Effects of model Maillard compounds on bone characteristics and functionality

Dietary Advanced Glycation End-Products (dAGEs) Intake and Bone Health: A Cross-Sectional Analysis in the Rotterdam Study

Animal studies suggest a role for dietary advanced glycation end-products (dAGEs) in bone health, but human studies on dAGEs in relation to bone are lacking. We aimed to study whether dAGEs intake is associated with the parameters of bone strength namely, bone mineral density (BMD), prevalent vertebral (VFs), and major osteoporotic fractures (MOFs = hip, wrist, proximal humerus, and clinical VFs). 3949 participants (mean age 66.7 ± 10.5 years) were included from a Rotterdam study for whom Carboxymethyllysine (CML—a dietary AGE) was estimated from food frequency questionnaires combined with dAGEs databases. Multivariable linear and logistic regression models were performed adjusting for age, sex, energy intake, dietary quality, physical activity, diabetes, smoking, renal function, and cohort effect and for models on fractures, subsequently for BMD. We observed no association of CML with BMD at both femoral neck (β = −0.006; p = 0.70) and lumbar spine (β = −0.013; p = 0.38). A higher intake of CML was linearly associated with VFs (Odds ratio, OR = 1.16, 95% CI (1.02–1.32) and a similar but non-significant trend with MOFs (OR = 1.12 (0.98–1.27). Additional adjustment for BMD did not change the associations. Our results imply a positive association between dietary intake of CML and VFs independent of BMD. Future studies are needed in order to elucidate whether associations found are causal.

Dietary Advanced Glycation End Products Have Sex- and Age-Dependent Effects on Vertebral Bone Microstructure and Mechanical Function in Mice

Back pain is a leading cause of global disability that can arise from vertebral fracture and osteoporosis. Although poor general health and obesity are among the strongest risk factors for back pain, there is remarkably little known about how diet influences spinal diseases. Advanced glycation end-products (AGEs) are implicated in increased fracture risk, yet no studies investigated how dietary AGEs affect spinal health. We tested the hypothesis that high dietary AGE ingestion will diminish vertebral structure and function in a sex- and age-dependent manner. Female and male mice were fed low-AGE (L-AGE) or high-AGE (H-AGE) isocaloric diets for 6 and 18 months and multiple measurements of bone structure and function were taken. AGE levels in serum and cortical vertebrae were increased only for 6-month-old H-AGE female mice while blood glucose and body weight remained normal for all animals. When fed an H-AGE diet, 6-month-old female mice had inferior vertebral trabecular structure with decreased bone mineral density (BMD) and bone volume fraction. Biomechanical testing and analytical modeling further showed functional deterioration in 6-month-old H-AGE females with reduced shear and compression moduli, and maximum load to failure. At 18 months, H-AGE mice of both sexes had significant but small decreases in cortical BMD and thickness, yet functional biomechanical behaviors were not distinguishable from other aging changes. We conclude that an H-AGE diet, without diabetic or overweight conditions, diminished vertebral microstructure, mechanical behaviors, and fracture resistance in young female mice in a manner suggesting accelerated bone aging. © 2017 American Society for Bone and Mineral Research.

Carboxymethyl-lysine: thirty years of investigation in the field of AGE formation

In 1985 carboxymethyl-lysine (CML), the first glycoxidation product, was discovered by Dr Ahmed while trying to identify the major products formed in reactions of glucose with lysine under physiological conditions. From that moment, a significant number of researchers have joined efforts to study its formation routes both in foods and in living beings, and the possibility of the existence of an additive action between food-occurring and in vivo produced CML and to explore all the implications associated with its appearance in the biological systems, regardless of its origin. This review presents interesting information on the latest advances in the research on CML sources, mitigation strategies, intake, metabolism and body fluid and tissue delivery, its possible in vivo synergy with highly modified advanced glycation end products-protein, and the physio-pathological implications derived from the presence of this compound in body fluids and tissues.

An advanced glycation end product (AGE)-rich diet promotes Nε-carboxymethyl-lysine accumulation in the cardiac tissue and tendons of rats

The purpose of this study was to investigate the intake, excretion, and tissue accumulation of carboxymethyl-lysine (CML), after feeding rats a diet containing advanced glycation end products (AGEs) from a glucose-lysine (GL) model system. Rats were distributed into two groups and assigned to a control diet or a diet including 3% heated GL (GL diet) for three months. Feces and urine were collected over the last week. After sacrifice, serum was obtained and some organs were removed for CML analysis. The percentage of fecal CML was 2.5-fold higher in the animals fed the GL diet (33.2 vs 76.5% for control and GL group), whereby total recovery was 91.8% compared with a level of 54.6% in the animals fed the control chow, evidencing the importance of the chemical form and the net quantity of dietary CML on its elimination. We suggest that dietary dicarbonyl compounds from GL diet or dietary CML itself are responsible for CML accumulation in hearts and tendons. The most significant result of the present study is that the regular consumption of dietary AGEs in healthy individuals promotes CML accumulation in some organs.

Maillard reaction products modulate gut microbiota composition in adolescents

SCOPE

Scarce data are available concerning effects of certain bioactive substances such as Maillard reaction products (MRP) on the gut microbiota composition, and the question of how a diet rich in MRP affects gut microbiota in humans is still open.

METHODS AND RESULTS

Two experiments were conducted. In expt. 1, adolescents consumed diets either high or low in MRP in a two-period crossover trial; in expt. 2, rats were fed diets supplemented or not with MRP model-systems. Intestinal microbiota composition in fecal (adolescents) or cecal (rat) samples was assessed by qPCR analysis. Negative correlations were found in the human assay between lactobacilli numbers and dietary advanced MRP (r = -0.418 and -0.387, for hydroxymethylfurfural and carboxymethyl-lysine respectively, p < 0.05), whereas bifidobacteria counts were negatively correlated with Amadori compounds intake. In the rat assay, total bacteria and lactobacilli were negatively correlated with MRP intake (r = -0.674,-0.675 and -0.676, for Amadori compounds, hydroxymethylfurfural and carboxymethyl-lysine respectively, p < 0.05), but no correlations were found with bifidobacteria.

CONCLUSIONS

Dietary MRP are able to modulate in vivo the intestinal microbiota composition both in humans and in rats, and the specific effects are likely to be linked to the chemical structure and dietary amounts of the different browning compounds.