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Research Project: Pediatric Clinical Nutrition

Location: Children's Nutrition Research Center

Title: Adaptation of in vivo amino acid kinetics facilitates increased amino acid availability for fetal growth in adolescent and adult pregnancies alike

Author
item Thame, Minerva - University Of The West Indies
item Hsu, Jean - Children'S Nutrition Research Center (CNRC)
item Gibson, Raquel - University Of The West Indies
item Baker, Tameka - University Of The West Indies
item Tang, Grace - Children'S Nutrition Research Center (CNRC)
item Badaloo, Asha - University Of The West Indies
item Fletcher, Horace - University Of The West Indies
item Jackson, Alan - Southampton General Hospital
item Jahoor, Farook - Children'S Nutrition Research Center (CNRC)

Submitted to: British Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2014
Publication Date: 12/14/2014
Citation: Thame, M.M., Hsu, J.W., Gibson, R., Baker, T.M., Tang, G.J., Badaloo, A.V., Fletcher, H.M., Jackson, A.A., Jahoor, F. 2014. Adaptation of in vivo amino acid kinetics facilitates increased amino acid availability for fetal growth in adolescent and adult pregnancies alike. British Journal of Nutrition. 112(11):1779-1786.

Interpretive Summary: For a pregnant woman and her baby to grow adequately during pregnancy, she has to provide extra amounts of special compounds called amino acids to her own body and to the baby growing in her womb. These amino acids are the building blocks used by our bodies to make new proteins but they can also be used to make energy for the cells in our bodies. The pregnant woman usually gets these amino acids from the proteins in her meals but when she is fasting, like during the night, she provides these extra amino acids to the growing baby by breaking down her own body proteins and conserving them by using less amino acids to make energy. Because teenage girls usually give birth to smaller babies we suspected that they may not be able to provide the extra amino acids to the growing baby when they were fasting. In this study performed in pregnant adult women and teenagers we found that just like adult women, after an overnight fast the teenagers can provide extra amino acids required to make new body proteins during pregnancy by increasing their body protein breakdown and decreasing the amount of amino acids used to make energy. The findings of this study are important because it shows that teenagers do not give birth to smaller babies because of an inability to provide a sufficient amount of amino acids to the growing baby.

Technical Abstract: During pregnancy, adult women with a normal BMI synthesize extra amino acids after an overnight fast by increasing body protein breakdown and decreasing amino acid oxidation. It is not known whether adolescent girls can make these adaptations during pregnancy. The present study aimed to measure and compare the protein, glutamine and alanine kinetics of adult women and adolescent girls at early-, mid- and late-pregnancy. Kinetics were measured in the overnight fasted state using intravenous infusions of 13C-leucine, 15N-glutamine and 15N-alanine in ten adults and twenty adolescents aged 14-17 years in the first and second trimesters (phase 1 study) and infusions of 13C-leucine and 15N2-urea in ten adults and eleven adolescents aged 16-17 years in the first and third trimesters (phase 2 study). In phase 1 study, there were no significant differences between the groups with regard to any of the kinetic parameters measured. In both groups, leucine flux increased (P< 0.05), the percentage of leucine flux oxidized decreased (P< 0.05) and non-oxidative leucine disposal to protein synthesis increased (P< 0.05) from the first to the second trimester. In phase 2 study, leucine flux was significantly slower (P< 0.05) in the adult group than in the adolescent group during both trimesters, and whole-body leucine flux and non-oxidative leucine disposal increased significantly in the adolescent group (P< 0.05, respectively) and were higher in the adult group from the first to the third trimester. These results suggest that similar to their adult counterparts after an overnight fast, adolescent girls with a normal BMI provide extra amino acids required for net protein deposition during pregnancy by increasing protein breakdown and decreasing amino acid oxidation.