Vitamin D Deficiency and Hair Loss | What’s The Real Connection?

There are few vitamins that have as strong a connection hair loss as Vitamin D.

But, why is this the case?

Based on a few observations from research, we can begin to make sense of the connection between vitamin D deficiency and hair loss.

In this article, I will share what the research says about vitamin D and how it might impact hair. I’ll also explain how to increase your vitamin D levels naturally.

Just keep reading!

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Vitamin D and Hair Loss: What Does the Research Say?

Vitamin D receptors are largely expressed in hair follicles and in the skin (1, 2). In animal studies, mice genetically modified to be depleted of these receptors fail to regrow new hair.

This observation shows us that vitamin D receptors play a key role in the initiation of hair regrowth. The activity of vitamin D in the skin surrounding the hair follicle (i.e. the scalp) is also essential for preserving hair.

When looking at human studies, the connection is strong between various forms of hair loss and vitamin D deficiency (3).

The strongest association in research is with a type of hair loss called Alopecia Areata (AA) (4). AA is characterized by an attack on the hair follicle by the immune system. Patients present with patches with complete loss of hair.

In most cases, AA spontaneously goes into remission (5). But, this is often unpredictable and isn’t the case for all AA patients.

Nevertheless, the duration of AA can be stressful in itself. Dealing with it can be frustrating, embarrassing, and lead to social distress.

So, researchers have set out to figure out how to effectively prevent and treat it.

In one meta-analysis, researchers found a strong link between vitamin D deficiency and AA (4). The deficiency was highly prevalent in AA patients when compared to healthy subjects.

Research also suggests a, albeit weaker, link to other forms of hair loss: pattern hair loss and Telogen Effluvium (TE).

How Does Vitamin D Deficiency Cause Hair Loss?

Researchers are still speculating on just how vitamin D deficiency might be involved in the progression of hair loss.

However, based on some general knowledge of hair loss and the way vitamin D works, we can make some connections.

Alopecia Areata: Vitamin D’s Effect on the Immune System

Probably the most well-established link is between vitamin D and it’s impact on AA.

This is because the immune system is inextricably involved in its development.

In our immune system, we have three “arms”: Th1, Th2, Th17. Each one produces different kinds of immune cells.

The Th1 and Th17 arms produce more pro-inflammatory molecules to kill off microbes like bacteria, fungi, and viruses (6, 7). Conversely, Th2 produces anti-inflammatory molecules that are necessary for tissue repair.

It’s crucial to have a balance between the three arms for healthy inflammatory responses.

Inflammation at the hair follicles
Inflammation within the hair follicles can lead to hair loss.

Depending on different stimuli, the immune system can polarize to one of these three arms. Too far of a polarization to Th2 can impair the body’s ability to fight infection, whereas polarization to Th1 and Th17 can lead to excessive inflammatory responses.

In AA, analyses show that patients favor Th1 and Th17 responses over Th2 (3, 8).

Vitamin D, on the other hand, helps to shift the immune system back towards a balanced immune response.

As of now, there are no clinical trials on oral supplementation with vitamin D for the treatment of AA. The only study available is one using topical vitamin D (9).

In this clinical trial, 59.1 percent of patients experienced hair regrowth, 36.4 percent were non-responders, and 0.04 percent experienced more hair loss.

There is also evidence to suggest that in some AA patients, they express lower levels of Vitamin D Receptors (VDRs) in their hair follicles (3). In these cases, bolstering vitamin D levels might not reverse the condition.

Lack of VDR in the scalp would limit the activity of vitamin D in the scalp even in the presence of sufficient levels.

As of right now, the research in support of vitamin D deficiency as a factor in AA is strong. However, no studies have yet been conducted to observe if restoring vitamin D levels relieves the condition.

Key Takeaways:

  • The data connecting vitamin D deficiency to AA is strong.
  • AA is characterized by a polarization to the inflammatory Th1 and Th17 arms of the immune system, away from the anti-inflammatory Th2 arm.
  • Vitamin D deficiency may be the culprit behind this polarization because vitamin D plays a crucial role in shifting the immune system back into a balance between the three arms.
  • However, whether returning vitamin D levels back to normal alleviates AA remains to be seen. There are currently no studies on oral supplementation as of yet.
  • There is only one study available looking at the use of topical vitamin D as a treatment for AA. 59.1 percent of patients experienced hair regrowth, 36.4 percent were non-responders, and 0.04 percent experienced more hair loss.
  • In some cases of AA, patients have depleted levels of VDR in their scalp. In these cases, restoring vitamin D levels may not be effective. Lack of VDR in the scalp would limit the activity of vitamin D in the scalp even in the presence of sufficient levels.

Androgenetic Alopecia: A Possible Link

There is a small amount of research available on vitamin D and Androgenetic Alopecia (AGA; pattern hair loss) compared to AA.

However, there are a few things that we do know.

Firstly, vitamin D deficiency seems to have greater impact on women than men (3). Studies show that there is a correlation between low D levels and the incidence of female pattern hair loss.

Secondly, skin and its sebaceous glands possess vitamin D receptors (2). Cell culture studies show that adding vitamin D to sebaceous gland cells downregulates their division in a dose-response manner. This means that the more vitamin D that accumulates in sebaceous glands, the less they divide and proliferate. In essence, this lowers their activity.

Because the main function of sebaceous glands is the secretion of a waxy lipid substance called sebum, decreasing the gland’s activity could lead to lower sebum output.

Research on patients with acne, who have increased sebum production, shows that they have decreased levels of vitamin D (10). Upon further investigation, researchers have found that vitamin D may be involved in the molecular signaling that leads to less sebum output.

But, what does this have to do with AGA?

In AGA scalps, excess sebum production and enlarged sebaceous glands can play a factor in its development (11).

An example of a healthy hair follicle and a clogged hair follicle
An example of a healthy hair follicle and a clogged hair follicle.

This is partially due to the fact that sebum feeds a strain of bacteria called P. acnes. When this bacteria reproduces rapidly, it can release substances that stimulate the Th17 arm of the immune system (2).

This leads to excessive inflammation around the hair follicle which can eventually cause tissue damage. As a result, the body repairs itself using fibrous scar tissue. Enough of this scar tissue around the hair follicle can lower blood supply and restrict growth space, leading to hair loss.

Vitamin D can prevent this in three ways: lowering the production of sebum through molecular signaling, restricting the enlargement of sebaceous glands, and reducing the Th17 response to P. acnes proliferation.

Vitamin D is also known to prevent prostate enlargement, a condition usually caused by excess Dihydrotestosterone (DHT) (12).

AGA is often correlated with prostate growth, so much so that early-onset AGA is an early marker of Benign Prostatic Hyperplasia (BPH), a usually harmless prostate enlargement (13). This is because DHT is a factor in both conditions.

DHT is formed by the conversion of testosterone into DHT by an enzyme called 5α-reductase (5α-R). Drugs that decrease the activity of this enzyme are often used to treat both BPH and AGA.

So, the question becomes: since vitamin D prevents prostate enlargement, does it work by blocking the activity of 5α-R?

Research actually indicates that vitamin D doesn’t have any effect on the activity of 5α-R enzymes (14). However, it does increase the activity of aromatase, the enzyme that converts testosterone into estrogen.

Estrogen therapy in AGA is known to stimulate hair regrowth.

But, these findings are limited in that the effects of vitamin D on these enzymes is contextual (15). This means that depending on the tissue that vitamin D is in, it may act differently.

Nonetheless, it does not rule out that vitamin D could potentially increase aromatase activity in the hair follicle. It just hasn’t been studied.

As we begin to put the pieces together, it’s plausible that vitamin D could benefit AGA considering its activity. Although, no studies have been published as of yet. There is one clinical trial in the works that is set to be completed towards the end of 2019 (16).

Key Takeaways:

  • When it comes to AGA, there is a possible connection. Vitamin D deficiency seems to play more of a role in female pattern baldness than male pattern baldness.
  • Vitamin D could potentially impact the development of AGA in a few ways.
  • Vitamin D receptors in skin have a few functions. They decrease sebum output by decreasing the growth of sebaceous glands, possibly through preventing molecular signaling known to increase sebum production.
  • Sebum also feeds P. acnes bacteria which release byproducts that stimulate the Th17 arm of the immune system. Vitamin D counteracts this by balancing the Th17 response and decreasing sebum output.
  • This could prevent hair loss by reducing inflammation that leads to perifollicular scarring and hair loss.
  • Vitamin D may also decrease DHT activity, a powerful male hormone implicated in AGA. However, some research suggests that vitamin D may not have much of an impact on the enzyme that converts testosterone into DHT.
  • There is evidence that it can increase estrogen levels through enhanced aromatase activity.
  • These findings are confounded by the fact that vitamin D’s effects seem to be highly contextual upon the environment they’re in. This means that it may act differently in certain tissues and conditions.
  •  But, this finding doesn’t rule out that vitamin D could lower DHT and increase estrogen in hair follicles. This is known to promote hair growth.
  • Considering these properties of vitamin D, it’s plausible that it could benefit AGA. There are no published studies, only one currently set to complete in late 2019.

Telogen Effluvium: Vitamin D and Stress

Some studies show that TE patients have lower vitamin D levels than healthy control subjects (3).

TE is a form of hair loss where multiple hairs go from the anagen (growing) phase to the telogen (resting) phase. This causes premature hair loss and thinning. It’s usually unrelated to the factors seen in both AA and AGA.

The potential explanation of TE with the most support behind it is stress.

In animal studies, stress causes excessive inflammation in the hair follicle, including mast cell activation (17). This is mirrored by research on TE: scalp biopsies revealed they had higher levels of activated mast cells (18).

Interestingly, vitamin D plays a role in stabilizing these mast cells (19).

Additionally, vitamin D might play a role in lowering stress (20). Researchers have observed an association between low vitamin D levels and increased levels of adrenaline and noradrenaline, two stress hormones.

Vitamin D’s effects on stress have also been observed elsewhere. In one clinical trial, healthy volunteers were instructed to take 2000IU of vitamin D3 daily (21). After supplementation, their cortisol levels were significantly reduced.

In light of vitamin D’s potential benefits for stress and stabilizing mast cells, optimizing levels could be advantageous in that case of TE.

Although, no studies have looked at the effects of vitamin D supplementation on TE.

Key Takeaways:

  • Some studies show that TE patients have lower vitamin D levels than healthy control subjects.
  • TE is a form of hair loss where multiple hairs go from the anagen (growing) phase to the telogen (resting) phase.
  • The main factor with the most support is stress which leads to mast cell activation. Activated mast cells are seen in TE scalp biopsies.
  • Vitamin D may combat the effects of stress by lowering cortisol and suppressing mast cell activation. In this way, it might be beneficial for TE.
  • Although, no studies have looked at the effects of vitamin D supplementation on TE.

A Case Study: Vitamin D Hair Loss Regrowth

There is one interesting case study examining the effects of vitamin D supplementation on hair loss (22).

A 34-year-old woman with non-scarring, diffuse hair loss was evaluated by researchers. She presented with an extremely low vitamin D level.

Researchers weren’t able to identify the cause of her hair loss because she didn’t consent to a scalp biopsy.

She was cleared for a weekly dose of 50,000IU of vitamin D3 for four weeks. This was followed by a daily dose of 1,000IU D3 for six months.

At the follow-up visit, the patient’s vitamin D levels had increased to the normal range. She had noticeable hair regrowth!

So, what does this mean?

Because the researchers weren’t able to diagnose the case, it’s unclear if vitamin D3 supplementation will benefit all forms of hair loss. However, this patient did have extremely low D3 levels.

This suggests that restoring vitamin D3 levels can lead to hair regrowth if that is the only factor involved.

Key Takeaway: One case study suggests vitamin D3 supplementation may lead to hair regrowth. However, researchers weren’t able to diagnose the patient. So, whether these results translate to all forms of hair loss warrants further research.

Is Vitamin D Deficiency and Hair Loss Reversible?

Hair loss associated with vitamin deficiencies is almost always reversible.

Irreversible hair loss is caused by excessive inflammation that leads to scarring. The scar tissue can deform the hair follicle, leading to complete damage and an inability to regrow hair.

So, in the case of vitamin D deficiency and hair loss, it is most likely reversible.

Key Takeaway: Hair loss resulting from vitamin D deficiency is most likely reversible.

How to Increase Your Vitamin D Levels

There are three ways you can increase your vitamin D levels: sun exposure, supplementation, and food.

A woman getting vitamin D from sunshine

Sun exposure is the most efficient and least expensive way to boost your vitamin D levels. However, take precaution when spending time in the sun to avoid burning.

Supplementation is also an effective way to obtain vitamin D. Be sure to supplement with vitamin D3 as opposed to vitamin D2.

Vitamin D2 has to be converted to vitamin D3 before it can be activated by the body. This means that it is less bioavailable and can’t be utilized as efficiently by the body.

Always consult your doctor before including vitamin D3 supplements in your daily routine.

Food is a less efficient way to increase vitamin D levels because it’s not often found in high quantities. Some foods with a moderate amount of D3 include fatty fish, fortified milk and non-dairy alternatives, and egg yolks.

Key Takeaways: 

  • There are three ways to obtain vitamin D: sun exposure, supplementation, and food.
  • Sun exposure is efficient and inexpensive. Take precaution to avoid harmful burns.
  • Supplementation is effective. Be sure to supplement with bioavailable D3 as opposed to D2.
  • Food is less efficient because it’s not usually found in high quantities. D3 can be found infatty fish, fortified milk and non-dairy alternatives, and egg yolks.

Too Much Vitamin D and Hair Loss

Unlike the extensive body of research available on vitamin D deficiency and hair loss, there is no data available on whether or not vitamin D toxicity induces hair loss.

So, we can’t draw any conclusions based on the data available to us.

The Verdict: Does a Vitamin D Deficiency Cause Hair Loss?

When examining the research available to us, there is a significant association between vitamin D deficiency and hair loss.

The strongest connection exists between vitamin D deficiency and AA. This is not surprising considering vitamin D plays an absolutely essential role in proper immune system function.

There are plausible mechanisms that suggest vitamin D may also be helpful for AGA and TE. But, the science to back this up just isn’t quite as robust.

To prevent vitamin D-associated hair loss, be sure to get safe sun exposure, take vitamin D3 supplements (as approved by your doctor), and eat foods that contain vitamin D3.

Do you get enough vitamin D3? How do you choose to obtain vitamin D3 in your daily routine? Let me know in the comments.

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