Effect of breads containing trans fat, soybean or rice on plasma lipid and fatty acid composition in healthy Korean adults

It has been reported that trans fat (tFA) may have adverse or beneficial effect depending upon the position and number of double bonds. The presence of tFA in human tissues and fluids is related to dietary intake, intestinal absorption, metabolism and storage, exchanges among compartments. This study investigated the effect of breads containing tFA, soybean or rice on postprandial plasma fatty acid and lipid composition. 33 healthy volunteers were divided into 3 groups and fed soybean bread, rice bread or wheat bread groups containing equivalent amounts of tFA (elaidic acid rich, 3.75 g/day), respectively. Postprandial lipid profiles at 0, 1, 2, 3 and 4 hours after a respective meal were studied. Plasma fatty acid was extracted by the method of Folch and methyl ester of fatty and prepared by acid transmethylation and analyzed by Gas Chromatography. Peaks were identified using pure reference compounds and quantified. Postprandial data indicated that consumption of soybean and rice breads with 3.75 g tFA retarded the appearance of C18:1 and C18:2 tFA in plasma lipid compared to that of wheat bread. Futhermore, soybean and rice bread groups showed lower plasma saturated fatty acid levels than wheat bread group. Postprandial TG level was significantly lowered in soybean bread group compared to that of rice and wheat bread groups. These results imply that soybean bread with high dietary fiber content and biologically active substances may inhibit or delay lipid absorption.