(PO11-14-22) Dietary Lysine Requirements of Females Over 60 Years Estimated Using Indicator Amino Acid Oxidation (IAAO) Technique Are Different From Current Recommendations

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Presenting Author(s)

MR

Mahroukh Rafii, BS
– Clinical Research Project Manager, The Hospital for Sick Children, Toronto, Ontario, Canada

Co-Author(s)

HH

Henry He
– The Hospital for Sick Children
BP

Beatriz Porto
– The Hospital for Sick Children
AP

Alyssa Paoletti, BSc, MSc
– PhD candidate, University of Toronto, Markham, Ontario, Canada
SS

Sylwia Szwiega, BASc, MSc(c)
– PhD Candidate , University of Toronto & The Hospital for Sick Children, Markham, Ontario, Canada
PP

Paul Pencharz, PhD
– The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
RB

Ronald Ball, PhD
– University of Alberta, Edmonton, Alberta, Canada
DK

Dehan Kong
– University of Toronto
LX

Libai Xu
– University of Toronto
Rajavel Elango, PhD
– Associate Professor, School of Population and Public Health, Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada
GC

Glenda Courtney-martin, PhD, RD
– The Hospital for Sick Children Research Institute, Toronto, British Columbia, Canada

Disclosure(s):

Mahroukh Rafii, BS: No relevant financial relationship(s) with ineligible companies to disclose.

Alyssa Paoletti, BSc, MSc: No relevant financial relationship(s) with ineligible companies to disclose.

Sylwia Szwiega, BASc, MSc(c): No relevant financial relationship(s) with ineligible companies to disclose.

Objectives: 1) Define the lysine requirements in female adults >60years using the indicator amino acid oxidation (IAAO) method with L-[1-¹³C]phenylalanine as the indicator and 2) Compare the derived estimates based on age; 60-69 and >70y.

Methods: Sixteen healthy women (> 60y) were randomly assigned to receive 3 to 7 lysine intakes from 10 to 80 mg. kg^-1. d^-1. Subjects were adapted to a standard liquid diet providing 1.0 g. kg^-1.d^-1 protein and adequate energy, for 2 days, with indicator oxidation measurements performed on day three. The rate of release of ¹³CO₂ from the oxidation of L-[1-¹³C]phenylalanine was measured in breath. A two-phase linear mixed effect model, and parametric bootstrap was used to determine mean lysine requirements and the 95% confidence intervals (CI). The overlap of the 95% CI between the 60-69 and >70 y 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 requirements of older females were 32.9 and 40.9 mg. kg^-1.d^-1 and 45.8 and 52.9 mg. kg^-1.d^-1 for the 60-69 and >70 y, respectively. These estimates were significantly different from each other.

Conclusions: This is the first study to report on the lysine requirements in older females >60 years. The results demonstrate that there is a significant effect of age on the derived estimates. These results are important as they provide a basis from which the adequacy of plant-based diets to meet amino acid needs of older adults can be assessed.

Funding Sources: CIHR