling pathway. The effect of the RAGE pathway on adipose tissue development and activity is then presented. Next, data from animal and human studies on the involvement of the RAGE pathway in obesity, diabetes, and cardiovascular diseases are summarized. Finally, therapeutic perspectives based on interference with the RAGE pathway are discussed.

In Vitro Antiglycation and Methylglyoxal Trapping Effect of Peppermint Leaf (Mentha × piperita L.) and Its Polyphenols

The most significant reactive α-dicarbonyl RCS involved in the pathomechanism of glycation and related diseases is methylglyoxal (MGO). Hyperglycemia promotes the generation of MGO and leads to the formation of advanced glycation end products (AGEs). Therefore, MGO trapping and glycation inhibition appear to be important therapeutic targets in prediabetes, diabetes, and in the early prevention of hyperglycemic complications. Peppermint leaf is commonly used as herbal tea, rich in polyphenols. Eriocitrin, its predominant component, in a double-blind, randomized controlled study reversed the prediabetic condition in patients. However, the antiglycation activity of this plant material and its polyphenols has not been characterized to date. Therefore, the aim of this study was to evaluate the ability of a peppermint leaf dry extract and its polyphenols to inhibit non-enzymatic protein glycation in a model with bovine serum albumin (BSA) and MGO as a glycation agent. Peppermint polyphenols were also evaluated for their potential to trap MGO in vitro, and the resulting adducts were analyzed by UHPLC-ESI-MS. To relate chemical composition to glycation inhibitory activity, the obtained peppermint extract was subjected to qualitative and quantitative analysis. The capability of peppermint leaf polyphenols to inhibit glycation (27.3-77.2%) and form adducts with MGO was confirmed. In the case of flavone aglycones, mono- and di-adducts with MGO were observed, while eriodictyol and eriocitrin effectively produced only mono-adducts. Rosmarinic acid and luteolin-7-O-glycosides did not reveal this action. IC₅₀ of the peppermint leaf dry extract was calculated at 2 mg/mL, equivalent to a concentration of 1.8 μM/mL of polyphenols, including ~1.4 μM/mL of flavonoids and ~0.4 μM/mL of phenolic acids. The contribution of the four major components to the anti-AGE activity of the extract was estimated at 86%, including eriocitrin 35.4%, rosmarinic acid 25.6%, luteolin-7-O-rutinoside 16.9%, luteolin-7-O-β-glucuronoside 8.1%, and others 14%. The effect of peppermint dry extract and polyphenols in inhibiting MGO-induced glycation in vitro was comparable to that of metformin used as a positive control.

Risk factors of severe periodontitis in kidney transplant recipients: A case-control study

BACKGROUND

Kidney transplant recipients (KTRs) represent a vulnerable group of patients who develop a number of comorbidities. Severe periodontitis (SP) is associated with the most common chronic systemic diseases including kidney diseases. The objective of this study was to explore the risk factors for SP in KTRs.

METHODS

In this study, KTRs were divided into those with or without periodontitis and in relation to the severity of periodontitis. A comprehensive medical and periodontal examination was performed and evaluated. Multivariate logistic regression was performed to examine possible risk factors for SP among KTRs.

RESULTS

A total of 100 KTRs were included in the analysis, of which 87% had periodontitis. Significant predictors of periodontitis were older age (OR = 1.07, 95% CI [1.01, 1.13], p = 0.016) and lower skeletal muscle mass (OR = 0.88, 95% CI [0.78, 0.99], p = 0.035). When examining periodontitis severity, predictors of SP (n = 21, 24%) were increased levels of uric acid (OR = 1.01, 95% CI [1.00, 1.02], p = 0.022) and dental plaque (OR = 1.04, 95% CI [1.01, 1.07], p = 0.013). In the subset analysis that included only KTRs with measured advanced glycation end products (AGE) (n = 47), 34% (n = 16) had SP. The predictors of SP were AGE (OR = 3.89, 95% CI [1.28, 11.82], p = 0.017) and dental plaque (OR = 1.07, 95% CI [1.01, 1.13], p = 0.028).

CONCLUSIONS

KTRs with SP had significantly higher uric acid levels and AGE, which may contribute to the systemic health status of this patient population.

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.

The Effect of the Restrictive Ketogenic Diet on the Body Composition, Haematological and Biochemical Parameters, Oxidative Stress and Advanced Glycation End-Products in Young Wistar Rats with Diet-Induced Obesity

Over the past few years, the interest in the application of the ketogenic diet (KD) for obesity management is growing. Although many studies have been performed on the effects of KD, the metabolic and physiological impact of KD is still not fully understood. Therefore, this study aimed to evaluate the effect of calorie-restricted KD on the body weight and composition, oxidative stress, and advanced glycation end products (AGEs) assessed in an animal model with young Wistar rats. KD was followed for 4 weeks in maturity after an obesity-inducing high-fat diet during adolescence, resulting in a slowing down of the weight gain but higher adiposity compared to a standard diet. Increased adiposity resulted in an deterioration of liver parameters, suggesting negative changes in this organ. No adverse effects of KD were determined in haematological parameters in young rats. KD did not affect AGEs; however, a decrease in oxidative stress was observed. Based on the presented results, it can be concluded that KD applied for weight loss in obesity induced in adolescence may reduce oxidative stress without compromising the haematological status; however, caution may be required to control adiposity, glucose level and liver health. Thus, KD therapy should be carefully controlled, especially in young subjects.

Personalized diet study of dietary advanced glycation end products (AGEs) and fatty acid desaturase 2 (FADS2) genotypes in obesity

Obesity prevalence have tripled in the past decades. It is logical to consider new approaches to halt its prevalence. In this concept, considering the effect of interaction between fatty acid desaturase 2 (FADS₂) gene variants and dietary advanced glycation end products (AGEs) on obesity-related characteristics seems to be challenging. The present cross-sectional study conducted among 347 obese individuals. A validated semi-quantitative 147-item food frequency questionnaire (FFQ) was used to estimate dietary intakes and American multiethnic database was used to calculate AGEs content of food items which were not available in Iranian Food Composition Table (FCT). FADS₂ gene variants were determined according to Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Analysis of covariance (ANCOVA) was used to evaluate the modifier effect of FADS₂ gene-dietary AGEs on biochemical values. Based on our findings, no significant differences was reported in term of biochemical variables between AGEs tertiles. In contrast, percent of macronutrients (carbohydrate, protein and fat) of total calorie intake, amount of daily intake of fiber and meat groups showed a significant differences among AGEs tertiles. Furthermore, statistical assays clarified the modifier effects of FADS₂ gene-AGEs on weight (P_interaction = 0.04), fat mass (P_interaction = 0.03), waist circumference (P_interaction = 0.008) and cholesterol (P_interaction = 0.04) level. Accordingly, higher consumption of protein or fat based foods constitute high amount of AGEs and heterozygote genotype for FADS₂ tended to show lower level of AGEs content. These findings address further investigation to develop new approaches for nutritional interventions.

Consumption of ultra-processed foods associated with weight gain and obesity in adults: A multi-national cohort study

BACKGROUND

There is a worldwide shift towards increased consumption of ultra-processed foods (UPF) with concurrent rising prevalence of obesity. We examined the relationship between the consumption of UPF and weight gain and risk of obesity.

METHODS

This prospective cohort included 348 748 men and women aged 25-70 years. Participants were recruited between 1992 and 2000 from 9 European countries in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Two body weight measures were available, at baseline and after a median follow-up time of 5 years. Foods and drinks were assessed at baseline by dietary questionnaires and classified according to their degree of processing using NOVA classification. Multilevel mixed linear regression was used to estimate the association between UPF consumption and body weight change (kg/5 years). To estimate the relative risk of becoming overweight or obese after 5 years we used Poisson regression stratified according to baseline body mass index (BMI).

RESULTS

After multivariable adjustment, higher UPF consumption (per 1 SD increment) was positively associated with weight gain (0·12 kg/5 years, 95% CI 0·09 to 0·15). Comparing highest vs. lowest quintile of UPF consumption was associated with a 15% greater risk (95% CI 1·11, 1·19) of becoming overweight or obese in normal weight participants, and with a 16% greater risk (95% CI 1·09, 1·23) of becoming obese in participants who were overweight at baseline.

CONCLUSIONS

These results are supportive of public health campaigns to substitute UPF for less processed alternatives for obesity prevention and weight management.

Effect of the consumption of yacon flour and energy-restricted diet on glycation markers, and association between these markers and factors linked to obesity in adults with excess body weight: A randomized, double-blind, placebo-controlled clinical trial

OBJECTIVES

Regardless of the positive effect of yacon on metabolic markers, this food contains fructose molecules, which can originate advanced glycation end products (AGEs). High AGEs serum concentrations can contribute to excess body weight. We evaluated the effect of consuming an energy-restricted diet and yacon flour on glycation markers concentrations, and the associations between these markers and factors linked to obesity in adults with excess body weight.

METHODS

Twenty-six adults with excess body weight were included in this randomized, parallel, double-blind, placebo-controlled, 6-week clinical trial. Subjects were randomly allocated to the control group (n = 13) or the yacon-flour group (n = 13), and daily consumed a breakfast drink either not containing or containing 25 g of yacon flour (8.7 g of fructooligosaccharides). Energy-restricted diets were prescribed for both groups. Biochemical markers, anthropometric variables, and body composition were evaluated at baseline and the end of the study.

RESULTS

AGEs and early glycation products did not increase in the yacon flour group. Soluble receptor for AGEs (sRAGE) decreased regardless of group. Besides, changes in AGEs were positively associated with changes in body fat (β = 0.04, P = 0.038) and in sRAGE, with insulin (β = 0.02, P = 0.035) and homeostasis model assessment index of insulin resistance (β = 0.01, P = 0.049).

CONCLUSIONS

The consumption of 25 g of yacon flour associated with an energy-restricted diet did not increase concentrations of glycation markers. Changes in glycation markers were positively associated with changes in consolidated anthropometric and biochemical markers related to being overweight. Assessing glycation markers may be a useful strategy for monitoring responses to dietary interventions in subjects with excess body weight.

Clinical health markers in dogs fed raw meat-based or commercial extruded kibble diets

The interest and demand for healthy and less processed foods for human consumption have been mirrored in the pet industry, with an explosion of alternative diets available. Several nontraditional feeding methodologies including raw meat-based diets (RMBDs) are believed by many dog owners to be superior to traditional extruded commercial dog foods. Despite the strong opinions, limited data are available comparing objective health measures among healthy dogs fed using different methods of diet preparation. Therefore, we compared health markers in client-owned dogs fed an RMBD to markers in dogs fed a high-quality extruded kibble. We hypothesized that healthy adult dogs fed RMBD would show differences in biochemical and hematological parameters and improved clinical health scores (e.g., dental, external ear canal, and integument scores) compared with dogs fed a kibble diet. A cross-sectional observational study was performed comparing hematology, serum biochemistry, urinalysis management history, and clinical health scores in healthy client-owned dogs reported as fed RMBD (n = 28) or kibble (n = 27) for >1 yr. Dental, external ear canal, and integument health scores were assigned by a single veterinary evaluator blinded to feed group, using a scale where 0 was normal and 3 was most severely affected. Spearman correlation coefficient (rs) was calculated to assess the strength and direction of the relationship of biochemical outcomes with age and body condition score (BCS), while analysis of variance was used to determine if biochemical analytes differed by breed or gender. Biochemical data were analyzed using multiple linear regression models, adjusting for the covariates gender, breed, age, and BCS. A composite clinical health score, (CCS) = 9 - (dental score + otitis score + integument score), was compared between feeding groups using Mann-Whitney test. Serum alkaline phosphatase activity (P < 0.001) and globulin concentration (P < 0.001) were lower, while lymphocyte count (P < 0.05) was higher in dogs fed RMBD. No differences were found in urinalysis between diet groups. Dogs fed RMBD showed a slight improvement in CCS compared with kibble-fed dogs (CCS: P = 0.03). Owner management significantly differed with a greater likelihood of management interventions including dietary supplements and sporting activities in the RMBD group. Further work is needed to specifically determine the impact of diet processing and nutrient content on canine health.

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.

Effect of dietary advanced glycation end-products restriction on type 2 diabetes mellitus control: a systematic review

CONTEXT

Reducing dietary advanced glycation end-products (AGEs) may favor diabetes control.

OBJECTIVE

Critically analyze studies about the effect of dietary AGEs restriction on inflammation, oxidative stress, and glycemic control in patients with type 2 diabetes mellitus (DM2).

DATA SOURCE

This systematic review was conducted according to PRISMA methodology. The PubMed, Web of Science, LILACS, and Cochrane Library databases were searched, using the terms "type 2 diabetes," "advanced glycation end products" and "diet."

DATA EXTRACTION

Seven original studies were included in this review. The duration of the studies ranged from 1 day to 16 weeks. All extracted data were compiled, compared, and critically analyzed.

DATA ANALYSIS

Glycemic variables were considered the primary outcomes. The secondary outcomes were glycation, inflammatory, and oxidative stress markers.

CONCLUSION

Although serum insulin, homeostasis model assessment of insulin resistance, and glycated hemoglobin values were lower after the consumption of AGEs restricted diets in most studies, there was a lack of unanimity regarding dietary AGEs' positive effect on inflammation, oxidative stress, and blood glucose.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42020152640.

Plasma Catestatin Levels and Advanced Glycation End Products in Patients on Hemodialysis

Catestatin (CST) is a pleiotropic peptide involved in cardiovascular protection with its antihypertensive and angiogenic effects. Considering that patients with end-stage renal disease (ESRD) who are undergoing hemodialysis (HD) are associated with higher cardiovascular risk, the aim of this study was to investigate plasma CST levels in HD patients, compare them to healthy controls and evaluate possible CST associations with advanced glycation end products (AGEs) and laboratory, anthropometric and clinical parameters. The study included 91 patients on HD and 70 healthy controls. Plasma CST levels were determined by an enzyme-linked immunosorbent assay in a commercially available diagnostic kit, while AGEs were determined using skin autofluorescence. Plasma CST levels were significantly higher in the HD group compared to the controls (32.85 ± 20.18 vs. 5.39 ± 1.24 ng/mL, p < 0.001) and there was a significant positive correlation between CST and AGEs (r = 0.492, p < 0.001). Furthermore, there was a significant positive correlation between plasma CST levels with both the Dialysis Malnutrition Score (r = 0.295, p = 0.004) and Malnutrition-Inflammation Score (r = 0.290, p = 0.005). These results suggest that CST could be playing a role in the complex pathophysiology of ESRD/HD and that it could affect the higher cardiovascular risk of patients on HD.

Mechanism of 'Invigorating Qi and Promoting Blood Circulation' Drug Pair Ginseng-Danshen on Treatment of Ischemic Heart Disease Based on Network Pharmacology

OBJECTIVE

Using network pharmacology to explore the mechanism of the 'invigorating qi and promoting blood circulation' drug pair Ginseng-Danshen (Salvia miltiorrhiza) on treatment of ischemic heart disease (IHD).

METHODS

The chemical constituents of ginseng and Danshen drug pair were identified by searching the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), and the potential targets of the pair were identified. The pharmacodynamics of the pair was analyzed using network pharmacology. The targets of IHD were identified by database screening. Using protein-protein interaction network, the interaction targets of Ginseng-Danshen on IHD were constructed. A "constituent-target-disease" interaction network was constructed using Cytoscape software, Gene Ontology (GO) term enrichment analysis and biological pathway enrichment analysis were carried out, and the mechanism of improving myocardial ischemia by the Ginseng-Danshen drug pair was investigated.

RESULTS

Seventeen active constituents and 53 targets were identified from ginseng, 53 active constituents and 61 targets were identified from Danshen, and 32 protein targets were shared by ginseng and Danshen. Twenty GO terms were analyzed, including cytokine receptor binding, cytokine activity, heme binding, and antioxidant activity. Sixty Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathways were analyzed, including phosphatidylinositol 3-kinase-serine-threonine kinase (PI3K-AKT) signaling pathway, p53 signaling pathway, interleukin 17 signaling pathway, tumor necrosis factor signaling pathway, and the advanced glycation end product (AGE)-the receptor for AGE (RAGE) signaling pathway in diabetic complications.

CONCLUSION

The specific mechanism of Ginseng-Danshen drug pair in treating IHD may be associated with improving the changes of metabolites inbody, inhibiting the production of peroxides, removing the endogenous oxygen free radicals, regulating the expression of inflammatory factors, reducing myocardial cell apoptosis and promoting vascular regeneration.

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.