The invention relates to the use of a particulate material derived from mammalian hair in the preparation of a paper or paperboard product, which particulate material has been prepared by means of a process, which comprises the following steps: (a) subjecting mammalian hair to an oxidation treatment in which the hair is contacted with a solution, which comprises a bleaching agent; (b) separating the oxidised hair from the solution; (c) drying the separated hair; and (d) subjecting the dried hair to a treatment in which the hair is formed into a particulate material having an average particle size in the range of from 0.5 to 4 mm. The invention further relates to a paper or paperboard product, or paper pulp comprising said particulate material.