The present invention relates to a composition in powder form comprising probiotic bacteria and at least one iron source selected from ferrous citrate, ferric citrate, ferrous sulphate monohydrate and mixtures thereof. Ferrous citrate, ferric citrate, ferrous sulphate monohydrate and mixtures thereof advantageously do not cause significant inhibition or reduction in the viability of the bacteria and thus these iron sources are advantageously used to fortify a composition in powder form comprising probiotic bacteria.