What’s the Deal with Vitamin Deficiency Hair Loss?

The Most Common Causes of Vitamin Deficiency Hair Loss

Anything that depletes your body’s store of essential vitamins may lead to hair loss. So what can cause a vitamin deficiency? Here’s the shortlist:

Poor dietary intake or restrictive diets

Our vitamin and mineral needs are usually met through a healthy, varied diet. But if you’re not eating enough nutrient-rich foods, you may end up with a vitamin deficiency. 

This is particularly true if you’ve limited or removed an entire food group from your diet — meat, say. 

According to data compiled by Oregon State University, vegans and vegetarians risk developing deficiencies in vitamin B12, vitamin D, calcium, and iron, to name a few. 

Those who are gluten-free don’t get off scot-free either. The same study found that people on a gluten-free diet might not get enough thiamin, riboflavin, niacin, folate, and iron. 

Nor do those on a restrictive diet for weight loss get a free pass. For example, the keto diet can impact the amount of nutrients you’re getting, leading to potential keto-related hair loss. 

Learn more about malnutrition and hair loss.

Malabsorption disorders and medical conditions

Malabsorption disorders — often caused by health issues in the small intestine — make it harder for your body to absorb vitamins and minerals, leading to vitamin deficiency. 

Common causes of malabsorption include:

• Cystic fibrosis
• Chronic pancreatitis
• Lactose intolerance
• Coeliac disease
• Parasites (such as giardia and hookworm)
• Irritable bowel syndrome
• Inflammatory bowel disease (such as Crohn’s disease and ulcerative colitis)

Thyroid disorders such as hypothyroidism can also cause vitamin deficiencies, partly because the condition appears to limit stomach acid levels essential for nutrient absorption and partly because it slows down digestion. 

Pregnancy may also cause a nutrient deficiency, thanks to the increased demand for vitamins and minerals to support the growth and development of the foetus. This may lead to hair loss in pregnancy. 

Want to know more?

• Learn about hair loss from thyroid disease
• Learn about hypothyroidism and hair loss

Chronic stress and other lifestyle factors

You don’t need to have a strict diet or medical condition to have a vitamin deficiency. Certain lifestyle factors, such as stress, smoking, and drinking, can also deplete levels of vitamins essential for hair growth.

Daily stresses may impact your vitamin levels — particularly if you find yourself too stressed or busy to eat a balanced, nutritious diet. 

But more severe forms of stress and mental health problems can also cause a vitamin deficiency. For example, a 2020 study of a population-based sample found that post-traumatic stress disorder is associated with a vitamin D deficiency. 

And in a 2024 academic review, researcher Hyun Wook Baik noted a clear link between low levels of certain nutrients (like vitamin D and vitamin B12) and mental health problems, such as depression and anxiety. 

Returning to the diet, it’s not just what you take out but what you put in that can cause a vitamin deficiency that may lead to hair loss. 

In a clinical review published in the Australian Journal of General Practice, Australian researchers noted that “alcohol has a significant effect on the digestion, absorption and metabolism of nutrients”.

According to the report, more than half of the patients admitted to hospital for substance use (including alcoholism) are deficient in vitamins, minerals or electrolytes — particularly deficiencies in vitamin C, vitamin A, and iron.

And it’s not just alcohol. 

A 2021 Spanish study found that smokers are more likely than non-smokers to have deficiencies in vitamins C, E, B1, B2, B12, folic acid, calcium, magnesium, iron, and iodine — largely because they tend to eat lower amounts of fruits, vegetables, cereals, and dairy products. 

Learn more about how smoking may cause hair loss.

Which Vitamin Deficiency Causes Hair Loss?

Some vitamins (and minerals) play an important role in keeping our hair follicles healthy. Among them:

• Vitamin D — helps stimulate hair follicles and support the hair growth cycle

• Vitamin B12 — helps produce red blood cells, which carry oxygen and nutrients to the scalp and hair follicles

• Biotin — supports keratin production (a key structural protein in hair)

• Iron — vital for haemoglobin production, which helps deliver oxygen to hair follicles
• Zinc — supports hair tissue growth and repair, while keeping the oil glands around the follicles functioning properly

When we don’t get enough of these vitamins and minerals, the resulting vitamin deficiency may disrupt the hair growth cycle, weaken the follicles, and cause hair loss. 

In most cases, a balanced diet and targeted supplementation can help restore these vitamin levels, preventing or even reversing any deficiency-related hair loss. 

But before we go any further, a word of caution: self-diagnosing and self-treating a deficiency can have harmful consequences. If you think you might have a nutritional deficiency, it’s best to get a blood test to confirm your suspicions and receive medical advice from your GP. 

We’ve listed the most common vitamin (and mineral!) deficiencies to cause hair loss. But there’s a little more to it, so let’s take a look at each nutrient in more detail. 

Vitamin D

The sun-loving vitamin D is known to stimulate cell growth, boost immunity, and strengthen our bones. But it also has a role in stimulating our hair follicles. 

We usually get most of our vitamin D through sun exposure but some foods, such as fatty fish and animal fats, are naturally rich in the vitamin. Some cereals, milks, and orange juices are also fortified with vitamin D. But vitamin D deficiencies do still occur. 

So, does vitamin D deficiency cause hair loss? 

Plenty of evidence suggests yes — a vitamin D deficiency may be linked to different types of hair loss, including female pattern hair loss and telogen effluvium, as well as the autoimmune condition alopecia areata. 

Multiple studies have also found that the lower the vitamin D levels, the more severe the hair loss.

Researchers suggest that giving vitamin D supplements to alopecia areata patients with a vitamin D deficiency may help reduce the severity of alopecia areata and possibly even bring about remission. 

Using low-dose supplements of vitamin D may also help improve the symptoms of androgenetic alopecia and telogen effluvium. 

Zinc

The research is pretty clear that zinc deficiencies play a role in all types of hair loss, including alopecia areata, male and female pattern hair loss, and telogen effluvium. 

The only source of zinc for humans is through the diet, with fish and meat being the two main dietary sources. 

Naturally, this means vegetarians and vegans may be at risk of developing a zinc deficiency. Other risk factors include inflammatory bowel disease, jejunal bypass surgery, and cystic fibrosis.

Zinc supplements have been shown to work in reversing or improving hair loss if you have low zinc levels. But if you don’t have a zinc deficiency, the jury is still out on whether supplements will do anything to improve your hair growth. 

Importantly, taking zinc supplements can cause toxicity if you don’t have a zinc deficiency and overdosing on zinc can cause pain, vomiting and diarrhoea. So it’s best to consult a doctor before self-prescribing.

Vitamin B group

There is a whole range of vitamins under the vitamin B umbrella — eight, to be precise. So when you ask ‘can a vitamin B deficiency cause hair loss’, the answer is: it depends on which vitamin B. 

Vitamins like biotin and B12 help create the red blood cells that carry oxygen and nutrients to the hair follicles. Biotin also aids the production of keratin, the protein hair is made of. 

So it makes sense that a deficiency in either of these vitamins can cause hair loss. But there’s a catch. 

Biotin deficiencies are rare. So rare, in fact, that a severe deficiency has never been reported in a healthy person eating a normal diet. 

For people without a biotin deficiency, clinical trials have shown time and time again that biotin supplements do little to treat hair loss. Taking supplements if you don’t have a deficiency can also be risky, so you should talk to your doctor before self-prescribing. 

Iron

OK, you caught us! Iron isn’t a vitamin — it’s a mineral. But its role in hair loss is so important that we couldn’t avoid mentioning it!

Iron deficiency, or anaemia, is the most common nutritional deficiency in the world and has known links to hair loss — though many researchers will not go so far as to say that the deficiency triggers hair loss.

People at risk of developing an iron deficiency include vegans and vegetarians, premenopausal women, and patients with malabsorption disorders (such as celiac disease) or gastrointestinal blood loss.

As with many research topics on nutritional deficiencies, the findings are by no means conclusive. But many studies recommend iron supplementation for people with hair loss and anaemia.

Learn more about anaemia and hair loss. 

Recognising the Symptoms of Vitamin Deficiency Hair Loss

Hair loss related to a vitamin deficiency can be tricky to spot for one simple reason: the most common symptom is diffuse thinning — that is, gradual thinning across the scalp over time. 

No patchy bald spots. No mass shedding event. 

Instead, you may only discover it once your hair has already thinned considerably, although you may also notice that you’re losing more hair than normal in the shower or on the brush. 

Other common symptoms include brittle strands, persistent scalp dryness, dandruff, or slower regrowth — all the result of a nutrient deficiency weakening hair follicles and inhibiting their ability to produce strong, healthy strands.

Hair Loss in Children Due to Vitamin Deficiency

A vitamin deficiency may cause hair loss in children in much the same way it does in adults — it weakens hair follicles, slows regrowth, and may cause thinning. 

In children, it can be a complex mix of circumstances that may lead to a vitamin deficiency. 

Often, poor nutrition is the culprit, caused by important gaps in their diet. A lack of adequate sun exposure may also lead to insufficient vitamin D levels. 

Some children may have an underlying health condition that may impair the body’s ability to absorb nutrients. 

If your child is experiencing excessive hair shedding, noticeable thinning, or delayed hair regrowth, it’s important to consult a paediatrician so that you can identify and treat the underlying cause.

How to Prevent Vitamin Deficiency Hair Loss?

It’s no surprise that the best way to prevent hair loss from vitamin deficiencies is to make sure your body is getting the nutrients it needs. 

Eating a healthy and nutritious diet is a great place to start. Nutrient-dense, protein-rich foods may help promote healthy hair growth. Try to keep plenty of healthy fats, fruits and vegetables, and proteins like fish, lean meat, and legumes in your daily diet. 

Learn more about the best foods for hair health. 

Hair growth supplements feel like an easy out, but it’s not as simple as visiting the health aisle of your nearest grocery store. 

Some supplements (such as vitamin D) appear to have some success in treating hair loss. For other nutrients — including zinc, riboflavin, vitamin E, folic acid, or B12 — there isn’t enough data to support using supplements for hair loss. 

Yet other nutrients can actually carry harmful consequences if taken as a supplement without a deficiency. In the case of vitamin A, vitamin E, and selenium, over-consuming these nutrients may lead to hair loss. 

Instead of plucking an all-in-one hair loss supplement off the shelf, a better approach is to ensure you’re only supplementing with the nutrients your body needs. 

Regular health check-ups are essential for this, particularly if you’re getting blood tests. With the results, your GP can monitor nutrient levels and help prevent a deficiency. 

Of course, if you do have a vitamin deficiency, a restrictive diet, or absorption issues, specific vitamin supplements may be required to treat or prevent a vitamin deficiency — which can in turn help prevent any related hair loss symptoms.

Effective Vitamin Deficiency Hair Loss Treatments

The most effective way to treat hair loss caused by a vitamin deficiency is to identify and correct the underlying nutrient imbalance — usually with the help of a GP and some blood test results. 

If you have a deficiency or low levels of a certain vitamin, your doctor will likely recommend dietary changes to boost your vitamin levels naturally. In the case of vitamin D deficiency, they may also recommend some time outdoors in the sun.

If this doesn’t work — or if the deficiency is severe — they may also recommend supplements. 

These measures can help treat hair loss from a vitamin deficiency by treating the underlying cause naturally. 

But hair regrowth treatments can also provide medically backed treatment for hair loss. This is where The Hairy Pill® may be able to help. 

Just fill out a form and our partner doctors can recommend a personalised hair growth treatment for you based on your needs — just one treatment containing the medical-grade ingredients, vitamins, and minerals made for you according to your body’s needs. You don’t have to do anything. The treatment will be delivered to your door and repeats are taken care of. Get started.

Regaining Hair Lost from Vitamin Deficiency: What to Expect?

The timeframe for full hair regrowth all depends on how quickly you identify and address the underlying vitamin deficiency. 

Once you start taking action to address the deficiency, it can still take a while to get those levels back to normal. For a severe deficiency, it can take even longer to recover. 

It’s important to remain consistent with your diet and any supplements to get those levels within a healthy range and keep them there. 

Even once you have treated the vitamin deficiency, it takes time for your hair follicles to transition back to an active period of healthy growth and for the regrowth to become visible. It takes on average 3–6 months to see improvements with your hair.

When to See a Doctor?

Whenever you’re concerned about the amount of hair you’re shedding, you should consider consulting a doctor — particularly if your hair loss is excessive, persistent, or accompanied by other symptoms (such as fatigue, brittle nails, or dizziness). 

A doctor can arrange blood tests to check for a vitamin deficiency. And if you’re deficient in any nutrients.

It’s important to get an early diagnosis and start treatment as soon as possible to prevent further hair thinning and improve your chances of healthy regrowth.

FAQs

1. Are vegans & vegetarians more prone to vitamin deficiency hair loss?

Yes, by removing a pivotal source of nutrients from their diet, vegans and vegetarians are more likely to develop a vitamin deficiency, which may in turn lead to hair loss.

Fatty fish are a good source of vitamin D, while red meats like beef and lamb are high sources of B12 and iron — three nutrients that are essential for hair growth and have proven links to hair loss when there is a deficiency. 

But it doesn’t end there. 

The iron found in animals compared to plants is different; your body can absorb the iron from animal products far more easily than plant-based sources. 

As a result, studies have shown that vegans and vegetarians risk developing deficiencies in these three nutrients, to name just a few. 

2. Can over-exercising or extreme dieting lead to hair loss due to vitamin deficiency?

Both over-exercising and extreme dieting have links to vitamin deficiencies that may cause hair loss. 

Very few studies look at direct links between over-exercising, vitamin deficiencies, and related hair loss. But most researchers agree that regular exercise is unlikely to cause hair loss (whether from a vitamin deficiency or something else). 

One interesting survey-based Korean study found a correlation between hair loss and low-intensity exercise — not, as you’d expect, high-intensity exercise. But they didn’t look at the role of vitamins or vitamin deficiencies. 

So let’s come at it from another angle. According to Carl L Keen, Professor of Nutrition and Internal Medicine at the University of California, long, intense exercise may cause noticeable changes in how the body handles minerals like iron and zinc (both essential for hair growth).

Keen suggests that this occurs either through bodily stress or from mineral loss caused by sweating. 

Another aspect of over-training is that it’s commonly associated with under-eating. After all, it’s estimated that disordered eating affects 62% of female athletes and 33% of male athletes.

Disordered eating and extreme dieting (like keto) may lead to nutritional deficiencies, causing hair loss from malnutrition or bodily stress. 

Learn more about hair loss and keto. 

3. Can certain medications interfere with vitamin absorption & lead to hair thinning?

Many commonly prescribed medications can inadvertently limit your body’s ability to absorb vitamins and minerals, leading to nutrient deficiencies that directly impact hair health.

Medication may interfere with nutrient absorption by:

• Directly interfering with how your gut absorbs nutrients
• Altering metabolic pathways, affecting how your body processes or stores nutrients
• Blocking the synthesis or availability of nutrients
• Wiping out beneficial gut bacteria, which play a key role in nutrient absorption and synthesis

Here are just some of the most common medications that may cause vitamin deficiencies related to hair loss:

• Anti-seizure medications — can decrease vitamin D levels
• Metformin — can indirectly lead to vitamin B12 deficiency
• Proton Pump Inhibitors (PPIs) — a 2013 review found PPIs can cause deficiencies in vitamin B12, vitamin C, calcium, iron, and magnesium.
• Antibiotics — may lead to deficiencies in the vitamin B complex or vitamin K

But here’s where it gets tricky: a depletion in nutrients can develop gradually, sometimes months or even years after you start medication, which can make it difficult to connect hair thinning to prescriptions.

4. Can a vitamin deficiency make existing conditions like dandruff, eczema, or psoriasis worse?

Plenty of studies suggest that some vitamin deficiencies may play a role in worsening skin conditions like dandruff, eczema, or psoriasis. 

Let’s start with dandruff, where Healthline confirms that a nutrient-poor diet and deficiencies in vitamin B6 and B2 (riboflavin) may aggravate dandruff.

As for psoriasis, significant links between vitamin D and psoriasis symptoms have been observed. For example, a 2018 observational study found that lower vitamin D levels may prolong psoriasis.

Vitamin D also has a role in eczema, with ‘lower serum vitamin D levels associated with increased incidence and severity of eczema symptoms’, according to Australian Associate Professor Dr Debbie Palmer. 

Vitamin C deficiency may also play its part, if you’re to believe an admittedly small study of 17 patients with eczema in 2016, which found that patients with more severe eczema had lower levels of vitamin C in their blood. 

5. Are professional hair treatments, like PRP therapy, useful for vitamin-related hair loss recovery?

Let’s be clear: the most effective treatment for vitamin deficiency hair loss is the treatment that will address the root cause of hair loss — in this case, the vitamin deficiency. 

Making sure your body gets the nutrients it needs — whether through diet or supplementation — is the best (and really the only) way to prevent hair loss from a vitamin deficiency. 

When it comes to reversing vitamin-related hair loss, it’s even more important to treat the underlying deficiency if you want lasting treatment.

Other professional hair treatments, like low-level laser therapy (LLLT) or platelet-rich plasma therapy (PRP), may help stimulate hair follicles and promote regrowth, especially if you’re dealing with more severe hair loss from a deficiency. 

But they shouldn’t be the only treatment you take for hair loss related to a vitamin deficiency. Instead, they should complement other measures that more directly address the deficiency, such as dietary changes or supplements.