Discovery of essential fatty acids

Abstract

Journal of Lipid Research Volume 56, 2015 11polyunsaturated fatty acid containing two double bonds (18:2 -6), cured this defi ciency disease and, therefore, was an essential fatty acid ( 2 ). These two seminal papers are now regarded as classics in biochemistry ( 3 ), but they initially met with considerable skepticism ( 4 ). To understand why, one must appreciate the paradigm-changing nature of the discovery and the stature of the experts whose views concerning dietary fat were being challenged by Burr's fi ndings. VIEWS ON THE ROLE OF DIETARY FAT IN THE EARLY 20th CENTURYProteins and carbohydrates were known to be indispensable dietary components by the fi rst decade of the 20th century. However, dietary fat was not considered to be essential because fatty acids were known to be synthesized from carbohydrates. The evidence concerning fat was not defi nitive due to the inability to completely extract fat from the other dietary components using the methods available in the early 1900s, and the experimental fat-free diets of that era contained traces of residual fat.Two of the most prominent physiological chemists of the early 20th century, Thomas B. Osborne of the Connecticut Agricultural Experiment Station and Lafayette B. Mendel of the Sheffi eld Scientifi c School at Yale University, began their studies on the role of dietary fat in 1912. Osborne and Mendel were working collaboratively in New Haven and were already recognized world-wide for their pioneering studies on dietary proteins. Their initial fi ndings indicated that rats gained weight normally when fed a fatfree food mixture, and they concluded that "true fats" are not required for growth ( 5 ). However, Osborne and Mendel were aware of the work of Wilhelm Stepp in Strasbourg, who found that a lipoid present in egg yolk was an essential nutrient for mice ( 6, 7 ). MacArthur and Luckett at the University of Illinois also reported that a lipoid extracted from egg yolk was necessary for optimum growth of mice ( 8 ).Abstract Dietary fat was recognized as a good source of energy and fat-soluble vitamins by the fi rst part of the 20th century, but fatty acids were not considered to be essential nutrients because they could be synthesized from dietary carbohydrate. This well-established view was challenged in 1929 by George and Mildred Burr who reported that dietary fatty acid was required to prevent a defi ciency disease that occurred in rats fed a fat-free diet. They concluded that fatty acids were essential nutrients and showed that linoleic acid prevented the disease and is an essential fatty acid. The Burrs surmised that other unsaturated fatty acids were essential and subsequently demonstrated that linolenic acid, the omega-3 fatty acid analog of linoleic acid, is also an essential fatty acid. The discovery of essential fatty acids was a paradigm-changing fi nding, and it is now considered to be one of the landmark discoveries in lipid research.

Decreased Fatty Acid <i>β</i>-Oxidation Is the Main Cause of Fatty Liver Induced by Polyunsaturated Fatty Acid Deficiency in Mice

“…The PUFA-containing oil used in this study was a n-6/n-3 PUFA-balanced oil composed of equal amounts of linoleic and α-linolenic acids (about 30% (w/w), respectively), which are the most important PUFA in mammals (Spector and Kim 2015). Moreover, the dosage of this oil was much lower than that in past studies (Ren et al 1997;Sekiya et al 2003;Martin et al 2007;Ducheix et al 2013), and it was close to the physiological requirement (Reeves 1997;FAO 2010).…”

“…Polyunsaturated fatty acids (PUFA) from the n-6 and n-3 series, including primarily linoleic acid (18:2, n-6) and α-linolenic acid (18:3, n-3), are essential nutrients for mammals (Spector and Kim 2015). These essential FA are the basic components of biological membranes and are important in maintaining cellular structure and function.…”

Synthesis and Molecular Structures of the Lowest Melting Odd- and Even-Numbered α,β-Unsaturated Carboxylic Acids—(E)-Hept-2-Enoic Acid and (E)-Oct-2-Enoic Acid

“…Essential fatty acids have attracted much interest in food, health, and nutrition sciences due to their role in biological processes especially for humans [1][2][3][4]. Oleic acid, (Z)-octadec-9-enoic acid, and linoleic acid, (9Z,12Z)-9,12-octadecadienoic acid, respectively, can be found, for example, in meat and milk products, nuts, olives, and oils.…”

The discovery and early structural studies of arachidonic acid

“…Lewkowitsch (11), who recorded these findings in the compilation of physical and chemical data of oils, fats, and waxes published in 1913 and Burr (15) and the emerging theme of the biochemistry of essential fatty acids. This was a recent topic of a historical review for the Journal of Lipid Research (16). Two investigators, one in the United States, James B.…”