Effect of an intensive nutrition intervention of a high protein and low glycemic-index diet on weight of kidney transplant recipients: study protocol for a randomized clinical trial

Abstract

Background: Excessive weight gain is commonly observed within the first year after kidney transplantation and is associated with negative outcomes, such as graft loss and cardiovascular events. The purpose of this study is to evaluate the effect of a high protein and low glycemic-index diet on preventing weight gain after kidney transplantation.

Methods: We designed a prospective, single-center, open-label, randomized controlled study to compare the efficacy of a high protein (1.3-1.4 g/kg/day) and low-glycemic index diet versus a conventional diet (0.8-1.0 g/kg/day of protein) on preventing weight gain after kidney transplantation. A total of 120 eligible patients 2 months after transplantation will be recruited. Patients with an estimated glomerular filtration rate through the modification of diet of renal disease (MDRD) formula < 30 mL/min/1.73 m2 or urinary albumin excretion > 300 mg/24 h will be excluded. Patients' diets will be allocated through simple sequential randomization. Patients will be followed-up for 12 months with nine clinic appointments with a dietitian and the evaluations will include nutritional assessment (anthropometrics, body composition, and resting metabolic rate) and laboratory tests. The primary outcome is weight maintenance or body weight gain under 5% after 12 months. Secondary outcomes include body composition, resting metabolic rate, satiety sensation, kidney function, and other metabolic parameters.

Discussion: Diets with higher protein content and lower glycemic index may lead to weight loss because of higher satiety sensation. However, there is a concern about the association of high protein intake and kidney damage. Nevertheless, there is little evidence on the impact of high protein intake on long-term kidney function outcome. Therefore, we designed a study to test if a high protein diet with low-glycemic index will be an effective and safe nutritional intervention to prevent weight gain in kidney transplant patients.

Trial registration: ClinicalTrials.gov identifier, NCT02883777 . Registered on 3 August 2016.

Keywords: High protein diet; Kidney transplantation; Low glycemic-index diet; Nutrition intervention; Weight.

Conflict of interest statement

Ethics approval and consent to participate

All procedures will be conducted in accordance with the ethical standards for human subject research set forth in the Declaration of Helsinki. Written informed consent will be obtained from all patients to be included in this clinical trial by the main researcher (EFP) who will have access to the final trial database. The research project was approved by the Research Ethics Committee of the Hospital de Clínicas de Porto Alegre (registration number 16-0121) and is registered in the ClinicalTrials.gov database under the identification number NCT02883777. Personal information about potential and enrolled patients will be maintained in a database in order to protect patients confidentially. Investigators will communicate trial results to participants, healthcare professionals, and other relevant groups via publication.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

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Figures

Fig. 1

SPIRIT diagram. *Timepoint of the protocol: -t0, enrolment; -t1, baseline; -t2, -t3, -t4, -t5, -t6, -t7, first semester monthly appointments; -t8, month 9; -t9, month 12