Kidney Transplant Low AGE Diet Study (Transplant LAD)
Research type
Research Study
Full title
A feasibility study exploring the impact of a low Advanced Glycation End-product (AGE) diet on skin autofluorescence levels in kidney transplant recipients.
IRAS ID
298681
Contact name
Catherine Johnson
Contact email
Sponsor organisation
University Hospitals of Derby and Burton NHS Foundation Trust
Clinicaltrials.gov Identifier
Clinicaltrials.gov Identifier
N/A , N/A
Duration of Study in the UK
1 years, 2 months, 30 days
Research summary
The purpose of the present study is to test the feasibility of conducting a larger randomised controlled trial (RCT) which will investigate whether a diet low in toxins called advanced glycation end-products (AGEs) decreases skin autofluorescence (SAF; AGE accumulation in the skin) levels and improves heart and circulatory (i.e. cardiovascular) health in persons with a kidney transplant.
The present study will be conducted in two parts:
Part 1: participants will be randomly assigned either to a low AGE diet (intervention group) or to a standard diet for persons with a kidney transplant (control group). Participants will be followed-up for 6 months and will receive precise oral and written advice on how to follow the diets. This advice will be tailored to their needs and food preferences. Adherence to diets will be evaluated by means of a 3-day food diary (2 weekdays and 1 weekend day) every month.
The research team will measure the accumulation of AGEs in the skin using a safe, quick and painless technique called SAF. Routine blood tests, measurements of weight, height, arm circumference and skinfold thickness (i.e. anthropometry), blood pressure, handgrip strength (a measure of muscle strength), aortic pulse wave velocity (a measure of cardiovascular health), as well as nutritional/diet and quality of life questionnaires will also be conducted. All study assessments will be performed at baseline, 3 and 6 months.
Part 2: interviews will be conducted after completion of the intervention study in order to assess whether the intervention (i.e. low AGE diet) is acceptable, as well as participant views and experiences of the intervention and the study process itself.
Summary of Results
LAY SUMMARY OF RESEARCH FINDINGSIRAS Project ID: 298681
Title of Study: A feasibility study exploring the impact of a low Advanced Glycation End-product (AGE) diet on skin autofluorescence (SAF) levels in kidney transplant recipients.
Name of Chief Investigator: Catherine Johnson
Local Researcher(s): Professor Maarten Taal, Dr Daniela Viramontes Hörner, Dr Janson Leung
Why was the research needed?
Advanced glycation end-products (AGEs) are compounds that form naturally in our bodies from the chemical reaction of sugars with proteins and fats. AGEs are also found naturally in foods and the content of AGEs in foods is increased considerably by using cooking methods that require high temperatures and dry heat, such as frying, roasting and grilling.AGEs accumulate in our bodies, mainly in blood vessels and in the skin. AGEs accumulation can be measured by using a technique called skin autofluorescence (SAF), and previous studies conducted in people with a kidney transplant have reported that high levels of SAF can lead to an increased risk of death and transplant rejection.
Previous studies have also reported that reduction of AGEs from the diet is associated with a decrease in AGE levels in the bloodstream, suggesting that a diet low in AGEs may also be associated with a decrease in SAF. Therefore, the purpose of this study was to investigate whether a low-AGE diet leads to a reduction in SAF levels in people with a kidney transplant.
Who participated in this study?
Thirty-eight adult participants who have had a kidney transplant for more than 12 months and had SAF levels above the general population reference value for their age agreed to take part in this small study.What happened during the study?
Participants were assigned 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 AGEs intake from the diet to <8000 kilounits/day (kU/day).We measured SAF, blood pressure, weight, height, handgrip strength (a measure of muscle strength), arm circumference (a measure of muscle mass), skinfold thickness (a measure of fat mass) and routine blood tests. Participants completed a questionnaire to assess quality of life and food diaries to calculate the amount of calories, proteins and fats in participants’ diets. We calculated AGEs intake from participants’ diet with a food frequency questionnaire. All of these measurements and questionnaires were taken at the start of the study, mid-way and at the end of the study.
At the end of the 6 months, we interviewed 10 participants from the intervention group and 5 from the control group to get their views and experiences of the study.
What were the results of the study?
Average participant age was 56 years. Twenty-seven participants were male and 32 were of white ethnicity. Seventeen participants in the control group and 13 participants in the intervention group completed 6 months of follow-up.AGEs intake decreased in the intervention group but remained high in the control group. However, only 9 participants in the intervention group managed to follow the diet and decrease their AGEs intake to <8000 kU/day. Body weight, calorie and fat intake decreased in the intervention group but there was no significant change in SAF. We did not observe any changes in both groups in blood pressure, handgrip strength, arm circumference, skinfold thickness, quality of life, protein intake or in the results from routine blood tests.
Asking participants their views and experience of the study provided assurance around acceptability of the study and its process.
How has this study helped patients and researchers?
In this small study, we observed a high withdrawal in the intervention group, which may explain our finding that reduction in AGEs intake from the diet did not seem to have any significant impact in decreasing SAF levels. This highlights the need for a larger study to determine the effect of a low-AGE diet on SAF levels in people with a kidney transplant.REC name
East Midlands - Nottingham 2 Research Ethics Committee
REC reference
21/EM/0245
Date of REC Opinion
25 Nov 2021
REC opinion
Further Information Favourable Opinion