Definition: Non-compounders are individuals who do not have a compound or complex substance in their body, as defined by the World Health Organization (WHO) and the International Agency for Research on Cancer (IARC). They can be found in various populations, such as those with genetic disorders, chronic diseases, or certain medical conditions. Non-compounders may also refer to individuals who do not have a specific substance in their body, such as a hormone, vitamin, or nutrient.