The Journal of nutrition · 2026
Methionine Requirements in Early and Late Stages of Healthy Canadian Pregnancies in the Presence of Cysteine Determined Using the Indicator Amino Acid Oxidation Method.
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Scherbinsky Kerri, Rasmussen Betina F, Li Bingqing, Kong Dehan, Ball Ronald O, Pencharz Paul B, Courtney-Martin Glenda, Elango Rajavel
Аннотация
BACKGROUND: Recently, total sulfur amino acid (TSAA; methionine + cysteine) requirements during pregnancy were found to be 11.1 and 15.0 mg/kg/d in early and late gestation, respectively. Methionine requirements in the presence of cysteine during pregnancy are unknown.
OBJECTIVES: The objective of this study was to determine methionine requirements in the presence of dietary cysteine during early (11-20 wk) and late (31-40 wk) gestation in healthy females with singleton pregnancies and to examine if differences in requirements exist between early and late gestation using the indicator amino acid oxidation (IAAO) technique.
METHODS: Twenty-three females aged 26 to 39 y with a healthy singleton pregnancy were studied using the IAAO technique in a repeated measures design for a total of 61 study days. On each study day, a methionine test intake (range: 0-15 mg/kg/d) was provided in 8 hourly, isonitrogenous and isocaloric meals with cysteine provided at 25 mg/kg/d. Breath samples were collected at baseline and isotopic steady state with oral provision of L-1-13C-phenylalanine for measurement of phenylalanine oxidation. Requirement was determined using a biphasic linear mixed-effects model to identify a breakpoint in 13CO2 production, representing the estimated average requirement (EAR).
RESULTS: Methionine requirement in healthy pregnant participants in early gestation was 7.9 mg/kg/d (R2m = 0.68, R2c = 0.75; 95% CI: 5.0, 10.8 mg/kg/d) and 9.1 mg/kg/d (R2m = 0.84, R2c = 0.91; 95% CI: 7.4, 10.8 mg/kg/d) in late gestation. Difference between confidence intervals of the 2 breakpoints was = -1.2 ± 3.3, and not statistically different.
CONCLUSIONS: Methionine EAR during early and late pregnancy are 7.9 and 9.1 mg/kg/d, respectively. These methionine needs represent 71% and 61% of mean TSAA requirements of 11.1 and 15.0 mg/kg/d in early and late gestation, respectively, as previously determined, suggesting that methionine needs are substantial throughout pregnancy. This trial was registered at clinicaltrials.gov as NCT04326322.
OBJECTIVES: The objective of this study was to determine methionine requirements in the presence of dietary cysteine during early (11-20 wk) and late (31-40 wk) gestation in healthy females with singleton pregnancies and to examine if differences in requirements exist between early and late gestation using the indicator amino acid oxidation (IAAO) technique.
METHODS: Twenty-three females aged 26 to 39 y with a healthy singleton pregnancy were studied using the IAAO technique in a repeated measures design for a total of 61 study days. On each study day, a methionine test intake (range: 0-15 mg/kg/d) was provided in 8 hourly, isonitrogenous and isocaloric meals with cysteine provided at 25 mg/kg/d. Breath samples were collected at baseline and isotopic steady state with oral provision of L-1-13C-phenylalanine for measurement of phenylalanine oxidation. Requirement was determined using a biphasic linear mixed-effects model to identify a breakpoint in 13CO2 production, representing the estimated average requirement (EAR).
RESULTS: Methionine requirement in healthy pregnant participants in early gestation was 7.9 mg/kg/d (R2m = 0.68, R2c = 0.75; 95% CI: 5.0, 10.8 mg/kg/d) and 9.1 mg/kg/d (R2m = 0.84, R2c = 0.91; 95% CI: 7.4, 10.8 mg/kg/d) in late gestation. Difference between confidence intervals of the 2 breakpoints was = -1.2 ± 3.3, and not statistically different.
CONCLUSIONS: Methionine EAR during early and late pregnancy are 7.9 and 9.1 mg/kg/d, respectively. These methionine needs represent 71% and 61% of mean TSAA requirements of 11.1 and 15.0 mg/kg/d in early and late gestation, respectively, as previously determined, suggesting that methionine needs are substantial throughout pregnancy. This trial was registered at clinicaltrials.gov as NCT04326322.