Vitamin D is known as the bone vitamin. Your hair follicles use it too. Each follicle carries a receptor for vitamin D, and that receptor is needed to start each new phase of hair growth.
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From Anirva, the maker of Hair Radiance. This article is general information, not medical advice. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
- Hair follicles are built to respond to vitamin D. The vitamin D receptor is needed for the normal hair growth cycle [2].
- People with hair loss often have low vitamin D. In a 2024 review of the studies, about half of the people with each common type of hair loss were deficient [3].
- Low vitamin D is common in everyone. Nearly one in four Americans has a blood level that is too low or borderline [1].
- Food does not close the gap. The average diet supplies about 5 mcg a day, and adults need 15 mcg [1].
- Hair Radiance contains 62.5 mcg (2,500 IU) of vitamin D3. This is the form that raises blood levels more [1][6].
That matters because low vitamin D is common, and food supplies very little of it. Here we explain what vitamin D does for hair, what the studies show, who tends to run low, and how much is in Hair Radiance.
Facts at a glance
| Fact | Detail |
|---|---|
| Ingredient and form | Vitamin D3 (cholecalciferol) [6] |
| Amount in Hair Radiance | 62.5 mcg (2,500 IU) a day, in 3 capsules [6] |
| Percent of Daily Value | 313% [6] |
| Recommended intake for adults | 15 mcg (600 IU) a day up to age 70; 20 mcg (800 IU) after 70 [1] |
| Amounts used in studies | One hair study used 200,000 IU every two weeks, a clinic dose [4] |
| Kinds of evidence | Animal and human genetic studies of the receptor; human studies of blood levels; one human study of vitamin D by mouth [2][3][4] |
| Human studies cited here | 1 pooled review of blood level studies, 1 study of vitamin D by mouth in 40 women |
| Adult upper limit | 100 mcg (4,000 IU) a day [1] |
| Last reviewed | October 14, 2026 |
What is vitamin D?
Vitamin D is a nutrient that also acts as a signal in the body. Your skin makes it in sunlight, and you get a little from food [1]. Many tissues carry a receptor for it [1].
Vitamin D helps the body absorb calcium, which is why it matters for bones. It also plays a part in cell growth, immune function and the control of inflammation [1].
Why does hair need vitamin D?
Hair grows in cycles. A follicle grows a hair, rests, then starts again. Vitamin D comes in at the start of each new growth phase.
Researchers call the vitamin D receptor "crucial" for the hair follicle. It is required for normal hair cycling [2]. The evidence comes from two directions, and they agree.
In animals
Mice bred without the vitamin D receptor form normal hair follicles. Then the follicles stop. After the resting phase, the growth phase does not start again [2].
In people
A few people are born with a receptor that does not work. They develop hair loss too [2].
There is one more link. Growing a hair means dividing cells, and vitamin D has a recognized role in cell division. European law allows that statement on labels [5].
Does vitamin D help hair growth? What the research shows
The research on vitamin D and hair is still growing, but the pattern across studies is hard to miss.
People with hair loss tend to have low vitamin D
A 2017 review looked at the studies of vitamin D in the common, non-scarring types of hair loss. Most of them found lower vitamin D in people with hair loss than in people without it [2]. In one study of women with hair shedding or pattern hair loss, the women with the lowest vitamin D had the most severe hair loss [2].
A 2024 review pooled the studies published up to September 2024 [3]. About half of the people with each common type of hair loss had vitamin D deficiency. That included pattern hair loss, hair shedding and patchy hair loss [3]. Women with pattern hair loss had clearly lower vitamin D than women without hair loss [3].
When vitamin D was given, most women improved (2021)
One study took the next step. It enrolled 40 adult women with diffuse hair shedding. They took a high dose of vitamin D3 by mouth every two weeks for about three months [4].
At the end, 82.5% of the women showed improved hair growth [4]. The dose was a clinic dose of 200,000 IU every two weeks. That is far more than a daily supplement provides, and it was given as part of a clinical study.
The authors of the 2017 review reached a practical conclusion. They call it a reasonable strategy to check vitamin D in people with hair loss, and to supplement when the level is low [2].
Study summary
| Source | Type of evidence | People | Main finding |
|---|---|---|---|
| Gerkowicz et al., 2017 [2] | Review of receptor and blood level studies | Animals and people | Receptor required for hair cycling; low vitamin D in most studies |
| Yongpisarn et al., 2024 [3] | Pooled review of blood level studies | People with five types of hair loss | About half were deficient |
| Sattar et al., 2021 [4] | Vitamin D3 by mouth, about 3 months | 40 women with hair shedding | 82.5% improved |
Who is most likely to be low in vitamin D?
A large part of the population. National survey data show that 18% of Americans have a borderline level and 5% are deficient [1]. Together that is nearly one in four.
The body relies on the sun for vitamin D, and modern life gets in the way. The National Institutes of Health names the groups most at risk [1]:
- People who get little sun, whether from indoor work, covering clothing or regular sunscreen use.
- People with darker skin. Melanin reduces the amount of vitamin D the skin makes.
- Older adults. The skin makes less vitamin D with age.
- People with obesity. Body fat holds on to vitamin D.
- People with conditions that limit fat absorption.
If you see yourself in this list and your hair has changed, your vitamin D level is worth knowing. A simple blood test measures it.
How much vitamin D is in Hair Radiance compared with the studies?
| Source | Amount | Notes |
|---|---|---|
| Hair Radiance (3 capsules) | 62.5 mcg (2,500 IU) a day, as vitamin D3 | 313% of the Daily Value, from the label [6] |
| Recommended intake | 15 mcg (600 IU) a day; 20 mcg (800 IU) after age 70 | From the National Institutes of Health [1] |
| Average intake from food | 5.1 mcg for men; 4.2 mcg for women | US adults [1] |
| 2021 hair study | 200,000 IU every two weeks | A clinic dose, for about 3 months [4] |
Look at the gap in this table. Adults need 15 mcg a day, and the average diet supplies about 5 mcg [1]. For most people, the rest has to come from the sun or from a supplement.
Hair Radiance provides 62.5 mcg a day. This is above the recommended intake and under the adult upper limit of 100 mcg [1]. It is much lower than the dose in the 2021 study.
22 ingredients, including 2,500 IU of vitamin D3
Hair Radiance is a daily three-capsule supplement that pairs vitamin D3 with zinc, biotin, plant extracts and probiotic strains. Every ingredient and amount is listed on the label.
See Hair RadianceWhich foods contain vitamin D?
Very few foods contain much vitamin D, which is why intake is low. Fatty fish leads the list [1]:
- Cod liver oil, 1 tablespoon: 34 mcg [1]
- Rainbow trout, 3 ounces, cooked: 16.2 mcg [1]
- Sockeye salmon, 3 ounces, cooked: 14.2 mcg [1]
- Fortified milk, 1 cup: 2.9 mcg [1]
Vitamin D is absorbed better when there is some fat in the meal [1].
Is vitamin D safe? Safety and interactions
Vitamin D is safe within clear limits. The upper limit for adults is 100 mcg (4,000 IU) a day [1]. Hair Radiance has 62.5 mcg [6].
Taking far too much vitamin D raises calcium in the blood. This can cause nausea, muscle weakness and kidney stones. Signs of toxicity are unlikely at daily intakes below 250 mcg (10,000 IU) [1].
Vitamin D can interact with some medicines. They include the weight-loss medicine orlistat, some statins, steroids and thiazide water pills [1].
Vitamin D is one part of Hair Radiance
Hair Radiance is a daily three-capsule hair growth supplement with 22 ingredients: vitamins, minerals, plant extracts, an amino acid and three probiotic strains. They were chosen to support healthy hair growth, to help promote silky, smooth hair, and to strengthen and maintain healthy hair. Vitamin D3 is one of them.
Hair Radiance has not been clinically tested as a finished product. For this reason, we cannot say how its ingredients work together. The studies in this article looked at vitamin D by itself.
If you take Hair Radiance, you are not relying on vitamin D alone. It is one of 22 ingredients in each serving. Every ingredient and amount is listed on the label [6].
- Take Hair Radiance with food. Some fat in the meal helps vitamin D absorption [1][6].
- Count your other sources. If a multivitamin or another supplement also has vitamin D, add the amounts and stay under 100 mcg (4,000 IU) a day [1].
- If you take orlistat, a statin, a steroid or a water pill, ask your doctor or pharmacist before you start [1].
If you are deciding
Here is the case in brief. Your hair follicles need the vitamin D receptor to start each new growth phase [2]. People with hair loss tend to have low vitamin D, and low vitamin D is common [1][3]. Food supplies about a third of what adults need [1]. A hair formula that leaves out vitamin D leaves a real gap, and Hair Radiance fills it with 62.5 mcg of vitamin D3 a day [6]. The directions are three capsules a day with food [6].
The short version
Hair follicles carry a receptor for vitamin D, and that receptor is required for the normal hair growth cycle. In a 2024 review, about half of the people with each common type of hair loss were deficient in vitamin D. Low vitamin D is common, and food supplies little of it. Hair Radiance provides 62.5 mcg (2,500 IU) of vitamin D3 a day.
Frequently asked questions
Does vitamin D help hair growth?
Can low vitamin D cause hair loss?
The two go together. In a 2024 review, about half of the people with each common type of hair loss had vitamin D deficiency [3].
How do I know if my vitamin D is low?
A blood test measures it. The National Institutes of Health describes a level of 20 ng/mL (50 nmol/L) or more as adequate for most people [1].
How much vitamin D is used for hair?
What is the difference between vitamin D3 and D2?
How long does vitamin D take to work for hair?
There is no set time. The study of women with hair shedding ran for about three months [4].
Which foods have vitamin D?
Fatty fish has the most. Trout, salmon and cod liver oil lead the list, and fortified milk adds a little [1].
How much vitamin D is in Hair Radiance?
Each serving of three capsules has 62.5 mcg (2,500 IU) of vitamin D3. This is 313% of the Daily Value [6].
References
- National Institutes of Health, Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/ (accessed October 7, 2026).
- Gerkowicz A, Chyl-Surdacka K, Krasowska D, Chodorowska G. The role of vitamin D in non-scarring alopecia. Int J Mol Sci. 2017;18(12):2653. doi:10.3390/ijms18122653. PMID: 29215595.
- Yongpisarn T, Tejapira K, Thadanipon K, Suchonwanit P. Vitamin D deficiency in non-scarring and scarring alopecias: a systematic review and meta-analysis. Front Nutr. 2024;11:1479337. doi:10.3389/fnut.2024.1479337. PMID: 39416654.
- Sattar F, Almas U, Ibrahim NA, Akhtar A, Shazad MK, Akram S, Khan MSN, Murtaza G. Efficacy of oral vitamin D3 therapy in patients suffering from diffuse hair loss (telogen effluvium). J Nutr Sci Vitaminol. 2021;67(1):68-71. doi:10.3177/jnsv.67.68.
- European Commission. Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods. https://eur-lex.europa.eu/eli/reg/2012/432 (accessed October 4, 2026).
- Anirva. Hair Radiance Supplement Facts label and product page. https://anirva.com/pages/hair-growth-supplement-with-probiotics (accessed October 7, 2026).
