A Mediterranean diet improves glycation markers in healthy people and in those with chronic diseases: a systematic review of clinical trials.

CONTEXT: Consumption of the Mediterranean diet (MedDiet) has beneficial effects on cardiometabolic health and aging. OBJECTIVE: This systematic review aimed to critically investigate the effect of the MedDiet on glycation markers in healthy or overweight individuals with type 2 diabetes or cardiovascular disease. DATA SOURCES: MEDLINE, EMBASE, Web of Science, and the Cochrane Library were searched, using the terms "Mediterranean diet" AND "glycation end products, advanced". DATA EXTRACTION: Three randomized and 3 nonrandomized clinical trials, containing data on 2935 adult and elderly individuals with normal weight or overweight, were included. All extracted data were compiled, compared, and critically analyzed. DATA ANALYSIS: The authors of most of the studies demonstrated a reduction in serum concentrations of advanced glycation end products (AGEs), such as εN-carboxymethyllysine and methylglyoxal, and in skin autofluorescence levels after at least 4 weeks of adherence to the MedDiet. The MedDiet also led to positive effects on gene expression of receptors for AGEs, as RAGE and AGER1, and an enzyme involved in detoxification (glyoxalase I). There is no evidence that short-term adherence affects glycation markers. CONCLUSIONS: Glycation markers improved in response to the MedDiet. The possible mechanisms involved may be related to the low AGE and refined sugars content of the diet, as well as its high monounsaturated fatty acid, phenolic compound, and dietary fiber contents. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42021284006.

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.

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.

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.

Effect of increased calcium consumption from fat-free milk in an energy-restricted diet on the metabolic syndrome and cardiometabolic outcomes in adults with type 2 diabetes mellitus: a randomised cross-over clinical trial.

We investigated the effects of high-Ca fat-free milk phase (MD) (prescription of approximately 1500 mg of Ca/d) v. low-Ca phase (CD) (prescription of approximately 800 mg of Ca/d) in an energy-restricted diet on the metabolic syndrome (MetS) and cardiometabolic measures in individuals with type 2 diabetes mellitus (T2DM) and low habitual Ca consumption (<600 mg/d). In this randomised cross-over design, fourteen adults with T2DM (49·5 (sd 8·6) years, BMI 29·4 (sd 4·5) kg/m2) consumed either MD or CD for 12 weeks, with a washout of 18 weeks between phases. A breakfast shake containing 700 mg (MD) or 6·4 mg (CD) of Ca was consumed in the laboratory. In addition, energy-restricted diets were prescribed (800 mg of dietary Ca/d). Waist circumference (WC), fasting glucose, fasting TAG, systolic (SBP) and diastolic blood pressure (DBP), fasting total cholesterol, fasting LDL-cholesterol, fasting HDL-cholesterol, HDL:LDL ratio, HDL:TAG ratio and lipid accumulation product (LAP) index were assessed at baseline and after each phase. Ca consumption during the study was equivalent to 1200 mg/d during MD and 525 mg/d during CD. There was a greater reduction in WC, SBP, DBP and LAP index after MD compared with CD. HDL:LDL ratio increased and total cholesterol, LDL-cholesterol, SBP, DBP and LAP index decreased only in MD. The consumption of approximately 1200 mg of Ca/d (700 mg from fat-free milk+500mg from other dietary sources) associated with an energy-restricted diet decreased some of the MetS components and cardiometabolic measures in adults with T2DM.

Acute and second-meal effects of peanuts on glycaemic response and appetite in obese women with high type 2 diabetes risk: a randomised cross-over clinical trial.

Nut consumption is associated with a reduced risk of type 2 diabetes mellitus (T2DM). The aim of the present study was to assess the effects of adding peanuts (whole or peanut butter) on first (0-240 min)- and second (240-490 min)-meal glucose metabolism and selected gut satiety hormone responses, appetite ratings and food intake in obese women with high T2DM risk. A group of fifteen women participated in a randomised cross-over clinical trial in which 42·5 g of whole peanuts without skins (WP), peanut butter (PB) or no peanuts (control) were added to a 75 g available carbohydrate-matched breakfast meal. Postprandial concentrations (0-490 min) of glucose, insulin, NEFA, glucagon-like peptide-1 (GLP-1), peptide YY (PYY), cholecystokinin (CCK), appetitive sensations and food intake were assessed after breakfast treatments and a standard lunch. Postprandial NEFA incremental AUC (IAUC) (0-240 min) and glucose IAUC (240-490 min) responses were lower for the PB breakfast compared with the control breakfast. Insulin concentrations were higher at 120 and 370 min after the PB consumption than after the control consumption. Desire-to-eat ratings were lower, while PYY, GLP-1 and CCK concentrations were higher after the PB intake compared with the control intake. WP led to similar but non-significant effects. The addition of PB to breakfast moderated postprandial glucose and NEFA concentrations, enhanced gut satiety hormone secretion and reduced the desire to eat. The greater bioaccessibility of the lipid component in PB is probably responsible for the observed incremental post-ingestive responses between the nut forms. Inclusion of PB, and probably WP, to breakfast may help to moderate glucose concentrations and appetite in obese women.

Pre-game hydration status, sweat loss, and fluid intake in elite Brazilian young male soccer players during competition.

In this study, we assessed the pre-game hydration status and fluid balance of elite young soccer players competing in a match played in the heat (temperature 31.0 ± 2.0 ° C, relative humidity 48.0 ± 5.0%) for an official Brazilian soccer competition. Fluid intake was measured during the match, as were urine specific gravity and body mass before and after the game to estimate hydration status. Data were obtained from 15 male players (age 17.0 ± 0.6 years, height 1.78 ± 0.06 m, mass 65.3 ± 3.8 kg); however, data are only analysed for 10 players who completed the full game. The mean (± s) sweat loss of players amounted to 2.24 ± 0.63 L, and mean fluid intake was 1.12 ± 0.39 L. Pre-game urine specific gravity was 1.021 ± 0.004, ranging from 1.010 to 1.025. There was no significant correlation between sweat loss and fluid intake (r = 0.504, P = 0.137) or between urine specific gravity and fluid intake (r = -0.276, P = 0.440). We conclude that young, native tropical soccer players started the match hypohydrated and replaced about 50% of the sweat lost. Thus, effective strategies to improve fluid replacement are needed for players competing in the heat.

Fluid balance of elite Brazilian youth soccer players during consecutive days of training.

In this study we investigated pre-training hydration status, fluid intake, and sweat loss in 20 elite male Brazilian adolescent soccer players (mean ± s: age 17.2 ± 0.5 years; height 1.76 ± 0.05 m; body mass 69.9 ± 6.0 kg) on three consecutive days of typical training during the qualifying phase of the national soccer league. Urine specific gravity (USG) and body mass changes were evaluated before and after training sessions to estimate hydration status. Players began the days of training mildly hypohydrated (USG > 1.020) and fluid intake did not match fluid losses. It was warmer on Day 1 (33.1 ± 2.4°C and43.4 ± 3.2% relative humidity; P < 0.05) and total estimated sweat losses (2822 ± 530 mL) and fluid intake (1607 ± 460 mL) were significantly higher (P < 0.001) compared with Days 2 and 3. Data also indicate a significant correlation between the extent of sweat loss and the volume of fluid consumed (Day 1: r = 0.560, P = 0.010; Day 2: r = 0.445, P = 0.049; Day 3: r = 0.743, P = 0.0001). We conclude that young, native tropical soccer players arrive hypohydrated to training and that they exhibit voluntary dehydration; therefore, enhancing athletes' self-knowledge of sweat loss during training might help them to consume sufficient fluid to match the sweat losses.

Metabolic responses to high glycemic index and low glycemic index meals: a controlled crossover clinical trial.

BACKGROUND: The consumption of low glycemic index (LGI) foods before exercise results in slower and more stable glycemic increases. Besides maintaining an adequate supply of energy during exercise, this response may favor an increase in fat oxidation in the postprandial period before the exercise compared to high glycemic index (HGI) foods. The majority of the studies that evaluated the effect of foods differing in glycemic index on substrate oxidation during the postprandial period before the exercise are acute studies in which a single meal is consumed right before the exercise. The purpose of this study was to investigate the effect of consuming two daily HGI or LGI meals for five consecutive days on substrate oxidation before the exercise and in the concentrations of glucose, insulin and free fatty acids before and during a high intensity exercise. METHODS: Fifteen male cyclists, aged 24.4 ± 3.8 years, with body mass index of 21.9 ± 1.4 kg.m⁻² and a V(O2 max) of 70.0 ± 5.3 mL.kg⁻¹.min⁻¹, participated in this crossover study. All test meals were consumed in the laboratory. On days 1 and 5, substrate oxidation (30 minutes before and 90 minutes after breakfast (HGI or LGI)) and diet-induced thermogenesis (90 minutes postprandial) were assessed before the exercise. The levels of glucose, insulin, and free fatty acids were determined during 2 h after breakfast on these same days. Ninety minutes after breakfast, subjects completed a 30 min cycloergometric exercise at 85 to 95% of their maximum heart rate, during which lactate concentrations were assessed. RESULTS: The consumption of HGI meals resulted in higher areas under the glycemic and insulinemic curves in the postprandial period. However, glycemia did not differ by study treatment during exercise. There were no differences in free fatty acids in the postprandial period or in lactate levels during exercise. LGI meals resulted in lower fat oxidation and higher carbohydrate oxidation than the HGI meal in the postprandial period. CONCLUSIONS: The results do not support a differential glycemia according to glycemic index during exercise. The ingestion of LGI foods did not lead to higher fat oxidation relative to the ingestion of HGI foods.

Effects of peanut processing on body weight and fasting plasma lipids.

Peanuts and peanut butter are commonly consumed as a snack, meal component and ingredient in various commercial products. Their consumption is associated with reduced CVD risk and they pose little threat to positive energy balance. However, questions have arisen as to whether product form (e.g. whole nut v. butter) and processing properties (e.g. roasting and adding flavours) may compromise their positive health effects. The present study investigated the effects of peanut form and processing on two CVD risk factors: fasting plasma lipids and body weight. One hundred and eighteen adults (forty-seven males and seventy-one females; age 29.2 (sd 8.4) years; BMI 30.0 (sd 4.5) kg/m2) from Brazil, Ghana and the United States were randomised to consume 56 g of raw unsalted (n 23), roasted unsalted (n 24), roasted salted (n 23) or honey roasted (n 24) peanuts, or peanut butter (n 24) daily for 4 weeks. Peanut form and processing did not differentially affect body weight or fasting plasma lipid responses in the total sample. However, HDL-cholesterol increased significantly at the group level, and total cholesterol, LDL-cholesterol and TAG concentrations decreased significantly in individuals classified as having elevated fasting plasma lipids compared with those with normal fasting plasma lipids. These observations suggest that the processing attributes assessed in this trial do not compromise the lipid-lowering effects of peanuts, and do not negatively impact body weight. Further studies are warranted to determine the effects of form and processing on other health risk factors.

Influence of glycemic index/load on glycemic response, appetite, and food intake in healthy humans.

OBJECTIVE: High glycemic index (GI)/load (GL) diets reportedly enhance appetite and promote positive energy balance. Support for this hypothesis stems largely from acute feeding trials and longer-term studies lacking control over the macronutrient composition and palatability of test foods. This study evaluated the effects of consuming high- and low-GI/GL meals, matched on macronutrient composition and palatability, plasma glucose and insulin, appetite, and food intake. RESEARCH DESIGN AND METHODS: Thirty-nine healthy adults consumed only low- or only high-GI foods ad libitum in the laboratory for 8 days in either high (three foods per meal)- or low (one food per meal)-variety conditions. Glucose and insulin concentrations as well as appetitive sensations were determined before and for 2 h following breakfast and lunch on days 1 and 8. Energy intake was monitored daily. RESULTS: There were no significant differences in plasma glucose or insulin responses, appetitive ratings, or food intake between treatments. CONCLUSIONS: These data indicate that the differential glycemic response of foods tested in isolation under fixed time are not preserved under conditions of chronic ad libitum consumption of mixed meals.

Effect of fat sources on satiety.

OBJECTIVE: There are inconsistent reports on the satiety value of different fatty acids. This study compared the appetitive effects of two fat sources rich in monounsaturated fatty acids (peanut oil and canola oil) with a source rich in saturated fatty acids (butter). RESEARCH METHODS AND PROCEDURES: After an overnight fast, lean participants completed a questionnaire eliciting information about hunger, fullness, desire to eat, and prospective consumption. They then consumed one of the preloads (muffins containing 40 g of each fat source or no fat) and 150 mL of water within 15 minutes. Questionnaires were completed again 30, 60, and 120 minutes after preload ingestion. Participants kept dietary records during the subsequent 24 hours. RESULTS: Canola and peanut oil muffins resulted in higher fullness, and butter, canola, and peanut oil muffins resulted in lower hunger ratings 30, 60, and 120 minutes after preload ingestion compared with the fat-free preload. No differences were observed among the fat-containing loads. Although energy intake 24 hours after consumption of the preloads was also comparable on days the three fat-containing loads were consumed, energy consumption after each study session was higher when the fat-free muffins were provided. However, total energy intake, including the calories provided by the preloads, was similar across treatments. DISCUSSION: These data do not support a differential satiety effect of fat sources rich in monounsaturated fatty acids relative to one rich in saturated fatty acids.