Habitual Intake of Dietary Advanced Glycation End Products Is Not Associated with Arterial Stiffness of the Aorta and Carotid Artery in Adults: The Maastricht Study

Cardiovascular risks and endothelial dysfunction in reproductive-age women with endometriosis

Endometriosis is a prevalent gynecological condition, affecting around 10% of reproductive-age women. Inflammatory processes associated with endometriosis may contribute to endothelial dysfunction. Increased skin accumulation of advanced glycation end-products (AGEs), reflecting arterial stiffness, potentially links endometriosis with elevated risk of cardiovascular events. We hypothesized that patients with endometriosis have impaired endothelial function as well as increased arterial stiffness and AGE skin accumulation, compared to healthy controls. We compared endothelial function, arterial stiffness, and levels of AGEs in patients suffering from endometriosis and in healthy controls. The study included 45 women aged 20 to 40: 21 patients with endometriosis and 24 healthy controls, matched in terms of age, BMI, and blood pressure values. Endo-PAT 2000 device was used for non-invasive assessment of (i) endothelial function, expressed as Reactive Hyperemia Index (RHI), and (ii) arterial stiffness, expressed as Augmentation Index (AI) and Augmentation Index at 75 heart beats/min (AI@75). Endothelial dysfunction was defined as an RHI value ≤ 1.67. AGE Reader device was used for non-invasive evaluation of skin AGE level accumulation. Patients with endometriosis had lower mean RHI values (1.69 ± 0.54 vs. 2.02 ± 0.48, p = 0.037) and a higher prevalence of endothelial dysfunction, (52.4% vs. 20.8%, p = 0.027) compared to healthy controls. Skin AGE level was higher in patients with endometriosis, compared to controls (2.00 ± 0.57 vs. 1.70 ± 0.24, p = 0.013). There were no significant differences in AI and AI@75 between the two groups. Patients with endometriosis have impaired endothelial function and higher AGE skin accumulation, which are well-established preclinical manifestations of increased cardiovascular risk. There is a great need for comprehensive cardiovascular risk assessments in women with endometriosis to prevent the development of potential atherosclerotic-based complications.

Dietary glycation compounds - implications for human health

The term "glycation compounds" comprises a wide range of structurally diverse compounds that are formed endogenously and in food via the Maillard reaction, a chemical reaction between reducing sugars and amino acids. Glycation compounds produced endogenously are considered to contribute to a range of diseases. This has led to the hypothesis that glycation compounds present in food may also cause adverse effects and thus pose a nutritional risk to human health. In this work, the Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG) summarized data on formation, occurrence, exposure and toxicity of glycation compounds (Part A) and systematically assessed potential associations between dietary intake of defined glycation compounds and disease, including allergy, diabetes, cardiovascular and renal disease, gut/gastrotoxicity, brain/cognitive impairment and cancer (Part B). A systematic search in Pubmed (Medline), Scopus and Web of Science using a combination of keywords defining individual glycation compounds and relevant disease patterns linked to the subject area of food, nutrition and diet retrieved 253 original publications relevant to the research question. Of these, only 192 were found to comply with previously defined quality criteria and were thus considered suitable to assess potential health risks of dietary glycation compounds. For each adverse health effect considered in this assessment, however, only limited numbers of human, animal and in vitro studies were identified. While studies in humans were often limited due to small cohort size, short study duration, and confounders, experimental studies in animals that allow for controlled exposure to individual glycation compounds provided some evidence for impaired glucose tolerance, insulin resistance, cardiovascular effects and renal injury in response to oral exposure to dicarbonyl compounds, albeit at dose levels by far exceeding estimated human exposures. The overall database was generally inconsistent or inconclusive. Based on this systematic review, the SKLM concludes that there is at present no convincing evidence for a causal association between dietary intake of glycation compounds and adverse health effects.

Accumulation of advanced glycation end products in skin and increased vascular ageing in the general population: the Malmö Offspring Study

OBJECTIVES

Advanced glycation end product (AGE) is an established risk marker for diabetic vascular disease, and associated with the degree of diabetes complications, renal failure, and atherosclerosis in middle-aged and older individuals. The relationship between AGEs and aortic stiffness has not been thoroughly examined in the younger general population. We aimed to evaluate the association between AGEs and aortic stiffness in the general population of young and middle-aged adults.

METHODS

We analysed cross-sectionally 2518 participants from a Swedish population-based cohort, the Malmö Offspring Study (mean age 41.8 ± 14.5 years, 52.2%). Advanced glycation end-products (AGEs) were measured by a well validated, noninvasive method using skin autofluorescence with AGE-Reader. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (PWV) and augmentation index (Aix) was calibrated to a standard heart rate of 75 bpm at the arteria radialis using SphygmoCor. Multivariable linear regression was performed stratified by age to analyse the association between skin AGE and aortic stiffness.

RESULTS

Increased levels of AGEs were significantly associated with higher direct measurements of aortic stiffness (vascular ageing) in younger individuals (PWV β 0.55 m/s, P  < 0.001) after adjustment for traditional cardiometabolic risk factors, however, not in older individuals (PWV β 0.23 m/s, P  = 0.10). Indirect vascular ageing was also significantly associated with higher levels of AGEs in both younger (Aix β 7.78, P  < 0.001) and older individuals (Aix β 3.69, P  < 0.001).

CONCLUSION

Higher levels of skin autofluorescence-AGEs are positively associated with increased vascular ageing in younger adults from the general population, independent of cardiometabolic risk factors.

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.

Association between dietary theobromine with depression: a population-based study

OBJECTIVE

The purpose of this study is to investigate the possible link between dietary theobromine intake and symptoms of depression.

MATERIALS AND METHODS

These results are based on the responses of 3637 people who took part in the National Health and Nutrition Examination Survey in 2017-2018. Participants' daily theobromine intake was determined using a 24-h food questionnaire from the 2017-2018 cycle. Presence of depression was defined as a score of 5 or above on the Patient Health Questionnaire. Association between theobromine intake and depression was examined using a multivariate logistic regression adjusting for several relevant sociodemographic, lifestyle and health-related factors.

RESULTS

A total of 6903 participants were included in the study. The results of multivariate logistic regression showed a correlation between depressive symptoms and theobromine intake (OR:1.17, 95%CI:1.02-1.34).

CONCLUSIONS

Our cross-sectional population based study suggests that increased theobromine intake is associated with increased risk for depression. Nevertheless, more investigations are needed to confirm our findings.

Dietary Nε-(carboxymethyl) lysine affects cardiac glucose metabolism and myocardial remodeling in mice

BACKGROUND

Myocardial remodeling is a key factor in the progression of cardiovascular disease to the end stage. In addition to myocardial infarction or stress overload, dietary factors have recently been considered associated with myocardial remodeling. N^ε-(carboxymethyl)lysine (CML) is a representative foodborne toxic product, which can be ingested via daily diet. Therefore, there is a marked need to explore the effects of dietary CML on the myocardium.

AIM

To explore the effects of dietary CML (dCML) on the heart.

METHODS

C57 BL/6 mice were divided into a control group and a dCML group. The control group and the dCML group were respectively fed a normal diet or diet supplemented with CML for 20 wk. Body weight and blood glucose were recorded every 4 wk. ¹⁸F-fluorodeoxyglucose (FDG) was used to trace the glucose uptake in mouse myocardium, followed by visualizing with micro-positron emission tomography (PET). Myocardial remodeling and glucose metabolism were also detected. In vitro, H9C2 cardiomyocytes were added to exogenous CML and cultured for 24 h. The effects of exogenous CML on glucose metabolism, collagen I expression, hypertrophy, and apoptosis of cardiomyocytes were analyzed.

RESULTS

Our results suggest that the levels of fasting blood glucose, fasting insulin, and serum CML were significantly increased after 20 wk of dCML. Micro-PET showed that ¹⁸F-FDG accumulated more in the myocardium of the dCML group than in the control group. Histological staining revealed that dCML could lead to myocardial fibrosis and hypertrophy. The indexes of myocardial fibrosis, apoptosis, and hypertrophy were also increased in the dCML group, whereas the activities of glucose metabolism-related pathways and citrate synthase (CS) were significantly inhibited. In cardiomyocytes, collagen I expression and cellular size were significantly increased after the addition of exogenous CML. CML significantly promoted cellular hypertrophy and apoptosis, while pathways involved in glucose metabolism and level of Cs mRNA were significantly inhibited.

CONCLUSION

This study reveals that dCML alters myocardial glucose metabolism and promotes myocardial remodeling.

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.

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.