Low levels of histidine have been attributed to higher activity of histidine decarboxylase, resulting in an accelerated decarboxylation of histidine to histamine, a mediator involved in inflammatory and immune responses associated with cancer initiation and progression (26).On the other hand, 3-hydroxybutyrate is a component of ketone bodies and an end-product of fatty acid β-oxidation. This evidence concerns the gene HDC and cancer.