If you pull out one white hair, three will grow back? Should you pull out your hair? Finally figured it out!

Will pulling out more white hair cause more of them? No.

Before solving this problem, let’s imagine, if white hair really increases in number, what form would be taken?

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One possibility: Based on the theoretical basis of rumors that toenails grow thicker the more you cut them, lip hair grows thicker the more you shave them, and sweat hair grows thicker the more you shave them, maybe pulling out one white hair will make two grow, pulling out two will make four grow. Tao begets one, one begets two, two begets three, and three begets all things. As long as you are cruel enough, you can turn a bald man into a chimpanzee. Walking upright for millions of years, you can go back to the pre-evolutionary period overnight. (People with hair loss and peribaldness say: You wish!)

Another possibility: pulling out a hair will not cause more hair to grow, but will only scare the remaining hair into turning pale. Or is it that the hair is possessed by the spirit of a dandelion you blew when you were young, turning white to seduce your restless hands? Then a new question arises: if the white hair is not pulled out but falls off naturally, then in order to appease the emotions of the other hair, do we need to glue it back? [1]

Back to the topic, why don’t the more you pull out your white hair, the more white hair you have? In fact, as long as you understand the basic principles of hair growth, this problem can be easily solved.

All hairs on human skin, including the head, vary in length, thickness, color, and shape, but their basic structure is the same. As shown in the figure, sweat glands are responsible for sweating, sebaceous glands are responsible for secreting oil to moisturize hair and skin, arrector pili muscles determine the direction of hair, and hair follicles are the starting point, breeding ground, and hometown of all hair.

Image source: Reference [2]

The hair bulb formed by the fusion of the hair follicle and the hair root at the bottom can be regarded as a hair processing factory. The stem cells here continuously produce new epithelial cells and push them outward, while melanocytes are responsible for producing pigments to be inserted into the epithelial cells. Therefore, the growth of hair is actually the epithelial cells with pigments pushing the front waves behind them, and epithelial cells stacking up on each other.

There are two main types of pigment particles that melanocytes put into hair, one is black melanin, and the other is yellow or red pheomelanin. Everyone's hair has different colors because of the different proportions of pigment particles. You can also understand that black, yellow, and red are the three primary colors of hair. (So in reality, natural hair will not grow into the colorful appearance in animation! Brave boy, give up your fantasy!)

Sometimes there are various reasons that lead to the lack of melanocytes or the inability to synthesize pigments smoothly. At this time, the hair will show the original color of the epithelial cells because the printer is out of ink - yes, the color of dandruff, white.

The color of each hair is determined at the moment it is formed, and is no longer affected by the body. The hair of Lady Xin Zhui in Mawangdui has not faded for more than 2,000 years, and Wu Zixu has no hair dye no matter how anxious he is. The cells in the hair are like a notebook, automatically synchronizing and sealing the state of the body at every moment, which is why doctors and forensic doctors can determine whether a person has been exposed to heavy metals or specific drugs or poisons in the past few months or even years by testing the hair.

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Hair follicles have a growth phase, a regression phase, and a resting phase, that is, a working time and a resting time, so hair will not grow all the time, and will fall off naturally when it reaches a certain size. Pulling out a white hair only ends the growth of the hair in advance, and there is no substantial difference from falling out a white hair.

The circulation between hair follicles is also relatively independent. [3] Whether a hair is plucked out or the entire follicle is dug out and moved to the front, the other hairs will not be saddened. So we don’t have to worry about other hairs turning gray because of the loss of a gray hair.

So far, the content of this article should be enough to explain why pulling out white hair will not make it more, but there must be many people who are confused because of their intuitive life experience. In the past, there were indeed some moments when I or my family members had obviously more white hair, but then they turned black again. If it is not caused by pulling out white hair, what is the reason?

As mentioned above, there are various reasons that affect the formation of hair pigmentation. Natural aging, hypopigmentation skin diseases, stress, immune factors, etc. can all be the cause of graying hair. A research team at Harvard University has discovered the specific mechanism of graying hair under stress. [4] Therefore, the sudden increase in the number of gray hairs is more likely to be due to some abnormal state of the body, which is reflected in the hair, rather than the pulling out of a certain gray hair.

The little mouse was so worried that he turned into a spotted mouse. I wonder if people’s leg hair will also turn white when they are under a lot of stress. Image source: Reference [4]

In conclusion, if you don’t like the appearance of white hair, feel free to pluck it. But only those of you with thick hair don’t care. For people like me with thinning hair, every hair is precious to me, so I can’t bear to pluck it.

References:

[1] O. Henry. (1907). The Last Leaf. McClure, Phillips & Co.

[2] Li Jicheng, Zeng Yuanshan (eds.). Undergraduate Clinical Western Medicine Textbook Histology and Embryology 9th Edition [M]. Beijing: People's Medical Publishing House, 2018.

[3] Steingrímsson E, Copeland NG, Jenkins NA. Melanocyte stem cell maintenance and hair graying. Cell. 2005;121(1):9-12. doi:10.1016/j.cell.2005.03.021

[4] Zhang B, Ma S, Rachmin I, He M, Baral P, Choi S, Gonçalves WA, Shwartz Y, Fast EM, Su Y, Zon LI, Regev A, Buenrostro JD, Cunha TM, Chiu IM, Fisher DE, Hsu YC. Hyperactivation of sympathetic nerves drives depletion of melanocyte stem cells. Nature. 2020 Jan;577(7792):676-681. doi: 10.1038/s41586-020-1935-3. Epub 2020 Jan 22. PMID: 31969699; PMCID: PMC7184936.

Author: Doctor Fei Dao Duan Yu

Review | Xu Min, deputy chief physician of the Department of Dermatology, Zhu Xianyi Memorial Hospital, Tianjin Medical University

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