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Protein requirement in healthy pregnant women in early and late gestation determined by indicator amino acid oxidation method
Author(s) -
Stephens Trina Victoria,
Payne Magdalene,
Ball Ronald,
Pencharz Paul,
Elango Rajavel
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.42.4
Subject(s) - gestation , phenylalanine , zoology , pregnancy , resting energy expenditure , tyrosine , population , gestational age , amino acid , energy requirement , chemistry , medicine , endocrinology , biology , energy metabolism , biochemistry , regression , mathematics , genetics , environmental health , statistics
Protein (PRO) requirements in healthy pregnant women at 16–18 and 34–36 weeks gestation were determined using the indicator amino acid oxidation (IAAO) method. Nine, healthy women (age 25–34) each randomly received a different test PRO intake (range = 0.22–2.56 g/kg/day) during each study day (n=20). The diets were isocaloric and provided energy at 1.7 X resting energy expenditure (REE). PRO was given as a crystalline amino acid mixture based on egg protein composition, except phenylalanine and tyrosine, which were maintained constant across intakes. PRO requirements were determined by measuring the oxidation of L‐[1‐ 13 C]‐phenylalanine to 13 CO 2 (F 13 CO 2 ). Breath and urine samples were collected at baseline and isotopic steady state. Linear regression crossover analysis identified a breakpoint (requirement) at minimal F 13 CO 2 in response to different PRO intakes. Preliminary results indicate the mean PRO requirements in early and late gestation to be ~14% and 48%, respectively, above the estimated average requirement of 0.88 g/kg/day currently recommended by the Dietary Reference Intakes (DRI 2005) for macronutrients. Our results also indicate gestational differences in protein requirement, a consideration that has not been addressed by current DRI recommendations. This study is the first to directly estimate gestational protein requirement in a population composed solely of pregnant women, and suggests that current recommendations based on the nitrogen balance method may be underestimated.