The importance of sulphur-containing natural products in primary and secondary metabolism. The role of hydrogen sulphide as a gasotransmitter and its uptake by living systems. The relevance of mustard oil glycosides (glucosinolates) and their enzymic breakdown products. Sulphur compounds of the genus Allium. Different approaches to the production of multiple sulphur compounds by Allium and Brassica species and its implications. The role of sulphur-containing natural products in chronic disease and their impact upon complex biological pathways. Inductive reasoning and natural products. Other potential bioactive compounds in Brassica species. Glucosinolates and their breakdown products and plant pathogenic fungal disease. Dithiocarbamates as potential storage forms of hydrogen sulphide. The importance of extra-oral bitter receptors. Natural products, reductionism, biological activity and statins. The weakness of nutritional epidemiology in the investigation of the effects of natural products.