Asda, the UK supermarket chain owned by US retailer Wal-Mart, will remove all artificial colours and flavours from its own-brand food and drinks by 2008.
Food companies are looking closely at what they put in the meals
The news comes after a recent report advised parents not to give their children food containing certain additives because of health concerns.
The move will cover 9,000 own-label food and drink products, Asda said.
Asda also announced that its earnings in the first three months of 2007 had risen from the same period a year ago.
The company said it was benefiting from lower prices and a broader product range.
"It's not rocket science," said Andy Bond, Asda's chief executive.
"There's still plenty to do, but with interest rates on the rise again people are feeling the pinch, so lowering prices is as important now as it's ever been," he added.
Explaining its decision to halt the use of artificial colours and flavours, Asda said it was acting because "mums and dads are becoming more and more concerned about what's in the food they buy".
Asda - which is owned by US retail giant Wal-Mart - will replace the fake flavours with natural ones where necessary, while many others will simply be removed.
Earlier this month, a study said that parents should avoid giving their children foods containing a number of so-called E numbers because they could have an effect on their behaviour.
A warning came after a team at the University of Southampton tested the additives tartrazine (E102), ponceau 4R (E124), sunset yellow (E110), carmoisine (E122), quinoline yellow (E104) and allura red AC (E129).
The Food Standards Agency (FSA) said it would not issue formal recommendations until the findings were published.