Is There Really a Connection Between Hair Loss and Vitamin D?

“It feels like I’m losing an unusually large amount of hair when I shampoo.”

This is something I often hear in the clinic.

Many people think it’s because they’re getting older or because of stress.

Of course, those can be causes too, but what is not widely known is that vitamin D deficiency can actually be a major factor in hair loss.

According to recent studies, vitamin D plays a key role in maintaining hair health beyond being just an immune vitamin.

In particular, if the crown or part line is gradually widening and your hair volume is decreasing,

you may need to check your vitamin D level.

Vitamin D stimulates the vitamin D receptor (VDR), which regulates the hair follicle cycle.

If this receptor does not function properly, hair cannot return to the anagen phase and remains in the telogen phase, making it easier to fall out.

In fact, mice with a VDR gene deletion showed a phenomenon in which hair did not grow back after growing once, and similar patterns appear in humans as well.

This means that VDR function is crucial for the regeneration and maintenance of hair follicles.

In several studies, about 80% of patients with alopecia areata were found to be deficient in vitamin D, and patients with androgenetic alopecia (male-pattern/female-pattern hair loss) also tended to have lower vitamin D levels than the general population.

In addition, in patients with telogen effluvium caused by stress, illness, or nutritional deficiency, vitamin D supplementation was observed to increase hair density and promote new hair growth.

Reasons for vitamin D deficiency

Even in environments with abundant sunlight, vitamin D deficiency is common.

The reasons are as follows.

• An indoor-centered lifestyle

• Increased use of sunscreen

• Reduced opportunities for skin exposure

• Bowel disease or genetic absorption disorders

And even if you get vitamin D through food or take supplements, several "cofactors" are needed for vitamin D to function properly in the body.

1. Ferritin (stored iron)

One of the main causes of female hair loss

If iron is lacking, hair cannot maintain the growth phase

and falls out.

2. Zinc

It helps the vitamin D receptor function and

is also involved in immune function and inflammation control.

3. Magnesium

It is essential for converting vitamin D into its active form.

If these three are deficient, it is difficult to see hair-loss improvement from vitamin D supplementation alone.

Hair loss symptoms caused by vitamin D

If the following symptoms appear, you may want to suspect hair loss caused by vitamin D deficiency.

1. Widening part line

2. Thinning hair around the crown

3. Hair breaks easily and growth is slow

4. Slow recovery even after seasonal hair loss

5. Accompanied by chronic fatigue, reduced concentration, and mood changes

If these changes become noticeable, it is a good idea to visit a hospital and check your vitamin D level and cofactor levels.

If hair loss due to vitamin D deficiency is suspected, I recommend the following.

1. Check your vitamin D level (25(OH)D)

o 40–60 ng/mL is the ideal level for hair health.

2. Redesign sun exposure

o Expose your arms/legs/face for about 10–20 minutes, 2–3 times a week, between 10 a.m. and 2 p.m.

3. Recheck after 2–3 months + track hair changes

o Take photos of the crown and part line to compare over time.

4. Check cofactor levels (ferritin, zinc, magnesium)

o Supplement if needed

Hair loss may be not just a change in appearance but an early sign that something in the body’s systems is out of balance.

Subtle symptoms such as fatigue, mood changes, and lowered immunity may appear first through the condition of the hair.

In particular, vitamin D is one of the hair-loss factors that can be corrected relatively easily and has a clear effect.

A single blood test, a little sunlight, and the necessary nutrient supplementation may greatly change the situation.

Before changing your shampoo, check your vitamin D first.

It’s time for hairhair, this was Kim Jin-oh.

필생신모(必生新毛).

[This post is written directly by a board-certified plastic surgeon for informational purposes in accordance with Article 56, Paragraph 1 of the Medical Services Act. Hair transplant surgery and treatment may have side effects, and you should make a careful decision after consulting with a specialist.] ​