The present invention relates to S-methylcysteine sulfoxide and compositions thereof for use in the treatment or prevention of prostate cancer. It also relates to analogues, derivatives or metabolites of S-methylcysteine sulfoxide for use in the treatment or prevention of prostate cancer. Compositions of S-methylcysteine sulfoxide or its analogues, derivatives or metabolites may be provided for oral consumption, for example as a pharmaceutical composition, a medicament or a food composition.