With age, white hair multiplies, both in women and men. This natural phenomenon, also known as canities, often raises many questions. Learn more about white hair, its origins, its peculiarities, and the various ways to respond to its appearance.
Understanding everything about white hair.
The hair pigmentation system, in brief.
The natural pigmentation of hair is primarily influenced by the proportion of two types of melanin within the hair fibers: theeumelanin and the pheomelanin. These pigments are produced in melanocytes, specialized cells located at the base of hair follicles. Eumelanin is responsible for shades of brown and black, while pheomelanin imparts hues of blonde, red, and copper. The relative proportion of eumelanin and pheomelanin in the hair determines the final color.
The production of melanin is regulated by a number of genes and environmental factors. The MC1R gene in particular plays a crucial role in determining hair pigmentation. Variations can lead to reduced or altered melanin production, resulting in lighter hair colors, such as blonde or red. Once synthesized from tyrosine under the influence of tyrosinase, melanin is transferred to the keratinocytes, cells located at the base of the hair bulb responsible for producing keratin. It's worth noting that keratin is the main component of hair (≈ 95%).
The causes of the appearance of white hair.
Graying is a natural process that typically begins around the age of 35. However, we are not all equal when it comes to the onset of white hair. Some people see their hair turn white as early as their twenties, while others still have naturally colored hair into their fifties. The causes of white hair appearance are diverse.
Most of the time, canities, or the graying of hair, is due to the natural aging of the body, which is accompanied by the gradual decrease in the number of melanocytes and their activity. Additionally, when a hair grows, hydrogen peroxide is released as a byproduct. This is a reactive species that triggers a chain of reactions leading to the degradation of melanin. The hydrogen peroxide is normally eliminated by an enzyme called catalase, but this enzyme becomes increasingly scarce in cells over time, contributing to the emergence of white hair.
The age at which our first gray hairs appear is largely dictated by genetics. Studies have shown that individuals of so-called Caucasian type generally see their hair turn gray in their early thirties, those of so-called Asian type notice it in their late thirties, and those of so-called African type see it during their forties. Several genes are involved, such as the MC1R gene, mentioned above, or the IRF4 gene. One or more mutations on these genes can accelerate or slow down the graying of hair.
Pollution, UV rays from the sun, and smoking exert oxidative stress on cells, leading to an excessive production of free radicals. These free radicals have the effect of degrading melanin, the pigment that gives hair its color, through a series of reactions. Thus, oxidative stress promotes the appearance of white hair.
Some autoimmune diseases.
Vitiligo is an acquired autoimmune disease characterized by white patches on the skin (leucoderma) and depigmentation of hair or fur. It occurs when the immune system attacks the melanocytes, which then die or become unable to function.
Chronic stress can be a contributing factor to the early onset of gray hair. Studies have suggested that prolonged exposure to stress can disrupt the functioning of melanocytes, the cells responsible for the production of melanin, thus leading to a decrease in hair pigmentation. The most well-known example is that of Marie Antoinette, whose hair reportedly turned white the night before her execution due to stress.
Some deficiencies in vitamins or nutrients.
Deficiencies in vitamin B12, vitamin D, vitamin B9, selenium, iron, or copper can impact hair color and cause premature graying. The mechanisms involved are diverse and depend on the nutrient in question. For instance, copper promotes the activity of tyrosinase, the enzyme that enables the conversion of tyrosine into melanin. Selenium and zinc, on the other hand, are antioxidants that protect melanin from free radicals.
The characteristics and specifics of white hair.
White hair has a slightly different texture than other hair types and is more fragile and sensitive to external aggressions. This characteristic is due to the low amount of melanin in their cortex, the middle layer of the hair fiber. Indeed, melanin does not only play an aesthetic role, but it also protects the hair, particularly from oxidative stress caused by UV rays or pollution.
Furthermore, the sebum production by the sebaceous glands decreases over time. Sebum is a protective lipid film synthesized on the scalp's surface and then slides down the hair lengths and tips. It is crucial for maintaining the hydration of the fibers and their protection. The decrease in sebum synthesis explains why white hair tends to be drier and more fragile.
It should be noted that white hair sometimes tends to yellow. Several causes are put forward to explain this yellowing, among which is the oxidation of residual melanin. This oxidation leads to a change in the chemical structure of melanin, resulting in a yellow color. All hair shades can be affected by this phenomenon, but it is more visible on white hair, for colorimetric reasons. Indeed, if you add white and yellow, you get a yellowish color, whereas if you add brown and yellow, you get more of a light chestnut color.
White hair: a unique maintenance.
Due to their fragility, white hair requires special care. To compensate for the lack of melanin and the decrease in sebum synthesis, it is recommended to hydrate white hair regularly with a nourishing mask or vegetable oils. You can also turn to treatments specifically formulated for white hair if you wish. These could be, for example, purple shampoos, which are yellowing, or restorative conditioners.
It is also recommended for individuals with white hair toavoid using heat styling tools, such as straighteners or heated brushes. Being very fragile, they poorly tolerate heat. Similarly, it is important to protect white hair from the sun's UV rays, which generate oxidative stress. To do this, you can cover your hair with a hat, cap, or scarf on particularly sunny days or use a hair-specific sun protection product.
First gray hairs: what to do?
Hair whitening is a natural phenomenon that affects everyone at some point in their life. There are several options when one discovers white hairs in their mane. The simplest is to accept them. It is then appropriate to manage the transition between colored hair and white hair to avoid a too pronounced demarcation.
Some people have a more drastic reaction when they first see white hair and decide to pluck them out. Although plucking a white hair will not cause two to appear, contrary to popular belief, it is still an action that is not recommended because it is harsh on the scalp.
If your white hair bothers you, you can choose to conceal it by changing your hairstyle, strategically placing your strands, or even resorting to hair dye or highlights. If you opt for the latter option, we advise you to consult a professional hairdresser because coloring hair is quite technical and it's not easy to do it yourself.
SEIBERG M. Age-induced hair greying - the multiple effects of oxidative stress. International journal of cosmetic science (2013).
RAWNSLEY J. & al. Hair Biology: Growth and Pigmentation. Facial plastic surgery clinics of North America (2018).
PHILPOTT M. Watching hair turn grey. eLife (2021).