Parfetts' suppliers must remove hydrogenated vegetable oil from their products by the end of 2008 - or face being delisted.
The cash & carry group has given manufacturers the ultimatum in a bid to put pressure on them to behave more responsibly as well as to raise awareness of the fat, which is linked to health problems such as heart disease. It will ban any brand from its depots which does not meet the challenge by the end of next year.
Group trading negotiator Matthew Oxley said: "We know that there are still manufacturers, and major brands included, that continue to use hydrogenated vegetable oil, despite there being cleaner and healthier alternatives available.
"I think the deadline of late 2008 is achievable and I've had encouraging noises from national account managers."