What Causes Grey Hair? The Science of Hair Greying

Grey hair develops when pigment-producing cells inside the hair follicle no longer supply enough melanin to a growing strand. Aging and genetics are the primary influences. Changes in melanocyte stem cells, oxidative stress, smoking, certain nutritional deficiencies, autoimmune conditions and some medications may also contribute, particularly when greying begins unusually early.

Grey hair is not simply a color change in the visible strand. It reflects changes within the living follicle that produces it.

Key takeaways

• Hair receives its color when melanocytes transfer melanin to developing hair cells during the anagen growth phase.
• Aging and genetics are the strongest predictors of when hair begins to grey.
• Melanocyte stem cells replenish the follicle’s pigment-producing cells across successive hair cycles.
• Research in mice shows that aging can disrupt the movement and regenerative function of these stem cells.
• Acute stress can deplete melanocyte stem cells in mice. Human research suggests that some pigment changes may track with psychological stress, although the response varies considerably.
• Premature greying can be associated with vitamin B12 deficiency, altered iron status, thyroid disease, autoimmune conditions, smoking and certain medications.
• Pueraria lobata and Fo-Ti are among the few botanicals studied specifically in relation to hair pigmentation.
• Caring for the scalp and hair fiber helps greying hair retain softness, shine, strength and manageability as it encounters ultraviolet exposure, coloring, heat and daily mechanical stress.

How does hair get its color?

To understand what causes grey hair, it helps to begin inside the follicle.

Each hair follicle is a small, regenerative organ containing specialized cells that produce the hair shaft, regulate growth and supply pigment. Explore the relationship among these structures in Origenere’s guide to hair biology.

Hair color comes primarily from two forms of melanin:

• Eumelanin contributes brown and black tones.
• Pheomelanin contributes yellow and red tones.

The amount, type and distribution of these pigments help determine whether hair appears black, brown, blonde or red.

Melanin is produced by cells called melanocytes. During the active growth phase of the hair growth cycle, melanocytes in the hair bulb transfer packets of pigment to developing keratinocytes. These cells become part of the growing hair shaft and carry the pigment with them as the hair emerges from the scalp.

Once a section of hair has grown beyond the scalp, it is no longer living tissue. New natural pigmentation must be incorporated while the strand is being produced inside the follicle.

What changes inside a greying hair follicle?

Hair turns grey when the follicle becomes less able to maintain its pigment-producing system.

• Fewer functional melanocytes remain available.
• Melanocytes produce or transfer less melanin.
• Oxidative stress affects pigment-producing cells and their environment.
• Melanocyte stem cells fail to generate enough mature melanocytes.
• Communication among melanocytes, epithelial hair-follicle cells and the surrounding stem-cell niche becomes disrupted.

These changes occur inside the follicular pigmentary unit. A strand appears grey when it grows with less pigment and white when it grows with little or no visible melanin.

For a closer look at the bulb, matrix, dermal papilla and other structures involved, see Hair Anatomy: The Structure of Hair From Root to Shaft.

The role of melanocyte stem cells

Mature melanocytes do not maintain hair pigmentation indefinitely on their own. The follicle contains melanocyte stem cells, commonly abbreviated McSCs, which help replenish pigment-producing cells during successive hair cycles.

Older models treated these cells as a relatively stationary reserve. Newer research reveals a more dynamic system.

In a 2023 mouse study, researchers used live imaging, lineage tracing and single-cell RNA sequencing to show that melanocyte stem cells move between different follicular compartments. Depending on their location and the signals surrounding them, these cells can enter a partially differentiated state, produce mature melanocytes or return to a more stem-like state.¹

With aging, increasing numbers of melanocyte stem cells became stranded in a follicular compartment where they no longer contributed effectively to pigment regeneration. This finding provides a more precise biological model for age-related greying and identifies stem-cell movement as an important direction for future research.

The work was performed primarily in mice. Human studies are still needed to determine whether restoring melanocyte stem-cell movement can become a practical approach to maintaining hair pigmentation.

What causes grey hair?

Aging

Aging is the most common cause of grey hair.

Across repeated hair cycles, the pigmentary unit becomes less able to regenerate functional melanocytes and sustain melanin production. Oxidative stress, mitochondrial changes, cellular senescence and dysfunction within the melanocyte stem-cell niche may all contribute.

The follicle can continue producing a strong hair after its pigmentary system has changed. This is why greying and hair loss may occur during the same stage of life while remaining biologically distinct processes.

Genetics

Genetics strongly influences when greying begins, how quickly it progresses and where it first becomes visible.

People whose close relatives developed grey hair early are more likely to follow a similar timeline. Genome-wide research has identified pigmentation-related variants associated with greying, including a variant near IRF4, a gene involved in melanocyte biology and the regulation of melanin production.²

Genes establish a substantial part of an individual’s baseline, while health, environment and lifestyle can add further influence.

Oxidative stress

Melanin synthesis is an oxidatively demanding process. Hair follicles must manage reactive oxygen species while melanocytes repeatedly produce pigment during anagen.

When oxidative activity exceeds the follicle’s antioxidant capacity, it can affect cellular proteins, lipids, mitochondria and DNA. Studies of greying human follicles have found evidence of oxidative damage, melanocyte loss and impaired antioxidant defenses.³

This makes oxidative stress a credible contributor to pigmentary aging and an important area of botanical and cellular research.

For a broader explanation, read Oxidative Stress and Hair Loss: How Free Radicals Affect Hair Follicle Health.

Smoking

Premature greying has been associated with cigarette smoking in observational studies. Tobacco smoke increases systemic oxidative stress and exposes tissues to compounds that impair cellular and vascular function.

Smoking is unlikely to explain every case of early greying, but the association has been reported across several studies and is biologically plausible.⁴

Stress

The relationship between psychological stress and grey hair is more sophisticated than the familiar expression suggests.

A landmark mouse study found that acute stress activated sympathetic nerves surrounding the hair follicle. Noradrenaline released from those nerves caused melanocyte stem cells to proliferate and differentiate abnormally, rapidly depleting the follicle’s stem-cell reservoir. Later hairs could no longer be pigmented normally.⁵

This was a sympathetic nervous system response rather than primarily a cortisol-mediated effect.

Human follicles also contain stress-responsive signaling systems. In a small human study, researchers mapped pigment changes along individual hair shafts and found that some greying and repigmentation events occurred alongside changes in psychological stress.⁶

Together, these findings establish a biological relationship between stress signaling and hair pigmentation. The degree to which stress changes visible greying in an individual depends on genetics, age, follicular biology and the remaining capacity of the pigmentary system.

Autoimmune and inflammatory conditions

Autoimmune conditions can affect melanocytes or change the balance between pigmented and unpigmented hair.

• Vitiligo can produce localized white hair when melanocytes are lost in an affected area.
• Alopecia areata may preferentially shed pigmented hairs, or regrowth may initially lack pigment.
• Certain inflammatory or scarring scalp disorders can disrupt normal follicular function.

A localized white patch of hair, known as poliosis, differs from the gradual, diffuse greying associated with aging and may warrant medical evaluation.

Medications and medical treatment

Changes in hair pigmentation have been reported with certain immunotherapies, targeted cancer treatments, retinoids, anti-inflammatory therapies and other medications.

Published reports include both greying and unexpected repigmentation. These observations provide useful insight into pigment-regulating pathways, although the responses are uncommon and unpredictable.⁷

Discuss a new hair-color change with the prescribing clinician before altering any medication.

What causes premature grey hair?

Premature greying means hair is losing pigment considerably earlier than expected for an individual’s age, family pattern and background.

Dermatology literature has traditionally described premature greying as beginning:

• Before age 20 in White populations
• Before age 25 in Asian populations
• Before age 30 in Black populations

These are historical clinical conventions rather than absolute biological cutoffs. Normal timing varies considerably among families and populations.

Grey hair in the 20s or 30s is often genetic. Rapid, extensive or localized greying deserves closer attention, particularly when it develops with other health changes.

Nutritional associations

Studies have reported associations between premature greying and low levels of:

• Vitamin B12
• Folate
• Ferritin or iron
• Vitamin D
• Calcium
• Copper
• Zinc

The strength and consistency of these associations vary.

Copper is biologically relevant because tyrosinase, an enzyme central to melanin synthesis, depends on copper. Vitamin B12, folate and iron also support cellular functions required by rapidly active tissues, including the hair follicle.

Testing is most useful when guided by medical history, dietary pattern, symptoms and examination. Identifying and correcting a true deficiency supports normal physiology while avoiding unnecessary high-dose supplementation.

Thyroid and other medical conditions

Premature greying has also been reported in association with:

• Thyroid dysfunction
• Vitamin B12 deficiency and pernicious anemia
• Vitiligo and other autoimmune conditions
• Disorders that impair nutrient absorption
• Significant protein-energy malnutrition
• Rare inherited pigmentary syndromes

Grey hair alone does not diagnose any of these conditions. The complete clinical picture determines whether laboratory evaluation is appropriate.

Botanicals and grey hair: what has actually been studied?

Botanicals have a long history in hair-pigmentation traditions, particularly in Chinese, Korean and Ayurvedic medicine. Modern research has begun examining several of these plants through defined pigmentary pathways.

The evidence is strongest when the preparation, experimental model and measured outcome are considered separately.

Botanical	Research model	Finding
Pueraria lobata	Small randomized human trial	Fewer newly developed grey hairs after 24 weeks
Fo-Ti, Polygonum multiflorum	Human follicles ex vivo	Greater follicular melanin and protection of melanocytes from oxidative stress
Fo-Ti, Polygonum multiflorum	Cells, zebrafish and mice	Increased activity across several melanogenesis-related pathways
Anu tailam	Limited clinical research	Preliminary traditional-medicine evidence requiring stronger trials
Amla, sage, bhringraj, hibiscus and related botanicals	Primarily traditional or laboratory evidence	Clinically meaningful repigmentation remains insufficiently studied

Pueraria lobata

A randomized, double-blind trial evaluated a topical compound containing Pueraria lobata extract in 44 women over 24 weeks.

The treated group developed fewer new grey hairs within the measured scalp area than the placebo group. The difference was statistically significant, although neither participants nor investigators observed a significant change in overall visible greyness.⁸

The study provides valuable human evidence while highlighting the difference between a measurable follicular effect and a cosmetically obvious result.

Fo-Ti and hair pigmentation research

Fo-Ti, also known as He Shou Wu or Polygonum multiflorum, is one of the few botanicals studied directly in relation to hair pigmentation.

Laboratory research has found that specific Fo-Ti extracts can influence melanogenesis-related pathways involving:

• MC1R
• MITF
• Tyrosinase
• α-MSH
• TRP-1
• TRP-2
• p38 MAPK signaling

In a study using cultured human melanocytes and ex vivo human hair follicles, a specially prepared Polygonum multiflorum extract reduced hydrogen-peroxide-induced oxidative stress, preserved melanocyte viability and increased follicular melanin compared with the control treatment.⁹

Additional cell, zebrafish and mouse studies have reported increased melanin synthesis and greater activity across pigment-regulating pathways.¹⁰¹¹¹²

This body of research gives Fo-Ti a genuine biological connection to hair pigmentation and supports further human investigation.

Fo-Ti is included in Sempre Hair Growth Organonutrients, Origenere’s physician-formulated combination of vitamins, minerals and botanical nutrients. Within Sempre, Fo-Ti forms part of a broader inside-out approach to healthy hair biology alongside the nutritional factors required for normal follicular function.

Botanical research is preparation-specific. Concentrated oral Polygonum multiflorum products have also been associated with liver injury. Formulated supplements should be used as directed, with professional guidance when liver disease, medication use, pregnancy or breastfeeding is relevant.

Traditional use and modern evidence

Amla, curry leaves, black sesame, sage, bhringraj and hibiscus are frequently associated with hair-darkening traditions. Many contain polyphenols or other antioxidant compounds, and some have demonstrated melanogenic activity in laboratory systems.

Human follicular pigmentation is a demanding clinical endpoint. Credible progress requires standardized extracts, defined concentrations, appropriate controls, objective hair counts and enough time to observe new growth. Most traditionally used botanicals have not yet been studied at that level.

Does grey hair differ in men and women?

Men and women develop grey hair through the same central pigmentary mechanisms.

The timing and distribution may differ among individuals, and some studies report variation in where greying first becomes visible. Current evidence does not support completely separate biological explanations for grey hair in men and women.

Women may notice changes around pregnancy, postpartum periods or menopause, while men may notice concurrent androgenetic hair loss. These events can alter density, texture or shedding without necessarily driving the pigmentary change.

Can hair suddenly turn grey?

A mature hair shaft generally does not lose all its pigment overnight.

Hair that appears to turn grey suddenly may reflect:

• Newly growing unpigmented hairs becoming more noticeable
• Rapid shedding that changes the ratio of pigmented to unpigmented hair
• Alopecia areata preferentially affecting pigmented hairs
• Changes in lighting, styling or color contrast
• A medical or autoimmune condition affecting pigmentation

Researchers have documented changes in pigment intensity along individual human hairs, showing that some follicles can alter pigment production over relatively short periods. This differs from an entire mature strand suddenly turning white.⁶

Rapid or patchy pigment change, especially when accompanied by shedding, scalp symptoms or loss of skin pigment, deserves professional evaluation.

Does sunlight cause grey hair?

Sunlight can alter the color and condition of an existing strand, but follicular greying begins deeper within the skin.

Ultraviolet radiation and environmental oxidation can degrade melanin and damage keratin within the exposed hair fiber. The visible results may include fading, yellowing, dryness, roughness, reduced shine and increased vulnerability to breakage.

True greying occurs when the follicle produces a new hair with less melanin. Photobleaching occurs when ultraviolet exposure alters pigment within hair that has already formed.

Read UVA vs. UVB: How Sun Exposure Affects Hair and Scalp for a closer examination of hair-fiber and scalp photodamage.

Can grey hair be reversed?

There is currently no single treatment that reliably restores pigment across ordinary age-related grey hair.

Repigmentation has been documented in selected circumstances:

• After correction of certain nutritional or medical abnormalities
• During treatment with particular medications
• Along individual hairs during periods associated with changing psychological stress
• In isolated cases of spontaneous follicular repigmentation

These observations show that pigment production can sometimes resume while a follicle retains enough functional melanocyte capacity.

Current clinical approach

1. Identify an underlying deficiency, thyroid disorder, autoimmune condition or medication effect when clinically indicated.
2. Correct the underlying abnormality.
3. Support adequate nutritional intake.
4. Limit tobacco exposure.
5. Protect the scalp and hair from avoidable environmental damage.
6. Use cosmetic color and fiber care according to individual preference.

Emerging research

Researchers are actively studying melanocyte stem-cell movement and maintenance, WNT, KIT and endothelin signaling, MC1R, MITF and tyrosinase regulation, oxidative stress, cellular senescence, melanocyte regeneration, botanical compounds and medication-associated repigmentation.

The most promising future treatments may come from preserving melanocyte stem-cell function before the follicle loses its capacity to generate pigment.

Should you pluck grey hair?

Plucking one grey hair does not cause several grey hairs to grow in its place.

Each follicle produces its own strand. When a plucked hair grows back, it will usually remain grey because the follicle’s pigmentary biology has not changed.

Repeated plucking can irritate the follicle and surrounding skin. Trimming or cosmetic coloring preserves the follicle while offering more predictable control over appearance.

How to care for greying hair

Grey hair continues to encounter ultraviolet radiation, repeated washing, heat, coloring, friction and daily grooming. Over time, these forces alter the cuticle and affect how the fiber reflects light, retains moisture and moves against neighboring strands.

An effective routine should address both the scalp and the visible fiber.

Cleanse the scalp and hair thoughtfully

Regular cleansing removes sebum, environmental particles and product residue from the scalp and hair. A well-designed shampoo cleans effectively while preserving a comfortable scalp environment and avoiding unnecessary roughness along the lengths.

Condition consistently

Conditioning agents deposit along the hair surface, improve lubrication and reduce friction during combing. Experimental research has shown that conditioning can reduce combing-related breakage in both untreated and chemically damaged hair.¹³

Modern silicone-free conditioning emulsions have also been shown to improve surface hydrophobicity, reduce friction and improve wet and dry combing after oxidative hair damage.¹⁴

These effects are particularly valuable for greying hair that is also frequently colored, heat-styled, sun-exposed or naturally dry.

Protect the cuticle

The cuticle forms the hair shaft’s outer protective surface. When its edges become raised, chipped or worn, hair loses smoothness and develops more friction, tangling and breakage.

Conditioning, gentle detangling, moderate heat and ultraviolet protection help preserve the cuticle and maintain a smoother fiber surface.

Choose a complete hair-care system

Origenere shampoos and conditioners combine targeted cleansing and conditioning systems with botanical extracts selected for the scalp and fiber environment. Together, they help remove buildup, improve lubrication, reduce combing stress and maintain softness, shine and manageability through repeated wash and styling cycles.

Explore Origenere shampoos and conditioners to find a collection suited to your scalp, texture and hair-care priorities.

When should premature greying be evaluated?

Consider discussing grey hair with a physician or dermatologist when it:

• Begins unusually early compared with family patterns
• Progresses rapidly
• Appears in a sharply localized white patch
• Occurs with patchy hair loss or significant shedding
• Is accompanied by fatigue, numbness or weakness
• Develops with unexplained weight or temperature changes
• Occurs with changes in skin pigmentation
• Begins after a new medication
• Develops alongside gastrointestinal symptoms or a highly restrictive diet

Depending on the history and examination, a clinician may consider vitamin B12, iron status, folate, thyroid function or other targeted testing.

Greying and hair loss are distinct processes. When pigment change occurs alongside thinning or shedding, review the broader guide to common causes of hair loss.

Frequently asked questions

What causes grey hair?

Grey hair develops when melanocytes inside the hair follicle produce less melanin or transfer less pigment to the growing hair shaft. Aging and genetics are the primary causes. Melanocyte stem-cell dysfunction, oxidative stress, smoking, certain deficiencies, autoimmune conditions and some medications may also contribute.

What causes grey hair in your 20s?

Grey hair in your 20s is frequently genetic. Rapid or extensive greying can also be associated with vitamin B12 deficiency, altered iron or folate status, thyroid disease, autoimmune conditions, smoking and certain medications.

What causes grey hair in your 30s?

Grey hair in the 30s may follow an individual’s normal genetic timeline. Clinical evaluation becomes more relevant when the change is rapid, patchy or accompanied by shedding, fatigue, neurological symptoms or pigment changes elsewhere.

At what age do people usually get grey hair?

There is no single normal age. Timing varies with genetics, ancestry and individual biology. Many people notice their first grey hairs during adulthood, with the proportion increasing gradually over time.

Can stress cause grey hair?

Acute stress can deplete melanocyte stem cells in mice through sympathetic-nerve signaling. Human studies have also associated some pigment changes with periods of psychological stress. Genetics, age and the condition of the follicular stem-cell reservoir influence the individual response.

Can vitamin B12 deficiency cause grey hair?

Vitamin B12 deficiency has been associated with premature greying. Testing is particularly relevant when early greying occurs with anemia, fatigue, numbness, dietary restriction or conditions that affect nutrient absorption.

Does Fo-Ti reverse grey hair?

Fo-Ti extracts have increased pigmentation-related activity in cell, zebrafish, mouse and ex vivo human-follicle studies. These findings support its biological relevance, while larger human clinical trials are still needed to determine its effect on visible grey hair.

Can grey hair turn dark again?

Pigment production can occasionally resume when follicles retain functional melanocytes or melanocyte stem cells. Repigmentation has been documented after treatment of certain underlying conditions, with some medications and along individual hairs associated with changing stress.

Does plucking one grey hair make more grow?

No. Each follicle produces its own hair, so plucking one grey strand does not create several others. The replacement strand will usually remain grey.

Is white hair different from grey hair?

Grey appearance often reflects a mixture of pigmented and unpigmented strands or a strand with reduced pigment. White hair contains very little visible melanin.

Does sunlight cause grey hair?

Ultraviolet exposure can fade melanin and damage keratin in an existing hair shaft. True follicular greying occurs when a new hair grows with reduced pigment.

Can supplements help premature grey hair?

Correcting a confirmed nutritional deficiency supports normal follicular biology and may improve pigment production in selected cases. Supplements are most useful when chosen according to nutritional needs, medical history and professional guidance.

Physician perspective

Grey hair is a visible expression of changing follicular biology.

The strongest evidence identifies aging and genetics as the principal determinants. Newer research shows that melanocyte stem cells are more dynamic than previously understood, moving among follicular compartments and cellular states as hair regenerates. Their age-related dysfunction offers a compelling direction for future prevention and repigmentation research.

Botanical research adds another layer. Fo-Ti has demonstrated activity across melanocyte survival and pigment-regulating pathways, while Pueraria lobata has produced a measurable signal in a small human trial. These findings deserve continued investigation with standardized preparations and clinically meaningful outcomes.

Today, the most complete approach combines appropriate evaluation of premature changes, adequate nutrition, protection from avoidable oxidative and mechanical stress, and deliberate care of the scalp and hair fiber.

References

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This article is intended for general educational purposes and does not provide medical diagnosis or individualized treatment advice. Consult a qualified healthcare professional regarding premature greying, rapid pigment changes, hair loss, nutritional testing, medication concerns or supplement use.