Long term feeding effects of heated and fried oils on lipids and lipoproteins in rats

Long term feeding effects (20 weeks) of heated and fried oils at 5 and 20% level in the diet on growth, plasma and tissue lipids were studied in rats. Three vegetable oils of widespread usage viz peanut oil, sesame oil and coconut oil with varying saturation and unsaturation were chosen for the study. No significant difference in growth rate, feed efficiency ratio, and liver weights were observed. Higher plasma cholesterol levels were observed in heated oil fed group of rats compared to corresponding fried oil groups. Low levels of HDL-c and increased LDL-c and VLDL-c were noted in heated/fried oil groups. Significantly low levels (p < 0.001) of triglyceride were observed in heated/fried sesame oil group of rats. No significant change in phospholipid was observed in any of the groups. Significantly low levels of liver cholesterol and high triglyceride levels (at 20%) were observed in coconut oil group. The fatty acid composition of plasma and liver reflected the type of diet consumed. Although linoleic acid levels were quite low in some of the heated/fried oil groups the arachidonic acid levels were quite high indicating repair mechanism. The results of the study however do not present any deleterious effect on growth, plasma and tissue lipid profile of rats as the conditions employed for heating/frying were not too drastic and the oils were not heat abused.