Palm is a name used not only to refer to the plant of the same name, but also to indicate, in food and cosmetic labels, palm oil.

Palm oil is obtained from the pulp of the plant by a process of breaking the plant and squeezing the marrow.

There are two oil extraction systems:

• dry: mechanical presses are used to crush the plant
• wet: hot water is used to filter the oil

The resulting product is impure, as there are plant residues, cellular debris and fibrous material. Then the hot water is inserted so as to form a barrier in which the solids fall towards the bottom of the container, releasing the oil that will pass through sieves.

The mixture thus obtained and liberated from extraneous substances is boiled for an hour or two and the palm oil, lighter than the water, rises to the surface and is decanted.

Then the oil goes to another stage where it is still heated and skimmed by impurities that will be used either for saponification or for fuel. The ashes have a high potassium content and are therefore useful for fertilizing.

Due to its low cost, this oil is a widespread nutritional source in developing countries.

It contains a high content of saturated fats and palmitic acid.

In the food industry it is used for two reasons:

• it's cheap
• preserves for longer the foods in which it is added

However, recent studies have shown that a connection has been established between this oil and certain cardiovascular disorders (1) especially when this oil is heated (2).

Since its inception in food, this oil was first challenged for the deforestation it produces as farmers and companies producing it tend to clear forests and woodlands to extract it, given the high demand. Later, however, as early as 1991, attention was paid to the health issue with studies finding it difficult to interpret the evidence for this oil unambiguously with respect to coronary heart disease and cancer (3).

Studies from 2004 drew attention to the risk that this oil could create, if oxidized and that is, not fresh, with the creation of a negative lipid profile, toxicity to kidney, lung, liver and heart, while red palm oil, by virtue of its beta carotene content could protect against vitamin A deficiency and some forms of cancer (4).

There is a strong component of saturated fatty acids in palm oil, particularly palmitic acid, and these ldel 2014 studies confirm this (5).

Another 2015 study reiterates the high saturated fat content and provides not encouraging findings on the increase in harmful LDL cholesterol (6).

At the level of comparison, between palm oil and sunflower oil, it is confirmed that palm oil as a highly saturated vegetable oil can induce dysfunction of liver lipid metabolism before touching serum lipid levels. Sunflower oil, on the other hand, a highly unsaturated vegetable oil, has been shown to be well metabolized in the liver (7).

All these studies agree in attributing to palm oil a high saturated fat content and, in a long and articulate examination of the biological and nutritional properties of this oil by a group of researchers at the University of Naples, controversial results from a health perspective (8).

A study aimed at detecting the mutations produced in palm oil, used as frying oil for potato chips, found that, at temperatures of 150, 165 and 180° thermo-oxidative alterations, changes in fatty acid composition and color alteration are produced. In summary, the higher the temperature, the more the oxidation of palm oil increases (9).

Another problem related to palm oil is the increasing deforestation carried out to plant huge quantities of palm trees.

There is also a "red" palm oil on the market with slightly better physical characteristics and taste.

Palm oil studies

References__________________________________________________________________

(1) Chen BK, Seligman B, Farquhar Multi-Country analysis of palm oil consumption and cardiovascular disease mortality for countries at different stages of economic development: 1980-1997. Global Health. 2011 Dec 16;7(1):45. doi: 10.1186/1744-8603-7-45.

(2) Xian TK, Omar NA, Ying LW, Hamzah A, Raj S, Jaarin K, Othman F, Hussan F.  Reheated palm oil consumption and risk of atherosclerosis: evidence at ultrastructural level.  Evid Based Complement Alternat Med. 2012;2012:828170. doi: 10.1155/2012/828170.

(3)  Cottrell RC. Introduction: nutritional aspects of palm oil.  Am J Clin Nutr. 1991 Apr;53(4 Suppl):989S-1009S. Review.

(4)  Edem DO. Palm oil: biochemical, physiological, nutritional, hematological, and toxicological aspects: a review.  Plant Foods Hum Nutr. 2002 Fall;57(3-4):319-41. Review.

(5) Fattore E, Bosetti C, Brighenti F, Agostoni C, Fattore G. Palm oil and blood lipid-related markers of cardiovascular disease: a systematic review and meta-analysis of dietary intervention trials. Am J Clin Nutr. 2014 Jun;99(6):1331-50. doi: 10.3945/ajcn.113.081190.

(6)  Sun Y, Neelakantan N, Wu Y, Lote-Oke R, Pan A, van Dam RM.  Palm Oil Consumption Increases LDL Cholesterol Compared with Vegetable Oils Low in Saturated Fat in a Meta-Analysis of Clinical Trials. J Nutr. 2015 Jul;145(7):1549-58. doi: 10.3945/jn.115.210575. Epub 2015 May 20. 

(7) Go RE, Hwang KA, Kim YS, Kim SH, Nam KH, Choi KC. Effects of palm and sunflower oils on serum cholesterol and fatty liver in rats. 
J Med Food. 2015 Mar;18(3):363-9. doi: 10.1089/jmf.2014.3163. 

(8) Biological and Nutritional Properties of Palm Oil and Palmitic Acid: Effects on Health http://www.mdpi.com/1420-3049/20/9/17339

(9) Aniołowska M, Kita A. The effect of frying on glycidyl esters content in palm oil.  Food Chem. 2016 Jul 15;203:95-103. doi: 10.1016/j.foodchem.2016.02.028. Epub 2016 Feb 3.