Endothelial dysfunction induced by postprandial lipemia is neutralized by addition of proteins to the fatty meal.
BACKGROUND
Postprandial lipemia is known to reduce endothelium-dependent flow-mediated vasodilation (FMD). Because postprandial lipemia can be acutely mitigated when proteins are added to the fatty meal, we investigated whether this mitigation could neutralize the lipemia-induced endothelial dysfunction.


METHODS
Sixteen healthy students (aged 19-23, eight males and eight females) received three different test meals at intervals of 1 week between successive tests. Each meal contained whipping cream alone or whipping cream together with either caseinate or soy protein. The whipping cream contained 33% fat, and 3 ml (= 1 g fat) was given per kg body weight. The proteins added were either 50 g sodium caseinate or 50 g soy protein. FMD was assessed by two-dimensional ultrasonography of the brachial artery in the fasting state and 1, 2, 3, 4, 5, 6, 7, and 8h after the fatty meal. Blood was withdrawn at the same time-points from the other arm. Triglycerides, free fatty acids, and insulin were determined using routine methods, and both L-arginine and asymmetric dimethylarginine (ADMA) were determined by LC-MS.


RESULTS
Postprandial lipemia reduced FMD, the reduction reaching a maximum of 58% after 3 h. This impairment of endothelial function was not observed when either of the test proteins had been added to the fatty meal (p < 0.01 for caseinate and p < 0.001 for soy protein). The effects of the protein addition were decreases in triglycerides and free fatty acids, increased insulin concentrations at all time-points, and an increased arginine/ADMA ratio between 1 and 5h after the meal, particularly in the case of the soy protein.


CONCLUSIONS
We suggest that the neutralization of the lipemia-induced endothelial dysfunction is caused by direct and indirect effects of the proteins insulinotropy and, secondly, by an increased supply of L-arginine.
Westphal
Sabine
S
Institute of Clinical Chemistry, Magdeburg University Hospital, Leipziger Street 44, D-39120 Magdeburg, Germany. Sabine.Westphal@Medizin.Uni-Magdeburg.de
Taneva
Elina
E
Kästner
Steffi
S
Martens-Lobenhoffer
Jens
J
Bode-Böger
Stefanie
S
Kropf
Siegfried
S
Dierkes
Jutta
J
Luley
Claus
C
D000328:Adult; D001120:Arginine / Q000031:analogs & derivatives / Q000097:blood; D001783:Blood Flow Velocity; D001916:Brachial Artery / Q000502:physiology; D002364:Caseins / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage / Q000009:adverse effects*; D004044:Dietary Proteins / Q000008:administration & dosage*; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D008055:Lipids / Q000097:blood*; D008297:Male; D019518:Postprandial Period; D030262:Soybean Proteins / Q000008:administration & dosage; D014280:Triglycerides / Q000097:blood; D014463:Ultrasonography; D014664:Vasodilation
D002364:Caseins; D004041:Dietary Fats; D004044:Dietary Proteins; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008055:Lipids; D030262:Soybean Proteins; D014280:Triglycerides; C018524:N,N-dimethylarginine; D001120:Arginine