The present invention relates to carriers for the controlled release of active agents, comprising a core, comprising surface reacted natural or synthetic calcium carbonate, and at least one active agent, wherein said at least one active agent is associated with said natural or synthetic surface-reacted calcium carbonate, and wherein said surface-reacted natural or synthetic calcium carbonate is a reaction product of natural or synthetic calcium carbonate with carbon dioxide and one or more acids, wherein the carbon dioxide is formed in situ by the acid treatment and/or is supplied from an external source, and a coating encapsulating the core. It furthermore relates to the preparation of loaded carriers, as well as their use in different applications.