Five or more grey hairs before the age of 20 indicates premature graying of hair.
(Or the ages of 25 or 30, depending.)
Serum iron, copper, and calcium levels were reduced in association with PHG and correlated with its severity. Premature graying may be an indicator that hair is not getting enough nutrients and minerals, and supplementation with these trace elements might reverse and is expected to prevent progression of canities; however, further studies are needed to find the underlying mechanism of this relationship.1
Canities is going gray before one's time, at least medically speaking, and comes from the Latin cānitiēs, referencing gray hair or old age, ultimately from cānus meaning hoary or gray. This can be a side effect of genetics, autoimmune disorders, smoking, nutrient deficiencies, atopy, and/or various other reasons such as oxidative stress.
The color of human hair is determined by the production of eumelanin and pheomelanin pigments in the melanocyte cells. During the anagen phase, melanin production is increased in the hair follicles. During the two other stages, catagen and telogen, melanogenesis decreases or is turned off completely. Hair may turn gray when the number of melanocytes in the hair follicles reduces during anagen.
Canities can also refer to any hair graying, premature or otherwise, as well as achromotrichia and canities subita.
1El-Sheikh, A. M., Elfar, N. N., Mourad, H. A., & Hewedy, E. S. (2018)
Relationship between Trace Elements and Premature Hair Graying
International Journal of Trichology, 10(6), 278–283.
https://doi.org/10.4103/ijt.ijt_8_18
HairQuest 2024