|Grusak, Michael - Mike|
Submitted to: Metabolism
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2003
Publication Date: 2/1/2004
Citation: ERKKILA, A.T., LICHTENSTIEN, A.H., JALBERT, S.M., DOLINKOWSKI, G.G., GRUSAK, M.A., AQUINO, K.A., PETERSON, J.W., BOOTH, S.L. FEASIBLITY OF USING DEUTERIUM-LABELED COLLARD GREENS FOR THE STUDY OF VITAMIN K ABSORPTION AND TRANSPORT. METABOLISM. 2004; 53:215-221. Interpretive Summary: Stable isotopes, which are naturally occurring elements in the environment, can be applied to understanding the absorption of vitamin K in amounts obtainable from food. A single serving of 100 g (equivalent to 396 µg vitamin K) of isotope-labeled collard greens was fed with a breakfast containing 24 g fat to five healthy men [mean age: 50 years, mean body mass index 25.5 kg/m2]. Eleven blood samples were obtained over 9 days. Vitamin K concentrations in plasma and lipoproteins were measured, and the abundances of isotope-labeled and normal vitamin K were determined. Plasma total vitamin K levels peaked at 6-9 hours, and returned to baseline by 24 hours. The triglyceride rich lipoproteins (TRL) was the major carrier of vitamin K in blood; low density and high density lipoproteins contained smaller amounts. By 6 hours following the breakfast, 88% of the plasma and 89% of the TRL vitamin K were enriched with the isotope label from the collard greens. This enrichment was reduced to 50% and 69%, respectively, by the end of a 24-hour period. Isotope-labeled vitamin K was not detectable at 72 hours. These results suggest rapid absorption of vitamin K from collard greens. Stable isotopes are feasible for use in vitamin K absorption studies.
Technical Abstract: Stable isotopes can be applied to understanding the in vivo absorption and transport of phylloquinone in physiological doses from food. A single bolus of 100 g (396±28 µg phylloquinone) of deuterium-labeled collard greens was fed with a breakfast containing 24 g fat to five healthy men [(mean±SD) 50±23 y, body mass index 25.5±2.8 kg/m2]. Eleven blood samples were obtained over 216 h. Phylloquinone concentrations in plasma and lipoprotein subfractions were measured using HPLC, and the ion abundances of deuterated and endogenous phylloquinone were determined using GC/MS. Plasma total phylloquinone levels peaked at 6-9 h (10.51±4.38, 8.30±4.64 nmol/L) and returned to baseline by 24 h (1.26±0.38 nmol/L). The triglyceride rich lipoprotein (TRL) fraction was the major carrier of phylloquinone; LDL and HDL fractions contained smaller amounts. Maximum enrichment of plasma and TRL phylloquinone with deuterium (88% and 89%, respectively) was reached at 6 h and the enrichment reduced to 50% and 69%, respectively, at 24 h (n=3). Deuterated-phylloquinone was not detectable at 72 h. These results suggest rapid uptake and transport of phylloquinone from collard greens. Stable isotopes are feasible for use in phylloquinone absorption studies, with some caveats.