Is it Actually Possible to Reverse Gray Hair?

It’s estimated that 50 percent of people will have at least some gray hair by age 50, with variations based on ethnicity and sex. However, many individuals experience premature graying, starting as early as their 20s. In this article, we’ll uncover the primary causes of graying hair and recent research on whether or not the reversal of gray hair is possible. 

The Basics of Hair Growth 

Every hair follicle has pigment cells containing melanin, which are produced by melanocytes. Natural differences in hair color are due to the ratio of two types of melanin pigment: the reddish-brown pheomelanin and the black-brown eumelanin. 

The hair growth process has three distinct stages: anagen, catagen, and telogen. Anagen is the active growth phase, which lasts four years on average. The shorter, 10-20 day catagen phase, also known as a transitional state, begins to shut down hair growth. Finally, the telogen phase is when hair growth is completely at rest, and the hair will then fall out. 

Unlike melanin in the skin, which continuously produces pigment, hair is only actively pigmented during the growth (anagen) stage of its cycle. With age, the melanocytes produce less melanin, thereby reducing the pigmentation of the hair follicle. In addition, graying hair also has significantly fewer melanosomes, organelles that synthesize, transport, and store melanin.

After about 10 full hair cycles, each cycle loses a bit more melanin production. With the active growth stage lasting about four years, this starts to occur around age 40. Gray hair occurs when the melanin pigment is diluted, while white hair occurs when there is a complete lack of pigment deposition onto the hair follicle. 

What Causes Gray Hair? 

While gray hair is mostly considered a vanity concern, it can be an external indicator of how quickly the body is aging. Although genetics does play a large role in the timing of when you go gray, there are many modifiable lifestyle factors that influence graying hair, which is also known as canities or achromotrichia. 

1. Oxidative Stress

Stress can occur in the body in multiple forms, one of which is oxidative stress. The accumulation of inflammatory molecules, such as free radicals and reactive oxygen species, is known to accelerate the aging process. 

Oxidative damage increases through exposure to UV radiation, pollution, pesticides, and smoke, as well as a diet high in inflammatory foods or low in antioxidant-rich foods.  

These damaging compounds can lead to graying hair, as oxidative stress accelerates apoptosis (cell death) of melanocyte stem cells. One contributor to oxidative stress is a buildup of hydrogen peroxide, a well-known compound that bleaches hair. In the body, the inability to clear out excess amounts of hydrogen peroxide, via the enzyme catalase and the antioxidant glutathione peroxidase, is linked to accelerated aging of follicular melanocytes. 

In a 2020 study published in the International Journal of Trichology, individuals with prematurely graying hair were significantly more likely to have biomarkers of oxidative stress, including high levels of malondialdehyde and low levels of glutathione and superoxide dismutase. 

2. Emotional Stress

In addition to internal oxidative stress, psychological or emotional stress is also associated with graying hair. While anecdotal evidence that stress leads to gray hair has been suggested for centuries — it’s said that Marie Antoinette’s hair suddenly turned white the day before her execution —not a lot of scientific research on this topic has been done.

Recently, a January 2020 study published in Nature discovered the mechanism behind how stress can lead to graying hair. Mice exposed to mild pain, psychological stress, or restricted movement all experienced hair graying and a reduction of melanocyte stem cells. 

The researchers found that the neurotransmitter norepinephrine, which activates the fight-or-flight stress response, was the link between emotional stress and gray hair. Even in non-stressed mice, an injection of norepinephrine led to graying hair and the depletion of melanocyte stem cells. 

3. Smoking

Cigarette smokers, especially those who chronically smoke, are more likely to experience earlier graying of the hair. That’s because smoking is more likely to increase in oxidative damage, resulting in a decrease in melanocyte stem cell production. 

4. Nutrient Deficiencies

Certain nutrient deficiencies, including inadequate levels of vitamin B12, folic acid, and biotin, and minerals copper, calcium, and iron, are associated with prematurely graying hair.  

The Research: Can You Reverse Graying Hair? 

As humans live longer, it’s natural to assume that many will want to delay or prevent the graying of their hair. Recent research has found that this hallmark characteristic of growing older may, in fact, be reversible.  

In a study preprinted in bioRxiv in May 2020, researchers took hair samples from 14 individuals of varying age, sex, and ethnicity. They found that some of the hairs began as gray or white and reverted back to their original pigmented color. In contrast, other hairs underwent double transitions and reversions, meaning the hair began dark, started to gray, then re-pigmented again. 

The researchers believe that an increase in acute mental stress triggered the double transitions of graying because pigmentation returned when the stress subsided. However, this stress-related reversal was only seen in the younger individuals in their 30s. 

In other gray hairs that reverted to their original hues, the researchers analyzed the timing of the graying and reversal. They hypothesized that metabolic and mitochondrial pathways were implicated in the reversal of graying hair, meaning the process could be targeted with pharmacological drugs. 

In addition, they looked at protein profiles of the hair samples and isolated certain proteins that were either increased or decreased with graying hair. Notably, the proteins indicated with gray hair also play a role in mitochondrial metabolism and the NAD+ pathways; a reduction in both NAD+ levels and mitochondrial function is linked to accelerated aging and, likely, to graying hair. 

Although it’s known that NMN is an effective way to boost NAD+ levels, the compound has not yet been studied for its effects on reversing graying hair. 

Other research has indicated that some vitamins, including biotin and pantothenic acid (vitamin B5), and certain pharmaceutical drugs may also be able to reverse graying hair. 

Until more studies have been conducted, some lifestyle habits to look at if you’re concerned about graying hair include managing your stress levels, consuming plenty of antioxidants, and quitting smoking. 

Key Takeaway: 

• Graying hair is caused by a combination of age, genetics, oxidative damage, emotional stress levels, smoking, and certain nutrient deficiencies. 
• Recent research using human hair samples has found that graying hair is a reversible process. 
• Certain proteins are implicated in the graying of hair, which are involved with mitochondrial and NAD+ function; future research may show that the NAD+ precursor, NMN, can prevent or reverse graying hair. 

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References:

Daulatabad D, Singal A, Grover C, Chhillar N. Prospective Analytical Controlled Study Evaluating Serum Biotin, Vitamin B12, and Folic Acid in Patients with Premature Canities. Int J Trichology. 2017;9(1):19-24. doi:10.4103/ijt.ijt_79_16

El-Sheikh AM, Elfar NN, Mourad HA, Hewedy ES. Relationship between Trace Elements and Premature Hair Graying. Int J Trichology. 2018;10(6):278-283. doi:10.4103/ijt.ijt_8_18

Kumar AB, Shamim H, Nagaraju U. Premature Graying of Hair: Review with Updates. Int J Trichology. 2018;10(5):198-203. doi:10.4103/ijt.ijt_47_18

Rosenberg A, Rausser S, Ren J, Mosharov E, Sturm G, Ogden RT, Patel P, et al. Human Hair Graying is Naturally Reversible and Linked to Stress. bioRxiv. Preprint 2020.05.18.101964; doi: https://doi.org/10.1101/2020.05.18.101964

Saxena S, Gautam RK, Gupta A, Chitkara A. Evaluation of Systemic Oxidative Stress in Patients with Premature Canities and Correlation of Severity of Hair Graying with the Degree of Redox Imbalance. Int J Trichology. 2020;12(1):16-23. doi:10.4103/ijt.ijt_99_19

Seiberg M. Age-induced hair greying - the multiple effects of oxidative stress. Int J Cosmet Sci. 2013;35(6):532-538. doi:10.1111/ics.12090

Yale K, Juhasz M, Atanaskova Mesinkovska N. Medication-Induced Repigmentation of Gray Hair: A Systematic Review. Skin Appendage Disord. 2020;6(1):1-10. doi:10.1159/000504414

Zhang B, Ma S, Rachmin I, et al. Hyperactivation of sympathetic nerves drives depletion of melanocyte stem cells. Nature. 2020;577(7792):676-681. doi:10.1038/s41586-020-1935-3