Sphingolipids in human ileostomy content after meals containing milk sphingomyelin.
BACKGROUND
Sphingomyelin occurs in modest amounts in the diet, in sloughed mucosal cells, and in bile. It is digested by the mucosal enzymes alkaline sphingomyelinase and ceramidase. In humans, alkaline sphingomyelinase is also secreted in bile. The digestion of sphingomyelin is slow and incomplete, which has been linked to the inhibition of cholesterol absorption and colonic carcinogenesis.


OBJECTIVE
We evaluated whether the supply of moderate amounts of milk sphingomyelin increases the exposure of the colon to sphingomyelin and its metabolites.


METHODS
Two experimental series were performed. In experiment A, we measured the content of sphingomyelin and ceramide in human ileostomy content by HPLC during 8 h after consumption of a test meal containing 250 mg milk sphingomyelin. In experiment B, we measured the molecular species of sphingomyelin and ceramide by HPLC-tandem mass spectrometry after doses of 50, 100, or 200 mg sphingomyelin.


RESULTS
In experiment A, the average increase in ileostomy content of ceramide plus sphingomyelin amounted to 19% of the fed dose of sphingomyelin. In experiment B, the output of C-22:0-sphingomyelin, C-23:0-sphingomyelin, C-24:0-sphingomyelin, and sphingosine increased significantly, and palmitoyl-sphingomyelin increased proportionally less. Outputs and concentrations of palmitoyl-ceramide and sphingosine showed great individual variation, and stearoyl-sphingomyelin and stearoyl-ceramide did not increase after the meals. Although the output of long-chain sphingomyelin species increased significantly, the data indicated that >81% of all measured sphingomyelin species had been digested.


CONCLUSIONS
Humans digest and absorb most of the sphingomyelin in normal diets. The amount of sphingolipid metabolites to which the colon is exposed can, however, be influenced by realistic amounts of dietary sphingomyelin.
Ohlsson
Lena
L
Department of Gastroenterology, Lund University, Lund, Sweden.
Hertervig
Erik
E
Jönsson
Bo Ag
BA
Duan
Rui-Dong
RD
Nyberg
Lena
L
Svernlöv
Rikard
R
Nilsson
Ake
A
D000328:Adult; D000818:Animals; D002518:Ceramides / Q000378:metabolism*; D003106:Colon / Q000378:metabolism*; D004032:Diet; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism; D005260:Female; D006801:Humans; D007081:Ileostomy; D008297:Male; D008875:Middle Aged; D008892:Milk / Q000737:chemistry / Q000378:metabolism*; D013109:Sphingomyelins / Q000008:administration & dosage / Q000378:metabolism*; D055815:Young Adult
D002518:Ceramides; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D013109:Sphingomyelins