Fats

Two significant changes have taken place in the average U.S. diet in the last 30 years [...]: the proportion of fat has gone up from31% to 41%, and the proportion of saturated to unsaturated fats has increased still more sharply. This is because unsaturated fats (corn, cottonseed and peanut oils and some olive oils) are usually liquid at room temperature, so they are messier than the solid saturated fats (lard, suet, butter). As a result, manufacturers of shortening usually hydrogenate their unsaturated fats – by adding a couple of hydrogen atoms under heat and pressure. This turns part of the unsaturated fats into saturated fats, which look better, smell better and keep better.

Time Magazine, 12 de Novembro de 1956