The Danger of Trans Fats
Trans fats are unsaturated fatty acids with at least one double bond in the trans configuration. While small amounts of trans fats are naturally present in meats and dairy products from cows, sheep, and other ruminants, the great majority of trans fats in our diet are industrially-produced, contained in foods made with partially hydrogenated vegetable oils. Partial hydrogenation, which converts vegetable oils into semi-solid fats for use in margarines, commercial cooking, and manufacturing processes, converts approximately 30% of the natural fats to trans fats. In the US, consumption of trans fats averages between 2-4% of total energy, with major sources being deep fried fast foods, bakery products (cakes, cookies, muffins, pies, etc.), packaged snack foods, margarines, and breads.
Considerable evidence exists for harmful effects of trans fat intake. Furthermore, trans fats from partially hydrogenated oils have no intrinsic health value. Thus, little justification can be made for the use of partially hydrogenated oils, compared with other natural oils or fats. Importantly, adverse effects are seen at very low intakes: for example, 1-3% of total energy, or approximately 2-7 grams (20-60 calories) for a person consuming 2000 calories/day. Thus, complete or near-complete avoidance of industrial trans fats (≤0.5% of energy) may be necessary to avoid adverse effects and minimize health risks.
In 2004, Denmark became the first country to legislate limits on trans fat content of foods, largely eliminating industrial trans fats from all foods (including restaurants) in that country. Canada is considering similar legislation, and the city of Chicago is also considering banning industrial trans fats from restaurants. If restaurants and food manufacturers will not voluntarily eliminate trans fats (as has largely been done in the Netherlands), several points validate the need for, and the importance, of legislative measures to reduce the consumption of trans fats: