The present invention refers to a new strain belonging to the species Lactobacillus paracasei able to convert linoleic acid into conjugated linoleic acid. The present invention refers also to nutritional or food preparations and/or pharmaceutical compositions, comprising the strain Lactobacillus paracasei, useful in the treatment and/or prevention of pathologies and/or physiological states related to conjugated linoleic acid deficiency or in the cases wherein the use of a probiotic is beneficial.