Dietary psyllium reverses hypercholesterolemic effect of trans fatty acids in rats

The objective of the study was to examine the effect of dietary psyllium fiber and trans fatty acid (TFA) on serum cholesterol. Fifty-five male, weaning, Sprague-Dawley rats were assigned to four groups for a four-week feeding period. Each group was fed modified standard rodent diet with one of four treatments: corn and olive oil mix (OIL), corn and olive oil mixture plus psyllium (OILP), corn-oil margarine (MAR), and corn-oil margarine plus psyllium fiber (MARP). Experimental lipids and fiber composed 15% and 5% of the diet by weight. Among the fatty acids in the margarine 16% were TFA while the mixture of oils was free of TFA. At the end of the feeding period, animal blood was collected for serum lipid measurements. Total cholesterol level of MAR fed rats was significantly higher than that of OIL fed rats, while HDL cholesterol levels were the opposite. The addition of psyllium significantly reduced total cholesterol of MAR fed rats but such effect was not observed in OIL fed animals. Fiber also significantly raised the level of HDL cholesterol of MAR fed animals. When the total fecal lipids were measured, it was found that dietary psyllium significantly reduced the fat absorption especially of those MARP fed animals. These findings not only confirmed the hypercholesterolemic effect of TFA, but also indicated that psyllium fiber has the ability to improve the serum lipid profile of those consuming a TFA rich diet. The hypothesized effect is that fiber interferes with the usage of TFA found in margarine. TFA may be bound by natural dietary fiber and then lost in the feces. Funded by University of Delaware Research Foundation. (C) 2000 Elsevier Science Inc.