This Article Full Text Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sunehag, A. Articles by Haymond, M. W. Search for Related Content PubMed PubMed Citation Articles by Sunehag, A. Articles by Haymond, M. W.

Contribution of Plasma Galactose and Glucose to Milk Lactose Synthesis during Galactose Ingestion

Department of Pediatrics, Children’s Nutrition Research Center, U.S. Department of Agriculture/Agricultural Research Service, Baylor College of Medicine, Houston, Texas 77030

Address all correspondence and requests for reprints to: M. W. Haymond, M.D., Children’s Nutrition Research Center, 1100 Bates Street, Houston, Texas 77030-2600. E-mail: mhaymond{at}bcm.tmc.edu.

We have previously demonstrated that plasma glucose contributed 80% in the fed and 60% in the fasted state to lactose synthesis in humans, and de novo synthesis in the breast contributing to both the glucose and galactose moieties accounted for the remaining 20% and 40%, respectively, of lactose. The present study was conducted to determine, in lactating women, whether oral galactose is directly incorporated from plasma galactose into glucose and galactose in milk lactose or via conversion of galactose to glucose in the liver. Six healthy exclusively breast-feeding women (30 ± 2 yr) (mean ± SE) ingested galactose at 22 µmol·kg^-1·min^-1 for 9 h after an overnight fast during infusion of [6,6-²H₂]glucose and [1-¹³C]galactose. We observed that 69 ± 6% of glucose and 54 ± 4% of galactose in lactose were derived directly from plasma glucose, whereas 7 ± 2% and 12 ± 2% of glucose and galactose in lactose, respectively, were derived directly from plasma galactose. De novo synthesis of glucose and galactose via hexoneogenesis accounted for 25 ± 8% and 35 ± 6%, respectively. We conclude that during ingestion of galactose the contribution from plasma glucose to glucose and galactose in lactose was similar to that of a short-term fasting, but part of the de novo synthesis of glucose and galactose in the breast was replaced by direct uptake of galactose.

This work was supported by grants from U.S. Department of Agriculture Cooperative Agreement #58-6250-6-001, NIH RO1DK 55478, and NIH HD37857. This work is a publication of the USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine (Houston, TX). The contents of this publication do not necessarily reflect the views of policies of the U.S. Department of Agriculture, nor does mention of trade names, commercial products, or organizations imply endorsement from the U.S. Government.

Abbreviations: GCMS, Gas chromatography-mass spectrometry; PCI, positive chemical ionization; Ra, rates of appearance.

This article has been cited by other articles:

				M. A. Mohammad, A. L. Sunehag, S. K. Chacko, A. S. Pontius, P. D. Maningat, and M. W. Haymond Mechanisms to conserve glucose in lactating women during a 42-h fast Am J Physiol Endocrinol Metab, October 1, 2009; 297(4): E879 - E888. [Abstract] [Full Text] [PDF]

				F.-Q. Zhao and A. F. Keating Expression and Regulation of Glucose Transporters in the Bovine Mammary Gland J Dairy Sci, June 1, 2007; 90(13_suppl): E76 - E86. [Abstract] [Full Text] [PDF]