AbstractHair shaft problems induced by extrinsic factors include environmental factors such as physical trauma like UV radiation or cosmetic treatments as thermal damage caused by hair dryers, ironing, and hair curling devices. Also, chemical straightening and hair coloring are examples of chemical causes of hair shaft fracture. Hair shaft fractures have a wide range of types and forms. These structural defects are linked to hair fragility and can be hereditary or acquired. Trichorrhexis nodosa, monilethrix, pseudo monilethrix, pili torti, trichoschisis, trichorrhexis invaginata and pseudopili annulati are all examples of hair shaft disorders. Cysteine, a semi-essential amino acid that is abundant in hair, plays a crucial role in maintaining the stability of the hair shaft through its involvement in disulfide bond formation. Glutamine might be a substantial source of energy for tissues that use aerobic glycolysis. As a result, metabolic data indicates that glutamine is a substantial fuel source in the hair follicle.
