HOME

TheInfoList




Hair color is the pigmentation of
hair follicle The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given orga ...

hair follicle
s due to two types of
melanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigments found in most organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individu ...

melanin
:
eumelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
and
pheomelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
. Generally, if more melanin is present, the color of the hair is darker; if less melanin is present, the hair is lighter. The tone of the hair is dependent on the ratio of black or brown eumelanin to yellow or red pheomelanin. Levels of melanin can vary over time causing a person's hair color to change, and it is possible to have hair follicles of more than one color on the same person. Some hair colors are associated with some
ethnic group An ethnic group or ethnicity is a grouping of people A people is any plurality of person A person (plural people or persons) is a being that has certain capacities or attributes such as reason, morality, consciousness or self-consciousn ...
s due to observed higher frequency of particular hair color within their geographical region, e.g. straight dark hair amongst East Asians, a large variety of dark, fair, curly, wavy and bushy hair amongst Europeans, curly, dark, and uniquely helical hair with Africans, whilst gray, white hair or "silver", is often associated with age and wisdom.


Genetics and biochemistry of hair color

The full genetic basis of hair color is complex and not fully understood.
Regulatory Regulation is the management of complex systems according to a set of rules and trends. In systems theory, these types of rules exist in various fields of biology and society, but the term has slightly different meanings according to context. For ...
DNA is believed to be closely involved in pigmentation in humans in general, and a 2011 study by Branicki et al. identified 13
DNA Deoxyribonucleic acid (; DNA) is a molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically neutral gro ...

DNA
variations across 11 different genes that could be used to predict hair color. Two types of pigment give hair its color, black-brown
eumelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
and reddish-brown/reddish-yellow
pheomelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
,
synthesized Synthesis or synthesize may also refer to: Science Chemistry and biochemistry *Chemical synthesis, the execution of chemical reactions to form a more complex molecule from chemical precursors **Organic synthesis, the chemical synthesis of or ...

synthesized
by
melanocytes Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale The ''stratum basale'' (basal layer, sometimes referred to as ''stratum germinativum'') is the deepest layer of the five layers of the ...
. Inside the melanocytes,
tyrosine -Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acid Amino acids are organic compound , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemi ...

tyrosine
is converted into
L-DOPA -DOPA, also known as levodopa and -3,4-dihydroxyphenylalanine, is an amino acid that is made and used as part of the normal biology Biology is the natural science that studies life and living organisms, including their anatomy, physical stru ...

L-DOPA
and then
L-dopaquinone -Dopaquinone also known as ''o''-dopaquinone is a metabolite of L-DOPA (L-dihydroxyphenylalanine) and a precursor of melanin. Biosynthesis of melanin occurs in melanocytes, where tyrosine is converted into DOPA and then dopaquinone, which goes on ...
, which in turn is formed into pheomelanin or eumelanin. Different hair color
phenotype right , Here the relation between genotype and phenotype is illustrated, using a Punnett square, for the character of petal color in pea plants. The letters B and b represent gene In biology, a gene (from ''genos'' "...Wilhelm Johannsen ...

phenotype
s arise primarily as a result of varying ratios of these two pigments in the human population, although Europeans show the greatest range in pigmentation overall. In addition, other genetic and environmental factors can affect hair color in humans; for instance, mutations in the
melanocortin 1 receptor The melanocortin 1 receptor (MC1R), also known as melanocyte-stimulating hormone receptor (MSHR), melanin-activating peptide receptor, or melanotropin receptor, is a G protein–coupled receptor that binds to a class of pituitary peptide hormones ...
(MC1R) gene can lead to red or auburn hair, and exposure to
ultraviolet radiation Ultraviolet (UV) is a form of electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, ...
can damage hair and alter its pigmentation.
Ultraviolet radiation Ultraviolet (UV) is a form of electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, ...
(UV radiation) triggers greater synthesis of several compounds, including
pro-opiomelanocortin Pro-opiomelanocortin (POMC) is a precursor polypeptide with 241 amino acid residues. POMC is Protein biosynthesis, synthesized in Corticotropic cell, corticotrophs of the anterior pituitary from the 267-amino-acid-long polypeptide precursor pre-pro ...
(POMC), , and
ACTH Adrenocorticotropic hormone (ACTH; also adrenocorticotropin, corticotropin) is a polypeptide Peptides (from Greek language Greek (modern , romanized: ''Elliniká'', Ancient Greek, ancient , ''Hellēnikḗ'') is an independent branch of the ...
, the end result being increased eumelanin production. UV radiation most commonly comes from the sun, and thus populations from places closer to the
equator The Equator is a , about in circumference, that divides into the and hemispheres. It is an located at 0 degrees , halfway between the and poles. In , as applied in , the equator of a rotating (such as a ) is the parallel (circle of l ...

equator
tend to have darker hair, because eumelanin is generally more photoprotective than pheomelanin. Pheomelanin colors hair
orange Orange most often refers to: *Orange (colour), occurs between red and yellow in the visible spectrum *Orange (fruit), the fruit of the tree species '' Citrus'' × ''sinensis'' ** Orange blossom, its fragrant flower *Some other citrus or citrus-li ...
and
red Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength Image:dominant wavelength.png, frame, Dominant/complementary wavelength example on the CIE color ...

red
. Eumelanin, which has two subtypes of
black Black is a color which results from the absence or complete absorption of visible light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that can be visual perception, perceived by t ...

black
or
brown Brown is a composite color Color (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United State ...

brown
, determines the darkness of the hair color; more black eumelanin leads to blacker hair, and more brown eumelanin to browner hair. All human hair has some amount of both pigments. Over 95% of melanin content in black and brown hair is eumelanin. Pheomelanin is generally found in elevated concentrations in blond and red hair, representing about one-third of total melanin content. If there is no black eumelanin, the result is strawberry blond. blond hair results from small amounts of brown eumelanin with no black eumelanin.


Natural hair colors

Natural hair color can be black, brown, red, blond, or white.


Color shade scale

The Fischer–Saller scale, named after
Eugen Fischer Eugen Fischer (5 July 1874 – 9 July 1967) was a German professor of medicine Medicine is the Art (skill), art, science, and Praxis (process) , practice of caring for a patient and managing the diagnosis, prognosis, Preventive medicine, p ...

Eugen Fischer
and , is used in
physical anthropology Biological anthropology, also known as physical anthropology, is a scientific discipline concerned with the biological and behavioral aspects of human beings, their extinct hominin The Hominini form a Tribe (biology), taxonomic tribe of the subf ...
and medicine to determine the shades of hair color. The scale uses the following designations: A (very light blond), B to E (light blond), F to L (
blond Blond or fair hair, also blonde, is a hair color Hair color is the pigmentation of hair follicles due to two types of melanin: eumelanin and pheomelanin. Generally, if more melanin is present, the color of the hair is darker; if less melanin ...

blond
), M to O (dark blond), P to T (), U to Y (dark brown to
black Black is a color which results from the absence or complete absorption of visible light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that can be visual perception, perceived by t ...
) and
Roman numerals Roman numerals are a that originated in and remained the usual way of writing numbers throughout Europe well into the . Numbers in this system are represented by combinations of letters from the . Modern style uses seven symbols, each with a ...
I to IV (
red Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength Image:dominant wavelength.png, frame, Dominant/complementary wavelength example on the CIE color ...

red
) and V to VI (red blond).


Image gallery

File:IU at the Yonsei University Akaraka Festival, 22 June 2014 01.jpg,
Black hair Black hair is the darkest and most common of all human hair colors globally, due to larger populations with this dominant trait. It is a dominant genetic trait, and it is found in people of all backgrounds and ethnicities. It has large amounts ...
File:Chinese American girl.jpg, Natural black hair File:Lymari Nadal.jpg, Deepest brown hair File:Short brown hair.jpg, Dark brown hair File:Woman with long brown hair, rear view.jpg, Medium brown hair File:Little girl with brown hair.jpg, File:Goofy Boy.jpg, Light brown hair File:Yvonne Catterfeld.jpg, Chestnut brown hair File:A child of chappargram.JPG, Light chestnut brown hair File:Rotschopf.jpg, Auburn hair File:Rupert Grint.jpg,
Red hair Red hair (also known as orange hair and ginger hair) is a hair colour found in one to two percent of the human population Humans (''Homo sapiens'') are the most populous and widespread species In biology, a species is the basic ...

Red hair
File:German Woman Portrait - Dutch summer festival of the Redhead Day in Breda, September 2010.jpg, Orange red hair File:נערה ג'ינג'ית.JPG, Copper hair File:Elena Kazantseva 00.jpg,
Titian hair Titian is a tint of red hair Red hair (or ginger hair) occurs naturally in one to two percent of the human population, appearing with greater frequency (two to six percent) among people of Northern or Northwestern European ancestry and le ...
File:Strawberry Blond Girl.jpg, Strawberry blond hair File:Lucy Merriam.jpg, Light blond hair File:Goldenblonde.JPG, Golden blond hair File:TKvamme.jpg, Medium blond hair File:Kofi Annan.jpg, Grey hair File:Rapolder uwe 600.jpg, White hair File:Albinisitic man portrait.jpg, White hair caused by
albinism Albinism is the congenital absence of any pigmentation or colouration in a person, animal or plant, resulting in white hair, feathers, scales and skin and pink eyes in mammals, birds, reptiles, amphibians and fish and invertebrates as well. V ...


Black hair

Black hair is the darkest hair color. It has large amounts of eumelanin and is more dense than other hair colors.


Brown hair

Brown hair is the second most common human hair color, after black. Brown hair is characterized by higher levels of eumelanin and lower levels of pheomelanin. Of the two types of eumelanin (black and brown), brown-haired people have brown eumelanin; they also usually have medium-thick strands of hair. Brown-haired girls or women are often known as brunettes. Chestnut hair is a hair color which is a reddish shade of brown hair. In contrast to auburn hair, the reddish shade of chestnut is darker. Chestnut hair is common among the native peoples of Northern, Central, Western, and Eastern Europe.


Auburn hair

Auburn hair ranges along a spectrum of light to dark red-brown shades. The chemicals which cause auburn hair are
eumelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
(brown) and
pheomelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
(red), with a higher proportion of red-causing pheomelanin than is found in average brown hair. It is most commonly found in individuals of Northern and Western European descent. It can also be the result of a mutation in the melanocortin 1 receptor gene.


Red hair

Red hair ranges from light strawberry blond shades to
titian Tiziano Vecelli or Vecellio (; 27 August 1576), known in English as Titian ( ), was an Italian Italian may refer to: * Anything of, from, or related to the country and nation of Italy ** Italians, an ethnic group or simply a citizen of the Ital ...
, copper, and completely red. Red hair has the highest amounts of
pheomelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
, around 67%, and usually low levels of
eumelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
. At 1–2% of the west Eurasian population, it is the least common hair color in the world. It is most prominently found in the
British Isles The British Isles are a group of islands in the North Atlantic off the north-western coast of continental Europe Continental Europe or mainland Europe is the contiguous continent A continent is any of several large landmasse ...

British Isles
and in
Udmurtia Udmurtia (russian: Удму́ртия, r=Udmúrtiya, p=ʊˈdmurtʲɪjə; udm, Удмуртия), or the Udmurt Republic, is a federal subject The federal subjects of Russia, also referred to as the subjects of the Russian Federation (russ ...
. Scotland has the highest proportion of redheads; 13 percent of the population has red hair and approximately 40 percent carry the recessive redhead gene.


Blond hair

Blond (sometimes ''blonde'' for women) hair ranges from pale white (platinum blond) to dark gold blond. Strawberry blond, a mixture of blond and red hair, is a much rarer type containing the most
pheomelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
. Blond hair can have almost any proportion of pheomelanin and
eumelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
, but has only small amounts of both. More pheomelanin creates a more golden or strawberry blond color, and more eumelanin creates an ash or sandy blond color. Blond hair is most commonly found in Northern and Western Europeans and their descendants but can be found spread around most of Europe. Studies in 2012 showed that naturally blond hair of Melanesians is caused by a recessive mutation in tyrosinase-related protein 1 (TYRP1). In the Solomon Islands, 26% of the population carry the gene; however, it is absent outside of Oceania.


Gray and white hair

Gray or white hair is not caused by a true gray or white pigment, but is due to a lack of pigmentation and melanin. The clear hairs appear as gray or white because of the way light is reflected from the hairs. Gray hair color typically occurs naturally as people age (see aging or achromotrichia below). In some cases, gray hair may be caused by thyroid deficiencies,
Waardenburg syndrome Waardenburg syndrome is a group of rare genetic conditions A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene In biology, a gene (from ''genos'' " ...

Waardenburg syndrome
or a vitamin B12 deficiency. At some point in the human life cycle, cells that are located in the base of the hair's follicles slow, and eventually stop producing pigment.
Piebaldism Piebaldism refers to the absence of mature melanin-forming cells (melanocytes) in certain areas of the skin and hair. It is a rare autosomal dominant In genetics Genetics is a branch of biology concerned with the study of genes, genetic var ...
is a rare
autosomal dominant In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the Phenotype, effect of a different variant of the same gene on Homologous chromosome, the other copy of the chromosome. The first ...

autosomal dominant
disorder of
melanocyte Melanocytes are melanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigments found in most organisms. Melanin is produced through a multistage chemical process known as melanogenesis, wher ...
development, which may cause a
congenital A birth defect, also known as a congenital disorder, is a condition present at birth Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiate ...
white forelock. Europeans often begin to grow gray hairs in their mid-30s while Asians begin graying in their late 30s, but most Africans retain their original hair color until their mid-40s. Permanently white hair starting in childhood can be genetically inherited, but unlike
albinism Albinism is the congenital absence of any pigmentation or colouration in a person, animal or plant, resulting in white hair, feathers, scales and skin and pink eyes in mammals, birds, reptiles, amphibians and fish and invertebrates as well. V ...
, there are no negative medical implications. The trait follows
X-linked recessive inheritance X-linked recessive inheritance is a mode of Mendelian inheritance, inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be always expressed in males (who are necessarily homozygous for the gene mutation because the ...
, and so is more common in men and women can be carriers without being affected. Graying is a gradual process; according to a study by L'Oreal, overall, of those between 45 and 65 years old, 74% had some gray hair, covering an average of 27% of their head, and approximately 1 in 10 people had no gray hairs even after the age of 60. Marie Antoinette syndrome is a proposed phenomenon in which sudden whitening is caused by stress. It has been found that some hairs can become colored again when stress is reduced.


Conditions affecting hair color


Aging or achromotrichia

Children born with some hair colors may find it gradually darkens as they grow. Many blond, light brown, or red haired infants experience this. This is caused by genes being turned on and off during early childhood and puberty. Changes in hair color typically occur naturally as people age, eventually turning the hair gray and then white. This is called achromotrichia. Achromotrichia normally begins in the early to mid-twenties in men and late twenties in women. More than 60 percent of Americans have some gray hair by age 40. The age at which graying begins seems almost entirely due to
genetics Genetics is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, ...

genetics
. Sometimes people are born with gray hair because they inherit the trait. The order in which graying happens is usually: nose hair, hair on the head, beard, body hair, eyebrows. In non-balding individuals, hair may grow faster once it turns gray. Unlike in the skin where pigment production is continuous,
melanogenesis Melanocytes are melanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigments found in most organisms. Melanin is produced through a multistage chemical process known as melanogenesis, wher ...
in the hair is closely associated with stages of the hair cycle. Hair is actively pigmented in the
anagen The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given org ...
phase and is "turned off" during the catagen phase, and absent during
telogen The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given org ...
. Thus, a single hair cannot be white on the root side, and colored on the terminal side. Several
gene In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mecha ...

gene
s appear to be responsible for the process of graying. ''Bcl2'' and ''Bcl-w'' were the first two discovered, then in 2016, the
IRF4 __NOTOC__ Interferon regulatory factor 4 also known as ''MUM1'' is a protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by ...
(interferon regulatory factor 4) gene was announced after a study of 6,000 people living in five
Latin America * ht, Amerik Latin, link=no * pt, América Latina, link=no , image = Latin America (orthographic projection).svg , area = , population = ( est.) , density = , ethnic_groups = , ethnic_groups_year = 2018 , ethnic ...

Latin America
n countries. However, it found that
environmental factor An environmental factor, ecological factor or eco factor is any factor, abiotic or biotic, that influences living organisms. Abiotic factors include ambient temperature, amount of sunlight, and pH of the water soil in which an organism lives. Biot ...
s controlled about 70% of cases of hair graying. The change in hair color occurs when melanin ceases to be produced in the hair root and new hairs grow in without pigment. The
stem cell In multicellular organisms Multicellular organisms are organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties ...
s at the base of
hair follicle The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given orga ...

hair follicle
s produce
melanocyte Melanocytes are melanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigments found in most organisms. Melanin is produced through a multistage chemical process known as melanogenesis, wher ...
s, the cells that produce and store pigment in hair and skin. The death of the melanocyte
stem cells In multicellular organisms Multicellular organisms are organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties o ...
causes the onset of graying. It remains unclear why the stem cells of one hair follicle may fail to activate well over a decade before those in adjacent follicles less than a millimeter apart. Vitamins and minerals that are known to slow down the graying process are vitamin , , D, , and the mineral
iron Iron () is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behav ...
. Also, an abnormal
pituitary gland upright=1.2, The Hypothalamus-Pituitary Complex. In vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingd ...

pituitary gland
or
thyroid gland The thyroid, or thyroid gland, is an endocrine gland Endocrine glands are ductless glands of the endocrine system The endocrine system is a messenger system comprising feedback loops of the hormones released by internal glands of an organis ...

thyroid gland
can cause hair to turn gray. Graying of hair may be triggered by the accumulation of
hydrogen peroxide Hydrogen peroxide is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together ...

hydrogen peroxide
and abnormally low levels of the enzyme
catalase Catalase is a common enzyme Enzymes () are protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , , , providing and , and from one loc ...

catalase
, which breaks down hydrogen peroxide and relieves oxidative stress in patients suffering from
vitiligo Vitiligo is a long-term skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic org ...

vitiligo
. Since vitiligo can cause eyelashes to turn white, the same process is believed to be involved in hair on the head (and elsewhere) due to aging. The
anti-cancer drug Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (list of chemotherapeutic agents, chemotherapeutic agents) as part of a standardized chemotherapy regimen. ...

anti-cancer drug
imatinib Imatinib, sold under the brand name Gleevec among others, is an oral chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic ag ...

imatinib
has recently been shown to reverse the graying process. However, it is expensive and has potentially severe and deadly
side effect In medicine Medicine is the science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts ( descriptive knowledge) ...
s, so it is not practical to use to alter a person's hair color. Nevertheless, if the
mechanism of action In pharmacology Pharmacology is a branch of , and concerned with or action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a biochemical or physiological effect on the ...

mechanism of action
of imatinib on melanocyte stem cells can be discovered, it is possible that a safer and less expensive substitute drug might someday be developed. It is not yet known whether imatinib has an effect on catalase, or if its reversal of the graying process is due to something else.


Stress

Anecdotes report that stress, both chronic and acute, may induce achromotrichia earlier in individuals than it otherwise would have. Proponents point to survivors of disasters, such as ''Titanic'' survivor
Harold Bride Harold Sydney Bride (11 January 1890 – 29 April 1956) was a British merchant seaman and the junior wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points that d ...

Harold Bride
, prisoner of war
John McCain John Sidney McCain III (August 29, 1936 – August 25, 2018) was an American politician, statesman, and United States Navy ), (unofficial)."''Non sibi sed patriae''" ( en, "Not for self but for country") (unofficial). , colors = ...

John McCain
, or high-level politicians such as
Bill Clinton William Jefferson Clinton ('' né'' Blythe III; born August 19, 1946) is an American politician and attorney who served as the 42nd president of the United States The president of the United States (POTUS) is the head of state and ...

Bill Clinton
or
Barack Obama Barack Hussein Obama II ( ; born August 4, 1961) is an American politician and attorney who served as the 44th president of the United States The president of the United States (POTUS) is the head of state and head of government ...

Barack Obama
. There is some evidence for chronic stress causing premature achromotrichia, but no definite link has been established. It is known that the stress
hormone A hormone (from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is appr ...

hormone
''
cortisol Cortisol is a steroid hormone, in the glucocorticoid class of hormones. When used as a medication, it is known as hydrocortisone. It is produced in many animals, mainly by the ''zona fasciculata'' of the adrenal cortex in the adrenal gland. ...

cortisol
'' accumulates in human hair over time, but whether this has any effect on hair color has not yet been resolved. A 2020 paper, published in the journal ''Nature'' reported that stress can cause hair to lose its pigment. An overactive immune response can destroy melanocytes and melanocyte stem cells in black-haired rats. When intentionally subjecting them to panic, they bleached their coat. The next time the rats’ coat grew, there were no melanocyte stem cells in these damaged follicles, so white hairs sprouted, and the color loss was permanent.


UV damage

Excessive exposure to the sun is the most common cause of structural damage of the hair shaft. Photochemical hair damage encompasses hair protein degradation and loss, as well as hair pigment deterioration Photobleaching is common among people with European ancestry. Around 72 percent of customers who agreed to be involved in a study and have European ancestry reported in a recent
23andMe 23andMe is a privately held personal genomics Personal genomics or consumer genetics is the branch of genomics Genomics is an interdisciplinary field of biology Biology is the natural science that studies life and living organisms, ...
research that the sun lightens their hair. The company also have identified 48 genetic markers that may influence hair photobleaching.


Medical conditions

Albinism Albinism is the congenital absence of any pigmentation or colouration in a person, animal or plant, resulting in white hair, feathers, scales and skin and pink eyes in mammals, birds, reptiles, amphibians and fish and invertebrates as well. V ...
is a genetic abnormality in which little or no pigment is found in human hair, eyes, and skin. The hair is often white or pale blond. However, it can be red, darker blond, light brown, or rarely, even dark brown.
Vitiligo Vitiligo is a long-term skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic org ...

Vitiligo
is a patchy loss of hair and skin color that may occur as the result of an
auto-immune disease An autoimmune disease is a condition arising from an abnormal immune response An immune response is a reaction which occurs within an organism for the purpose of defending against foreign invaders. These invaders include a wide variety of differen ...
. In a preliminary 2013 study, researchers treated the buildup of hydrogen peroxide which causes this with a light-activated pseudo-
catalase Catalase is a common enzyme Enzymes () are protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , , , providing and , and from one loc ...

catalase
. This produced significant media coverage that further investigation may someday lead to a general non-dye treatment for gray hair.
Malnutrition Malnutrition is 'a state of nutrition in which a deficiency or excess (or imbalance) of energy, protein and other nutrients causes measurable adverse effect on tissue and body form (body shape, size and composition) and function and clinical ou ...
is also known to cause hair to become lighter, thinner, and more brittle. Dark hair may turn reddish or blondish due to the decreased production of melanin. The condition is reversible with proper nutrition.
Werner syndrome Werner syndrome (WS) (sometimes Werner's syndrome), also known as "adult progeria",James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. . is a rare, autosomal recessive ...
and
pernicious anemia Vitamin B12 deficiency anemia, of which pernicious anemia (PA) is a type, is a disease in which not enough red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucl ...
can also cause premature graying. A 2005 uncontrolled study demonstrated that people 50–70 years of age with dark eyebrows but gray hair are significantly more likely to have
type II diabetes Type 2 diabetes (T2D), formerly known as adult-onset diabetes, is a form of diabetes Diabetes mellitus (DM), commonly known as diabetes, is a group of metabolic disorders characterized by a high blood sugar level over a prolonged period of ...
than those with both gray eyebrows and hair.


Artificial factors

A 1996
British Medical Journal ''The BMJ'' is a weekly peer-reviewed medical trade journal, published by the trade union A trade union (or a labor union in American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English ...
study found that
tobacco smoking Tobacco smoking is the practice of burning tobacco Tobacco is the common name of several plants in the ' of the , and the general term for any product prepared from the of these plants. of tobacco are known, but the chief commerci ...

tobacco smoking
may cause premature graying. Smokers were found to be four times more likely to begin graying prematurely, compared to nonsmokers. Gray hair may temporarily darken after inflammatory processes, after electron-beam-induced alopecia, and after some chemotherapy regimens. Much remains to be learned about the physiology of human graying. There are no special diets, nutritional supplements, vitamins, or proteins that have been proven to slow, stop, or in any way affect the graying process, although many have been marketed over the years. However, French scientists treating
leukemia Leukemia ( also spelled leukaemia and pronounced ), is a group of blood cancer Tumors of the hematopoietic and lymphoid tissues (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English ...

leukemia
patients with
imatinib Imatinib, sold under the brand name Gleevec among others, is an oral chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic ag ...

imatinib
, a new cancer drug, noted an unexpected side effect: some of the patients' hair color was restored to their pre-gray color.


Changes after death

The hair color of buried bodies can change. Hair contains a mixture of black-brown-yellow eumelanin and red pheomelanin. Eumelanin is less chemically stable than pheomelanin and breaks down faster when oxidized. The color of hair changes faster under extreme conditions. It changes more slowly under dry oxidizing conditions (such as in
burial Burial, also known as interment or inhumation, is a method of wherein a dead person or non-human animal is placed into the ground, sometimes with objects. This is usually accomplished by excavating a pit or trench, placing the deceased and ob ...

burial
s in sand or in ice) than under wet reducing conditions (such as burials in wood or plaster coffins).


Hair coloring

Hair color can be changed by a chemical process. Hair coloring is classed as "permanent" or "semi-permanent". Permanent hair color means that the hair's structure has been chemically altered until it is eventually cut away. This does not mean that the synthetic color will remain permanently. During the process, the natural color is removed, one or more shades, and synthetic color has been put in its place. All pigments wash out of the cuticle. Natural color stays in much longer and artificial will fade the fastest (depending on the color molecules and the form of the dye pigments). Permanent hair color gives the most flexibility because it can make hair lighter or darker as well as changing tone and color, but there are negatives. Constant (monthly or six-weekly) maintenance is essential to match new hair growing in to the rest of the hair, and to remedy fading. A one-color permanent dye creates a flat, uniform color across the whole head, which can look unnatural and harsh, especially in a fair shade. To combat this, the modern trend is to use multiple colors—usually one color as a base with added highlights or lowlights in other shades. Semi-permanent color washes out over a period of time—typically four to six weeks, so root regrowth is less noticeable. The final color of each strand is affected by its original color and porosity, so there will be subtle variations in color across the head—more natural and less harsh than a permanent dye. However, this means that gray and white hair will not dye to the same color as the rest of the head (in fact, some white hair will not absorb the color at all). A few gray and white hairs will blend in sufficiently not to be noticeable, but as they become more widespread, there will come a point where a semi-permanent alone will not be enough. The move to 100% permanent color can be delayed by using a semi-permanent as a base color, with permanent highlights. Semi-permanent hair color cannot lighten hair. Hair can only be lightened using chemical lighteners, such as bleach. Bleaching is always permanent because it removes the natural pigment. "Rinses" are a form of temporary hair color, usually applied to hair during a shampoo and washed out again the next time the hair is washed.


See also

* *
Human skin color Human skin color ranges from the darkest brown to the lightest hues. Differences in skin color among individuals is caused by variation in pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast ...


References


External links

{{Authority control Biological anthropology