Higher Intake of Essential Amino Acids Associated with a Significant Increase in High Muscle Strength in Older Adults

by | Sep 27, 2022 | 2022, Aging, Amino Acids

Written by Taylor Woosley, Staff Writer. Study findings show that meeting the RNI of dietary EAAS resulted in a significant improvement in high muscle strength, with a positive dose-response relationship noted between the total EAAS and high muscle strength.

man with weightsThe increase in the aging population has emerged as a major global phenomenon1. By 2050, the worldwide population of those aged 65 years is expected to increase by approximately 10%, reaching 2.1 billion2. Sarcopenia, a gradual loss of skeletal muscle mass and loss of muscle function, is one of the leading health issues of older adults3. Subjects with sarcopenia are at an increased risk of falls, fractures, disability, and mortality4.

As a modifiable risk factor, nutrition is a potential target to prevent the loss of physical function in older adults5. Apart from dietary protein intake, circulating amino acids are important factors in controlling the rate of muscle protein synthesis and catabolism6. Amino acids are fundamental constituents of body proteins and nine amino acids are considered essential amino acids (EAA) and must be obtained through diet7. Research has shown that the metabolism of amino acids plays an essential role in regulating muscle mass and strength, with lower amino acid levels being associated with lower skeletal muscle index8.

Im et al. conducted a study to better calculate a score to assess the intake levels relative to the Dietary Reference Intakes for Koreans (KDRIs) and to also observe the association between the EAA score and high strength among older adults aged ≥65 years. The data evaluated was from the 2014-2019 Korea National Health and Nutrition Examination Survey (KHANES), a large-scale cross-sectional survey that provides representative statistics related to public health status. Subjects (n=5971) completed surveys including health interviews, examinations, and nutritional surveys, with an included parameter evaluating grip strength as the main outcome measure. Calculations of EAA levels in food was used to establish intake values for the nine EAAs. Each achieved intake level of EAAs was further scored based on the sex- and age-specific RNI values according to the 2020 KDRIs, with EAAS values being divided into quartiles for analysis.

The chi-square test was used for categorical variables, along with the mean ± standard error using liner regression for continuous variables. Odds ratio (OR) and 95% confidence interval (CI) was used to assess the association between the total EAAs and high muscle strength. Significant findings of the study are as follows:

  • Higher levels of total EAAS were associated with a higher intake of total energy, carbohydrate, fat, protein, and protein/body weight (all, p < 0.001).
  • Higher levels of total EAAS were associated with a higher handgrip strength (p<0.001).
  • Specifically, the OR for high muscle strength was 2.17 times higher in the group with the highest total EAAS (Q4) than in the group with the lowest total EAAS (OR: 2.17, 95% CI: 1.83-2.57).
  • The OR for high muscle strength was 1.38 times higher in the group with the highest total EAAS (Q4) than in the group with the lowest total EAAS (OR: 1.38, 95% CI: 1.07-1.79).
  • The intake values for the nine EAAS increased with the increasing total EAAS (all p<0.001).

Findings of the study show that high muscle strength was significantly increased when the RNI for all EAAs was met. An increase in the intake of total EAAs was noted from animal sources and was associated with a significant increase in high muscle strength. Study limitations include the possibility of a residual confounding effect, the inability to establish a reverse causality bias between EAA intake and grip strength, and the potential recall bias of participants’ diets based on a single 24 h recall data survey.

Source:  Im, Jihyun, Hyoungsu Park, and Kyong Park. “Dietary Essential Amino Acid Intake Is Associated with High Muscle Strength in Korean Older Adults.” Nutrients 14, no. 15 (2022): 3104.

© 2022 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 (https:// creativecommons.org/licenses/by/ 4.0/).

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Posted September 27, 2022.

Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.

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