Effect of dietary phytosterols (PS) on rat tissue lipid composition

The objective of the present study was to examine the effect of dietary PS on sterol content and fatty acid composition of rat tissues. Male Sprague-Dawley rats, weighing 240-270 g, were fed a purified diet containing 0.2% cholic acid in the absence (control) or presence of 2% PS mixture (56% β-sitosterol, 28% campesterol, 10% stigmasterol and 6% dihydrobrassicasterol) The control diet contained 12 mg PS/100g compared to 2012 mg/100g in the supplemented diet. Animals were fed the diets ad lib for 3 wks. The sterol and fatty acid composition were examined in microsomes (liver, testis, ventral prostate and kidney) or lipids of plasma and epididymal fat. The major sterols detected were cholesterol, β-sitosterol and campesterol. Feeding the PS diet resulted in 5 fold increase in plasma PS compared to controls (7.7 versus 1.5 mg/dl, resp.) In the controls, the highest PS level was found in testis. No PS were detected in control prostate microsomes and adipose tissue lipids. Two tissues were found to accumulate PS upon feeding the supplemented diet, adipose tissue and liver. There was no effect of PS incorporation on microsomal cholesterol content with the exception of testis in which dietary PS reduced cholesterol content by 25 %. Dietary PS had no effect on fatty acid composition of liver, prostate and testis microsomes. The data suggest that dietary PS induce alterations in tissue sterols that may alter tissue function.