ARS | Publication request: Measurement of de novo lipogenesis in humans during lactation

Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2009
Publication Date: April 21, 2009
Citation: Mohammad, M.A., Sunehag, A.L., Haymond, M.W. 2009. Measurement of de novo lipogenesis in humans during lactation. Journal of Federation of American Societies for Experimental Biology. 42:546.11

Technical Abstract: Milk fat is composed of 98% triglycerides (TG) and provides infants with approximately 50% of their calories. Mammary gland de novo lipogenesis contributes significantly to milk fat in animals. However, there are no data regarding this process in humans. Incorporation of 13C carbons from [U-13C]glucose into fatty acids (FAs) and glycerol in TG will be, higher in milk TG than in plasma, and higher during H-CHO than H-F diet.Seven healthy lactating women were studied in a crossover, randomized design during isocaloric, isonitrogenous, H-F (30%CHO, 55%fat) and H-CHO (60%CHO, 25%fat) diets. Following feeding for 7 days on each diet, women were continuously infused with [U-13C]glucose for 5h following a 12h fast and during 7h of feeding. Incorporation of 13C from [U-13C]glucose into FAs and glycerol was measured in both plasma and milk using GC-MS. Incorporation of 13C from [U-13C]glucose into milk FAs increased (p<0.05) with the increased chain length of the FAs from C2 to C12, then declined in C14 and was not detected in FAs longer than C16. During meal absorption, enrichment of 13C was approximately 3-fold higher in milk FA and approximately 7 fold higher in milk glycerol compared to plasma FAs and glycerol. During fasting, 25% and 6% of medium chain FAs (MCFAs) (C6-C12) were derived from glucose following H-CHO and H-F diets, respectively. However, during feeding, de novo lipogenesis from glucose was 60% and 20% of MCFAs during both H-CHO and H-F diet, respectively. The human mammary gland is capable of de novo lipogenesis, mainly MCFAs, which is increased during a H-CHO diet.