Effect of diet restricted in advanced glycation end products (low-AGEs) on vascular adhesion, inflammatory markers, vascular vasodilation (FMD), energy expenditure and brown adipose tissue activity in patients treated with angioplasty

The aim of this study is to determine the effect of diet restricted in advanced glycation end products (low-AGEs) on vascular adhesion, inflammatory markers, vascular vasodilation (Flow Mediated Dilation), energy expenditure and brown adipose tissue activity in patients treated with angioplasty.

The present study is a parallel randomized clinical trial with a control group.

Patients are randomly divided into two groups of 21: intervention and control. Food record questionnaire to measure and control macronutrients and AGEs intake in the diet and physical activity registration to measure energy expenditure and adjustment of physical activity effect on AGEs production in body will be evaluated in beginning and every two weeks during the study. Ten milliliter fasting blood will be taken from all patients at the beginning and end of the intervention.

Patients aged 50 to 70 years whose BMI is between 18.5 to 35 kg/m2 and are required to undergo angioplasty due to obstruction in one or two vessels, will be enrolled. Patients with a history of diabetes, chronic kidney diseases, autoimmune diseases and cancer, consumed multivitamin-mineral supplements over the past 3 months, followed any weight loss or other special diets during last year, or smoke won't be entered in study.

To the intervention group, the low-AGEs diet, and to the control group, the cardiovascular diet based on general recommendations provided by AHA with focusing on the reduction of saturated fats and salt will be given. Both groups will be required to follow their diet for 12 weeks.

The amount of energy expenditure and vascular vasodilatation (FMD) and serum levels of IL-6, TNF-α, VCAM, hs-CRP, MDA, NRG4, FGF21 and carboxy methyl lysine will be measured in both groups before and After the intervention.

Due to the outbreak of COVID-19, the work process of the hospital was disrupted and sampling was stopped for several months, and now that the work process of the hospital has returned to the previous state, the admission rate of patients is much lower than before. On the other hand, a large number of patients are reluctant to participate in the study due to the need to go to the hospital after the intervention and the high risk of developing COVID-19 if they go to the hospital. In general, these problems have disrupted the sampling of the study. At the beginning of the patients’ recruitment, during ultrasound examinations, we found out that a large percentage of the patients had non-alcoholic fatty live disease (NAFLD), but were unaware of it. Given that NAFLD is one of the cardiovascular risk factors and increases the risk of atherosclerotic events in these patients, and recent studies have shown the causative role of AGEs in the pathogenesis of NAFLD, thus our intervention (restricting AGEs in the diet) may probably also be effective on reducing hepatic fat accumulation and the risk factors associated with NAFLD. Therefore, a number of extra outcomes related to NAFLD were added to the study, and in patients who also had NAFLD, these outcomes were measured before and after the study.

Since the variable of gender affect the outcomes of the study, and the two groups must be similar in terms of this variable, randomization is done using stratified randomization based on this variable. Therefore, we will have two categories: men and women. Then for each of these categories, random binary blocks are determined using table of random numbers. Eligible individuals entered the study, are placed in their own category according to their gender and based on the randomized sequences defined for that category, are assigned to either of the two groups receiving low-AGEs diet or cardiovascular diet (on basis of AHA recommendations). Given that the intervention of this study is diet and the person who enters the patients in the study and describes the type of diet for each patient, cannot be blind to the type of diet that each patient receives, allocation concealment does not apply in this study.