Open Collections

Gaytan Gonzalez, Saul Alejandro

University of British Columbia

Background: A protein intake above the recommended dietary allowance (RDA) (i.e., 0.8 g∙kgˉ¹∙dayˉ¹) might benefit muscle strength (MS) and skeletal muscle mass (SMM). However, whether a higher protein intake would benefit MS and SMM (depending on sex, age group, and physical activity level) at younger ages is still to be determined. Objective: To examine whether a protein intake above the RDA is associated with a higher MS and SMM depending on sex, age group, and physical activity level in young and middle-aged adults. Methods: A secondary data analysis from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 was conducted. We analyzed data from participants aged 20 to 59, with dietary intake (24 h dietary recall), combined handgrip strength (HGS), dual-energy x-ray absorptiometry-derived appendicular lean soft tissue (ALST), accelerometer-assessed physical activity, among other variables (n = 3406). The protein intake was categorized as <0.8, 0.8 to 1.0, 1.0 to 1.6, and ≥1.6 g∙kgˉ¹∙dayˉ¹. HGS and ALST were adjusted for BMI (HGS-BMI, and ALST-BMI, respectively). Physical activity was categorized as low, moderate, and high. The HGS-BMI and ALST-BMI were compared among the protein intake groups, setting the 0.8 to 1.0 g∙kgˉ¹∙dayˉ¹ group as the reference. This analysis was carried out for the whole sample, by sex (males, females), age group (young, middle-aged), physical activity level (low, moderate, high), and their corresponding 12 subgroups in one model adjusted for confounding variables per outcome variable. Results: Protein intake per day was positively associated with MS in almost all the subgroups (11 out of 12, p < 0.05), whereas it was associated with SMM in half of the subgroups (7 out of 12), mainly in males (5 out of 6). Overall, the proportional benefit observed with a higher protein intake was greater in MS (≈30% vs the reference group), and it began to be observed at lower doses (starting at 1.0 g∙kgˉ¹∙dayˉ¹) than in SMM (≈10% vs the reference group), which was evident above 1.6 g∙kgˉ¹∙dayˉ¹. Conclusions: A slightly high protein intake (>1.0 g∙kgˉ¹∙dayˉ¹) was associated with a higher MS, while higher protein amounts (≥1.6 g∙kgˉ¹∙dayˉ¹) would be necessary to observe a higher SMM.

Text

2023-01-06

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/83607

Kinesiology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/