Diet Can Play an Important Role in Reducing Serum Cholesterol
in: Harper’s Illustrated Biochemistry, 29e © 2012 > Chapter 26. Cholesterol Synthesis, Transport, & Excretion
Kathleen M. Botham, PhD, DSc
Hereditary factors play the most important role in determinin g individual serum cholesterol concentrations; however, dietary and environmental factors also play a part, and the most beneficial of these is the substitution in the diet of polyunsaturated and monounsaturated fatty acids for saturated fatty acids.
Plant oils such as corn oil and sunflower seed oil contain a high proportion of polyunsaturated fatty acids, while olive oil contains a high concentration of monounsaturated fatty acids.
On the other hand, butter fat, beef fat, and palm oil contain a high proportion of saturated fatty acids.
Sucrose and fructose have a greater effect in raising blood lipids, particularly triacylglycerols, than do other carbohydrates.
The reason for the cholesterol-lowering effect of polyunsaturated fatty acids is still not fully understood. It is clear, however, that one of the mechanisms involved is the upregulation of LDL receptors by poly- and monounsaturated as compared with saturated fatty acids, causing an increase in the catabolic rate of LDL, the main atherogenic lipoprotein.
In addition, saturated fatty acids cause the formation of smaller VLDL particles that contain relatively more cholesterol, and they are utilized by extrahepatic tissues at a slower rate than are larger particles—tendencies that may be regarded as atherogenic.