Conditions affecting hair color Human hair color

1 conditions affecting hair color

1.1 aging or achromotrichia
1.2 stress
1.3 medical conditions
1.4 artificial factors
1.5 changes after death

conditions affecting hair color

aging or achromotrichia

children born hair colors may find gradually darkens grow. many blond, light brown, or red haired infants experience this. caused genes being turned off , on during childhood , puberty.

changes in hair color typically occur naturally people age, turning hair gray , white. called achromotrichia. achromotrichia begins in mid-twenties in men , late twenties in women. more 60 percent of americans have gray hair age 40. age @ graying begins seems entirely due genetics. people born gray hair because inherit trait.

the order in graying happens usually: nose hair, hair on head, beard, body hair, eyebrows.

in non-balding individuals hair may grow faster once turns gray.

several genes appear responsible process of graying. bcl2 , bcl-w first 2 discovered, in 2016, irf4 (interferon regulatory factor 4) gene announced after study of 6,000 people living in 5 latin american countries. however, found environmental factors controlled 70% of cases of hair graying.

the change in hair color occurs when melanin ceases produced in hair root , new hairs grow in without pigment. stem cells @ base of hair follicles produce melanocytes, cells produce , store pigment in hair , skin. death of melanocyte stem cells causes onset of graying. remains unclear why stem cells of 1 hair follicle may die on decade before in adjacent follicles less millimeter apart.

graying of hair may triggered accumulation of hydrogen peroxide. abnormally low levels of enzyme catalase, breaks down hydrogen peroxide , relieves oxidative stress in patients suffering vitiligo. since vitiligo can cause eyelashes turn white, same process believed involved in hair on head (and elsewhere) due aging.

the anti-cancer drug imatinib has been shown reverse graying process. however, expensive , has potentially severe , deadly side effects, not practical use alter person s hair color. nevertheless, if mechanism of action of imatinib on melanocyte stem cells can discovered, possible safer , less expensive substitute drug might someday developed. not yet known whether imatinib has effect on catalase, or if reversal of graying process due else.

stress

anecdotes report stress, both chronic , acute, may induce achromotrichia earlier in individuals otherwise have. proponents point survivors of disasters, such titanic survivor harold bride, or high-level politicians such bill clinton or barack obama. there evidence chronic stress causing premature achromotrichia, no definite link has been established. known stress hormone cortisol accumulates in human hair on time, whether has effect on hair color has not yet been resolved.

medical conditions

albinism genetic abnormality in little or no pigment found in human hair, eyes, , skin. hair white or pale blond. however, can red, darker blond, light brown, or rarely, dark brown.

vitiligo patchy loss of hair , skin color may occur result of auto-immune disease. in preliminary 2013 study, researchers treated buildup of hydrogen peroxide causes light-activated pseudo-catalase. produced significant media coverage further investigation may someday lead general non-dye treatment grey hair.

malnutrition known cause hair become lighter, thinner, , more brittle. dark hair may turn reddish or blondish due decreased production of melanin. condition reversible proper nutrition.

werner syndrome , pernicious anemia can cause premature graying.

a 2005 uncontrolled study demonstrated people 50–70 years of age dark eyebrows gray hair more have type ii diabetes both gray eyebrows , hair.

artificial factors

a 1996 british medical journal study found tobacco smoking may cause premature graying. smokers found 4 times more begin graying prematurely, compared nonsmokers.

gray hair may temporarily darken after inflammatory processes, after electron-beam-induced alopecia, , after chemotherapy regimens. remains learned physiology of human graying.

there no special diets, nutritional supplements, vitamins, nor proteins have been proven slow, stop, or in way affect graying process, although many have been marketed on years. however, french scientists treating leukemia patients new cancer drug noted unexpected side effect: of patients hair color restored pre-gray color.

changes after death

the hair color of mummies or buried bodies can change. hair contains mixture of black-brown-yellow eumelanin , red pheomelanin. eumelanin less chemically stable pheomelanin , breaks down faster when oxidized. reason egyptian mummies have reddish hair. color of hair changes faster under extreme conditions. changes more under dry oxidizing conditions (such in burials in sand or in ice) under wet reducing conditions (such burials in wood or plaster coffins).