#3805 A FEASIBILITY STUDY EXPLORING THE IMPACT OF A LOW ADVANCED GLYCATION END-PRODUCT DIET ON SKIN AUTOFLUORESCENCE IN KIDNEY TRANSPLANT RECIPIENTS
Authors: Hörner Daniela Viramontes , Taal Maarten , Leung Janson , Patullo Ellen , Johnson Catherine 
Published: June 2023

Abstract

Background and Aims
Advanced glycation end-products (AGEs) are uremic toxins that result from hyperglycaemia and oxidative stress. AGEs are also formed in food, especially during cooking using dry-heat methods. AGE accumulation can be measured by skin autofluorescence (SAF) and increased SAF is a strong predictor of death and graft loss in kidney transplant recipients (KTR). Previous studies have reported that reduction of dietary AGE intake is associated with a decrease in circulating AGE levels, suggesting that a low-AGE diet may also be associated with a decrease in SAF. The aim of this feasibility study was to investigate whether a low-AGE diet leads to a reduction in SAF levels in KTR.

Methods
Thirty-eight KTR were randomly allocated to a usual diet (control group, n = 19) or a low-AGE diet (intervention group, n = 19) and then followed-up for 6 months. The intervention group was provided with detailed written advice and counselling on how to choose foods low in AGEs, and to use high-water content cooking methods (stewing, steaming, boiling, poaching), instead of dry-heat methods (frying, grilling, roasting). The goal was to reduce dietary AGE intake to &lt;8000 kilounits/day (kU/day). SAF was measured at baseline, 3 and 6 months. Rate of change in SAF (i.e., SAF trend) was calculated using the SLOPE function in Microsoft Excel. Dietary AGE intake, biochemistry and nutritional assessments were performed at baseline and 6 months.

Results
Mean age of the whole cohort was 56±11 years. Mean SAF was high at 2.9±0.7 arbitrary units (AU) compared to the reference value of 2.1±0.4 AU. Transplant vintage ranged from 42 to 126 (median 88) months. The majority of the participants were male (71%) and of white ethnicity (84%). Prevalence of diabetes, hypertension and heart disease was 16%, 53%, and 10%, respectively. Median dietary AGE intake was high at 18558 (15164 to 25341) kU/day. There were no significant differences between the intervention and control groups at baseline in SAF, dietary AGE intake, estimated glomerular filtration rate (eGFR), demographics, and clinical, biochemical and nutritional characteristics. Baseline SAF was negatively associated with eGFR (r = −0.387; p = 0.02), energy intake (r = −0.464; p = 0.003) and fat intake (r = −0.438; p = 0.006). Seventeen participants in the control group and 13 participants in the intervention group completed 6 months of follow-up (Fig. 1). Adherence to the low-AGE diet was moderate (69%). Dietary AGE intake decreased significantly in the intervention group but remained high in the control group. Body weight, energy, and fat intake decreased in the intervention group but there was no significant change in SAF (Table 1). The mean SAF trend observed was a decrease of 0.45±1.19 and 0.22±0.75 AU/year in the intervention and control groups, respectively (p = 0.7 for comparison between groups).

Conclusion
In this feasibility study, we observed a high drop-out rate in the intervention group, which may explain our finding that reduction in dietary AGE intake did not seem to have any significant effect in decreasing SAF levels. This highlights the need for a larger trial to determine the effect of dietary AGE restriction on SAF levels in KTR.