Daily Leucine Intake Is Positively Associated with Lower Limb Skeletal Muscle Mass and Strength in the Elderly

Abstract

Higher daily protein intake, with an emphasis on leucine content, is thought to mitigate age-related anabolic resistance, potentially counteracting age-related morphological and functional declines. The present study investigated potential associations between total daily leucine intake and dependent variables, including quadriceps muscle cross-sectional area (CSA) and maximum dynamic muscle strength (1-RM) in a cohort of healthy free-living older individuals of both sexes (n = 67; 34/33 men/women). Participants performed three 24 h dietary recalls and underwent a magnetic resonance imaging exam followed by 1-RM tests. Our results demonstrate moderate associations between total daily leucine and both quadriceps CSA (r = 0.42; p = 0.004) and 1-RM (r = 0.45; p = 0.001). Furthermore, our exploratory biphasic linear regression analyses, adjusted for sex, age, and protein intake relative to body weight, revealed a plateau for daily leucine intake and muscle mass and muscle strength (~7.6–8.0 g·day−1) in older adults. In conclusion, we demonstrated that total daily leucine intake is associated with muscle mass and strength in healthy older individuals and this association remains after controlling for multiple factors, including overall protein intake. Furthermore, our breakpoint analysis revealed non-linearities and a potential threshold for habitual leucine intake, which may help guide future research on the effects of chronic leucine intake in age-related muscle loss.

The Effect of Leucine Supplementation on Sarcopenia-Related Measures in Older Adults: A Systematic Review and Meta-Analysis of 17 Randomized Controlled Trials

“…A previous study by Chae et al has observed a positive correlation between daily leucine intake and skeletal muscle mass index in middle-aged individuals, skeletal muscle mass index increased by 0.29%, when each 1g/day increased in leucine (45). Similarly, the study by Lixandrão et al showed there was a moderate and positive association between total daily leucine intake (g/day) and both quadriceps muscle crosssectional area (β = 1.7) and maximum dynamic muscle strength (β = 2.4) (When the leucine dose changes by one unit, maximum dynamic muscle strength and muscle cross-sectional area change by β units) (46). However, in our meta-analysis, leucine-isolated supplementation showed no effect on total lean mass, handgrip strength and leg press.…”

Protein and Leucine Intake at Main Meals in Elderly People with Type 2 Diabetes

“…In view of the important role that the content of branched-chain amino acids, in particular leucine, plays in promoting the synthesis of muscle proteins [ 16 , 21 , 22 , 43 ], in the present study we specifically evaluated leucine intake at each meal. In our patients, the average daily intake of leucine was ~4300 mg, a value significantly lower than that recommended; interestingly, none of the patients met the threshold at breakfast, 29% reached it at lunch, and 13% reached it at dinner.…”

Association between Branched-Chain Amino Acid Intake and Physical Function among Chinese Community-Dwelling Elderly Residents

“…A low serum concentration of leucine was associated with decreased muscle mass, strength, and function in older adults [ 15 ]. A cross-sectional study reported an independently positive association between dietary leucine intake and increased muscle mass and strength among healthy older individuals in Brazil [ 44 ]. These contradictory results may be partly ascribed to the interactions among different BCAAs, and the amount of each of the three amino acids specifically did not reach the effective value after separating the influence of any one amino acid from the others [ 45 ].…”