This review of
corn oil provides a scientific assessment of the current knowledge of its contribution to the American diet. Refined
corn oil is composed of 99%
triacylglycerols with
polyunsaturated fatty acid (PUFA) 59%,
monounsaturated fatty acid 24%, and
saturated fatty acid (SFA) 13%. The PUFA is
linoleic acid (C18:2n-6) primarily, with a small amount of
linolenic acid (C18:3n-3) giving a n-6/n-3 ratio of 83.
Corn oil contains a significant amount of
ubiquinone and high amounts of alpha- and gamma-
tocopherols (
vitamin E) that
protect it from oxidative rancidity. It has good sensory qualities for use as a salad and cooking oil.
Corn oil is highly digestible and provides energy and
essential fatty acids (EFA).
Linoleic acid is a dietary essential that is necessary for integrity of the skin, cell membranes, the immune system, and for synthesis of
icosanoids.
Icosanoids are necessary for reproductive, cardiovascular, renal, and gastrointestinal functions and resistance to disease.
Corn oil is a highly effective food oil for lowering serum
cholesterol. Because of its low content of SFAs which raises
cholesterol and its high content of PUFAs which lowers
cholesterol, consumption of
corn oil can replace SFAs with PUFAs, and the combination is more effective in lowering
cholesterol than simple reduction of SFA. PUFA primarily lowers
low-density-lipoprotein cholesterol (
LDL-C) which is atherogenic. Research shows that PUFA has little effect on
high-density-lipoprotein cholesterol (HDL-C) which is protective against
atherosclerosis. PUFA generally improves the ratio of
LDL-C to HDL-C. Studies in animals show that PUFA is required for the growth of
cancers; the amount required is considered to be greater than that which satisfies the EFA requirement of the host. At this time there is no indication from epidemiological studies that PUFA intake is associated with increased risk of breast or
colon cancer, which have been suggested to be promoted by high-fat diets in humans. Recommendations for minimum PUFA intake to prevent gross EFA deficiency are about 3% of energy (en%). Recommendations for prevention of
heart disease are 8-10 en%. Consumption of PUFA in the United States is 5-7 en%. The use of
corn oil to contribute to a PUFA intake of 10 en% in the diet would be beneficial to heart health. No single source of salad or cooking oil provides an optimum
fatty acid (FA) composition. Many questions remain to be answered about the relation of FA composition of the diet to various physiological functions and disease processes.