Serum and liver lipids in rats fed mixtures of corn and palm oils ± cholesterol

Abstract Rats were fed diets containing various mixtures of corn and palm oils ranging from 100% corn (CO) or palm oil (PO) to 90:10, 75:25, or 50:50 CO, and 75:25, 10:90, or 100% PO. One set of diets was augmented with 0.4% cholesterol and 0.1% cholic acid. When the diets were cholesterol-free, there were virtually no differences between groups in serum total or HDL cholesterol. Serum triglyceride levels were lowest in the rats fed 100% PO. Liver cholesterol levels were virtually the same in all groups. As the PO contribution to the dietary fat was increased, liver triglyceride levels fell, being lowest in rats fed 100% PO. Serum total and HDL cholesterol levels in rats fed CO plus cholesterol-cholic acid were the same as those seen in rats on the cholesterol-free diet. Introduction of the lowest level of PO raised serum cholesterol levels significantly and they continued to rise as more palm oil (palmitic acid) was introduced into the diet. Serum triglyceride levels were similar in all groups, but liver triglycerides fell with increasing dietary PO. The data support the assertion of Hayes and Khosla that palmitic acid becomes hypercholesterolemic only in cholesterol-containing diets. The observed effects of palmitic acid on serum and liver triglyceride levels, especially the latter, merit further study.