Dietary Lysine Requirements of Older Adults Stratified by Age and Sex

Mahroukh Rafii; Alyssa Paoletti; Henry He; Beatriz Porto; Sylwia Szwiega; Paul B Pencharz; Ronald O Ball; Dehan Kong; Libai Xu; Rajavel Elango; Glenda Courtney-Martin

doi:10.1016/j.tjnut.2024.04.034

Dietary Lysine Requirements of Older Adults Stratified by Age and Sex

J Nutr. 2024 May 11:S0022-3166(24)00237-2. doi: 10.1016/j.tjnut.2024.04.034. Online ahead of print.

Authors

Affiliations

¹ Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada.
² Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada; Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada; Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada.
³ Department of Agriculture, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada.
⁴ Department of Statistical Sciences, University of Toronto, Toronto, Ontario, Canada.
⁵ Department of Pediatrics, School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada; BC Children's Hospital Research Institute, BC Children's Hospital, Vancouver, British Columbia, Canada.
⁶ Department of Pediatrics, School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada; BC Children's Hospital Research Institute, BC Children's Hospital, Vancouver, British Columbia, Canada; School of Mathematical Sciences, Soochow University, Suzhou, Jiangsu, China.
⁷ Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada; Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada. Electronic address: glenda.courtney-martin@sickkids.ca.

PMID: 38735574
DOI: 10.1016/j.tjnut.2024.04.034

Abstract

Background: Current recommendation for lysine in older adults, 30 mg/kg/d, is based on young adult data. Evidence suggests that amino acid requirements may differ between young and old adults with both sex and age having an effect in the elderly.

Objectives: This study aimed to define the lysine requirements in healthy older adults using the indicator amino acid oxidation (IAAO) method with L-[1-¹³C] phenylalanine as the indicator and to compare the derived estimates based on age: 60-69 y and >70 y.

Methods: Fourteen healthy males and 16 healthy females [>60 y, body mass index (BMI) = 26.3 kg/m²] were randomly assigned to receive 3-7 lysine intakes from 10 to 80 mg/kg/d. Subjects were adapted to a standard liquid diet providing 1.0 g/kg/d protein and adequate energy, for 2 d, with indicator oxidation measurements performed on day 3. The rate of release of ¹³CO₂ from the oxidation of L-[1-¹³C] phenylalanine was measured in breath. A 2-phase linear mixed-effect model, and parametric bootstrap were used to determine mean lysine requirements and the 95% confidence intervals (CIs). The overlap of the 95% CI between the 2 age groups were used to compare the requirement estimates. The null hypothesis was accepted if the interval contained zero.

Results: The mean and upper 95% CI of the lysine requirement for females were 32.9 and 40.9 and 46.2 and 53.7 mg/kg/d for those aged 60-69 y and >70 y, respectively. The mean and upper 95% CI of the lysine requirement for the 2 groups of males were not different so was combined to yield a mean and 95% CI of 32.2 and 38.2 mg/kg/d.

Conclusions: To our knowledge, this is the first study to report on the lysine requirement in adults aged >60 y. These results provide a basis from which the adequacy of diets to meet lysine needs of older adults can be assessed. The trial was registered at clinicaltrials.gov as NCT02008955 (https://clinicaltrials.gov/study/NCT02008955).

Keywords: amino acid requirement; elderly; indicator amino acid oxidation; lysine requirement; stable isotopes.

Associated data

ClinicalTrials.gov/NCT02008955