Comparison of leucine and dispensable amino acid kinetics between Indian women with low or normal body mass indexes during pregnancy.
BACKGROUND
Evidence suggests that in women with a normal to high body mass index (BMI; in kg/m(2)), the extra amino acids needed during pregnancy are met through reduced oxidation. It is not known whether a woman with a low BMI can make this adaptation successfully.


OBJECTIVE
The objective was to measure and compare leucine kinetic parameters and alanine-nitrogen, glutamine amide-nitrogen, and glycine and cysteine fluxes in Indian women with a low and normal BMI in early and midpregnancy.


METHODS
Fasted- and fed-state kinetics were measured by infusing 1-[(13)C]leucine, [(2)H(2)]cysteine, [(2)H(2)]glycine, [5-(15)N]glutamine, and [(15)N]alanine in groups of 10 women with a low BMI (<18.5) and 10 women with a normal BMI (18.5-25) in the first and second trimesters of pregnancy.


RESULTS
Leucine, glutamine, glycine, and cysteine fluxes were faster in women with a low BMI in both trimesters, but there was no difference in alanine flux between groups. This difference was explained in the first trimester by a higher proportion of fat-free mass in low-BMI women. Leucine oxidation and percentage of dietary leucine oxidized were higher in low-BMI women in both trimesters, but nonoxidative disposal was not different between groups.


CONCLUSIONS
Although they use dietary protein less efficiently, low-BMI women maintain net protein synthesis at the same rate as do normal-BMI women and produce similar quantities of labile nitrogen for the de novo synthesis of other dispensable amino acids such as glycine and cysteine. The extra amino acids required for increased maternal protein synthesis during pregnancy are provided by an overall decrease in amino acid catabolism in women with normal or low BMI.
Kurpad
Anura V
AV
St John's Research Institute, St John's National Academy of Health Sciences, Bangalore, India. a.kurpad@sjri.res.in
Dwarkanath
Pratibha
P
Thomas
Tinku
T
Mhaskar
Arun
A
Thomas
Annamma
A
Mhaskar
Rita
R
Jahoor
Farook
F
D000328:Adult; D000596:Amino Acids / Q000378:metabolism*; D001823:Body Composition; D001825:Body Fluid Compartments; D015992:Body Mass Index; D004044:Dietary Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D007930:Leucine / Q000378:metabolism*; D010084:Oxidation-Reduction; D011247:Pregnancy / Q000378:metabolism*; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D012016:Reference Values; D013851:Thinness / Q000378:metabolism*; D055815:Young Adult
D000596:Amino Acids; D004044:Dietary Proteins; D007930:Leucine