The invention relates to a composite material based on water-insoluble polysaccharide. The composite material includes particles of at least one light scattering material, the surface of which is essentially covered by at least one water-insoluble polysaccharide material. The invention also relates to a method for the preparation of the composite material. Further, the invention relates to a paper and board manufacturing process, in which said composite materials are employed as manufacturing materials. Both highly organic end products with exceptional heat capacities and cheap, high filler end products can be manufactured. The invention also relates to a method for improving retention of light scattering filler material in the manufacture of paper and board.