Can grape polyphenols affect glycation markers? A systematic review.

Advanced glycation end-products (AGEs) favor inflammation and oxidative stress, playing a role in chronic diseases pathogenesis. Grape polyphenols exert antiglycative and antioxidant effects which may contribute to prevent chronic diseases. However, clinical evidence of grape polyphenols on chronic disease prevention and treatment by glycation markers modulation are limited. Therefore, we aimed to critically analyze studies about that topic to investigate the antiglycative power of dietary grape polyphenol, and to explore the molecular mechanism involved. This systematic review was conducted and reported according to PRISMA guidelines. The following search terms were used: "grape", "extract", "grape seed extract", "grape skin extract", "polyphenol extract", "grape polyphenol(s)", "grape juice", "resveratrol", "quercetin", "catechin", "epicatechin", "procyanidin(s)", and "anthocyanin(s)". Seven studies were included. Glycated hemoglobin was not affected. The interventions duration may not have been enough to detect changes. Grape polyphenols reduced fructosamine and methylglyoxal (MGO) concentrations, and increased endogenous secretory RAGE (esRAGE) gene expression but did not affect the serum concentration. Resveratrol antiglycative effects are mainly due its ability to trap MGO and downregulate RAGE. In conclusion, grape polyphenols may have a positive impact on early glycation products, AGEs and esRAGE. Future studies are needed to explore how they modulate AGEs and receptors in chronic diseases.

Does dietary fat affect advanced glycation end products and their receptors? A systematic review of clinical trials.

CONTEXT: Dietary fat seems to affect advanced glycation end products (AGEs) and their receptors. This systematic review assesses studies that evaluated the effect of dietary fat on markers of glycation. OBJECTIVE: The aim of this systematic review was to analyze the effect of dietary fat on markers of glycation and to explore the mechanisms involved. DATA SOURCES: This study was conducted according to PRISMA guidelines. PubMed, Cochrane, and Scopus databases were searched, using descriptors related to dietary fat, AGEs, and the receptors for AGEs. STUDY SELECTION: Studies were selected independently by the 3 authors. Divergent decisions were resolved by consensus. All studies that evaluated the effects of the quantity and quality of dietary fat on circulating concentrations of AGEs and their receptors in adults and elderly adults with or without chronic diseases were included. Initially, 9 studies met the selection criteria. DATA EXTRACTION: Three authors performed data extraction independently. Six studies were included. RESULTS: Consumption of a Mediterranean diet rich in monounsaturated fatty acids (MUFAs) and low in dietary AGEs reduced serum concentrations of AGEs, reduced expression of the receptor for AGE (RAGE), and increased expression of the AGE receptor 1 (AGER1) when compared with consumption of a Western diet rich in saturated fatty acids and dietary AGEs. Supplementation with omega-3 polyunsaturated fatty acids (PUFAs) resulted in decreased concentrations of fluorescent AGEs and decreased expression of RAGE as well as increased expression of AGER1. CONCLUSIONS: Increased consumption of MUFAs and omega-3 PUFAs and reduced consumption of saturated fatty acids seem to be effective strategies to beneficially affect glycation markers, which in turn may prevent and control chronic diseases. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration number CRD42021220489.

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.

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.