IDO1 and postmenopausal osteoporosis: In women with postmenopausal osteoporosis, compared with healthy controls, less basal secretion of interferon gamma by CD4+ cells was reported by Breuil and colleagues.(32) Interferon gamma may promote bone loss through upregulation of RANKL and TNF‐alpha.(33) In addition to inflammation, IDO‐1 activity is also modulated by diet.