Does vitamin B12 improve hair growth? Supplement companies say yes, but scientific studies reveal a much murkier (and nuanced) relationship between vitamin B12, hair loss, and hair growth… one you’ll want to understand before you start supplementing.

In this article, we’ll dive into the arguments for and against a connection between vitamin B12 and hair growth. We’ll explore methylation, vitamin B12’s role in the hair cycle, and B12’s connection to different hair loss disorders. Then, we’ll reveal when vitamin B12 might (and might not) help our hair.

Finally, we’ll outline some potential best-practices for those who want to supplement with vitamin B12 for hair growth. After all, too little (and too much) of this vitamin may be counterproductive to both our hair and overall health.

What is vitamin B12?

Vitamin B12 is a singular vitamin apart of the greater B complex family. Like many B vitamins, vitamin B12 acts as an enzymatic cofactor for essential functions of the body (1). Specifically, vitamin B12 helps us metabolize food, produce red blood cells, and “methylate” DNA (more on this later). It also plays a protective role in cardiovascular health, as it helps to reduce excess amounts of a protein called homocysteine – which, at high levels, is inflammatory.

Vitamin B12 Supplement Mockup

Given its importance in so many bodily functions, it’s natural to wonder: does vitamin B12 also help fight hair loss? After all, it seems to be a staple ingredient in most hair health nutritional supplements. So, what does the evidence show?

The case for a vitamin B12-hair loss connection

From a scientific perspective, vitamin B12 might support hair growth in many ways.

1. Vitamin B12 help support the production of DNA – which is necessary to maintain the rapid cell division that drives hair growth (2). Without cell division, not only can hair not grow… but human life cannot sustain itself, either. In this respect, technically anything that supports human survival – even water – supports hair growth.
2. Vitamin B12 helps us produce hemoglobin – a molecule inside our red blood cells that carries oxygen and iron into our tissues (3). When someone has low hemoglobin, they often have an iron deficiency (i.e., anemia). Interestingly, anemia is highly correlated with hair loss – particularly in women ages 14-40 – and vitamin B12 supplementation can help improve hemoglobin product and thereby iron levels for those who are deficient.

But there’s also another reason that vitamin B12 might support hair growth – and it happens to do with one of the biggest buzzwords surrounding this vitamin: methylation.

In the simplest terms, methylation is a way in which our bodies can “turn on” or “turn off” certain genes. In other words, methylation helps change our gene expression – and thereby influences our ability to prevent cancer, reduce inflammation, and everything in between.

Here are just a few roles that methylation – and our methylation cycle – regulates inside our bodies:

• Production of methionine and cysteine. These are two sulfur-based amino acids that play integral roles in muscle building, inflammation regulation, and antioxidant production.
• Glutathione production. Sulfur amino acids are a major precursor for glutathione, the body’s master antioxidant.
• Homocysteine reduction. High levels of homocysteine in the blood are linked to a variety of inflammatory diseases.
• Production of SAMe. This protein is believed to support mental health, among many other things (4).

So, how does methylation relate to B12 and hair loss?

In one study on rabbits, researchers found methionine to be a promoter of hair growth. The mechanism behind this? An increase in the activity of the Wnt/β-catenin signaling pathway (5).

The Wnt/β-catenin pathway is important to this discussion for a few reasons:

1. This pathway helps promote the creation of stem cells, which are required for hair growth and hair follicle function (6).
2. In androgenic alopecia (AGA) – the most common form of hair loss in adult men – male hormones interfere with Wnt/β-catenin signaling. Specifically, this signaling pathway is dampened, also known as downregulated. As a result, hair follicle stem cell activity is impaired, which prevents proper hair cycling. This shortens the growth stage of a hair follicle, causing it to prematurely shed. Over time, this hinders hair growth and may even accelerate hair follicle miniaturization – a defining hallmark of male and female pattern hair loss (7).

Here’s where vitamin B12 might come into play:

Vitamin B-12 is a cofactor in the methylation cycle, meaning that it helps to activate methylation. Interestingly, vitamin B-12 deficiencies are believed to be a major driver of a dysfunctional methylation cycle – as evidenced by an association between homocysteine levels and vitamin B-12 deficiency (8). This suggests that the methylation cycle is “backed up”, preventing homocysteine from being converted to cysteine and methionine.

Thus, B-12 deficiency may impair methionine synthesis from the methylation cycle. Because we know that methionine contributes to Wnt/β-catenin signaling, it’s possible that a reduction in methionine may lead to reduced Wnt/β-catenin activity. And therefore, it’s possible that a vitamin B12 deficiency in scalp tissues might play a role for people dealing with androgenic alopecia.

Summary (so far): how vitamin B12 might help fight hair loss

There are a variety of ways that vitamin B12 might be connected to hair loss in humans:

• Vitamin B12 helps support DNA synthesis. Without DNA synthesis, we would die. We can’t grow much hair if we’re dead.
• Vitamin B12 helps normalize hemoglobin production (and thereby iron levels). For females with both hair loss and an iron deficiency, vitamin B12 might be a great way to improve iron status and encourage hair growth.
• Vitamin B12 helps support methylation. This might have ramifications for one of the world’s most common hair loss disorders – male pattern hair loss (AGA. In AGA-affected hair follicles, the Wnt / β-catenin signaling pathway is dampened, which leads to shorter-growing hair, premature hair shedding, and potentially even hair follicle miniaturization. If this happens to be the direct result of a deficit in localized methylation in scalp tissues, then vitamin B12 might help improve methylation and thereby improve Wnt / β-catenin signaling, which would allow for hairs to grow longer, shed less prematurely, and (hopefully) not miniaturize as quickly.

But it’s important to stress: these suspected mechanism are all hypothetical. Yes, vitamin B12 is connected to each mechanism. Yes, these mechanisms are linked to hair loss (and hair growth). But there’s a difference between association and causation. And this difference, unfortunately, is consistently forgotten by companies trying to sell you B12 supplements. Thus, to prove a strong association or causation, the real questions we should be asking are:

1. Are vitamin B12 deficiencies (in skin tissues or throughout the body) observed more frequently in people who are balding?
2. Does vitamin B12 – through supplementation or topical application – actually improve hair loss outcomes?

In answering these questions, we can actually discern whether or not it makes sense for most people to spend money on vitamin B12 supplements to try and regrow their hair.

And as you can guess, these questions happen to lead us to our next section: the case against a vitamin B12-hair loss connection.

The case against a vitamin B12-hair loss connection

While there is hypothetical evidence linking vitamin B12 to hair loss and hair growth, this argument begins falls apart when we zoom out and start looking at the broader evidence.

Specifically, we’re going to talk about the following:

1. Misconceptions about methylation, B12, Wnt/β-catenin pathways, and hair loss
2. Vitamin B12 levels of hair loss patients
3. Observations in birth control-induced vitamin B12 deficiencies, and what this does (or doesn’t do) to hair

Methylation misconceptions

Earlier we discussed how, in balding hair follicles, a deficiency in the methylation cycle might interfere with Wnt/β-catenin signaling pathways, which might accelerate hair loss. We argued that because vitamin B12 supports methylation, this vitamin might also help reverse this methylation deficiency, and thereby help fight hair loss from androgenic alopecia.

But it’s important to note: vitamin B12 is just one (of many) vitamins and nutrients that support methylation. For instance, many other B-vitamins also support methylation, and these B-vitamins are found in abundance in foods like beef, eggs, and poultry.

This means that even if you do have a vitamin B12 deficiency, your body will likely be able to compensate for this – at least from a methylation perspective – via your dietary choices. Therefore, in balding hair follicles, even if Wnt / β-catenin downregulation were exclusively due to a methylation issue (it isn’t), your body would still have many “fallback” vitamins to address that methylation issue. So, in androgenic alopecia, changes to a hair follicle’s gene expression cannot be significantly attributed to a vitamin B12 deficiency.

Therefore, it also shouldn’t be surprising to find out that there aren’t any differences in vitamin B12 levels between those with and without hair loss.

Looking at B12 levels in the blood of hair loss patients

When we zoom out beyond the actual hair follicle and look at studies on people with common hair loss disorders like AGA, telogen effluvium (TE), or alopecia areata (AA) – the data are consistently clear: there is no difference in blood measurements of vitamin B12 between people with and without hair loss (9). In other words, people who are losing their hair and who have full heads of hair appear to have the same vitamin B12 levels.

Even more compelling, recent literature reviews have found no evidence to support the use of vitamin B12 for hair loss of any type (9). That means that not only are vitamin B12 levels the same across those with and without hair loss, but that for those with hair loss, vitamin B12 supplementation generally doesn’t improve hair loss outcomes.

What about women with hair loss due to an iron deficiency? Doesn’t vitamin B12 help improve iron stores, and have some therapeutic benefit here?

Yes and no.

Earlier, we argued a connection between hemoblogin, iron, vitamin B12, and hair loss. As a refresher, hemoglobin is a molecule found in red blood cells. Hemoglobin carries oxygen and iron, and in general, when someone has low hemogloblin levels, they also have low iron (10). Low iron levels are often found in women ages 14-40 with hair loss. Vitamin B12 is a key cofactor in hemoglobin formulation. Therefore, you might be able boost hemoglobin production with vitamin B12, and therefore potentially normalize low iron levels. If someone is dealing with hair loss as a direct result of low iron levels, then vitamin B12 supplementation might help to normalize these levels and maybe regrow some hair.

So, in a situation where someone’s hair loss is due to poor iron status, and their poor iron status is a direct result of low vitamin B12, then it absolutely makes sense to supplement with vitamin B12. In doing so, you’d improve hemoglobin production, oxygen and iron transport, and (very likely) hair loss outcomes. This is why a lot of popular hair loss supplements – like Nutrafol – contain B12.

At the same time, a vitamin B12 deficiency is only one possible contributor toward an iron deficiency. A more likely contributor? A deficiency in iron itself (11). So, while vitamin B12 is probably therapeutically useful in some circumstances of iron deficiency-related hair loss, it’s not the only reason – or even the biggest reason – for why the iron deficiency arises.

Therefore, B12 is likely useful for a much smaller percentage of women than advertisements for these hair health supplements might lead you to believe.

Observations in birth control-induced B12 deficiency

This argument is further strengthened by another observation researchers have made: women with vitamin B12 deficiencies caused by hormonal birth control don’t experience hair loss or adverse changes to hair growth (9). As such, even when a deficiency is present, it doesn’t seem to negatively impact hair growth. In fact, many women on hormonal contraceptives report the opposite effect – hair regrowth – which is why some contraceptives are also used off-label as a hair loss treatment.

The good news? Vitamin B12 might help reverse premature hair graying

In regard to hair health, there is one way that vitamin B12 might positively impact hair health outcomes. It might help to prevent, or even reverse, premature graying.

To be clear, the majority of research doesn’t indicate B12 deficiency is a cause of hair loss. But, there are several reports supporting an association between inadequate B12 levels and premature hair graying, which is grey hair that onsets before the ages of 20-30 (depending on the demographic) (12).

For instance, one small study demonstrated that individuals with premature hair graying had lower vitamin B12, folate, and biotin levels than control subjects without premature gray hair (13). Additionally, some studies report a higher incidence of premature graying in pernicious anemia, a blood condition sometimes caused by B12 deficiency (14).

There are also three case reports of patients reversing their premature gray hair with B12 supplementation (15-17). Needless to say, there seems to be evidence of both an association of low B12 and early greying, and a reversal of early greying following B12 supplementation.

The association between B12 deficiency and premature graying isn’t fully established, and there are absolutely other factors that can lead to premature hair graying. Moreover, B12 supplementation is really only relevant to reversing graying hair in the context of B12 deficiency.

That being said, a vitamin B12 deficiency may be worth investigating for anyone experiencing premature hair graying – regardless of whether you’re losing your hair.

The verdict: in most situation, vitamin B12 likely has no effect on hair loss (and hair regrowth), but vitamin B12 might reverse premature hair graying in the presence of B12 deficiency

Although hypothetical evidence suggests an absence of B12 activity could negatively impact hair growth, in vivo human studies indicate that either (1) there is no relationship between vitamin B12 deficiency and hair loss and/or (2) there is an overriding factor (like methionine provision outside of the methylation cycle) that prevents B12 deficiency from causing hair loss.

The exception to this is if someone has iron deficiency-related hair loss, and if their iron deficiency is exclusively the result of poor hemoglobin production due to a vitamin B12 deficiency. In this case, vitamin B12 supplementation can address the deficiency, improve hemoglobin production, and thereby drastically improve iron transport (and, ultimately, hair growth). But it goes without mentioning that this is a very specific scenario that is not faced by the majority of hair loss sufferers in the developed world.

In any case, it’s clear that supplementing with B12 is probably not the best solution for improving hair growth – at least as a standalone therapy.

That being said, it’s important to note that having adequate B12 is essential for optimal health. Even if it doesn’t cause hair loss, B12 deficiency can still lead to anxiety, fatigue, neuropathy, and cardiovascular issues, among other health issues. Moreover, B12 deficiency appears to be one potential cause of premature hair graying.

As such, even if it doesn’t improve hair loss, some may still find it necessary to supplement with vitamin B12. So, in these cases, what’s the best approach for supplementation?

Things to keep in mind when supplementing with vitamin B12

Vitamin B12 supplements are available in three forms: cyanocobalamin, methylcobalamin, and adenosylcobalamin. Methyl- and adenosylcobalamin are naturally-occurring forms of B12 whereas cyanocobalamin is synthetic.

Though synthetic is not always subpar to naturally-occurring forms of B12, in this case, supplementing with methyl- and adenosylcobalamin B12s is much more efficient. The reason for this is they are already in their active forms, ready to be used by the body. Cyanocobalamin, on the other hand, requires enzymatic processing before it can be utilized. On top of this, cells don’t seem to retain cyanocobalamin as well as some of the other forms (18).

Additionally, some researchers have raised concerns with long term cyanocobalamin supplementation, due to the cyanide present in the compound (18). Even though these concerns aren’t yet substantiated, an abundance of caution may be warranted here.

The bottom line? If your diet isn’t providing you with enough vitamin B12 and you choose to supplement, consider opting for a B-complex or multivitamin formulated with methyl- or adenosylcobalamin.

Summary

Vitamin B12 deficiency isn’t likely to be a cause for hair loss. As such, claims that supplementing with B12 will improve hair growth are largely unfounded. This is despite some pretty compelling theoretical evidence – like B12’s role in hemoglobin formation, nucleic acid synthesis, and the methylation cycle that produces growth-supporting methionine.

It just goes to show how important it is that we don’t rely on studies of isolated nutrients in cell cultures. Moreover, we shouldn’t have high hopes for products marketed on these premises when it comes to regrowing our hair.

That being said, vitamin B12 deficiency can still cause real problems and, in some cases, may be an underlying factor in premature hair graying. So, for those who are dealing with early-onset gray hair, it may be worth checking your B12 levels. And if you are deficient? Restoring your B12 levels may just reverse the condition.

So, if supplementing is warranted in your case, opt for a methyl- or adenosylcobalamin-containing supplement over one containing cyanocobalamin. They’re more bioavailable and may be safer in the long-term.

But, for the overwhelming majority? You’re likely to get all the vitamin B12 you need from food — more than enough to rule it out as a plausible factor in hair loss.

Have any questions about vitamin B12? Leave them below.

References

1. Al Amin ASM, Gupta V. Vitamin B12 (Cobalamin) [Updated 2020 Jun 23]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559132/
2. Almohanna HM, Ahmed AA, Tsatalis JP, Tosti A. The Role of Vitamins and Minerals in Hair Loss: A Review. Dermatol Ther (Heidelb). 2019;9(1):51-70. doi:10.1007/s13555-018-0278-6
3. Ferreira GC. Heme biosynthesis: biochemistry, molecular biology, and relationship to disease. J Bioenerg Biomembr. 1995;27(2):147-150. doi:10.1007/BF02110029
4. Sharma A, Gerbarg P, Bottiglieri T, et al. S-Adenosylmethionine (SAMe) for Neuropsychiatric Disorders: A Clinician-Oriented Review of Research. J Clin Psychiatry. 2017;78(6):e656-e667. doi:10.4088/JCP.16r11113
5. Zhu Y, Wu Z, Liu H, Liu G, Li F. Methionine promotes the development of hair follicles via the Wnt/β-catenin signalling pathway in Rex rabbits. J Anim Physiol Anim Nutr (Berl). 2020 Jan;104(1):379-384. doi: 10.1111/jpn.13238. Epub 2019 Nov 15. PMID: 31732998.
6. Choi YS, Zhang Y, Xu M, et al. Distinct functions for Wnt/β-catenin in hair follicle stem cell proliferation and survival and interfollicular epidermal homeostasis. Cell Stem Cell. 2013;13(6):720-733. doi:10.1016/j.stem.2013.10.003
7. Chen X, Liu B, Li Y, et al. Dihydrotestosterone Regulates Hair Growth Through the Wnt/β-Catenin Pathway in C57BL/6 Mice and In Vitro Organ Culture. Front Pharmacol. 2020;10:1528. Published 2020 Jan 23. doi:10.3389/fphar.2019.01528
8. Gilfix BM. Vitamin B12 and homocysteine. CMAJ. 2005;173(11):1360. doi:10.1503/cmaj.1050170
9. Almohanna HM, Ahmed AA, Tsatalis JP, Tosti A. The Role of Vitamins and Minerals in Hair Loss: A Review. Dermatol Ther (Heidelb). 2019;9(1):51-70. doi:10.1007/s13555-018-0278-6
10. National Academy of Sciences (US) and National Research Council (US) Division of Medical Sciences. Conference on Hemoglobin: 2–3 May 1957. Washington (DC): National Academies Press (US); 1958. THE ROLE OF IRON IN HEMOGLOBIN SYNTHESIS. Available from: https://www.ncbi.nlm.nih.gov/books/NBK224286/
11. Trost LB, Bergfeld WF, Calogeras E. The diagnosis and treatment of iron deficiency and its potential relationship to hair loss. J Am Acad Dermatol. 2006 May;54(5):824-44. doi: 10.1016/j.jaad.2005.11.1104. PMID: 16635664.
12. 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
13. 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
14. Dawber RP. Integumentary associations of pernicious anaemia. Br J Dermatol. 1970 Mar;82(3):221-3. doi: 10.1111/j.1365-2133.1970.tb12428.x. PMID: 5441758.
15. Noppakun N, Swasdikul D. Reversible hyperpigmentation of skin and nails with white hair due to vitamin B12 deficiency. Arch Dermatol. 1986 Aug;122(8):896-9. PMID: 3740873.
16. Carmel R. Hair and fingernail changes in acquired and congenital pernicious anemia. Arch Intern Med. 1985 Mar;145(3):484-5. PMID: 3977516.
17. Niiyama S, Mukai H. Reversible cutaneous hyperpigmentation and nails with white hair due to vitamin B12 deficiency. Eur J Dermatol. 2007 Nov-Dec;17(6):551-2. doi: 10.1684/ejd.2007.0285. Epub 2007 Oct 19. PMID: 17951150.
18. Paul C, Brady DM. Comparative Bioavailability and Utilization of Particular Forms of B₁₂ Supplements With Potential to Mitigate B₁₂-related Genetic Polymorphisms. Integr Med (Encinitas). 2017;16(1):42-49.

Rob English

Rob English is a researcher, medical editor, and the founder of perfecthairhealth.com. He acts as a peer reviewer for scholarly journals and has published five peer-reviewed papers on androgenic alopecia. He writes regularly about the science behind hair loss (and hair growth). Feel free to browse his long-form articles and publications throughout this site.