Why Does Hair Turn Gray Early? Real Causes and Myths
No hair actually turns gray: it grows out of the root already without color. Here are three real causes of premature gray hair, two widespread myths, and what is actually worth checking.
Why hair loses its color
Hair gets its color from melanocytes. These cells are replenished from a reservoir of stem cells located next to the follicle.
When that reservoir runs out, new hair grows in without pigment. That is why a gray hair doesn't fade over time: it grows in that way.
Gray hair is considered premature when it appears before age 20 in people of European descent and before age 30 in people of African descent.
First cause: genetics
This is the cause you can't choose. In 2016, University College London analyzed the DNA of more than six thousand Latin Americans.
The study identified the first gene linked to gray hair: IRF4. If your parents went gray early, you are more likely to do the same.
Second cause: smoking
This cause is within your control. A 2013 study of 207 people found that smokers were two and a half times more likely to go gray before age 30.
The main hypothesis is the oxidative stress that smoke inflicts on melanocytes.
Third cause: stress
This is the most frequently cited cause. In 2020, a Harvard team confirmed it in mice. Stress activates the nerves in the follicle, which release noradrenaline. That substance depletes the stem cell reservoir within days, and permanently.
In 2021, researchers at Columbia measured the pigment in human hairs millimeter by millimeter. They found gray hairs that had darkened again from the root, coinciding with periods of lower stress.
The sample was small, and the effect appears to be limited to recent gray hairs. Even so, it suggests that not all gray hair is permanent.
Two myths about gray hair
Myth one: going gray overnight, as the story goes about Marie Antoinette. It's impossible. Hair that has already grown out is dead keratin and does not lose its color.
The likely explanation is alopecia areata. This condition causes pigmented hairs to fall out suddenly, revealing the gray hairs that were already there.
Myth two: if you pull out a gray hair, more will grow back. This is false. Each follicle works independently. That said, repeatedly pulling out the same gray hair can damage the follicle.
What is worth checking
If you are going gray very early, ask your doctor or a dermatologist for blood work.
Deficiencies in vitamin B12, iron or vitamin D, as well as thyroid problems, are associated with premature gray hair. And these causes can be treated.
One last fact: hair grows about one centimeter per month. Hair 30 centimeters long holds roughly two and a half years of your life.
Frequently asked questions
At what age is gray hair considered premature?
Before age 20 in people of European descent and before age 30 in people of African descent.
Can you go gray overnight?
No. Hair that has already grown out is dead keratin and does not lose its color; the likely explanation is alopecia areata, which causes pigmented hairs to fall out and reveals the gray hairs that were already there.
If I pull out a gray hair, will more grow back?
No, because each follicle works separately. However, repeatedly pulling out the same gray hair can damage the follicle.
What tests should I ask for if I'm going gray very early?
Blood work that checks vitamin B12, iron, vitamin D and thyroid function. These imbalances are associated with premature gray hair and can be treated.
Informative article written with the help of AI tools from the verified script of the video. The video is in Spanish.