Biotoxins derived from bacteria, fungi and algae in food play an important role for development of diseases of unknown aetiology. Furthermore, dietary components modulate their toxicity and carcinogenicity. Current progress on their mode of action postulated the contribution of cytochrome P‐450 system as well as oxygen radicals, and phosphoprotein phospatases are the target of several tumour promoters. For prevention of biotoxin‐mediated development of diseases, a detailed study and information on biological function of dietary components and a possible association between diet/toxins are needed.