In 1909 Procter & Gamble in Cincinnati acquired the US rights to the Normann patent from Crosfield's and in 1911 they began marketing Crisco, the first hydrogenated shortening, which contained a large amount of cottonseed oil. In America, however, six other firms had been working since 1915 according to the patents of C.E. Kayser (1910) and Carleton Ellis (1912), and with a number of other processes, most of which were never published. After a long period of litigation, initiated by Procter & Gamble, for alleged infringement of patent rights, a US court decision held the 1915 Burchenal patent (US Patent 1,135,351), under whose broad claims P&G's shortening was then being made, to be invalid. This opened the way for a number of firms to begin manufacture of hydrogenated shortenings and, from 1915, margarines.Hydrogenated vegetable oil wasn't widely eaten until 1920:
Before the use of hydrogenation, the production of shortening and margarine had been entirely dependent on animal fats as a source of raw materials. Increased demand soon caused these to grow scarce and expensive. Thus hydrogenation liberated shortening and margarine from their dependence on animal fats and made it possible for cooks to have products resembling lard and butter made from vegetable oils. Nevertheless it was not until after 1920 that hydrogenated vegetable oils were widely used in margarine and shortening. During the 1930s the use of hydrogenation worldwide took a quantum leap forward, as production increased greatly.Death from coronary heart disease was rare until 1925. It peaked in the 1950s, remaining high through the 1970s and diminishing only due to modern medical interventions. Coincidence? I don't know, but it's awfully suspicious.
By the late 1970s roughly 60% of all edible oils and fats in the US were partially hydrogenated (Dutton, in Emken and Dutton 1979). And an estimated 75% of the soy oil used in the US was hydrogenated to make shortening and margarine, as well as large amounts of lightly hydrogenated soy cooking and salad oils (Kromer 1976).
Rizek et al. (1974) estimated that in the period from 1937 to 1972 per capita annual consumption of trans fatty acids increased by 81%, from 6.3-11.4 gm. During the same period per capita consumption of vegetable oils and fats increased by only 64% (from 36-59 gm).
Here is a description of the hydrogenation process. Makes my mouth water:
Typically, a mixture of refined oil and finely powdered nickel catalyst (comprising 0.05-0.1% of the weight of the oil) is pumped into a cylindrical pressure reactor of 5-20 tons capacity. It is heated by heating coils to 120-188°C (248-370°F) at 1-6 atmospheres pressure. Hydrogen is pumped into the bottom of the reactor and dispersed by a stirrer, continuously, as bubbles into the oil... After hydrogenation is completed to the desired degree, the oil is filtered to remove the catalyst (which may be reused) then pumped to a storage tank; it may later be blended with other harder or softer fats or oils to make margarine or shortening.Who in his right mind would think this stuff is suitable for human consumption? Hydrogenated vegetable oil is ubiquitous in processed food, because of its low cost and long shelf life, although the amounts are diminishing since the FDA required it to be included on nutrition labels in 2006. The implication here is that consumers know it's unhealthy, but manufacturers aren't going to stop putting it in foods until someone shines a spotlight on them.
It will be interesting to see if CHD incidence drops with decreasing trans fat intake. The obesity epidemic does seem to be leveling off in the U.S. This also corresponds with other recent dietary improvements such as a small decrease in sugar, wheat and vegetable oil consumption (see this post).