Grape-Nuts Brand Manager Kristin DeRock said the cereal is made using “a proprietary technology and a production process that isn’t easily replicated.”
She says that process has made it more difficult to shift production and meet the increased demand.
DeRock told CNN Business that she expects the wheat and barley cereal to be widely available by spring.
Post Holdings, owner of Grape-Nuts, does not plan to discontinue the product.
The company has apologized for any inconvenience shoppers may experience and is working to get the product fully back in stores.