If you Google "vitamins for hair loss," vitamin D is almost always in the top three. And for good reason. In the Netherlands, a large part of the population has a deficiency, especially in the winter months. But how significant is the role of vitamin D in hair loss, really?
This is an honest answer, without exaggeration.
What does vitamin D do in your body?
Vitamin D is, strictly speaking, not a vitamin but a hormone. Your body produces it when your skin is exposed to UV-B radiation from the sun. You can also get it through food or supplements, but through food alone, you rarely get enough.
In the Netherlands, a large part of the population has a deficiency. Research by the RIVM shows that about 50% of Dutch people have values below the recommended levels during the winter months. This makes it a real area of concern.
Vitamin D receptors in your hair follicle
Hair follicles contain vitamin D receptors, also known as VDR (Vitamin D Receptor). These receptors play a role in regulating the hair growth cycle, particularly in the transition from the telogen phase to the next growth phase.
A 2023 study in the scientific journal Life Science Alliance showed that hair follicles in mice without a properly functioning vitamin D receptor do not function normally. The hairs, as it were, got stuck in an intermediate phase of the hair growth cycle, disrupting new hair growth. As a result, the hair follicles could not regenerate properly, and the normal hair growth cycle remained out of balance.
Simply put: without an active vitamin D receptor, the hair growth cycle does not proceed correctly. This is animal research. The translation to humans is not one-to-one.
Connection with hair loss: what the research shows
In humans, several observational studies show a link between low vitamin D levels and various forms of hair loss.
In alopecia areata, the form of baldness where the immune system attacks its own hair follicles, low vitamin D levels are more frequently found. There is also evidence that reduced VDR expression is associated with less activity of the Wnt signaling pathway, which regulates hair follicle growth.
A connection with vitamin D deficiency has also been found in diffuse hair loss (telogen effluvium). This is the temporary but sometimes severe shedding that occurs after stress, illness, or a nutritional deficiency.
In hereditary hair loss (androgenetic alopecia), the most common form in men, the direct evidence is weaker. Vitamin D does not directly affect DHT levels or the sensitivity of follicles to DHT.
What vitamin D cannot do
If you have hereditary hair loss, where your hair follicles are sensitive to DHT and slowly thin, vitamin D will not stop that process. That is a mechanism that is deeper in the tissue and driven by other factors.
What vitamin D CAN do: rectify a deficiency that exacerbates the problem. If your hair follicles are already under pressure from DHT, and you also have a vitamin D deficiency, then something extra is going wrong in the growth cycle. Supplementing in that case is useful as a basic step. But it is not a standalone treatment for hair loss.
How do you know if you have a deficiency?
The only way to know for sure is through a blood test. You can have this done through your GP or through a commercial laboratory.
Common reference values: below 30 nmol/L is considered a severe deficiency. Between 30 and 50 nmol/L is a deficiency. Between 50 and 75 nmol/L is suboptimal. Above 75 nmol/L is considered sufficient by most guidelines.
Symptoms associated with a vitamin D deficiency include fatigue, muscle pain, reduced immunity, and a despondent feeling. Hair loss alone is not a sufficient reason to assume a deficiency, but if you recognize several of these symptoms and are rarely outdoors, a test is worthwhile.
Supplementing: what works?
Sunlight is the most direct source. But in the Netherlands, from October to April, the sun is too low to produce enough UV-B for vitamin D synthesis. Even in clear winter weather, you won't get far.
Diet contributes limitedly. Fatty fish (herring, salmon, mackerel), egg yolk, and fortified products provide some, but rarely enough to fully resolve a deficiency.
Supplements are the most practical option if you know you have a deficiency. The Health Council advises 10 micrograms per day (400 IU) for adult men, and 20 micrograms (800 IU) for people at increased risk. Vitamin D3 is more absorbable than D2. Preferably take it with a meal containing some fat, as it is a fat-soluble vitamin.
Vitamin D as part of a broader approach
If you notice your hair thinning or your hairline slowly receding, vitamin D is one of the basic steps you can take. But it is no more than that: a basic step.
Rectifying a deficiency gives your hair follicles a better starting position. But if you want to actively do something about hair loss, you need ingredients that work directly on the follicle. Such as Redensyl, which activates the hair follicle stem, or Procapil, which stimulates blood circulation to the hair root.
The Hairborn Growth Serum combines several of these active ingredients in one daily product, without side effects. If you want to do something directly for your hair in addition to correcting a deficiency, that is a logical next step.
Summary
Vitamin D plays a role in the health of hair follicles. A deficiency is common in the Netherlands and can disrupt the hair growth cycle. In alopecia areata and diffuse hair loss, the link with vitamin D is strongest. In hereditary hair loss, supplementing a deficiency has a contributory value, but it is not a solution in itself.
Want to know if you have a deficiency? Get it tested. That's the only way to be sure.