On Food and Cooking

The Rise of Vegetable Margarine Modern
margarine is now made not from solid animal
fats, but from normally liquid vegetable oils.
This shift was made possible around 1900 by
German and French chemists who developed
the process of hydrogenation, which hardens
liquid oils by altering the structures of their
fatty acids (p. 801). Hydrogenation allowed
manufacturers to make a butter substitute that
spreads easily even at refrigerator
temperature, where butter is unusably hard.
An unanticipated bonus for the shift to
vegetable oils was the medical discovery after
World War II that the saturated fats typical of
meats and dairy products raise blood
cholesterol levels and the risk of heart
disease. The ratio of saturated to unsaturated
fat in hard stick margarine is only 1 to 3,
where in butter it is 2 to 1. Recently, however,
scientists have found that trans fatty acids
produced by hydrogenation actually raise
blood cholesterol levels (see box). There are