Research Team

Vitamins and Hair Growth: An In-Depth Guide

There are so many supplements out there that sometimes it’s hard for us to tell which ones we need, and which ones we don’t. There are vitamins and nutrients hiding in the food that we eat, as well.

Just like everything else in our bodies, our hair needs vitamins to be healthy. But which ones are really good for our hair, and which ones might you be deficient in?

This article will help you find out. We’ll go into the different types of vitamins that your hair needs, how they work, and what it looks like if you’re not getting enough.

Biotin/Vitamin H

You’ve probably heard of this one. Biotin is also known as Vitamin H. It’s marketed widely in the beauty and cosmetics industry as a supplement that can help your hair in the following ways:

  • Grows longer and stronger hair
  • Nourishes hair from within
  • Improves overall health
  • Increases hair strength
  • Improves hair elasticity
  • Stops hair breakage

That’s an impressive list. But are these claims true? Can anyone take biotin and automatically have more elastic, longer, stronger hair?

Let’s look into the science of biotin and your hair.

What is Biotin?

Biotin is a B vitamin that some bacteria in our bodies produce. We get most of our biotin from our diet, though. The vitamin is usually found bound to proteins, such as eggs, meat, seeds, fish, and nuts (1). It’s even found in some vegetables, such as sweet potatoes. The FDA recommends that people get 30 mcg of biotin a day. For reference, one egg contains 10 mcg of biotin. Based on this, getting 30 mcg of biotin a day doesn’t seem too hard!

Biotin is water-soluble, meaning it dissolves in water. In addition to being a vitamin, it serves as a coenzyme for five carboxylases in our bodies. This means they help enzymes catalyze reactions that regulate processes such as carbohydrate or amino acid metabolism (2, 3). But what we’re really interested in is how biotin affects hair growth.

Role of Biotin in Hair Growth

The role of biotin in hair growth is actually not that well known.

In the last section we mentioned that biotin works as a coenzyme for carboxylases. In addition to carbohydrate and amino acid metabolism, these carboxylases also have to do with protein synthesis, and among these proteins is keratin (4).

Keratin and Hair

You’ve probably heard of keratin, but you may not know exactly what it does for your hair. Well, keratin is important for your hair because it’s a protein that makes up the structure of epithelial cells, which are cells that make up skin, hair, and nails (5). They are a tough protein, and their toughness is what gives skin, hair, and nails their resilience. If you scratch an itch on your arm, the epithelial cells there are able to remain undamaged because of keratin.

So what’s the relationship between biotin and hair strength in the end? Well, keratin is definitely important for your hair, and biotin is important if you want your body to produce enough keratin to keep your hair and nails strong.

Do You Need Biotin Supplements?

So we’ve established that biotin is important because it plays a role in your body’s keratin production. But can biotin supplements help your hair loss?

The answer to that seems to depend. Hair loss and brittle hair and nails are side effects of biotin deficiency, along with (1):

  • red scaly rash near body openings (mouth, nose, eyes)
  • conjunctivitis
  • abnormal amounts of acid in urine
  • lethargy
  • seizures
  • skin infections

If you do have a biotin deficiency that’s causing your hair problems, biotin supplements should definitely help to make your hair healthier. However, the probability that you do have a biotin deficiency is pretty low, especially if you have a pretty varied diet. The average daily biotin intake in western countries is 35-70 mcg per day, meaning that most people get more than enough biotin to take care of their keratin production.

There are limited clinical studies on the use of biotin to treat hair loss, but experts seem to agree that biotin isn’t really effective to treat hair loss unless you do have a biotin deficiency (6, 7, 8).

The people most at risk for biotin deficiency are pregnant women, people with biotinidase deficiency, and people who consume alcohol chronically. If that doesn’t sound like you, it might be a smart idea to save your money for another hair loss treatment.

Vitamin D

There are two different types of Vitamin D: Vitamin D2 and Vitamin D3 (9). Vitamin D2 can be found in some sun-exposed mushrooms, and can’t be produced by the human body.

Vitamin D3 is produced in our bodies when UV rays from sunlight hit our skin, triggering Vitamin D synthesis (10). It’s actually not commonly found in natural foods, but foods such as milk, cereal, and orange juice are fortified with Vitamin D so people can get their daily dose.

This vitamin helps calcium get absorbed into your gut, so it’s actually as important as calcium is in maintaining our bone health. This means that getting enough Vitamin D prevents osteoporosis in the elderly.

Researchers think Vitamin D also has anti-inflammatory and immunomodulatory effects, and could prevent the spread of cancer by stopping cell proliferation. But does it have any affect on hair health? Let’s find out.

Role of Vitamin D in Hair Growth

There’s some evidence that Vitamin D can affect hair health. Research has found that Vitamin D levels tend to be lower in people affected by alopecia areata, although the connection hasn’t been confirmed (11). Some experts also think Vitamin D could be correlated with diffuse hair loss, meaning hair loss all over the head (12).

There are two ways Vitamin D might work in your hair follicles (13):

  1. Regulating growth of keratinocytes by binding to vitamin D receptors
  2. Promoting cell differentiation in the hair follicle

These points are a little dense. Let’s break them down a bit.


Keratinocytes are epidermal cells that produce keratin, whose importance to hair was established earlier in this article (11). If you need a refresher, keratin makes up the structure of your epithelial cells, which make up your hair, skin, and nails. It follows that if we want our hair, skin, and nails to be healthy, keratinocytes are important.

However, there’s no evidence that a Vitamin D deficiency leads to lack of functionality in the keratinocytes of the body.

If we’re looking for a direct relationship between Vitamin D deficiency and alopecia, the second point might be where we want to look. Experts agree that Vitamin D is important for promoting cell differentiation, or specialization, in the hair follicle (14, 15).

But what is cell differentiation? It actually turns out that keratinocytes differentiate into different layers of the hair follicle (16):

  • The companion layer
  • The glassy layer (or dermal sheath)
  • Henle, Huxley, and cuticle layers of the inner root sheath

This differentiation occurs during the active phase of the follicle, anagen. This all means that there are many different parts, or tissues, that make up the hair follicle. It’s important that all of them exist for your follicle to be active and healthy, because that ensures that your follicle is healthy.

So based on the role of Vitamin D in the scalp, the relationship between vitamin D deficiency and hair loss seems to be that Vitamin D regulates keratinocytes, which differentiate into the layers of the hair follicle, which may affect hair growth.

But this isn’t quite conclusive. We want to know whether a vitamin D deficiency really can cause hair loss, and if the fact has been proven in research.

Can a Vitamin D Deficiency Cause Hair Loss?

Here we’ll look at two types of evidence: hair loss in a disease that causes vitamin D deficiency, and clinical studies.


The biggest piece of evidence that vitamin D deficiency can cause hair loss isn’t a clinical trial, it’s a rare type of rickets.


Vitamin D dependent rickets type II (VDDR-II) is a hereditary type of rickets that usually shows up in children (17). It’s caused by a mutation in the vitamin D receptor gene, meaning that the body can’t process vitamin D normally. This essentially means that people with this disease are vitamin D deficient (18).

Rickets has many side effects. It causes softening and weakening of the bones, leading to bone pain, delayed growth, deformed limbs, dental abnormalities, and muscle weakness (19).

This specific type of rickets can also cause alopecia totalis, or hair loss all over the body, which indicates that there is a link between vitamin D deficiency and alopecia.

Clinical Studies

There is also some research to back up the idea that a lack of vitamin D can cause hair loss. We mentioned earlier the study that found that people with alopecia areata have lower levels of vitamin D (11). Not only did another study come to the same conclusion, but it also found that there was a negative correlation between the levels of vitamin D and the severity of alopecia areata in the subjects (20). In other words, the lower the vitamin D, the higher the severity of hair loss!

Still another study concluded that vitamin D supplementation could be helpful in treating alopecia (21). However, keep in mind that the research in this area is pretty limited. Hair loss isn’t listed among the major symptoms of vitamin D deficiency, so it doesn’t currently seem to be an area of concern for dermatologists and hair experts. So is this a problem for you?

Is Your Hair Loss Caused by a Vitamin D Deficiency?

It’s possible! If you have any other symptoms of vitamin D deficiency, such as bone pain, muscle weakness, osteoporosis, fatigue, or muscle aches, get yourself checked out (22). Even if you don’t have other symptoms and suspect that you’re not getting enough vitamin D, get tested. The majority of vitamin D-deficient patients don’t show symptoms at all.

Vitamin E

Vitamin E is found in foods like nuts, seeds, vegetable oil, leafy greens, and fortified cereals (23). The reason some believe it’s good for your hair is because vitamin E is actually an antioxidant!

Antioxidants and Hair

There has long been research on the effects of oxidative stress on your hair, and experts generally agree that oxidative stress can cause aging, hair graying, and hair loss (24). This is why everyone talks about antioxidants. They can counteract the effects of oxidation in your body!

But let’s back up for a second. What exactly is oxidative stress?

Oxidative stress is what happens to your body when free radicals, which are uncharged and unstable molecules, take electrons from other atoms to become more stable (25). This taking of electrons changes the atoms or molecules the free radicals steal from, causing cell damage. The most notable case is when lipids are oxidized. Researchers have noticed high levels of lipid peroxidation in areas of the body with disease, aging, and stress (26).

This happens on your scalp as well. In scalps affected by alopecia areata, scientists noted much higher levels of lipid peroxidation breakdown product than in other tissues (27).

Although this isn’t proof that oxidative stress causes disease, aging, or hair loss, it does establish that there is some kind of link.

The Role of Vitamin E in Hair Growth

If Vitamin E is an antioxidant, it should theoretically help hair loss that is caused by oxidative stress. However, research in this area is thin, and not at all conclusive.

One study had subjects suffering from alopecia take capsules of tocotrienol, a type of Vitamin E that is also a strong antioxidant, for a period of eight months (28). The number of hairs increased by 34.8 percent for the treated group against the placebo group, but the density of the hair strands themselves didn’t change.

Other than this study, we couldn’t find any other evidence that treatment with Vitamin E supplements can halt or reverse hair loss. In fact, there’s even some evidence that supplementing Vitamin E can have a negative effect on hair growth.

Either way, we don’t think there’s enough evidence either way for us to advise you to take or not take Vitamin E for your hair.

However, we do encourage you to make sure you’re still getting enough Vitamin E. After all, it plays other important roles in your body, including (29):

  • Antioxidant activity
  • Improving immune function
  • Cell signaling
  • Gene expression

Vitamin E deficiency is rare, so we wouldn’t worry too much about getting enough of it.


You’ve certainly seen iron out in the world before, but did you know that it’s also in our bodies?

It may surprise you to learn that iron deficiency is the most common nutritional deficiency in the world (30). Doctors can detect iron deficiency by measuring the amount of an iron-binding protein, serrum ferritin, in your blood. Iron is an essential component of hemoglobin, which is a protein that carries oxygen in your blood (31).

There are actually two types of dietary iron: heme and nonheme. Meat, seafood, and poultry contain both heme and nonheme iron. Nonheme iron is found in vegetables, nuts, seeds, grains, and some fortified grains. It’s also available as a supplement.

The people most at risk for iron deficiencies are:

  • Pregnant women
  • Women with heavy menstrual cycles
  • Infants and children
  • Frequent blood donors
  • Cancer patients
  • People with heart failure
  • Those with gastrointestinal diseases
  • Those who have undergone gastrointestinal surgery

That’s a pretty long list. So how do you know if you have an iron deficiency? Well, the most common side effects are fatigue, weakness, impaired cognitive function, poor body temperature regulation, and — last but not least — hair loss (particularly in women).

Role of Iron in Hair Loss

The link between iron deficiency and hair loss is the subject of much speculation in the scientific realm. Multiple studies have been conducted that confirm that low serum ferritin levels in women correspond with alopecia, but don’t agree on which type of alopecia (32, 33, 34).

There also isn’t enough evidence for scientists to recommend screening for iron deficiency in hair loss patients.

One study found that women with iron deficiency are more likely to have telogen hair loss, which is when hair falls out in the telogen stage, usually at the top of the head (35). This is different from androgenetic alopecia or alopecia areata where the hair falls out in patches.

Another study had similar results, finding that anemia (iron deficiency) was the most common cause of alopecia in a group of 135 patients, and that the most common type of alopecia was telogen effluvium (36).

On the opposite end of the spectrum, a different study found that iron levels made no difference in the expression of alopecia areata at all (37).

Mechanism of Action

Another gray area is how, exactly, an iron deficiency affects the hair follicles: the mechanism of action through which iron deficiency can cause hair loss isn’t exactly known (7). However, researchers do have some guesses, based on the fact that hair follicle cells divide extremely quickly.

Iron is important for many processes in the body, but the one that we’re interested is its role as a cofactor for ribonucleotide reductase, which controls the rate of DNA synthesis. If the body needs iron to regulate the rate of division of hair follicle cells, it makes sense that an iron deficiency would lead to problems in the hair growth cycle.

The other guess they have is that iron may regulate one or more of the genes in the human hair follicle. Either way, we think it’s safe to say that while iron seems to cause telogen effluvium, or diffuse hair loss in women, we don’t know why or how.

Is Iron Deficiency Causing Your Hair Loss?

If you’re a woman experiencing diffuse hair loss on the top of your head, it’s well within the realm of possibility. The same is true if you are included on the list above of people who are at risk for iron deficiency.

If your iron deficiency is moderate, you may not have other symptoms. If the deficiency is more severe, you might experience symptoms such as (38):

  • Brittle nails
  • Cracks at the side of mouth
  • Pale skin
  • Swelling of the tongue
  • Chest pain
  • Coldness in the hands and feet
  • Fatigue
  • Irregular heartbeat
  • Cravings for non-food items such as paint, ice, or dirt
  • Restless leg syndrome

If you suspect that you have an iron deficiency that’s contributing to your hair loss, ask a doctor about getting tested, or take iron supplements and monitor your hair loss.


Like iron, zinc is an essential mineral that our bodies can’t produce (7). Hundreds of enzymes in our bodies need zinc, and the mineral is also important in gene expression (11). It also helps wounds heal and is important for our sense of taste and smell (39).

Zinc is found naturally in many foods, including oysters and other seafood, meat, poultry, beans, nuts, whole grains, and dairy products. It’s also found in fortified foods such as cereal.

People at risk for zinc deficiencies are:

  • Vegetarians
  • People who have had gastrointestinal surgery
  • People with digestive disorders
  • Alcoholics
  • Older infants who are breastfed
  • People with sickle-cell disease

Otherwise, you probably are getting enough zinc. Symptoms of zinc deficiency include:

  • Diarrhea
  • Eye and skin sores
  • Loss of appetite
  • Hair loss
  • Weight loss
  • Problems with wound healing

Let’s focus on the hair loss. How does that work, exactly?

Role of Zinc in Hair Growth

Again, the mechanism of action of zinc in the hair follicle isn’t exactly known. In the research we found, there were three proposed possibilities (7, 40):

  1. Zinc’s role in protein synthesis and cell division
  2. Zinc’s role in the Hedgehog signaling pathway, which is critical for hair follicle development
  3. DNA polymerase’s dependence on zinc

However, even these possibilities are not well-founded hypotheses. On the bright side, the idea that zinc can help with hair loss seems to be a common belief among researchers. This belief is based on clinical studies, some of which we will look at next.


The first study we will look at was conducted in 2005, using mice as subjects (41). It found that treatment of chemotherapy-induced hair loss in the mice with high doses of zinc (20 mg) had both positive and negative results. The positive result was that treatment with zinc slowed down the catagen phase of the hair follicle, leading to longer hair cycles and slower hair loss.

The negative result was that prolonged treatment with the high-dose zinc eventually inhibited hair growth by delaying the anagen (active) phase of the hair follicle cycle.

Another study studied 40 male patients with alopecia areata and found that 15 of them had low zinc levels (42). These 15 were treated with oral zinc supplements for 12 weeks, after which researchers found marked visual improvement in areas of hair loss for nine of them.

Their zinc levels also improved, as compared to the six who showed less improvement. This suggests that the six who were unaffected by the zinc treatment may not have been able to absorb the mineral properly, which would have prevented its positive effects from showing.

Still another study looked at 60 male patients with androgenetic alopecia and found that their zinc levels overall were low when compared to healthy controls, and concluded that supplementation of treatment with zinc should be recommended for patients with androgenetic alopecia (43).

Can Zinc Supplements Reverse Your Hair Loss?

We don’t advise taking a whole bunch of zinc supplements just because you’re experiencing some type of alopecia. Although the idea that zinc deficiency might lead to hair loss seems to be a common suspicion among hair experts, there’s still a real lack of research.

There’s also evidence to show that taking too much zinc can inhibit your hair growth, as demonstrated in the first study we looked at in the section above. If you get tested and find that your zinc levels are low, by all means take a supplement that is an appropriate dose, consulting a doctor beforehand. If your hair loss improves, great! But it’s not a magic pill by any means.

You may be more likely to have a hair loss problem related to zinc deficiency if you’re, say, a vegetarian, or otherwise found on the list we mentioned above.

Vitamins and Minerals that Can Contribute to Hair Loss

We’ve gone over some vitamins and minerals that could potentially help your alopecia. However, there are some cases where something that is good for your body can harm it in excessive amounts. Selenium and Vitamin A are some examples. In the next section, we’ll give you an overview of these supplements and how they can be bad for your hair.


Selenium is a mineral, or element that is essential to many metabolic processes in the human body (44). Getting enough of it is essential to our health, just like any other vitamin. Like iron, it’s also an element on the periodic table.

It’s a pretty powerful nutrient. It has an important place in our endocrine, musculoskeletal, cardiovascular, reproductive, neurological, and cognitive systems. Selenium is found as selenoproteins in the body, and there are different types of selenoproteins. One even acts as an antioxidant, like Vitamin E.

Selenium wasn’t always recognized for the role it plays in keeping us healthy. In fact, after its discovery in 1817, it was thought of as a carcinogen (45)! The element is found in the soil, and the amount in the soil determines how much is in the plants and mushrooms we eat.

Selenium Deficiency

If our bodies need selenium just like it needs vitamins, is there such thing as a selenium deficiency? Yes, there is! Selenium deficiency is usually a population-based problem, as it may be caused by a lack of it in local soil. This can cause illnesses such as Keshan disease and Kashin-Beck disease (44).

The problems that come from selenium deficiency mostly have to do with heart muscles and joints. These are hard to detect, as they come in the form of other common health issues such as infertility in men, higher susceptibility to prostate cancer, growth disorders, and rheumatoid arthritis. The symptoms most commonly affect children of ages 5-13.

Selenium Toxicity

Selenium supplements shouldn’t be taken for any old reason. Oversupplementation of selenium can actually be toxic.

One case of selenium poisoning was caused by a supplement that contained 200 times the amount of selenium it claimed to have. The people affected experienced hair loss, nail brittleness, muscle and joint pain, fatigue, or gastrointestinal weakness. 227 people were affected by the improperly labeled supplement.

So unless you’re sure that you have a selenium deficiency, please don’t overload your body with selenium supplements!

Did you catch that interesting side effect of selenium poisoning? That’s right! It’s what we’re all about — hair loss! If excess selenium can cause hair loss, can selenium deficiency do the same thing? Let’s find out.

The Role of Selenium in Hair Loss

The role of selenium in hair loss is more unclear than that of the other vitamins and nutrients listed in this article. Although there have been some cases where scientists treated patients with selenium, who then experienced hair growth and reversal of alopecia, those few cases are not enough to demonstrate a link (7). There isn’t a proposed mechanism of action, and there’s significant evidence that too much selenium can cause hair loss.

Because of this, we can’t recommend that you try treating your hair loss with selenium.

Vitamin A

Vitamin A is a group of fat-soluble retinoids that are important for vision, immune function, and cellular growth and specialization (8). That last point means it’s also important in the formation and maintenance of organs like the heart, lungs, kidneys, and more (46).

There are two forms available that humans can get from their diet: preformed vitamin A and provitamin A carotenoids. Don’t worry too much about this point; it simply means one type of vitamin A is found in dairy, fish, and meat, and the other is found in vegetables.

Some of the best sources of vitamin A are fish oil, milk and eggs, leafy green vegetables, tomatoes, and vegetable oils.

Vitamin A Deficiency

If you eat a balanced diet, you shouldn’t have a problem with vitamin A deficiency. In developing countries, the deficiency is common and emerges in infancy (46). It’s also common among pregnant or lactating women in developing countries, premature babies, and people with cystic fibrosis.

The most common side effect for people with a vitamin A deficiency is xerophthalmia, or the inability to see in low light or at night. People with low vitamin A levels may also have anemia and are more susceptible to developing infections.

Vitamin A and Hair Loss

Studies have shown that taking too much vitamin A can cause hair loss.

In one case, a woman who was on dialysis treatment noticed she was losing an excessive amount of hair (8). It turns out that her vitamin A supplements were giving her hypervitaminosis, which looked similar to the symptoms of chronic kidney failure.

Although the mechanism isn’t quite clear, hypervitaminosis seems to be related to the liver. When the body has normal amounts of vitamin A, it’s stored in the liver and only dispersed throughout the body in regulated amounts. When there’s too much, the overflow spills into the blood and causes imbalance throughout the body.

We know it can be tempting to take health supplements and think they are making our bodies better. However, if you are eating a balanced diet, you might not need those extra vitamins and minerals at all, and too much can actually hurt you. So be careful about what you put into your body, even if the bottle tells you its contents are good for you!


There are lots of vitamins and minerals out there that can affect your hair positively or negatively. They each play a special role among the systems of your body, so the way a deficiency or oversupplementation shows up can affect your hair differently for each.

In this article, we’ve given you an overview of some vitamins and minerals that your hair follicles need. However, the key is still figuring out what your body needs.

If you have a biotin deficiency, biotin supplements might help you. But your hair loss could just as easily be caused by a different condition, such as stress or a hair fungus. We hope that this article is a valuable guide for you as you navigate the world of supplements that can help you with your hair loss.

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