Hair care

Last updated

Hair care in Tianjin, China, in late Qing dynasty Barbiers en plein air le long des murs de Tien-Tsin.jpg
Hair care in Tianjin, China, in late Qing dynasty

Hair care or haircare is an overall term for hygiene and cosmetology involving the hair which grows from the human scalp, and to a lesser extent facial, pubic and other body hair. Hair care routines differ according to an individual's culture and the physical characteristics of one's hair. Hair may be colored, trimmed, shaved, plucked or otherwise removed with treatments such as waxing, sugaring and threading. Hair care services are offered in salons, barbershops and day spas, and products are available commercially for home use. Laser hair removal and electrolysis are also available, though these are provided (in the US) by licensed professionals in medical offices or speciality spas. [1] [2]

Contents

Hair cleaning and conditioning

Biological processes and hygiene

Human hair close-up Human hair closeup-08960-nevit.jpg
Human hair close-up

Care of the hair and care of the scalp skin may appear separate, but are actually intertwined because hair grows from beneath the skin. The living parts of hair (hair follicle, hair root, root sheath and sebaceous gland) are beneath the skin, while the actual hair shaft which emerges (the cuticle which covers the cortex and medulla) has no living processes. Damage or changes made to the visible hair shaft cannot be repaired by a biological process, though much can be done to manage hair and ensure that the cuticle remains intact. [3]

Scalp skin, just like any other skin on the body, must be kept healthy to ensure a healthy body and healthy hair production. If the scalp is cleaned regularly by those who have rough hair or have a hair-fall problem, it can result in loss of hair. However, not all scalp disorders are a result of bacterial infections. Some arise inexplicably, and often only the symptoms can be treated for management of the condition (example: dandruff). There are also bacteria that can affect the hair itself. Head lice is probably the most common hair and scalp ailment worldwide. Head lice can be removed with great attention to detail, and studies show it is not necessarily associated with poor hygiene. More recent studies reveal that head lice actually thrive in clean hair. In this way, hair washing as a term may be a bit misleading, as what is necessary in healthy hair production and maintenance is often simply cleaning the surface of the scalp skin, the way the skin all over the body requires cleaning for good hygiene. [4]

The sebaceous glands in human skin produce sebum, which is composed primarily of fatty acids. Sebum acts to protect hair and skin, and can inhibit the growth of microorganisms on the skin. Sebum contributes to the skin's slightly acidic natural pH somewhere between 5 and 6.8 on the pH spectrum. This oily substance gives hair moisture and shine as it travels naturally down the hair shaft, and serves as a protective substance by preventing the hair from drying out or absorbing excessive amounts of external substances. Even though sebum serves as a protective substance, too much of this oily substance can cause blockage around hair follicles. This blockage is usually from dandruff or even dead skin. As a result, "blocked or obstructed hair follicles" may prevent hair from producing. [5] Sebum is also distributed down the hair shaft "mechanically" by brushing and combing. When sebum is present in excess, the roots of the hair can appear oily, greasy, and darker than normal, and the hair may stick together.

Hair cleaning

Washing hair removes excess sweat and oil, as well as unwanted products from the hair and scalp. Often hair is washed as part of a shower or bathing with shampoo, a specialized surfactant. Shampoos work by applying water and shampoo to the hair. The specific shampoo for oily or dry hair breaks the surface tension of the water, allowing the hair to become soaked. [6] [7] This is known as the wetting action. The wetting action is caused by the head of the shampoo molecule attracting the water to the hair shaft. Conversely, the tail of the shampoo molecule is attracted to the grease, dirt and oil on the hair shaft. The physical action of shampooing makes the grease and dirt become an emulsion that is then rinsed away with the water. This is known as the emulsifying action. Sulfate free shampoos are less harming on color treated hair than normal shampoos that contain sulfates. Sulfates strip away natural oils as well as hair dye. Sulfates are also responsible for the foaming effect of shampoos. Shampoos have a pH of between 4 & 6. Acidic shampoos are the most common type used and maintain or improve the condition of the hair as they do not swell the hairshaft and do not strip the natural oils.[ citation needed ]

Hairstyling tools

Hairstyling equipment

Hairstyling equipment which helps in creating hairstyles include:

Hair products

Cosmetics products used in creating and maintaining hairstyles include:

Hair lengths

Chemical alteration

Chemical alterations like perming, coloring can be carried out to change the perceived color and texture of hair. All of these are temporary alterations because permanent alterations are not possible at this time.

Chemical alteration of hair only affects the hair above the scalp; unless the hair roots are damaged, new hair will grow in with natural color and texture.

Hair coloring

Hair coloring is the process of adding pigment to or removing pigment from the hair shaft. Hair coloring processes may be referred to as coloring or bleaching, depending on whether pigment is being added or removed.

Temporary hair tints simply coat the shaft with pigments which later wash off.

Most permanent color changes require that the cuticle of the hair be opened so the color change can take place within the cuticle. This process, which uses chemicals to alter the structure of the hair, can damage the cuticle or internal structure of the hair, leaving it dry, weak, or prone to breakage. After the hair processing, the cuticle may not fully close, which results in coarse hair or an accelerated loss of pigment. Generally, the lighter the chosen color from one's initial hair color, the more damaged it may be. Other options for applying color to hair besides chemical dyes include the use of such herbs as henna and indigo, or choosing ammonia-free solutions.

Perms and chemical straightening

Perms and relaxation using relaxer or thermal reconditioning involve chemical alteration of the internal structure of the hair in order to affect its curliness or straightness. Hair that has been subjected to the use of a permanent is weaker due to the application of chemicals, and should be treated gently and with greater care than hair that isn't chemically altered. [8]

Special considerations for hair types

Long hair

Many industries have requirements for hair being contained to prevent worker injury. This can include people working in construction, utilities, and machine shops of various sorts. Furthermore, many professions require containing the hair for reasons of public health, and a prime example is the food industry. There are also sports that may require similar constraints for safety reasons: to keep hair out of the eyes and blocking one's view, and to prevent being caught in sports equipment or trees and shrubs, or matted hair in severe weather conditions or water. Safety is usually the reason behind not allowing hair to fly loose on the backs of motorcycles and open-topped sports cars for longer tresses.

Delicate skin

Scalp skin of babies and the elderly are similar in subdued sebaceous gland production, due to hormonal levels. The sebaceous gland secretes sebum, a waxy ester, which maintains the acid mantle of the scalp and provides a coating that keeps skin supple and moist. The sebum builds overly, between every 2–3 days for the average adult. Those with delicate skin may experience a longer interval. Teenagers often require daily washing of the hair. Sebum also imparts a protective coating to hair strands. Daily washing will remove the sebum daily and incite an increase in sebum production, because the skin notices the scalp skin is lacking sufficient moisture. In cases of scalp disorders, however, this may not be the case. For babies and elderly, the sebaceous gland production is not at peak, thus daily washing is not typically needed.

Treatment of damage

Split ends

Split ends, known formally as trichoptilosis, happen when the protective cuticle has been stripped away from the ends of hair fibers.

This condition involves a longitudinal splitting of the hair fiber. Any chemical or physical trauma, such as heat, that weathers the hair may eventually lead to split ends. Typically, the damaged hair fiber splits into two or three strands and the split may be two to three centimeters in length. Split ends are most often observed in long hair but also occur in short hair that is not in good condition.

As hair grows, the natural protective oils of the scalp can fail to reach the ends of the hair. The ends are considered old once they reach about 10 centimeters since they have had long exposure to the sun, gone through many shampoos and may have been overheated by hair dryers and hot irons. This all results in dry, brittle ends which are prone to splitting. Infrequent trims and lack of hydrating treatments can intensify this condition.

Breakage and other damage

Hair can be damaged by chemical exposure, prolonged or repeated heat exposure (as through the use of heat styling tools), and by perming and straightening. Oil is harmful for rough hair and for dry scalp as it decreases nourishment for hair leading to split and hair fall. When hair behaves in an unusual way, or a scalp skin disorder arises, it is often necessary to visit not only a qualified physician, but sometimes a dermatologist, or a trichologist. Conditions that require this type of professional help include, but are not limited to, forms of alopecia, hair pulling/picking, hair that sticks straight out, black dots on the hair, and rashes or burns resulting from chemical processes. Gel provides a shiny look but dries the hair and makes it rough.

There are a number of disorders that are particular to the scalp. Symptoms may include:

Any of these symptoms may indicate a need for professional assistance from a dermatologist or trichologist for diagnosis.

Scalp skin can suffer from infestations of mites, lice, infections of the follicles or fungus. There could be allergic reactions to ingredients in chemical preparations applied to the hair, even ingredients from shampoo or conditioners. Common concerns surrounding dandruff (often associated with excessive sebum); psoriasis, eczema, or seborrheic dermatitis.

An odor that persists for a few weeks despite regular hair washing may be an indication of a health problem on the scalp skin.

Not all flakes are dandruff. For example, some can merely be product buildup on the scalp skin. This could result from the common practice of applying conditioner to scalp skin without washing. This would dry upon the scalp skin and flake off, appearing like dandruff and even causing itchiness, but have no health effects whatsoever.

There are various reasons for hair loss, most commonly hormonal issues. Fluctuations in hormones will often show in the hair. Not all hair loss is related to what is known as male pattern baldness, women can suffer from baldness just as men do. Formulas for addressing this specific cause of lack of hair growth yet typically they require around three months of consistent use for results to begin to appear. Cessation may also mean that gained growth may dissipate.

Particularly among women, thyroid disease is one of the more under-diagnosed health concerns. Hair falling out in clumps is one symptom of a set of symptoms that may indicate a thyroid concern. In many gynecological exams a blood screen for thyroid is now a common protocol. Thyroid often shows up first in the behavior of the hair.

During pregnancy and breast feeding, the normal and natural shedding process is typically suspended (starting around month three because it takes a while for the body to recognize and reset for the hormonal shifts the body goes through) for the period of gestation and extended longer if one breast feeds (this includes pumping for breast milk). Upon cessation of either of these, it typically takes around two months for the hormones to shift again to the normal hormonal settings, and hair shedding can increase exponentially, for approximately 3–6 months until hair returns to its normal volume. It is commonly noticed that hair seems thicker and shinier, even, during pregnancy and breast feeding in response to the influx of shifting hormones. It is not unusual also for hair color to change, or hair structure to change (e.g., straighter hair, curlier hair). These changes can occur more often than people may realize yet isn't often reported.

General hair loss

Some choose to shave their hair off entirely, while others may have an illness (such as a form of cancer—note that not every form of cancer or cancer treatment necessarily means one will lose their hair) that caused hair loss or led to a decision to shave the head.

Hair care and nutrition

Genetics and health are factors in healthy hair. Proper nutrition is important for hair health. The living part of hair is under the scalp skin where the hair root is housed in the hair follicle. The entire follicle and root are fed by a supply of arteries, and blood carries nutrients to the follicle/root. Any time an individual has any kind of health concern from stress, trauma, medications of various sorts, chronic medical conditions or medical conditions that come and then wane, heavy metals in waters and food, smoking etc. these and more can affect the hair, its growth, and its appearance.

Generally, eating a full diet that contains protein, fruits, vegetables, fat, and carbohydrates is important (several vitamins and minerals require fat in order to be delivered or absorbed by the body). Any deficiency will typically show first in the hair. A mild case of anemia can cause shedding and hair loss. Among others, the B group of vitamins are the most important for healthy hair, especially biotin. B5 (pantothenic acid) gives hair flexibility, strength and shine and helps prevent hair loss and graying. B6 helps prevent dandruff and can be found in cereals, egg yolk and liver. Vitamin B12 helps prevent the loss of hair and can be found in fish, eggs, chicken and milk.

When the body is under strain, it reprioritizes its processes. For example, the vital organs will be attended to first, meaning that healthy, oxygenated blood may not feed into the hair follicle, resulting in less healthy hair or a decline in growth rate. While not all hair growth issues stem from malnutrition, it is a valuable symptom in diagnosis.

Scalp hair grows, on average, at a rate of about 1.25 centimeters per month, and shampoos or vitamins have not been shown to noticeably change this rate. Hair growth rate also depends upon what phase in the cycle of hair growth one is actually in; there are three phases. The speed of hair growth varies based upon genetics, gender, age, hormones, and may be reduced by nutrient deficiency (i.e., anorexia, anemia, zinc deficiency) and hormonal fluctuations (i.e., menopause, polycystic ovaries, thyroid disease). [9]

The essential omega-3 fatty acids, protein, vitamin B12, and iron, found in fish sources, prevent a dry scalp and dull hair color. Dark green vegetables contain high amounts of vitamins A and C, which help with production of sebum and provide a natural hair conditioner. Legumes provide protein to promote hair growth and also contain iron, zinc, and biotin. Biotin functions to activate certain enzymes that aid in metabolism of carbon dioxide as well as protein, fats, and carbohydrates. A deficiency in biotin intake can cause brittle hair and can lead to hair loss. In order to avoid a deficiency, individuals can find sources of biotin in cereal-grain products, liver, egg yolk, soy flour, and yeast. [10] Nuts contain high sources of selenium and therefore are important for a healthy scalp. Alpha-linolenic acid and zinc are also found in some nuts and help condition the hair and prevent hair shedding that can be caused by a lack of zinc. Protein deficiencies or low-quality protein can produce weak and brittle hair, and can eventually result in loss of hair color. Dairy products are good sources of calcium, a key component for hair growth. A balanced diet is extremely necessary for a healthy scalp and furthermore healthy hair.

See also

Related Research Articles

<span class="mw-page-title-main">Hair loss</span> Loss of hair from the head or body

Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarring is not usually present. Hair loss in some people causes psychological distress.

<span class="mw-page-title-main">Dandruff</span> Skin condition of the scalp

Dandruff is a skin condition that mainly affects the scalp. Symptoms include flaking and sometimes mild itchiness. It can result in social or self-esteem problems. A more severe form of the condition, which includes inflammation of the skin, is known as seborrhoeic dermatitis.

<span class="mw-page-title-main">Hair coloring</span> Practice of changing the hair color

Hair coloring, or hair dyeing, is the practice of changing the color of the hair on humans' heads. The main reasons for this are cosmetic: to cover gray or white hair, to alter hair to create a specific look, to change a color to suit preference or to restore the original hair color after it has been discolored by hairdressing processes or sun bleaching.

<span class="mw-page-title-main">Hair follicle</span> Organ found in the dermal layer of the mammalian skin that regulates hair growth

The hair follicle is an organ found in mammalian skin. It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regulates hair growth via a complex interaction between hormones, neuropeptides, and immune cells. This complex interaction induces the hair follicle to produce different types of hair as seen on different parts of the body. For example, terminal hairs grow on the scalp and lanugo hairs are seen covering the bodies of fetuses in the uterus and in some newborn babies. The process of hair growth occurs in distinct sequential stages: anagen is the active growth phase, catagen is the regression of the hair follicle phase, telogen is the resting stage, exogen is the active shedding of hair phase and kenogen is the phase between the empty hair follicle and the growth of new hair.

<span class="mw-page-title-main">Sebaceous gland</span> Gland to lubricate the hair and skin

A sebaceous gland or oil gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest number on the face and scalp, but also on all parts of the skin except the palms of the hands and soles of the feet. In the eyelids, meibomian glands, also called tarsal glands, are a type of sebaceous gland that secrete a special type of sebum into tears. Surrounding the female nipple, areolar glands are specialized sebaceous glands for lubricating the nipple. Fordyce spots are benign, visible, sebaceous glands found usually on the lips, gums and inner cheeks, and genitals.

<span class="mw-page-title-main">Seborrhoeic dermatitis</span> Skin disease

Seborrhoeic dermatitis is a long-term skin disorder. Symptoms include flaky, scaly, greasy, and occasionally itchy and inflamed skin. Areas of the skin rich in oil-producing glands are often affected including the scalp, face, and chest. It can result in social or self-esteem problems. In babies, when the scalp is primarily involved, it is called cradle cap. Seborrhoeic dermatitis of the scalp may be described in lay terms as dandruff due to the dry, flaky character of the skin. However, as dandruff may refer to any dryness or scaling of the scalp, not all dandruff is seborrhoeic dermatitis. Seborrhoeic dermatitis is sometimes inaccurately referred to as seborrhoea.

<span class="mw-page-title-main">Hair conditioner</span> Hair care product

Hair conditioner is a hair care cosmetic product used to improve the feel, texture, appearance and manageability of hair. Its main purpose is to reduce friction between strands of hair to allow smoother brushing or combing, which might otherwise cause damage to the scalp. Various other benefits are often advertised, such as hair repair, strengthening, or a reduction in split ends.

<span class="mw-page-title-main">Cradle cap</span> Human medical condition

Cradle cap causes crusty or oily scaly patches on a baby's scalp. The condition is not painful or itchy, but it can cause thick white or yellow scales that are not easy to remove. Cradle cap most commonly begins sometime in the first three months but can occur in later years. Similar symptoms in older children are more likely to be dandruff than cradle cap. The rash is often prominent around the ear, the eyebrows or the eyelids. It may appear in other locations as well, where it is called infantile seborrhoeic dermatitis. Cradle cap is just a special—and more benign—case of this condition. The exact cause of cradle cap is not known. Cradle cap is not spread from person to person (contagious). It is also not caused by poor hygiene. It is not an allergy, and it is not dangerous. Cradle cap often lasts a few months. In some children, the condition can last until age 2 or 3.

A relaxer is a type of lotion or cream generally used by people with tight curls or very curly hair which makes hair easier to straighten by chemically "relaxing" the natural curls. The active agent is usually a strong alkali, although some formulations are based on ammonium thioglycolate or formaldehyde.

Artificial hair integrations, more commonly known as hair extensions, hair weaves, and fake hair add length and fullness to human hair. Hair extensions are usually clipped, glued, or sewn on natural hair by incorporating additional human or synthetic hair. These methods include tape-in extensions, clip-in or clip-on extensions, micro/nano rings, fusion method, weaving method, and wigs.

<span class="mw-page-title-main">Baby shampoo</span> Personal care product

Baby shampoo is a hair care product that is used for the removal of oils, dirt, skin particles, dandruff, environmental pollutants and other contaminant particles that gradually build up in hair; specially formulated for use on infants and young children by means of substituting chemicals which are purportedly less irritating to the eyes than those commonly found in regular shampoo.

Cat skin disorders are among the most common health problems in cats. Skin disorders in cats have many causes, and many of the common skin disorders that afflict people have a counterpart in cats. The condition of a cat's skin and coat can also be an important indicator of its general health. Skin disorders of cats vary from acute, self-limiting problems to chronic or long-lasting problems requiring life-time treatment. Cat skin disorders may be grouped into categories according to the causes.

<span class="mw-page-title-main">Hair straightening</span> Hair styling technique

Hair straightening is a hair styling technique used since the 1890s involving the flattening and straightening of hair in order to give it a smooth, streamlined, and sleek appearance. It became very popular during the 1950s among black males and females of all races. It is accomplished using a hair iron or hot comb, chemical relaxers, Japanese hair straightening, Brazilian hair straightening, or roller set/blowdryer styling. In addition, some shampoos, conditioners, and hair gels can help to make hair temporarily straight.

<span class="mw-page-title-main">Shampoo</span> Hair care product

Shampoo is a hair care product, typically in the form of a viscous liquid, that is used for cleaning hair. Less commonly, shampoo is available in solid bar format. Shampoo is used by applying it to wet hair, massaging the product into the scalp, and then rinsing it out. Some users may follow a shampooing with the use of hair conditioner.

<span class="mw-page-title-main">Dry shampoo</span> Hair product

Dry shampoo otherwise known as hybrid shampoo is a type of shampoo which reduces hair greasiness without the need for water. It is in powder form and is typically administered from an aerosol can. Dry shampoo is often based on corn starch or rice starch. In addition to cleansing hair, it can also be used as a tool for hair-styling as it can create volume, help tease hair, keep bobby pins in place, and be used in place of mousse in wet hair. Dry shampoo proponents attest that daily wash-and-rinse with detergent shampoo can strip away natural oils from hair. However, others attest that spraying dry shampoo every day will lead to a build-up of product that can dull hair color and irritate the scalp, arguing that the scalp needs regular cleansing and exfoliating to get rid of bacteria, remove dead skin cells, and stay healthy.

Hair washing without commercial shampoo, sometimes called no poo, includes water-only hair washing or hair washing with non-commercial products, such as baking soda and vinegar. Advocates argue that commercial shampoo is an unnecessary expense and may contain harmful ingredients.

<span class="mw-page-title-main">Sebaceous adenitis</span> Skin disease

Sebaceous adenitis in an uncommon skin disease found in some breeds of dog, and more rarely in cats, rabbits and horses. characterised by an inflammatory response against the dog's sebaceous glands, which can lead to the destruction of the gland. It was first described in veterinary literature in the 1980s.

Greasy hair is a hair condition which is common in humans, one of four main types of hair conditioning— normal, greasy, dry and greasy dry. It is primarily caused by build-up of the natural secretion from the sebaceous glands in the scalp and is characterised by the continuous development of natural grease on the scalp. A chronic condition of greasy hair may often accompany chronic greasy skin conditions on the face and body and oily skin and acne. Excessive carbohydrate, fat and starch consumption can increase the likelihood of developing greasy hair and also poor personal hygiene and not washing the hair for a long duration will lead to a buildup of sebum in the hair follicles. Hair conditioners can decrease the likelihood of developing greasy hair after shampooing. Some cosmetics companies produce shampoos and conditioners specifically to deal with greasy hair and for oily or dry hair problems. Massaging the scalp and exposure to the sun can reduce the problem of greasy hair.

<span class="mw-page-title-main">Beard oil</span> Cosmetic product

Beard oil is a cosmetic product that is used to nourish both the skin under the beard and the beard itself in order to keep it "soft, shiny, and smooth". Beard oil mimics the natural oils produced by skin, such as sebum, and is composed mainly of carrier oils and essential oils.

<span class="mw-page-title-main">Hair oil</span> Oil applied to the hair.

Hair oil is an oil-based cosmetic product intended to improve the condition of hair. Various types of oils may be included in hair oil products. These often purport to aid with hair growth, dryness, or damage.

References

  1. ↑ Cruz, C. F.; Fernandes, M. M.; Gomes, A. C.; Coderch, L.; Martí, M.; Méndez, S.; Gales, L.; Azoia, N. G.; Shimanovich, U.; Cavaco-Paulo, A. (2013). "Keratins and lipids in ethnic hair". International Journal of Cosmetic Science (in French). 35 (3): 244–249. doi:10.1111/ics.12035. hdl: 1822/22666 . ISSN   1468-2494. PMID   23301816. S2CID   5490781.
  2. ↑ Rothstein, A. (2020-05-25). "6 Benefits of Shampoo and Conditioner". Minnesota School of Cosmetology. Retrieved 2021-10-22.
  3. ↑ Mamillapalli, Raja Sekhar; Pasumarthi, Visweswara Rao (2021-07-16). Occupational Health and Hygiene in Industries. Pharmamed Press /BSP Books. ISBN   978-93-90211-47-0.
  4. ↑ Mamillapalli, Raja Sekhar; Pasumarthi, Visweswara Rao (2021-07-16). Occupational Health and Hygiene in Industries. Pharmamed Press /BSP Books. ISBN   978-93-90211-47-0.
  5. ↑ March, Bridget; Schroeder, Roberta (2021-01-06). "#SkinSchool: Understanding scalp health (for better hair)". Harper's BAZAAR. Retrieved 2022-05-11.
  6. ↑ Zhang, Yuchen; Alsop, Richard J.; Soomro, Asfia; Yang, Fei-Chi; Rheinstädter, Maikel C. (2015-10-01). "Effect of shampoo, conditioner and permanent waving on the molecular structure of human hair". PeerJ. 3: e1296. doi: 10.7717/peerj.1296 . ISSN   2167-8359. PMC   4636411 . PMID   26557428.
  7. ↑ Punyani, Supriya; Tosti, Antonella; Hordinsky, Maria; Yeomans, Dawn; Schwartz, James (2021). "The Impact of Shampoo Wash Frequency on Scalp and Hair Conditions". Skin Appendage Disorders. 7 (3): 183–193. doi:10.1159/000512786. ISSN   2296-9195. PMC   8138261 . PMID   34055906.
  8. ↑ Miranda-Vilela, A. L.; Botelho, A. J.; Muehlmann, L. A. (2014). "An overview of chemical straightening of human hair: technical aspects, potential risks to hair fibre and health and legal issues". International Journal of Cosmetic Science. 36 (1): 2–11. doi: 10.1111/ics.12093 . ISSN   1468-2494. PMID   24102549. S2CID   5096776.
  9. ↑ The World of Hair, A Scientific Companion by Dr. John Gray, Macmillan Press Limited, 1977, pp. 23–24.
  10. ↑ Kurtzweil P, Young TA (1991). "Vitamin of the month: Biotin". FDA Consumer. 25 (8): 34.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.