Described is the use of soluble indigestible fiber for inducing lysis of the cell walls of eukaryotic microalgae in the lumen of the intestine of an omnivorous or carnivorous animal including an intestinal flora and also for synergistically increasing the effect of the indigestible fiber in the induction of the growth of the intestinal flora of an omnivorous or carnivorous animal. The subject matter of the invention is also the composition intended for this use and for a method of improving the health or of food supplementation.
