1. A nano-fibrillar cellulose suspension wherein cellulose fibres are at least partially broken down to primary fibrils obtained by the process comprising the steps of:(a) providing cellulose fibres contained in pulps selected from the group consisting of eucalyptus pulp, spruce pulp, pine pulp, beech pulp, hemp pulp, cotton pulp, or any mixture thereof;
(b) providing a filler, wherein the filler is natural ground calcium carbonate, and further wherein the filler has a median particle size of from 0.03 to 15 ?m;
(c) combining the cellulose fibres from step (a) and the filler from step (b); and
(d) fibrillating the cellulose fibres and the filler from step (c) until the cellulose fibres are partially broken down to primary fibrils and the Schopper Riegler degree is increased at least 4° SR; wherein the fibrillating in step (d) is carried out by a device selected from an ultra-fine friction grinder, a refiner, or a homogenizer, and wherein in step (d) the weight ratio of fibres to filler on a dry weight basis is from 1:10 to 10:1.