Palm oil: Biochemical, physiological, nutritional, hematological and toxicological aspects: A review

Abstract

The link between dietary fats and cardiovascular diseases has necessitateda growing research interest in palm oil, the second largest consumedvegetable oil in the world. Palm oil, obtained from a tropical plant, Elaeis guineensis contains 50% saturated fatty acids, yet it does notpromote atherosclerosis and arterial thrombosis. The saturated fatty acidto unsaturated fatty acid ratio of palm oil is close to unity and it containsa high amount of the antioxidants, β-carotene, and vitamin E. Although palm oil-based diets induce a higher blood cholesterol level thando corn, soybean, safflower seed, and sunflower oils, the consumption ofpalm oil causes the endogenous cholesterol level to drop. Thisphenomenon seems to arise from the presence of the tocotrienols and thepeculiar isomeric position of its fatty acids.The benefits of palm oil to health include reduction in risk of arterialthrombosis and atherosclerosis, inhibition of endogenous cholesterolbiosynthesis, platelet aggregation, and reduction in blood pressure. Palm oilhas been used in the fresh state and/or at various levels of oxidation.Oxidation is a result of processing the oil for various culinary purposes.However, a considerable amount of the commonly used palm oil is in theoxidized state, which poses potential dangers to the biochemical andphysiological functions of the body. Unlike fresh palm oil, oxidized palm oilinduces an adverse lipid profile, reproductive toxicity and toxicity of thekidney, lung, liver, and heart. This may be as a result of the generation oftoxicants brought on by oxidation. In contrast to oxidized palm oil, red orrefined palm oil at moderate levels in the diet of experimental animalspromotes efficient utilization of nutrients, favorable body weight gains,induction of hepatic drug metabolizing enzymes, adequatehemoglobinization of red cells and improvement of immune function. However, high palm oil levels in the diet induce toxicity to the liver asshown by loss of cellular radial architecture and cell size reductions whichare corroborated by alanine transaminase to aspartate transaminase ratioswhich are higher than unity.The consumption of moderate amounts of palm oil and reduction in thelevel of oxidation may reduce the health risk believed to be associated withthe consumption of palm oil. Red palm oil, by virtue of itsβ-carotene content, may protect against vitamin A deficiency andcertain forms of cancer.