Docosahexaenoic acid-rich fish oil and pectin have a hypolipidemic effect, but pectin increases risk factor for colon cancer in rats

Abstract

This study was designed to compare the effect of fish oil rich in DHA and pectin on the level of plasma lipids, hepatic HMG CoA reductase activity, microsomal membrane fluidity, colonic luminal content of short chain fatty acids (SCFA) and fecal excretion of bile acids and neutral sterols in rats. Male SD rats (7wks) were divided into three groups according to dietary fat sources, beef tallow (BT), corn oil (CO), fish oil (FO) and each group was subdivided into cellulose and pectin groups. The rats were fed for 25 wks the experimental diet containing 15% fat and 6% fiber and all rats were intramuscularly injected. with DMH. FO significantly reduced the levels of plasma Chol, TG, LDL-C, VLDL-C and hepatic HMG CoA reductase activity and increased membrane fluidity as compared with BT and CO. Pectin significantly reduced the levels of plasma Chol, VLDL-C and LDL-C, but increased HDL-C, HMG CoA reductase activity and membrane fluidity (p<0.05). However, pectin significantly increased the luminal content of butyrate and propionate in CO-fed rats and increased fecal excretion of deoxycholic acid and lithocholic acid in BT and CO-fed rats (p<0.05). Overall, fish oil had a protective effect against CVD by inhibiting hepatic HMG CoA reductase activity and increasing hepatic microsomal fluidity, thus leading to a reduction in plasma lipids. Pectin also had a protective effect against CVD by increasing fecal excretion of neutral sterols and hepatic microsomal fluidity. Pectin, however, increased risk factors for colon cancer by increasing the production of secondary bile acids and SCFA in the colon.