Location: Children's Nutrition Research CenterTitle: Whole body methionine kinetics, transmethylation, transulfuration and remethylation during pregnancy Author
Submitted to: Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2012
Publication Date: 2/1/2014
Citation: Kurpad, A.V., Anand, P., Dwarkanath, P., Hsu, J.W., Thomas, T., Devi, S., Thomas, A., Mhaskar, R., Jahoor, F. 2014. Whole body methionine kinetics, transmethylation, transulfuration and remethylation during pregnancy. Clinical Nutrition. 33(1):122-129. Interpretive Summary: A huge number of affluent healthy Indian women that have normal body weight give birth to babies with abnormally low birth weight. This suggests that in addition to good nutrition other factors may be causing their babies to be small. One of these factors may be a metabolic adaption that occurs in healthy pregnant women. For example, during pregnancy American women increase the rate at which they convert a compound called methionine to other important compounds needed by the mother to support the growing baby. Methionine is also needed to make proteins in both the mother and child. We studied how methionine was used to make protein and its conversion to other compounds in Indian women during early and late pregnancy. We found that although the pregnant women were making protein adequately from methionine they did not increase the rate at which they were converting it to other important compounds needed by the mother and growing baby. Finally, we found that this inability to increase methionine conversion may be related to the inadequate amount of protein in the diets of Indian women. This shows the importance of pregnant Indian woman increasing the protein content in their meals to increase the birth weight in their babies.
Technical Abstract: There is evidence from a study of pregnant American women that methionine transmethylation (TM) and remethylation (RM) rates increase and transulfuration (TS) decreases as pregnancy progresses from trimester 1 to 3. To determine whether pregnant Indian women can make this adaptation successfully, methionine kinetics TS, TM, and RM were measured in Indian women in early and late pregnancy. Measurements were made in the postabsorptive and fed states in the 1st and 3rd trimesters of pregnancy by infusing 1-13C,2H3-methionine in 24 women, 12 with low (</=150 pmol L-1) and 12 with normal (>/=200 pmol L-1) vitamin B12 status at recruitment. From trimester 1 to 3, except RM which decreased significantly, there was no change in any weight-specific methionine kinetic parameter. When expressed per whole body, methionine flux from protein breakdown increased significantly from trimester 1 to 3 in the fed and postabsorptive states. Flux to protein synthesis also increased significantly in the fed state. Rates of TM, TS, and RM did not change, regardless of vitamin B12 status at recruitment. Protein and methionine intakes correlated with TM and RM rates, and the change in RM from trimester 1 to 3 correlated with the change in dietary protein intake. These results suggest that methionine flux and its utilization for protein synthesis increases in Indian women as pregnancy progresses from trimester 1 to 3. TM and RM rates do not increase however, possibly because of inadequate protein intake and not because of vitamin B12 deficiency at trimester 1.