The firm is the first major retailer in the UK to place a blanket ban on hydrogenated fats, and could set in place a trend that snowballs, with consumer choice increasingly informed by health and nutritional knowledge.
Hydrogenated fats are oils that have been processed through a chemical hardening method to achieve increased stiffness of the liquid oils. The process can create trans fatty acids, which are generally man-made, but can also form naturally in cow's milk and in vegetable fats.
These interfere with metabolic absorption efficiencies and tend to congregate at adipose tissue sites. In addition, they have effectively been linked to higher blood levels of bad (LDL) cholesterol that increases the risk of heart disease.
In the US, where food companies are desperately looking to remove the substance from their products before the 1 January labelling deadline that will require all food companies to label the amount of trans-fat in their products, consumer awareness is high.
But Europe has been slower to catch on.
Nonetheless, the European Food Safety Authority (EFSA) did issue a statement last year saying that the effects of trans fatty acids (TFAs) on heart health may be greater than that of saturated fatty acids. And while there are no such labelling rules in the European Union certain national governments are pushing for change.
Indeed, 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.
M&S's announcement to ban trans fats can therefore be seen as an anticipatory step. Consumer demand for trans fat-free food in Europe is growing, driving ingredient makers and food manufacturers to develop new, innovative products.
The move also follows the UK retailer's recent initiative to remove all artificial flavourings, artificial colourings and hydrogenated fats from all its chilled ready meals.
The company says that additive and hydrogenated fat-free ready meals have been in store since October. However, the confirmation that all its foods would be free from hydrogenated fats by mid 2006 has driven the stakes higher.
"We know that consumers are concerned about additives and believe we are well ahead of any other retailer in terms of removing additives from all our foods," said Guy Farrant, director of food at Marks & Spencer.
"Over the past few months we've gone back to the kitchen to make over 450 recipe changes to our ready meals to remove artificial colourings, artificial flavourings and hydrogenated fats and most of these lines have no artificial preservatives.
"Having removed artificial colourings, artificial flavourings and hydrogenated fats from our ready meals, we are now actively working to remove hydrogenated fat from all our food products, including confectionery, by mid 2006."
The move has been welcomed by leading charity, The Hyperactive Children's Support Group (HACSG).
"We welcome the move by Marks & Spencer to remove additives from its ready meals and applaud its commitment to further remove all hydrogenated fats from its entire food range by mid 2006," said Nick Giovannelli, project director of HACSG.
"This is a significant undertaking and one that we believe consumers will welcome."