Appendix 1
A molecular presentation of transfat.
Excerpt from Circulation Magazine
Trans fatty acids contain at least one double bond in the trans configuration. The carbon/carbon double bonds of fatty acids can exist in either the cis or trans configuration. When the two hydrogen atoms are on opposite sides of the double bond, the configuration is termed trans; when the two hydrogen atoms are on the same side of the double bond, the configuration is termed cis. Lack of rotational mobility precludes interconversion of configurations under normal circumstances. The bond angle is larger for a trans than a cis double bond. Therefore, the presence of a trans, relative to a cis, double bond results in acyl chains that can pack together more tightly.
Trans double bonds occur in nature as such. They are the result of anaerobic bacterial fermentation in ruminant animals and are thereby introduced into the food chain. Humans consume them in the form of meat and dairy products. Trans double bonds are also formed during the hydrogenation of either vegetable or fish oils. Oils are hydrogenated to increase their plasticity and chemical stability, hence their potential use in food products. It is important to note that hydrogenation results in a number of changes in the acyl chain of the fatty acid moiety, all of which can impact physiological parameters: conversion of cis to trans double bonds, saturation of double bonds, and migration of double bonds along the acyl chain resulting in multiple positional isomers."
Source : Alice H. Lichtenstein, “Trans Fatty Acids, Plasma Lipid Levels, and Risk of Developing Cardiovascular Disease. A Statement for Healthcare Professionals from the American Heart Association,” Circulation , 1997; 95:2588-2590.