Abstract: The present invention relates to a method of forming dihydroferulic acid comprising providing ferulic acid and incubating the ferulic acid with a bacterial preparation of Lactobacillus johnsonii CNCM 1-1225 or a bacterial preparation of natural derivatives of Lactobacillus johnsonii CNCM 1-1225. An aspect of the invention is a composition comprising dihydroferulic acid and a bacterial preparation of Lactobacillus johnsonii CNCM 1-1225 or its natural derivatives. A further aspect of the invention is a composition comprising ferulic acid and a bacterial preparation of Lactobacillus johnsonii CNCM 1-1225 or its natural derivatives for use in the treatment or prevention of metabolic disease. Further aspects of the invention are the use of a bacterial preparation of Lactobacillus johnsonii CNCM 1-1225 or its natural derivatives; and a kit for preparing a food product.