Written by Chrystal Moulton, Staff Writer. Leucine supplementation had no effect on muscle mass; however, it did improve physical performance and respiratory muscle function in nursing home participants.
Sarcopenia (loss of skeletal muscle) is a common symptom that occurs in aging. This gradual decrease in muscle mass is associated with increased risk of falling 1,2, poor quality of life 3,4, and mortality 3,4. Leucine, an essential branched chained amino acid, can increase protein synthesis and controls the rate of protein turnover by decreasing proteolysis in skeletal muscles 5,6. In the current trial, researchers studied the effects of supplementation with leucine alone on respiratory muscle function and sarcopenia in elderly participants who were living in a nursing home 7.
In a randomized, double-blind, placebo controlled clinical trial, 50 elderly participants aged 65 and older were assigned to receive 6g of leucine or 6g of lactose daily for 13 weeks. Doses were administered by a nurse or the participants themselves in the morning (3g of assigned protocol) and in the afternoon (3g of assigned protocol). Sarcopenia was measured indirectly by measures of muscular function such as low walking speed (≤ 0.8 m/s for a 4.6m distance), handgrip strength (men ≤ 30 kg/m2 and women ≤ 30 kg/m2) and loss of lean mass based on whole body bioimpedance assessment (men ≤ 7.25 kg/m2 and women ≤ 5.5 kg/m2). Respiratory muscle function was measured via spirometry. Psychiatric and nutritional assessments as well as a questionnaire assessing physical activity questionnaire were also conducted during the trial.
No significant difference was observed between the groups with regards to age, sexes across both groups, and energy intake. The average age of the participants was 78.9 ± 7.9 (range 65-93 years old). Data from 23 participants in the leucine supplementation group and 19 participants from the placebo group was available for analysis. No significant differences were observed between groups for indirect measures of sarcopenia from baseline to end of trial in hand grip strength (p = 0.55), muscle mass index (p = 0.08), and walking time values (p = 0.285). Researchers found a significant difference in the change in walking time between both groups compared from baseline to end of trial. A significant increase was observed in the placebo group compared to intervention group (Leucine: 101.43 ± 6.00 vs placebo 134.41 ± 10.47; p 0.011). As a result of this increase in walking time, more placebo group members compared to intervention group met the criterion for sarcopenia by the end of the trial (p = 0.027). Significant differences for respiratory function were not observed between both groups from baseline to end of trial. However, significant decline in expiratory muscle strength was observed in the placebo group (Leucine: 99.05 ± 6.8 vs. placebo: 77.97 ± 5.85, p = 0.026). Routine blood analysis showed no significant changes from baseline to end of trial in either group.
Overall, supplementation with leucine in elderly volunteers provided little effect on muscle mass index. However, researchers noted that these effects were due to a comparative decline in muscle mass index in the placebo group. In other words, leucine maintained muscle mass index within the supplementation group, but did not increase it. Further studies will be needed to assess the effects of leucine on this specific population.
Source: Martínez-Arnau, Francisco M., Rosa Fonfría-Vivas, Cristina Buigues, Yolanda Castillo, Pilar Molina, Aldert J. Hoogland, Femke van Doesburg, Leo Pruimboom, Julio Fernández-Garrido, and Omar Cauli. “Effects of Leucine Administration in Sarcopenia: A Randomized and Placebo-controlled Clinical Trial.” Nutrients 12, no. 4 (2020): 932.
© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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Posted October 8, 2020.
Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.
References:
- Sim M, Prince RL, Scott D, et al. Utility of four sarcopenia criteria for the prediction of falls-related hospitalization in older Australian women. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. 2019;30(1):167-176.
- Follis S, Cook A, Bea JW, et al. Association Between Sarcopenic Obesity and Falls in a Multiethnic Cohort of Postmenopausal Women. J Am Geriatr Soc. 2018;66(12):2314-2320.
- Janssen I. The epidemiology of sarcopenia. Clin Geriatr Med. 2011;27(3):355-363.
- Cruz-Jentoft AJ, Baeyens JP, Bauer JM, et al. Sarcopenia: European consensus on definition and diagnosis: Report of the European Working Group on Sarcopenia in Older People. Age Ageing. 2010;39(4):412-423.
- Bonnefoy M, Gilbert T, Bruyère O, et al. Protein supplementation to prevent loss in muscle mass and strength in frail older patients: a review. Geriatrie et psychologie neuropsychiatrie du vieillissement. 2019;17(2):137-143.
- Laveneziana P, Albuquerque A, Aliverti A, et al. ERS statement on respiratory muscle testing at rest and during exercise. The European respiratory journal. 2019;53(6).
- Martínez-Arnau FM, Fonfría-Vivas R, Buigues C, et al. Effects of Leucine Administration in Sarcopenia: A Randomized and Placebo-controlled Clinical Trial. Nutrients. 2020;12(4).
