The present invention relates to probiotic Propionibacterium strains and their use in the preparation of probiotic supplements and foods. The invention relates to the provision of Vitamin B.sub.12, propionic acid, folacin and bacteriocins by probiotic strains, stimulation of bifidobacteria growth, production of favourable effects on the lipid metabolism and on the immune system of hosts through immunostimulation, immunomodulation or use of a probiotic strain as an adjuvant, reduction of homocysteine and .beta. glucuronidase and the prevention, treatment or amelioration of conditions associated with a need for these activities. The probiotic bacteria of the invention can be used in humans or other animals. In at least some applications, the bacteria can be used dead and parts rather than whole cells may be used. The present invention also relates to the preparation of vaccines for use in protecting patients from infectious diseases, in particular tuberculosis.