Effects of Nutritional Support with a Leucine-Enriched Essential Amino Acid Supplement on Body Composition, Muscle Strength, and Physical Function in Stroke Patients Undergoing Rehabilitation

Background/Objectives: Dietary protein intake can potentially influence renal function. This study aimed to elucidate the association between dietary protein supplementation and a decrease in the estimated glomerular filtration rate (eGFR) in Japanese stroke patients undergoing rehabilitation. Methods: From July 2017 to June 2021, 60 patients undergoing post-stroke rehabilitation were randomly assigned to a rehabilitation alone or rehabilitation nutrition group, which received 120 g Reha-Time Jelly® after each session. Both groups were followed up for 3 months. Serum nutritional markers (prealbumin and retinol-binding protein), muscle strength, body composition, renal function markers (eGFR based on creatinine [eGFR-Cr] and cystatin C [eGFR-Cys]), urinary protein-to-creatinine ratio (UPCR), and motor function (walking speed, 2-min walk distance, and chair stand test) were assessed at baseline and post-intervention. Results: Of the 60 participants (mean age: 70.2 ± 10.0 years), 39 were men (65.0%) and 19 (31.7%) had chronic kidney disease. Initial eGFR-Cr and eGFR-Cys values were 70.5 ± 17.2 and 66.6 ± 14.8 mL/min/1.73 m2, respectively. After the intervention, the rehabilitation nutrition group demonstrated a significantly greater increase in body mass index (BMI) and a smaller decrease in bone mineral content than the rehabilitation alone group. However, no significant between-group differences were noted in serum marker levels or motor function, including grip strength and knee extensor strength, on the paralyzed and non-paralyzed sides. The change in chair stand test performance indicated a trend toward improvement in the rehabilitation nutrition group. No significant differences were observed in the changes in renal function. Conclusions: A 3-month nutritional supplementation intervention may help increase BMI, preserve bone mineral content, and support physical activity levels in patients undergoing post-stroke rehabilitation without negatively affecting renal function.