Length of Adaptation Has No Effect on the Threonine Requirement Determined in Healthy Young Adult Males Using the Indicator Amino Acid Oxidation Method

Sylwia Szwiega; Paul B Pencharz; Ronald O Ball; Libai Xu; Dehan Kong; Rajavel Elango; Glenda Courtney-Martin

doi:10.1016/j.tjnut.2023.03.033

Length of Adaptation Has No Effect on the Threonine Requirement Determined in Healthy Young Adult Males Using the Indicator Amino Acid Oxidation Method

J Nutr. 2023 Jul;153(7):2016-2026. doi: 10.1016/j.tjnut.2023.03.033. Epub 2023 Mar 31.

Authors

Sylwia Szwiega¹, Paul B Pencharz², Ronald O Ball³, Libai Xu⁴, Dehan Kong⁴, Rajavel Elango⁵, Glenda Courtney-Martin⁶

Affiliations

¹ Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada.
² Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada; Departments 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; British Columbia Children's Hospital Research Institute, British Columbia Children's Hospital, Vancouver, British Columbia, Canada.
⁶ Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada; Departments of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada; Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada. Electronic address: glenda.courtney-martin@sickkids.ca.

PMID: 37004875
DOI: 10.1016/j.tjnut.2023.03.033

Abstract

Background: The indicator amino acid oxidation (IAAO) method is minimally invasive; therefore, it is applicable to study the amino acid (AA) requirements of individuals in various age groups. However, the accuracy of this method has been criticized because of the 8 h (1 d) protocol, which has been suggested to be too short an adaptation time for estimating AA requirements.

Objectives: The IAAO method was used to determine whether 3 or 7 d of adaptation to each threonine intake alters the threonine requirement in adult men compared to 1 d of adaptation.

Methods: Eleven healthy adult men (19-35 y, body mass index (BMI) 23.4 in kg⋅m^-2) were studied at 6 threonine intakes; each intake was studied over a 9 d period. Following 2 d of pre-adaptation to adequate protein intake (1.0 g·kg^-1⋅d^-1), subjects received experimental diets containing the randomly assigned test threonine intake (5, 10, 15, 20, 25, or 35 mg·kg^-1·d^-1) for 7 d. IAAO studies were performed on days 1, 3, and 7 of adaptation to the experimental diet. The rate of release of ¹³CO₂ from the oxidation of L-[1-¹³C]phenylalanine (F¹³CO₂) was measured, and the threonine requirement was determined by applying mixed-effect change-point regression to the F¹³CO₂ data in R version 4.0.5. The 95% confidence interval (CI) was calculated using parametric bootstrap, and the requirement estimates on days 1, 3, and 7 were compared using analysis of variance (ANOVA).

Results: The mean threonine requirements (upper, lower 95% CI) for days 1, 3, and 7 were 10.5 (5.7, 15.9), 10.6 (7.5, 13.7), and 12.1 (9.2, 15.0 mg·kg^-1·d^-1), respectively; and these requirements were not statistically different (P = 0.213).

Conclusions: We demonstrated that the short, 8 h IAAO protocol results in a threonine requirement that is not statistically different from that obtained on days 3 or 7 of adaptation in healthy adult males. This trial was registered at www.

Clinicaltrials: gov as NCT04585087.

Keywords: adaptation; amino acid requirement; carbon oxidation; indicator amino acid oxidation; threonine.

Publication types

Randomized Controlled Trial
Research Support, Non-U.S. Gov't

MeSH terms

Amino Acids* / metabolism
Carbon Dioxide / metabolism
Carbon Isotopes
Humans
Male
Nutritional Requirements
Oxidation-Reduction
Phenylalanine / metabolism
Threonine*
Young Adult

Substances

Amino Acids
Carbon Dioxide
Carbon Isotopes
Phenylalanine
Threonine

Associated data

ClinicalTrials.gov/NCT04585087

Grants and funding

PJT 178141/CIHR/Canada