The culprit of premature graying has been caught! Can gray hair turn black again?

Recently, a short video of a senior high school student with gray hair recorded by a class teacher has been circulating on the Internet. A quick search on social media platforms also shows that the topic of "young people with premature gray hair" is everywhere. Nowadays, gray hair is no longer exclusive to the elderly, and more and more young people are experiencing the problem of gray hair.

Image source: TV series "The Legend of Zhen Huan"

01 How can I have white hair at such a young age?

This starts with the formation of hair color. The color of hair mainly depends on the melanocytes in the hair follicles, which transfer melanin particles to the hair through the dendritic structure and are responsible for dyeing the hair. The human hair growth cycle is 3.5 years, and the hair begins to turn white after about 10 cycles. Generally speaking, hair does not suddenly turn white. In the hair bulb of the hair follicle (located in the upper 1/3 of the hair follicle), there is a special cell- melanocytic stem cells . These stem cells are the source of melanocytes and the core of melanocyte regeneration. They continuously differentiate and regenerate to maintain the stability of hair color. However, when the homeostasis of melanocyte stem cells is disrupted, the supply of melanocytes will be affected, causing the hair color to gradually become lighter and eventually turn white.

Comparing normal hair with hair under stress, the homeostasis of melanocyte stem cells is disrupted, leading to the generation of gray hair. Image source: Reference 1

Studies have found that stress is the culprit of "premature graying of hair "! There was almost no scientific evidence to prove this until 2020, when the Yajie Xu Laboratory of Harvard University (Dr. Bing Zhang is the first author) published a research article titled "Hyperactivation of sympathetic nerves drives depletion of melanocyte stem cells" in the journal Nature, pointing out that stress can trigger the consumption of pigment stem cells in mouse hair follicles, causing the mouse hair to turn gray. This study revealed for the first time the specific mechanism by which stress causes gray hair : stress can activate nerves related to the fight or flight response, causing permanent damage to pigment stem cells in hair follicles. Young people may be entangled in gray hair without realizing it under the tremendous pressure of study and work.

Complex sympathetic nerves (green) surrounding pigment stem cells (red).

Acute stress induces overactivation of the sympathetic nervous system, releasing large amounts of the neurotransmitter norepinephrine. Norepinephrine drives rapid depletion of melanocyte stem cells and causes hair to gray. Image source: Reference 1

In addition, the deficiency of nutrients such as vitamins (vitamin B12, serum biotin), trace elements (zinc, iron, etc.) and folic acid is closely related to the occurrence of gray hair. Genetics, albinism, hypothyroidism and other diseases can also cause gray hair.

02 Can the white hair that has grown out turn black?

Unfortunately, there is no way to turn the already grown white hair back to black. Once the self-maintenance and renewal ability of melanocyte stem cells is destroyed, the subsequent melanocyte lineage will eventually lose its function and cannot be restored. All we can do is slow down or delay the speed of hair graying. Perhaps with the advancement of technology, this problem will be solved.

Image source: Photo Network

As for the saying that "pulling gray hair will cause more hair to grow", there is no scientific evidence yet. Studies have found that plucking the hair of mice over and over again will cause the hair to turn gray. Although no studies have shown that this phenomenon will occur in humans, pulling out hair will definitely damage hair follicles. A gentler method is to cut gray hair close to the scalp, but the hair that grows back will still be white.

03 How to prevent gray hair?

Relax: Learn to relax. You can try yoga, meditation or exercise to release stress and make you feel happy.

Reasonable diet: Eating more nuts, green leafy vegetables, beans, etc. can help maintain healthy hair.

Regular work and rest schedule: ensure adequate sleep and never stay up late again!

Massage and conditioning: Regular scalp massage can speed up local blood circulation, thereby promoting hair follicles to better absorb nutrients and play an auxiliary improvement role.

I wish everyone can grow black, thick and healthy hair!

Image source: Photo Network

References

[1]Zhang B, Ma S, Rachmin I, et al. Hyperactivation of sympathetic nerves drives depletion of melanocyte stem cells. Nature. 2020 Jan;577(7792):676-681.

[2] Dou Jinjin, Rui Xue, Zhang Xiwu. Pathogenesis of vitiligo and current status of traditional Chinese medicine treatment[J]. Journal of Traditional Chinese Medicine and Pharmacy, 2021, 27(10): 118-126.

[3] Qu Qian, Miao Yong, Hu Zhiqi. Research progress on the regulation of gray hair production by disruption of melanocyte stem cell homeostasis[J]. Chinese Journal of Plastic Surgery, 2017(4): 313-316.

Author: Ma Jiaoyang, attending physician of the Dermatology Department, Putuo Hospital Affiliated to Shanghai University of Traditional Chinese Medicine

Planning & Editing: Tiara