Starting this month, Cheestrings will contain 25% of children's recommended daily allowance of calcium, compared with 18% of RDA at the moment. Kerry is also fortifying Cheestrings with vitamin D for the first time.
"The rollout will begin this month and we aim to have all Cheestrings products containing 25% calcium and Vitamin D on shelf by early 2012," a spokeswoman for Kerry said.
The front of the new packs will read 'rich in calcium'. Kerry said it was considering an additional flash highlighting Cheestring's vitamin D content once the rollout was complete.
The company has already reduced the salt content of Cheestrings by 25% over the past eight years, but said it was looking to reduce this even further.