Leucine-Enriched Protein Supplementation Increases Lean Body Mass in Healthy Korean Adults Aged 50 Years and Older: A Randomized, Double-Blind, Placebo-Controlled Trial

Abstract

Early prevention of sarcopenia could be an important strategy for muscle retention, but most studies have focused on subjects aged 65 or older. Therefore, in this study we investigated the effects of leucine-enriched protein supplementation on muscle condition in a sample including late middle-aged adults. A 12-week intervention was performed for 120 healthy community-dwelling adults by providing either leucine-enriched protein supplement [protein 20g(casein 50%+ whey 40%+ soy 10%, total leucine 3000 mg), vitamin D 800IU(20 ug), calcium 300 mg, fat 1.1 g, carbohydrate 2.5 g] or isocaloric carbohydrate supplement twice per day. Appendicular skeletal muscle mass (ASM) and lean body mass (LBM) were measured by dual-energy X-ray absorptiometry. A total of 111 participants completed the study, with a dropout rate of 9.2%. LBM normalized by body weight (LBM/Wt) was significantly increased (p < 0.001) in the intervention group (0 wk: 63.38 ± 0.85 vs. 12 wk 63.68 ± 0.83 in the intervention group; 0 wk: 63.85 ± 0.82 vs. 12 wk: 63.29 ± 0.81 in the control group). In subgroup analyses, significant differences remained only in subjects between 50 and 64 years of age. We concluded that leucine-enriched protein supplementation can have beneficial effects by preventing muscle loss, mainly for late middle-aged adults.

Higher Branched-Chain Amino Acid Intake Is Associated with Handgrip Strength among Korean Older Adults

“…Dietary intake of amino acids and the intake of nutraceuticals, especially branched-chain amino acids (BCAAs) including leucine, isoleucine, and valine, are known to promote muscle protein synthesis and increase muscle strength as well as tendon health [ 17 , 18 , 19 , 20 ]. Several previous studies have examined the association between BCAA intake and muscle strength [ 21 , 22 , 23 , 24 , 25 , 26 ]; however, most of these studies have reported on the short-term effects of amino acid supplementation through clinical trials [ 21 , 22 , 23 , 24 ]. Furthermore, few community-based epidemiological studies have evaluated the association between habitual dietary BCAA intake and muscle strength in the Asian older population, particularly in South Korea, where the diet entails relatively low total energy intake and a large dependency on rice [ 27 , 28 ].…”

Nutrition and Muscle Health

“…A dietary pattern based on white rice, fish and seaweeds was associated with a lower prevalence of low muscle mass in Korean men and women, whereas a higher condiment, vegetables and meats consumption was associated with a higher prevalence of low muscle mass in men [10]. In the same way, Kang et al [11] demonstrated that a complex of leucineenriched protein, calcium and vitamin D improved the muscle mass in a cohort of Korean healthy subjects between 50 and 64 years of age. In particular, the vitamin D pathway and vitamin D receptor gene seemed to be responsible for different degrees of fragilization, mainly in women in an Italian cohort composed of very old subjects [12].…”

Changes in 24‐h energy expenditure, substrate oxidation, and body composition following resistance exercise and a high protein diet via whey protein supplementation in healthy older men

“…These findings are consistent with others that observed no individual (Björkman et al, 2020; Kim et al, 2012; Kirk et al, 2020; Verreijen et al, 2017; Zhu et al, 2015) or synergistic effects (Arnarson et al, 2013; Candow et al, 2006; Dulac et al, 2021; Holm et al, 2008; Holwerda et al, 2018; Kirk et al, 2020; Kukuljan et al, 2009; Leenders et al, 2013; Thomson et al, 2016; Verdijk et al, 2009) of increased dietary protein intake on FFM in healthy older adults habitually consuming ample amounts of dietary protein (~1.0–1.2 g/kg/d). In contrast, studies conducted in older adults who were either sarcopenic/frail or reported lower habitual intakes of dietary protein (<1.0 g/kg/d) have observed both individual (Bauer et al, 2015; Bo et al, 2019; Kang et al, 2020; Park et al, 2018; ten Haaf et al, 2019) and augmented increases in FFM (Kang et al, 2019; Rondanelli et al, 2016, 2018; Tieland et al, 2012b; Yamada et al, 2019; Zdzieblik et al, 2015). The relatively good health status of participants who habitually consumed adequate amounts of dietary protein in this study may have masked any effects of increased intake via supplementation.…”