Abstract: The disclosure relates to a plant fiber product for oral use, the product containing a mixture of at least: plant fibers; and at least one added substance intended to be released from the product when the product is used. The product contains an alginate composition, dispersed in the product and comprising at least water, alginate and the added substance, the composition containing an alginate matrix that firmly retains at least a major proportion of the added substance so long as the matrix is intact, and the alginate matrix being formed so as to disintegrate and/or dissolve in the chemical and physical environment that exists in a user's mouth. The disclosure also relates to a method for preparing such a plant fiber product.