When hair starts thinning or shedding more than usual, we often look to genetics, stress, or hormones for answers. But sometimes the cause is simpler and more treatable than we realise. Vitamin B12 deficiency, a surprisingly common condition affecting around 6% of the UK population, may be contributing to your hair loss without you knowing.
In this guide, we explore the connection between B12 and hair health, examine what the research actually shows, and explain how correcting a deficiency could help restore your hair’s vitality.
What Is Vitamin B12?
Vitamin B12, also known as cobalamin, is an essential nutrient your body cannot produce on its own. It must be obtained through diet or supplementation. See our B12 page for more detail.
B12 plays a crucial role in several vital functions:
- Red blood cell formation — B12 is essential for producing healthy red blood cells that carry oxygen throughout your body
- DNA synthesis — Required for cell division and replication, including the rapidly dividing cells in hair follicles
- Nervous system function — Maintains the protective myelin sheath around nerves
- Energy metabolism — Helps convert food into usable energy
- Protein synthesis — Supports the production of keratin, the protein that makes up your hair
Because B12 is involved in so many fundamental processes, a deficiency can affect multiple body systems — including your hair.
How Does B12 Affect Hair Growth?
Your hair follicles are among the fastest-dividing cells in your body, with cells in the hair bulb dividing every 23 to 72 hours. This rapid growth requires a constant supply of oxygen, nutrients, and the raw materials for cell division — all of which depend on adequate B12 levels.
Here’s how B12 supports healthy hair:
Oxygen Delivery to Hair Follicles
At the base of each hair follicle sits the papilla, a structure rich in blood vessels that connects follicles to your body’s blood supply. B12’s role in red blood cell production is critical here. Without enough healthy red blood cells, your scalp receives less oxygen, and hair follicles may struggle to function optimally.
Cell Division and Growth
Hair growth depends on rapid cell division in the follicle. B12 is essential for DNA synthesis — the process that allows cells to replicate. When B12 is deficient, this process can slow, potentially affecting the hair growth cycle.
Protein Metabolism
Your hair is made primarily of a protein called keratin. B12 helps metabolise the amino acids needed to produce keratin and other structural proteins, supporting the creation of strong, healthy hair strands.
What Does the Research Say?
The relationship between B12 and hair loss is real but nuanced. Here’s what current research tells us:
The Evidence For a Connection
Several studies have found associations between low B12 and hair problems:
- A case-control study of patients with chronic telogen effluvium (a common form of diffuse hair shedding) found that 60% had B12 deficiency, significantly higher than the control group
- Research in pregnant women with severe hair loss showed significantly lower vitamin B12 levels compared to those without hair loss
- Multiple studies, particularly from India, have found higher rates of B12 deficiency among patients experiencing hair shedding
- B12 deficiency has been strongly linked to premature greying — one study found significantly lower B12, folate, and biotin levels in people with premature grey hair (greying before age 20-30)
The Mixed Picture
However, not all studies agree:
- A 2019 literature review concluded there is currently insufficient evidence to recommend B12 supplementation for hair loss in those without confirmed deficiency
- Three Turkish studies totalling 147 patients with alopecia areata found no difference in B12 levels between those with hair loss and healthy controls
- One study specifically evaluating B12 levels found that reducing B12 had no adverse effects on hair shedding or growth
The Bottom Line
The research suggests that:
- If you’re B12 deficient, correcting the deficiency may help improve hair health
- If you’re not deficient, B12 supplementation is unlikely to boost hair growth
- B12 deficiency appears more strongly linked to premature greying than to hair loss itself
- Hair loss is typically multifactorial — B12 may be one contributing factor among several
This is precisely why testing is so important. Supplementing B12 when you don’t need it won’t help your hair, but identifying and treating a genuine deficiency can make a real difference.
Signs of B12 Deficiency
B12 deficiency often develops gradually, and symptoms can be subtle at first. Beyond hair changes, watch for these warning signs:
Energy and Physical Symptoms:
- Persistent fatigue and weakness
- Breathlessness
- Pale or yellowish skin
- Heart palpitations
- Dizziness or lightheadedness
- Cold hands and feet
Neurological Symptoms:
- Tingling or numbness in hands and feet (pins and needles)
- Difficulty walking or balance problems
- Muscle weakness
Cognitive and Mood Symptoms:
- Brain fog or difficulty concentrating
- Memory problems
- Mood changes, irritability, or depression
- Confusion
Other Signs:
- Sore, red tongue (glossitis)
- Mouth ulcers
- Changes in vision
- Loss of appetite
Hair and Appearance Changes:
- Increased hair shedding
- Hair thinning
- Premature greying
- Brittle hair
- Dry skin
- Weak, ridged nails
If you’re experiencing several of these symptoms alongside hair changes, B12 deficiency could be a contributing factor worth investigating.
Who Is at Risk of B12 Deficiency?
While anyone can become B12 deficient, certain groups face higher risk:
Vegans and Vegetarians
B12 is found almost exclusively in animal products — meat, fish, eggs, and dairy. Those following plant-based diets are at significantly higher risk of deficiency unless they actively consume fortified foods or supplements. It can take several years for deficiency to develop in those switching to a vegan diet, as the body stores B12 in the liver.
Older Adults
B12 deficiency affects approximately 6% of those under 60 but rises to around 20% of those over 60. In some studies, up to 31% of elderly individuals show low B12 levels. This increase occurs partly because stomach acid production decreases with age, reducing B12 absorption from food.
People with Absorption Issues
Several conditions can impair B12 absorption:
- Pernicious anaemia — An autoimmune condition that’s the most common cause of severe B12 deficiency in the UK
- Crohn’s disease or coeliac disease
- Previous gastric surgery — Including gastric bypass
- Chronic use of certain medications — Including proton pump inhibitors (PPIs), metformin, and some anti-seizure medications
Others at Risk
- Pregnant and breastfeeding women (who have increased B12 requirements)
- Heavy alcohol consumers
- Those with chronic inflammation affecting gut health
- People taking certain oral contraceptives
B12 Deficiency in the UK: How Common Is It?
Vitamin B12 deficiency is more prevalent than many people realise:
- Around 6% of the UK population has B12 deficiency
- This rises to approximately 20% in those over 60
- An estimated 1 in 10 people in the UK may have inadequate B12 levels
- 6% of men and 10% of women aged 19-64 have low serum B12 concentrations
- Among women of reproductive age (19-49), 11% have low B12
Interestingly, research suggests that deficiency is often due to absorption problems rather than dietary intake. One major study found that 39% of the general population had borderline or deficient B12 levels, with no significant difference between meat-eaters and vegetarians — suggesting that how well your body absorbs B12 matters as much as how much you consume.
Testing for B12 Deficiency
If you suspect your hair loss might be related to a B12 deficiency, getting tested is the essential first step. Self-diagnosis isn’t reliable because B12 deficiency symptoms overlap with many other conditions.
What Testing Involves
A simple blood test can measure your serum B12 levels. According to NHS guidelines:
- Below 200 ng/L (148 pmol/L) — Generally indicates deficiency
- Below 100 ng/L (75 pmol/L) — Usually shows clinical or metabolic evidence of deficiency
- Most healthy people have levels around 500 ng/L
However, it’s worth noting that some people experience symptoms even with B12 levels in the “normal” range, particularly older adults. Your doctor may also test:
- Full blood count — To check for anaemia
- Folate levels — Often tested alongside B12, as both affect similar processes
- Ferritin (iron stores) — Another common cause of hair loss
- Intrinsic factor antibodies — If pernicious anaemia is suspected
At Hair Loss Studios, we offer blood testing to help identify nutritional deficiencies that may be contributing to your hair loss. This provides valuable information for creating a targeted treatment plan.
Treating B12 Deficiency for Hair Health
If testing confirms you’re B12 deficient, there are several treatment options:
Dietary Changes
For mild deficiency caused by diet, increasing B12-rich foods may help. Good sources include:
- Meat (especially liver and kidney)
- Fish (salmon, trout, tuna, sardines)
- Shellfish (clams, mussels)
- Eggs
- Dairy products (milk, cheese, yoghurt)
- Fortified foods (breakfast cereals, plant milks, nutritional yeast)
The recommended daily intake for adults is 2.4 micrograms. Half a pint of milk provides approximately 1.2 μg, two boiled eggs contain about 1.4 μg, and a single serving of many fortified cereals provides the full daily requirement.
Oral Supplements
For those with dietary deficiency and normal absorption, oral B12 supplements can be effective. Typical doses range from 50-150 micrograms daily. However, oral supplements aren’t ideal for everyone — particularly those with absorption issues.
B12 Injections
For moderate to severe deficiency, or when absorption is impaired, B12 injections deliver the vitamin directly into the bloodstream, bypassing the digestive system entirely. This ensures 100% of the dose is available for your body to use.
Injections are particularly beneficial for:
- Those with pernicious anaemia or other absorption disorders
- People who haven’t responded to oral supplementation
- Anyone needing rapid restoration of B12 levels
- Those who struggle with daily supplement compliance
At Hair Loss Studios, we recommend B12 injections following a specific protocol for optimal results: one injection weekly for 4 weeks, followed by one injection monthly for maintenance.
What Results Can You Expect?
If B12 deficiency is contributing to your hair loss, here’s a realistic timeline for improvement:
First 24-72 Hours (After Injection)
- Energy levels often improve noticeably
- Mental clarity may begin to return
- Some people report immediate mood improvements
First 1-2 Weeks
- Fatigue and weakness typically continue to improve
- Sleep quality may get better
- Neurological symptoms like tingling may begin to ease
4-6 Weeks
- Hair shedding often starts to slow
- Scalp health may improve
3-4 Months
- Visible new hair growth may become apparent
- Hair grows at approximately 1cm per month, so patience is essential
- Existing hair may feel stronger and healthier
6-12 Months
- Significant improvement in hair density (if B12 was a contributing factor)
- Hair follicles have had time to complete full growth cycles
- Long-term benefits become established
Important note: Results depend on B12 being a genuine contributor to your hair loss. If your hair loss has other primary causes (such as androgenetic alopecia), correcting B12 deficiency alone may not resolve the issue — though it will support overall hair health as part of a comprehensive approach.
B12 and Premature Greying
One area where B12’s role is more clearly established is in premature greying — grey hair that appears before age 20-30 (depending on ethnicity).
Research has found:
- People with premature greying often have significantly lower B12 levels than those without
- Higher rates of premature greying occur in those with pernicious anaemia
- Some case reports document reversal of grey hair following B12 supplementation
B12 is thought to play a role in melanin production — the pigment that gives hair its colour. When B12 is deficient, melanin production may be affected, leading to premature loss of hair colour.
If you’re noticing grey hairs appearing earlier than expected, alongside other B12 deficiency symptoms, it’s worth investigating your B12 status.
Combining B12 With Other Hair Loss Treatments
Because hair loss is typically multifactorial, B12 supplementation often works best as part of a broader treatment strategy. At Hair Loss Studios, we may recommend combining B12 injections with:
PRP Therapy
PRP (Platelet-Rich Plasma) uses your own blood’s growth factors to stimulate hair follicles. When combined with optimised B12 levels, your follicles have both the growth signals and the nutritional support they need.
LED Light Therapy
LED therapy stimulates cellular activity in hair follicles. Adequate B12 ensures the oxygen and nutrients are available for follicles to respond effectively to this stimulation.
Mesotherapy
Mesotherapy delivers nutrients directly to the scalp. Combining this with systemic B12 optimisation addresses hair health from multiple angles.
Addressing Other Deficiencies
B12 deficiency often occurs alongside other nutritional gaps. Our blood testing can identify whether you also need support with:
- Iron — Another common cause of hair loss, especially in women
- Folate — Works closely with B12 and is often low when B12 is deficient
- Vitamin D — Frequently deficient in the UK and linked to various hair conditions
- Zinc — Essential for hair follicle function
When B12 Isn’t the Answer
It’s important to have realistic expectations. B12 supplementation will only help your hair if deficiency is genuinely contributing to the problem.
B12 is unlikely to be the primary cause of your hair loss if:
- Your B12 levels are normal
- You have a strong family history of pattern hair loss
- Your hair loss follows a typical male or female pattern baldness distribution
- You have no other symptoms of B12 deficiency
In these cases, other treatments like PRP therapy or LED light therapy may be more appropriate — though optimising your B12 status can still support overall hair health.
This is why we always recommend a thorough assessment before beginning treatment. Understanding the root cause of your hair loss ensures you invest in solutions that will actually help.
Take the First Step
If you’re experiencing hair loss alongside symptoms like fatigue, mood changes, or tingling sensations, a B12 deficiency could be worth investigating. Even if B12 isn’t the primary cause, ensuring optimal levels supports your hair — and your overall health.
At Hair Loss Studios, we offer:
- Blood testing to identify nutritional deficiencies
- B12 vitamin injections — £45 per session or £200 for 8 sessions
- Free consultations to assess your hair loss and recommend a personalised treatment plan
Don’t guess at the cause of your hair loss. Let us help you find the answers.
Call us: 020 8290 0099 Visit us: 14 Market Square, Bromley, London BR1 1NA
Frequently Asked Questions
Can B12 deficiency cause hair loss?
Yes, B12 deficiency can contribute to hair loss, though the research is mixed. B12 is essential for red blood cell production and DNA synthesis — both crucial for healthy hair follicle function. Studies have found higher rates of B12 deficiency among people experiencing hair shedding, particularly telogen effluvium. However, B12 supplementation will only help if you’re actually deficient.
How long does it take for B12 to help hair growth?
If B12 deficiency is contributing to your hair loss, you may notice reduced shedding within 4-6 weeks of restoring adequate levels. Visible new growth typically takes 3-4 months, as hair grows approximately 1cm per month. Full improvement can take 6-12 months as hair follicles complete their growth cycles.
Should I take B12 supplements for hair loss?
Only if you’re actually deficient. Taking B12 when your levels are already adequate won’t boost hair growth. Get tested first to confirm whether deficiency is an issue. If you are deficient, injections are often more effective than oral supplements, particularly if you have absorption problems.
What’s the best form of B12 for hair loss?
For those with confirmed deficiency, B12 injections (hydroxocobalamin or methylcobalamin) deliver the vitamin directly into your bloodstream, ensuring full absorption. This is especially important for anyone with absorption issues. For mild dietary deficiency with normal absorption, oral supplements or dietary changes may be sufficient.
Can B12 reverse grey hair?
There’s evidence linking B12 deficiency to premature greying, and some case reports document grey hair returning to its original colour after B12 supplementation. However, this typically only occurs if the greying was specifically caused by B12 deficiency. Age-related greying won’t be reversed by B12.
How do I know if my hair loss is due to B12 deficiency?
Look for other B12 deficiency symptoms alongside hair loss: fatigue, weakness, pins and needles in hands or feet, mood changes, poor concentration, or a sore tongue. However, the only way to confirm is through a blood test. At Hair Loss Studios, we offer blood testing to help identify whether nutritional deficiencies are contributing to your hair loss.
Is it safe to have B12 injections?
Yes. B12 injections are very safe with minimal side effects. Some people experience slight discomfort at the injection site, and minor side effects like headache or nausea are rare. B12 has very low toxicity, and excess amounts are simply excreted by the body. There’s no evidence that increased B12 levels are dangerous.
Who should avoid B12 supplementation?
B12 is safe for most people. However, those with certain rare conditions (like Leber’s disease) should consult their doctor before supplementing. If you’re taking any medications, discuss B12 supplementation with your healthcare provider to rule out interactions.
Sources
- PMC. “The Role of Vitamins and Minerals in Hair Loss: A Review.” https://pmc.ncbi.nlm.nih.gov/articles/PMC6380979/
- Hims. “Vitamin B12 Deficiency and Hair Loss: What’s The Connection?” August 2024. https://www.hims.com/blog/vitamin-b12-hair-loss
- Perfect Hair Health. “Vitamin B12 & Hair Growth: What To Know Before Supplementing.” September 2025. https://perfecthairhealth.com/vitamin-b12-and-hair-growth/
- Journal of Dermatology and Dermatologic Surgery. “Serum Vitamin B12 in Chronic Telogen Effluvium Patients.” https://journals.lww.com/jdds/fulltext/2022/26020/serum_vitamin_b12_in_chronic_telogen_effluvium.2.aspx
- Wikipedia. “Vitamin B12 deficiency.” https://en.wikipedia.org/wiki/Vitamin_B12_deficiency
- SW London Integrated Medicines Optimisation Committee. “Vitamin B12 deficiency.” https://swlimo.southwestlondon.icb.nhs.uk/clinical-guidance/nutrition-and-blood/vitamin-deficiency/vitamin-b12/
- PMC. “Vitamin B12 deficiency – A 21st century perspective.” https://pmc.ncbi.nlm.nih.gov/articles/PMC4953733/
- British Journal of General Practice. “Patient safety, self-injection, and B12 deficiency.” December 2022. https://bjgp.org/content/72/725/e891
- Wimpole Clinic. “Does Vitamin B12 Deficiency Cause Hair Loss or Is It a Myth?” December 2025. https://wimpoleclinic.com/blog/does-vitamin-b12-deficiency-cause-hair-loss-expert-review/
- Elon Health Urgent Care. “How Fast Do B12 Injections Work? Results Timeline Explained.” December 2025. https://elonhealthurgentcare.com/how-fast-do-b12-injections-work/