Running a full-page ad in The New York Times this week, the Center for Science in the Public Interest (CSPI) urged McDonalds to complete a promise it made in 2002 to stop frying in partially hydrogenated vegetable oil (PHO).
Pressure is mounting on food industry players to remove trans fatty acids (TFAs) from food formulations due to ongoing research that suggests trans fats raise LDL (bad) cholesterol levels, causing the arteries to become more rigid and clogged. An increase in LDL cholesterol levels can lead to heart disease.
"America's favorite French fries are about to get even better," claimed McDonald's in a 2002 press release announcing that the company would reformulate its cooking oil with less trans fat.
In 2003, the fast-food firm issued a statement that said it would "extend the timeframe" for the change, which has not yet occurred. McDonald's is currently being sued in California by BanTransFat.com, for misleading the public about the abandoned switch.
Formed when liquid vegetable oils go through a chemical process called hydrogenation, TFAs are common in a range of food products - biscuits, chips, doughnuts, crackers. Hydrogenated vegetable fat is used by food processors because it is solid at room temperature and has a longer shelf life.
But a raft of manufacturers are switching to non-trans fat alternatives. Kraft foods said earlier this year that it had launched a trans fat free version of its iconic Oreo biscuit. The move followed a court case against Kraft's owner Nabisco - which attracted massive media attention in the US - whereby BanTransFats called on the firm to remove the biscuits from sale because of the harm trans fats could cause to children. Swiss food behemoth Nestle is also working to reduce trans fat presence.
"We have taken the decision to reduce trans fats levels to less than 1 per cent of total food energy, the level recommended by the World Health Organisation," a spokesperson from the firm recently told FoodNavigator.com.
From January 2006 food manufacturers working in the US market will have to label trans fat content on food products. Europe has yet to introduce a similar rule, but consumer organisations are pressing for such transparency.
Last year Denmark became the first country in the world to introduce restrictions on the use of industrially produced trans fatty acids. Oils and fat are now forbidden on the Danish market if they contain trans fatty acids exceeding 2 per cent.