Effects of dietaryTrans‐fat on biliary and fecal steroid excretion and serum lipoproteins in rats

Abstract

Rats were fed cholesterol-free or cholesterol-enriched diets containing olive oil or partially hydrogenated corn oil at the 10% level for ca. 30 days (c-18:1, 77.0% in the former diet and c-18:1,24.7% and t-18:1,42.5% in the latter). The linoleic acid content of these fat diets was made equivalent (1.7 energy %). After feeding cholesterol-free diets, trans fat compared to cis fat showed (a) no untoward effects on growth parameters, (b) a reduction of serum cholesterol levels without influencing concentrations of serum apolipoproteins A-1, B and E, (c) no effects on the bile flow and the concentration of biliary cholesterol and bile acids, (d) an increasing trend of fecal excretion of neutral and acidic steroids, both in terms of mg/day and mg/g feces, and (e) rather equivocal change in the composition of fecal, but not biliary steroids. Similar response patterns were also observed when cholesterol-enriched diets were fed except for a decrease in serum apo B and an ineffectiveness to increase fecal acidic steroids. Together with the results obtained from experiments simultaneously performed with safflower oil and completely hydrogenated corn oil, it seems that the steroid metabolism can be specifically modified by the geometry of dietary fats.

Differential Effects of Geometrical Isomers of Octadecadienoic Acids on Ketogenesis and Lipid Secretion in the Livers from Rats Fed a Cholesterol-Enriched Diet

“…in the feeding trials [5][6][7][8][9], since they appar ently repressed the net influx of cholesterol and triglyceride from liver into the blood stream. Fatty acid compositions of triglyceride, phospholipid and cholesterol ester in perfu sate obtained at 4 h and postperfused livers are summarized in table 4.…”

“…cis.trans/trans.cis-and trans.trans-18:2 acids on ketogenesis and lipid secretion in the perfused liver system was also recipro cal and appeared to depend on the number and position of the /ram-double bond in the molecule [4], These observations emphasized, in the liver of rats fed a diet free of cholesterol, that isomerization of the cw-double bond to /ram-configuration at the specified position in the unsaturated fatty acids is crucial for an altered partition between the pathways of oxi dation and esterification. In this context, rats fed the diets containing /raw-fatty acids as compared to d.v-fatty acids showed a marked reduction in the concentration of hepatic tri glyceride and cholesterol [5][6][7][8][9], There is, how ever, little information whether these re sponses could be duplicated when rats were fed a cholesterol-enriched diet.…”

Effects of Dietary Trans Fatty Acids on Fat Accumulation and Metabolic Rate in Rat

“…In the present study, the levels of linoleic and linolenic acids were both 0.4 of total energy, which could meet the minimal requirements of these essential FA shown in Bourre s report 32 . However, the essential FA levels were slightly lower compared to other studies that investigated the effects of dietary TFAs 26,27 , and further studies investigating the effects of TFAs on fat metabolism are needed on the bases of sufficient amounts of essential FAs in TFA diets.…”

“…Sugano et al 27 also reported that feeding TFAs to rats for 4 weeks significantly decreased the serum total CHO concentration. These finding were consistent with the present findings.…”

Morphological evaluation of the atherogenecity of corn oil, hydrogenated corn oil, and butter fat in quail.

“…The basal diet (Kyoei Co., Ltd., Okinawa) contained l8% protein, 3.8% fat, 6.3% ash, 3.5% fi ber, and 2,842 kcal/kg. The fatty acid composition of various diets was analyzed by gas-liquid chromatography as described elsewhere (9,10).…”