The binding legal principle established is that regulations made under section 35 of the Medicines and Related Substances Act 101 of 1965 are ultra vires and invalid to the extent that they purport to regulate substances that are not "medicines" as defined in the Act. A substance qualifies as a "medicine" under the Act only if it is used, purports to be suitable for use, or is manufactured or sold for use for a therapeutic or medicinal purpose, specifically: (i) the diagnosis, treatment, mitigation, modification or prevention of disease, abnormal physical or mental state or the symptoms thereof in humans; or (ii) restoring, correcting or modifying any somatic, psychic or organic function in humans. Substances used merely for maintaining, complementing or assisting normal physical or mental state, or for complementing health, supplementing diet, or providing nutritional effect, without a therapeutic purpose, do not fall within the statutory definition of "medicine" and therefore cannot be regulated under the Act's regulation-making powers.