Trans fats are the Frankensteins of the fat world. They’re what happens when you pump hydrogen into an oil to make it solid. Trans fat consumption gained a foothold during World War II, when margarine was adopted as a substitute for butter. Subsequently, manufacturers used hydrogenation to turn cheap, subsidized soy oil into cheap, shelf-stable shortening for cookies, crackers, and snack foods—and to feed the fryer at the local fast food joint.
Initially, hydrogenated oils appeared to be healthier than saturated animal fats (think butter, lard, schmaltz), which were known to raise blood cholesterol levels. But research has shown that, while saturated fats are bad, trans fats can be monsters. These abnormal fats raise blood cholesterol, specifically LDL, or bad, cholesterol.
The FDA required trans fat labeling beginning in 2006. Since then, we’ve seen an explosion of foods bearing the label “trans fat free.” But a product can be trans fat free and still have a significant amount of total fat, increasing the risk of obesity, heart disease and cancer. In addition to looking for the words “trans fat” on food labels, also look for “partially hydrogenated oil.”
Two unfortunate twists: As a substitute for hydrogenated soy oil, manufacturers have turned to palm oil, one of the few vegetable fats that’s solid. Unfortunately, palm oil is wickedly effective at raising blood cholesterol. Also, trace levels of trans fat occur naturally in butter. Research indicates that these natural trans fats might actually be good for us, but in the frenzy to rid the world of trans fats, some high-quality bakeries have been forced to swap their butter for unnatural alternatives.
—By Jo Marshall, a food writer in Deephaven, Minn.