Lecturer - İstinye University, Faculty of Pharmacy, Department of Pharmacology

"Hair color is affected by heat, and its color lightens after repeated shampooing and drying."

Title:

The importance of hair for our health

The hair structure is intricate, comprising multiple components that play a crucial role in safeguarding the scalp, as well as enhancing physical attractiveness and fostering a sense of beauty. The protective function of hair is attributed to its dual role in safeguarding the scalp from external elements and its contribution to the regulation of body temperature.

Hair health has a crucial role in human social relationships and exerts a substantial influence on self-perception, image of oneself, and self-sufficiency. Optimal hair health contributes to the enhancement of emotional and psychological well-being, as well as the bolstering of self-assurance and charm. The vitality, nourishment, and smoothness of hair depend on several external factors, the use of hair treatments, and the adherence to basic hair care routines.

Structure of hair

Hair follicle

A follicle is a conical anatomical feature situated within the dermis. The hair follicle's superior region may have a complex network of blood arteries that provide nourishment to the hair and support its growth by delivering vital nutrients.

Hair shaft (visible part of the hair)

There are three distinct layers in the hair shaft:

The medulla is the central component of the spinal cord. It often consists of a vacant tube or contains cells. While a significant number of feathers lack a medulla, some possess a medulla that is either continuous or divided into segments. It forms the central region of the hair shaft. The absence of this layer is particularly observed in fine hairs.
The cortex, which is the largest segment of the hair shaft, is primarily responsible for the pigmentation of the hair, known as melanin.
The cuticle refers to the translucent outer covering of the hair shaft. The structure consists of overlapping scales that provide protection for the inner layers of the hair. The proximal end of the hair, which is in closest proximity to the scalp, is the location where the scales terminate.

Asians exhibit greater hair thickness and a higher number of medulla in comparison to Caucasians. Like roof shingles, the medulla's overlapping scales (keratinocytes) can lead to hair separation by forming a vulnerable area that facilitates the propagation of cracks along the fiber axis. The diverse frictional impacts on hair arise from disparities in the morphology and alignment of the cuticle cells.

The life cycle of hair

All types of hair undergo periodic phases of active growth and rest. The duration of each hair cycle varies depending on the individual's age and the specific area of the body where the hair is grown. The cycle of the follicle is characterized by three distinct phases: the anagen, which represents the active growth phase; the catagen, which represents the intermediate period; and the telogen, which represents the rest phase.

Anagen phase

At the point of follicle elongation, there is an increase in the number of matrix cells responsible for the synthesis of several constituents of the hair shaft, such as the inner sheath, cuticular layers, cortex and medulla, and inner root sheath. In tandem with the process of epilation, the inner and outer sheaths of the anagen hair remain interconnected and envelop the hair bulb.

Catagen phase

Hair in its evolutionary condition can be distinguished from telogen (bulk) hair by two distinct properties. The keratinized proximal section exhibits a darker coloration compared to the club hair. The exterior and inner sheaths of the object are more effectively protected.

Telogen phase

The remnants of the epithelial sac, including around 100,000 to 105,000 scalps in an adult (irrespective of gender), can also be encased within the remnants. These scalps do not undergo growth and shed spontaneously, with approximately 90% of them being in the growth or anagen phase. The resting phase, also known as the telogen phase, accounts for the remaining 10%.

The importance of hair care

Hair significantly influences an individual's appearance and the manifestation of their character. Certain procedures conducted within hairdressing salons, such as hair cutting, dyeing, and styling, primarily serve the goal of embellishment. Certain daily care routines, such as grooming habits, have been found to contribute to the enhancement of hair texture and visual appeal. The act of brushing, cleaning, and applying cosmetic items is crucial in attaining these outcomes. These applications have a crucial role in maintaining the cleanliness of the hair and scalp, preserving the hair's overall condition, and addressing or minimizing damage resulting from external sources. Due to its composition of deceased cells, hair lacks the ability to undergo biological renewal. Therefore, the only way to restore its qualities is by physically restoring it, which may be done by using a conditioner and/or other hair care products that can successfully hide or restore the damaged surface of the hair shaft.

Factors that cause hair problems

Hair damage refers to the process by which the hair shaft undergoes chemical or physical deterioration, resulting in the loss of some hair components and an increased vulnerability to breakage. Damage can arise from various factors such as cosmetic operations, inadequate hair care practices, prolonged exposure to ultraviolet (UV) radiation, or environmental circumstances, among others.

Certain cosmetic procedures have been found to be highly abrasive, resulting in heightened levels of structural and chemical harm to hair fibers. It is widely recognized that chemical processes, including bleaching, perming, relaxing, and straightening, can result in substantial harm to hair strands. Nevertheless, insufficient practices and routines for everyday hair care might also result in hair damage. Insufficient brushing or combing, as well as extremely high temperatures when blow-drying, can lead to physical harm.

Hair attrition refers to a gradual and ongoing process of degradation wherein the hair shaft experiences a loss of the external protective layer known as the cuticles. This loss of protection has a detrimental impact on the cortex's capacity to retain moisture. During the early phase, this phenomenon leads to a reduction in both shine and softness. However, as time progresses, the resulting damage can lead to a decline in the hair's strength, elasticity, and ultimately its structural integrity, finally resulting in hair breakage. Hair is subject to a multitude of environmental factors during its lifespan. This implies that older hair is more susceptible to experiencing a greater level of damage compared to the recently developed hair shaft.

Physical damage

The most prevalent cause of damage is mechanical harm, which happens on a daily basis, such as when hair is combed using plastic or wooden combs or brushes. Repetitive brushing in a specific region leads to the detachment of the cuticle edges, resulting in partial or complete wear, particularly at the outside edges of the hair strand. The act of cutting hair can result in mechanical harm, particularly when performed without the use of suitable instruments. Utilizing a razor or even dull scissors in lieu of scissors leads to an unhygienic incision and increases the susceptibility of the cuticle to peeling.

While shampoos serve the aim of cleansing and maintaining hair health, the process of shampooing can potentially harm the hair by causing distortion and abrasion/erosion when the hair strands are twisted and brushed. Furthermore, it has been observed that the presence of anionic surfactants in shampoos might enhance the capacity for cleaning, hence promoting the decomposition of structural lipids and proteins.

Environmental factors

Melanin, the pigment molecules found in hair strands, shield the hair from UV rays by absorbing and filtering them. This filtration mechanism largely inhibits the degradation of proteins caused by radiation. However, it does result in the degradation or bleaching of pigments, hence altering the visual characteristics of the hair. The susceptibility of cuticles to photodamage is heightened because of their exposure to greater-intensity radiation and the exclusive presence of melanin in the cortex. Sunlight exposure elicits modifications in amino acids, namely within the cuticles, leading to the rupture and detachment of the outer layers and the division of the extremities. Furthermore, it causes hair to become dry and damaged, reduces its shine and color, and leads to a rough texture. Photochemical degradation of proteins leads to a decrease in their structural integrity. The observed process occurs when the disulfide bonds that link structural units experience cleavage, resulting in the creation of new bonds through the interaction between carbonyl groups and amino groups that are present both inside and between the structural units. Regardless of the kind of hair, UVB radiation is the main component responsible for protein depletion in hair, while UVA radiation is responsible for changes in color. The nature of hair damage is solely determined by the wavelength of the radiation, while the extent of damage is based on the specific hair type. Varying hair types exhibit distinct photostability as a result of disparities in melanin composition and concentration. Black hair has greater light resistance compared to blonde hair and offers enhanced protection against UV light in the melanin-rich cortex. Irradiation only causes a minor alteration in fiber proteins. When doing a comparison between photodamage and cuticles, it is shown that protein loss in black and light brown hair exhibits similarities. This can be attributed to the lack of melanin present on the surface of the hair fibers. The variation in hair color is contingent upon the kind of hair, with lighter-colored hair exhibiting more pronounced changes compared to black hair.

Chemical agents

Chemical techniques employed in hair styling, such as chemical straightening, bleaching, or coloring, have been found to result in significant harm to the hair, particularly when executed by individuals lacking adequate training. Chemical straightening is a chemical process that has been implemented as a durable substitute for thermal straightening. The process of styling hair involves the use of chemical relaxants that target disulfide bonds, resulting in a flat appearance. Furthermore, alongside the reorganization of disulfide bonds, the hair shaft experiences structural impairment as a result of alterations in keratin connections, leading to a decrease in hair strength and a reduction in tensile strength. The process of bleaching involves the oxidation of melanin pigments in the cortex of hair, resulting in a lighter coloration. This process causes the disintegration of disulfide bonds and increases the porosity of cuticles, resulting in reduced tensile strength and a fragile look. Melanin's photoprotective properties are compromised during oxidation, rendering bleached hair more vulnerable to additional harm caused by ultraviolet (UV) radiation.

Permanent dyes are utilized to modify the color of hair strands. Similar to the bleaching process, the outcomes of this therapy are obtained through oxidation reactions occurring within the hair shaft. Alkaline solutions, such as ammonia, are provided to enhance the penetration of these chemicals into the hair shaft. The utilization of this application results in the disruption of the protective cuticle barrier, hence increasing the susceptibility of the hair to additional harm. The utilization of alkaline treatments results in the removal of the 18-MEA layer, hence contributing to the improvement of hair friction and hydrophilicity. Without this hydrophobic layer, the hair's smooth texture is reduced and it becomes more prone to brittleness.

Thermal factors

The utilization of blow dryers for hair drying is a widely adopted practice. Nevertheless, frequent usage causes harm to the hair strands. Air-dried hair exhibits a thoroughly shielded surface, whereas blow-dried hair displays a greater extent of harm. With rising temperatures, the hair surface experiences greater damage. The utilization of a blow dryer for hair drying results in the concavity of the scale margins, which can be attributed to the division of the cuticle layer. Blow drying induces structural alterations that extend beyond the fiber surface and also manifest inside the inner cuticle layers. The color of hair is also influenced by thermal conditions, resulting in a lighter hue following multiple instances of shampooing and drying. The color changes become perceptible after just 10 blow-drying cycles at a temperature of 95°C.

Using a hot straightener or curling iron to style the hair can potentially cause harm to the hair. These phenomena take place under elevated temperatures, and the consequences of style arise from a transient reorganization of hydrogen and disulfide bonds within the hair shaft. Thermal straightening leads to excessive heat buildup in the hair shaft, resulting in its weakening and breaking.

Common hair problems

Hair loss (alopecia)

While hair loss/thinning hair has traditionally been associated with men, it is as prevalent among women. For several males, this results in male pattern alopecia. The frequent causes of hair loss in women include stress, medication, hormonal fluctuations, and even menopause. Moreover, numerous hair styling products, such as chemicals and high heat, have been found to potentially contribute to hair loss.

Dry hair

Excessive shampooing leads to hair dryness. Although having shiny and clean hair is beneficial, many individuals tend to excessively wash their hair, washing it once, sometimes twice, or even once a day, resulting in the removal of all its natural oils.

Split ends

Split ends can be caused by excessive brushing, excessive perming, excessive heat, and a lack of effective conditioner.

Oily hair

Oily hair is characterized by the overproduction of sebum, a natural oily substance, by the scalp. Sebum is synthesized by the sebaceous glands, which may occasionally exhibit excessive activity, resulting in an overproduction of oil.

Curly hair

Frizzy hair is characterized by a decrease in hair moisture levels below the usual range, and it may also have a hereditary component.

Matte hair

Various factors contribute to the appearance of hair that seems dull, such as damage caused by chemical or heat styling and contamination from the environment.

Heat-damaged hair

Excessive use of a curling iron or straightener might result in hair damage.

Color-damaged hair

The process of hair coloring involves the application of chemicals to lighten the hair strand, resulting in increased porosity, brittleness, and susceptibility to breaking.

Gray hair

Gray hair is often regarded as a symbol of prestige by numerous individuals. Nevertheless, some individuals opt to eliminate gray hair due to its heightened fragility and difficulty in being controlled compared to other hair types.

Dandruff

Dandruff refers to the presence of tiny, white patches of dead skin that reside on or detach from an individual's hair. Malassezia Globosa, a yeast caused by the fungus Restrata (formerly known as Pityrosporum), is believed to be responsible for skin and scalp infections. Failure to brush one's hair, allergies, stress, insufficient showering, and so on. There are several causes.

Products used in hair care

Shampoos

Contemporary civilization necessitates a shampoo that possesses multiple attributes: it must effectively wash the scalp and hair, while also being visually appealing, avoiding dryness and skin irritation, enhancing hair beauty, and being cost-effective.

A shampoo is composed of a range of 10-30 chemicals that are categorized based on their distinct functions. The composition of a shampoo formulation comprises the subsequent categories of constituents:

Surfactants are washing agents that eliminate sebum or skin scales.
Hair care ingredients that promote hair suppleness;
The active constituents utilized in the therapeutic management of particular ailments, such as dandruff;
The inclusion of product additives, such as preservatives, plays a significant role in enhancing the stability and comfort of the product.

Conditioners

The majority of shampoos typically have conditioning agents, although individuals frequently opt to apply a conditioner subsequent to shampooing in order to reduce hair frizz and enhance hair manageability and shine. Hence, the application of a conditioner can effectively mitigate the adverse effects of chemical or mechanical stress on the hair, including but not limited to permanent dyes, bleaching, and excessive brushing.

Conditioning agents possess positive charges, whereas the hair shaft carries negative electrical charges. Conditioners bind to positive charges, thereby neutralizing the negative electrical charge in the hair fiber and lubricating the hair cuticle. This ultimately leads to a decrease in the hydrophilicity of the fiber. Conditioners additionally encourage the elongation of the soft cuticles towards the hair's surface, thereby safeguarding the hair's color and enhancing its smoothness.

1. Alessandrini A and Piraccini B, Essential of Hair Care Cosmetics. (2016). 2. Cruz C, et al., Human Hair and the Impact of Cosmetic Procedures: A Review on Cleansing and Shape-Modulating Cosmetics. (2016). 3. Coderch L, et al., Hair Lipid Structure: Effect of Surfactants. (2023). 4. Pereira-Silva M, et al., Nanomaterials in hair care and treatment. (2022). 5. Lin KK, et al., Circadian clock genes contribute to the regulation of hair follicle cycling. (2009). 6. Natarelli N, Gahoonia N, and Sivamani RK, Integrative and Mechanistic Approach to the Hair Growth Cycle and Hair Loss. (2023). 7. Fernandes C, et al., On Hair Care Physicochemistry: From Structure and Degradation to Novel Biobased Conditioning Agents. (2023).

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