7 Nutritional Deficiencies That Can Cause Hair Loss

Are you noticing more hair on your brush, pillow, or shower drain? A nutritional deficiency may be one possible reason for increased shedding. Hair follicles need a steady supply of protein, vitamins, minerals, energy, and oxygen to support normal growth.

When the body lacks an essential nutrient, it may direct available resources toward more urgent functions. As a result, hair growth can slow, and more follicles may enter the resting or shedding phase. Depending on the cause, you may notice diffuse shedding, weaker strands, slower growth, or reduced density.

However, hair loss does not automatically mean that you have a vitamin or mineral deficiency. Genetics, thyroid disease, hormonal changes, illness, medication, stress, inflammation, rapid weight loss, and scalp conditions can cause similar symptoms.

This guide explains seven nutritional deficiencies that may contribute to hair loss. It also covers the signs to watch for, the tests that may help, and why you should avoid taking high-dose supplements without confirming what your body actually needs.

How Nutritional Deficiencies Can Affect Hair Growth

Hair follicles contain rapidly dividing cells. Therefore, they need enough energy, amino acids, vitamins, minerals, and oxygen to function normally.

A major deficiency, restrictive diet, illness, or rapid weight loss can disrupt the normal hair growth cycle. In some cases, more follicles move from the active growth phase into the resting phase. Consequently, increased shedding may appear several weeks or months after the original trigger.

This pattern is often called telogen effluvium. Typically, it causes diffuse shedding across the scalp rather than one isolated bald patch.

Hair Loss May Have More Than One Cause

A nutritional deficiency may exist alongside another form of hair loss. For example, someone may have low iron stores and genetic pattern thinning at the same time.

Correcting a deficiency can support normal growth. However, it may not fully reverse androgenetic alopecia, scarring alopecia, autoimmune hair loss, traction alopecia, or another separate condition.

Symptoms Cannot Confirm a Deficiency

Fatigue, brittle nails, dry skin, low mood, shedding, and weak hair may occur with several deficiencies. However, these symptoms can also result from many medical and lifestyle factors.

For this reason, laboratory tests and clinical assessment are more useful than choosing supplements based only on a symptom list.

1. Vitamin D Deficiency and Hair Loss

The body uses vitamin D for many important processes. In addition, vitamin D receptors are present in hair follicles. This has led researchers to study possible links between low vitamin D and several types of hair loss.

Some studies have found lower vitamin D levels in people with alopecia areata, telogen effluvium, and other forms of hair loss. However, an association does not prove that low vitamin D caused every case.

If testing confirms a deficiency, correcting it may support general health and normal follicle function. Even so, it should not replace treatment for another diagnosed hair-loss condition.

Possible Signs of Vitamin D Deficiency

A person with low vitamin D may have no obvious symptoms. When symptoms do occur, they may include:

• Fatigue or low energy.
• Muscle weakness or aches.
• Bone pain or tenderness.
• Low mood.
• Increased shedding or reduced hair density alongside other causes.

These symptoms are not specific to vitamin D deficiency. Therefore, a blood test is needed to measure vitamin D status.

Taking care of your hair starts with understanding what your body may be missing rather than guessing from symptoms alone.

How to Address Low Vitamin D

1. Ask about testing. A healthcare professional may use a 25-hydroxyvitamin D blood test to assess vitamin D status.
2. Include vitamin D-rich foods. For example, fatty fish, egg yolks, fortified milk, fortified plant-based drinks, and some fortified cereals can contribute to intake.
3. Use sunlight safely. The amount of vitamin D produced through sunlight varies with skin tone, season, location, clothing, age, and sunscreen use.
4. Use supplements only when appropriate. The correct dose depends on your blood level, medical history, diet, and professional advice.
5. Take supplements as directed. Because vitamin D is fat-soluble, taking more than recommended can cause toxicity.

For a closer look at testing, symptoms, and treatment considerations, read our full guide to vitamin D3 deficiency and hair loss.

2. Iron Deficiency and Hair Shedding

Iron helps the body produce haemoglobin, the protein in red blood cells that transports oxygen. Moreover, this mineral supports cell growth and many enzyme systems.

Several factors can lead to low iron. These include heavy menstrual bleeding, pregnancy, blood loss, restrictive diets, digestive conditions, low dietary intake, and poor absorption.

When iron deficiency becomes significant, it may contribute to diffuse shedding. However, hair loss has many possible causes. Therefore, iron results should form part of a broader assessment.

How Iron and Ferritin Relate to Hair Health

Ferritin is a protein that stores iron. Clinicians often measure it when investigating possible iron deficiency.

A low result may indicate reduced iron stores. However, inflammation, infection, liver disease, and other conditions can raise ferritin. Therefore, clinicians should not always interpret it by itself.

Instead, a clinician may review ferritin together with haemoglobin, serum iron, transferrin saturation, total iron-binding capacity, symptoms, menstrual history, diet, and other findings.

There is no single ferritin target that guarantees hair growth for every person. Consequently, treatment should focus on confirmed iron deficiency and its underlying cause rather than chasing an arbitrary number.

For more detail, read our guide on hair loss and ferritin deficiency.

Possible Signs of Iron Deficiency

• Fatigue or weakness.
• Shortness of breath.
• Pale skin.
• Dizziness or headaches.
• Cold hands and feet.
• Brittle nails.
• Restless legs.
• Diffuse hair shedding.

Seek medical care if you suspect iron deficiency. In particular, it is important to identify why iron levels are low when blood loss or a digestive condition may be involved.

How to Address Iron Deficiency

1. Request appropriate testing. Your clinician may consider ferritin, serum iron, transferrin saturation, total iron-binding capacity, and a full blood count.
2. Identify the cause. Heavy periods, gastrointestinal bleeding, pregnancy, low intake, or poor absorption may require separate treatment.
3. Eat iron-rich foods. Sources include red meat, poultry, seafood, lentils, beans, tofu, leafy greens, and fortified cereals.
4. Pair plant-based iron with vitamin C. For example, citrus fruit, berries, tomatoes, and bell peppers may improve non-haem iron absorption.
5. Separate common absorption blockers. Tea, coffee, calcium supplements, and some medicines may reduce iron absorption when taken at the same time.
6. Use iron supplements only under guidance. Otherwise, excessive iron can damage organs and cause serious side effects.

3. Zinc Deficiency and Hair Loss

Zinc supports immune function, wound healing, DNA synthesis, protein production, and normal cell division. Therefore, it matters to rapidly growing tissues, including hair follicles.

A genuine deficiency may contribute to hair loss, skin changes, poor wound healing, altered taste, or impaired immune function.

However, zinc supplementation does not automatically improve hair growth when levels are already adequate.

How Zinc Supports Hair Follicles

The body needs zinc to make proteins and DNA. It also supports enzymes involved in cell growth and repair.

Researchers have reported low zinc levels in some people with alopecia areata, telogen effluvium, and other hair conditions. Still, its role can vary. Therefore, supplementation should follow an appropriate assessment.

Long-term high-dose zinc can reduce copper absorption. As a result, copper deficiency may cause anaemia, nerve problems, and possible changes in hair quality.

Who May Be at Greater Risk?

Risk factors for zinc deficiency may include:

• Severely restrictive diets.
• Digestive diseases or malabsorption.
• Long-term diarrhoea.
• Alcohol-use disorder.
• Pregnancy or breastfeeding with inadequate intake.
• Long-term use of excessive zinc that disrupts copper balance.

How to Improve Zinc Intake

1. Choose zinc-rich foods. Oysters, beef, poultry, crab, dairy products, beans, nuts, seeds, and whole grains provide zinc.
2. Use varied food sources. Plant sources contain zinc, although phytates can reduce absorption.
3. Include dairy if appropriate. Yogurt and cheese can contribute zinc and protein.
4. Avoid high-dose self-treatment. After all, more zinc is not necessarily better.
5. Consider copper balance. A clinician may review copper if you have used high-dose zinc for an extended period.

4. Biotin Deficiency and Hair Changes

Biotin, also called vitamin B7, helps enzymes process fats, carbohydrates, and amino acids. For this reason, it is often included in products marketed for hair, skin, and nails.

A true deficiency can cause hair thinning, skin rash, brittle nails, and neurological symptoms. However, this condition is uncommon in people who eat a varied diet.

Most people with hair loss do not have isolated biotin deficiency. Therefore, high-dose biotin is unlikely to solve hair loss caused by genetics, low iron, thyroid disease, stress, inflammation, or another condition.

Who May Develop Biotin Deficiency?

In unusual situations, biotin deficiency may occur. Examples include:

• Rare inherited metabolic disorders.
• Long-term consumption of large amounts of raw egg white.
• Long-term intravenous nutrition without adequate biotin.
• Some anticonvulsant medicines.
• Severe malnutrition or certain absorption problems.

Biotin and Hair Strength

This vitamin supports normal metabolic functions linked with keratin-producing tissues. However, taking more biotin does not automatically create faster hair growth in people who already have enough.

When a true deficiency exists, correcting it may improve related symptoms. In contrast, evidence for high-dose biotin as a hair-growth treatment is weak when levels are already adequate.

Food Sources of Biotin

• Cooked eggs
• Liver and other organ meats
• Salmon
• Almonds and walnuts
• Sunflower seeds
• Milk and some dairy products
• Sweet potatoes
• Whole grains

Important Biotin Blood-Test Warning

High-dose biotin can interfere with certain laboratory tests. For example, it may affect tests for thyroid hormones, heart-related markers such as troponin, and some other hormones.

Therefore, tell your doctor and laboratory staff if you take biotin. Then follow their instructions about whether and when to stop it before testing.

5. Vitamin C Deficiency and Hair Health

Vitamin C supports collagen production, antioxidant defence, wound healing, and the absorption of non-haem iron from plant foods.

Severe deficiency can cause scurvy. Possible symptoms include fatigue, gum problems, easy bruising, poor wound healing, and distinctive changes around hair follicles.

In addition, low vitamin C may affect hair quality or worsen iron deficiency by reducing iron absorption. However, it is not a common isolated cause of hair loss in people who eat a varied diet.

How Vitamin C May Affect Hair

This vitamin contributes to collagen formation and helps protect cells from oxidative damage. Collagen, in turn, forms part of the supportive structure around skin and hair follicles.

Its role in iron absorption may be especially important for people who rely mainly on plant-based iron sources.

Still, taking large amounts of vitamin C will not treat hair loss when levels are already adequate or when another condition is responsible.

Possible Signs of Severe Vitamin C Deficiency

• Fatigue or weakness.
• Easy bruising.
• Bleeding or swollen gums.
• Poor wound healing.
• Dry or rough skin.
• Corkscrew-shaped body hairs in severe cases.
• Iron deficiency caused or worsened by reduced absorption.

Food Sources of Vitamin C

• Citrus fruits: Oranges, grapefruit, lemons, and limes.
• Berries: Strawberries, blackcurrants, and raspberries.
• Bell peppers: Red and yellow peppers are especially rich sources.
• Kiwi and guava: Both provide substantial vitamin C.
• Broccoli and Brussels sprouts: These vegetables also provide fibre and other nutrients.
• Leafy greens: Spinach and kale contribute vitamin C and folate.

For most people, fresh produce provides enough vitamin C. Therefore, supplements should not replace a varied diet unless a clinician recommends them.

6. Vitamin E Deficiency and Scalp Health

Vitamin E is a fat-soluble antioxidant that helps protect cell membranes from oxidative damage. It also supports immune function and skin health.

A genuine deficiency is rare. Usually, it occurs because of a disorder that prevents the body from absorbing fat rather than because of an ordinary diet.

Evidence does not show that routine supplementation reliably treats hair loss in well-nourished people. Furthermore, high-dose vitamin E may increase bleeding risk and interact with medicines.

How Vitamin E Supports the Skin and Scalp

This nutrient contributes to antioxidant protection and normal skin-barrier function. Consequently, these roles may help maintain the general health of the scalp.

However, a healthy scalp does not guarantee hair regrowth. Vitamin E cannot reverse genetic follicle miniaturisation, scarring, autoimmune disease, or other established causes of hair loss.

Who May Be at Risk of Vitamin E Deficiency?

Risk may be higher in people with:

• Severe fat-malabsorption disorders.
• Certain inherited conditions.
• Some liver, pancreatic, intestinal, or biliary diseases.
• Very restricted diets combined with other medical problems.

Food Sources of Vitamin E

1. Almonds and hazelnuts: These provide vitamin E, healthy fats, and protein.
2. Sunflower seeds: Add them to salads, yogurt, or oatmeal.
3. Plant oils: Sunflower, safflower, and wheat-germ oils contain vitamin E.
4. Leafy vegetables: Spinach and Swiss chard provide smaller amounts.
5. Avocado: It contributes vitamin E and monounsaturated fat.

Therefore, do not use high-dose vitamin E supplements for hair loss without professional guidance.

7. Selenium Deficiency and Hair Loss

Selenium is a trace mineral involved in antioxidant defence, DNA production, reproduction, and thyroid hormone metabolism.

Both low and excessive intake can cause health problems. Importantly, too much selenium can itself lead to hair loss and brittle nails.

Because this mineral has a relatively narrow safe range, you should not take it in high doses simply because hair shedding is present.

Why Selenium Balance Matters

Selenium forms part of antioxidant enzymes that protect cells from oxidative stress. In addition, it supports enzymes involved in converting and regulating thyroid hormones.

Thyroid imbalance can affect hair growth. However, selenium supplementation is not a general treatment for thyroid-related hair loss. In fact, it may be harmful when intake is already adequate.

Possible Signs of Selenium Excess

Excess selenium, sometimes called selenosis, may cause:

• Hair loss.
• Brittle or damaged nails.
• Nausea or diarrhoea.
• A metallic taste.
• A garlic-like odour on the breath.
• Skin rash.
• Nervous-system symptoms in severe cases.

Safer Selenium Guidance

1. Review your total intake. Check multivitamins, hair supplements, thyroid products, and individual selenium products.
2. Do not diagnose deficiency from shedding alone. After all, hair loss has many more common causes.
3. Use Brazil nuts cautiously. Their selenium content varies widely, and a small number may already provide a large amount.
4. Avoid excessive dosing. Otherwise, high intake can directly cause the symptom you are trying to treat.
5. Review thyroid symptoms properly. Thyroid testing may be more useful than assuming selenium is the missing factor.
6. Ask a qualified professional before supplementing. This is especially important if you already take a multivitamin or thyroid medication.

Other Nutritional Factors That Can Affect Hair

The seven nutrients above are commonly discussed. However, they are not the only nutritional factors linked with shedding or poor hair quality.

Protein Deficiency

Hair is made mainly from keratin, a protein. Therefore, very low protein intake, severe calorie restriction, malnutrition, or poor absorption may contribute to shedding and weak hair growth.

People following restrictive diets should ensure that they receive adequate protein from suitable animal or plant sources.

Vitamin B12 and Folate

Vitamin B12 and folate support red blood cell formation and DNA production. When a deficiency occurs, it may cause anaemia, fatigue, neurological symptoms, and changes in general health.

The direct relationship between isolated B12 deficiency and hair loss is less clear than the relationship with some other nutrients. Still, testing may be appropriate when risk factors or symptoms are present.

For more information, read our guide to vitamin B12 and hair health.

Rapid Weight Loss and Low-Calorie Diets

Rapid weight loss, crash dieting, weight-loss surgery, eating disorders, and very low-calorie diets can trigger telogen effluvium.

In these cases, the trigger may involve reduced energy intake, insufficient protein, iron deficiency, zinc deficiency, or the physical stress of rapid weight change.

Vitamin A Excess

Vitamin A is essential. However, excessive intake can contribute to hair loss. This risk is more likely with high-dose supplements or certain medicines than with ordinary food intake.

Therefore, check the combined vitamin A content of multivitamins, hair supplements, skin products, and other supplements before taking them together.

Blood Tests That May Be Considered for Hair Loss

There is no universal blood-test panel that every person with hair loss needs. Instead, testing should depend on your symptoms, diet, medical history, medications, menstrual history, examination, and type of hair loss.

Based on these factors, a healthcare professional may consider some of the following:

• Full blood count: Helps assess anaemia and blood-cell patterns.
• Ferritin and iron studies: May help assess iron stores and iron availability.
• Thyroid-stimulating hormone and related thyroid tests: Useful when thyroid disease is possible.
• Vitamin D: May be considered when risk factors or symptoms are present.
• Vitamin B12 and folate: May be useful with restrictive diets, anaemia, digestive conditions, or neurological symptoms.
• Zinc or copper: May be appropriate when deficiency risk, malabsorption, or high-dose supplementation exists.
• Other targeted tests: These may depend on hormonal symptoms, autoimmune signs, inflammation, illness, or medication use.

A trichologist can help document the hair and scalp pattern. However, an appropriately qualified clinician should order and interpret blood tests and provide a medical diagnosis.

How Long Does Hair Take to Recover?

Correcting a nutritional deficiency does not produce an immediate visible change. Instead, hair follicles need time to move through their cycle and create new growth.

In some cases, shedding may begin to settle after the underlying problem has been corrected. However, visible improvements in density or length often take several months.

What Influences Recovery Time?

• The severity and duration of the deficiency.
• The type of hair loss.
• Whether another condition is also present.
• How quickly the underlying cause is corrected.
• Age, genetics, medications, and general health.
• Ongoing stress, illness, inflammation, or restrictive dieting.

If shedding continues despite corrected laboratory results, further assessment may be needed. In that case, a deficiency may not have been the only cause.

How to Use Hair Supplements More Safely

Hair supplements often combine many ingredients in large doses. As a result, taking several products together can lead to duplicated ingredients and excessive intake.

Check Every Label

First, compare the amounts of vitamin A, vitamin D, vitamin E, iron, zinc, selenium, and biotin across all products. Include multivitamins, beauty supplements, fortified powders, and individual tablets.

Avoid Treating Test Results Without Context

A laboratory value should be interpreted with symptoms, medical history, medications, diet, and other test results. Therefore, a result near the lower end of a laboratory range does not automatically mean that high-dose treatment is required.

Tell Your Clinician What You Take

Bring a complete list of supplements and doses to medical appointments. Some products affect laboratory results, interact with medication, or create symptoms that resemble another condition.

Choose Food First Where Practical

A varied diet provides nutrients alongside protein, fibre, healthy fats, and other compounds. However, supplements may be useful when a deficiency, medical need, or dietary gap has been identified.

Frequently Asked Questions About Nutritional Deficiencies and Hair Loss

Common Deficiencies and Hair Shedding

Which vitamin deficiency causes hair loss?

Several deficiencies may contribute to hair loss, including deficiencies of iron, zinc, biotin, vitamin D, and protein. In addition, severe deficiencies involving vitamin C, vitamin E, selenium, vitamin B12, or other nutrients may affect general hair health. The likely cause depends on your diet, symptoms, medical history, examination, and test results.

Can low vitamin D cause hair loss?

Low vitamin D has been associated with several hair-loss conditions, including alopecia areata and telogen effluvium. However, a low result does not prove that it caused the hair loss. Therefore, testing and a broader assessment are important.

Can low iron cause hair loss without anaemia?

Low iron stores may exist before haemoglobin falls enough to meet the definition of anaemia. As a result, some people with low ferritin and diffuse shedding may benefit from correcting confirmed iron deficiency. However, ferritin should be interpreted alongside other iron tests and clinical findings.

Can zinc deficiency cause hair loss?

Yes. True zinc deficiency may contribute to hair loss, skin changes, and poor wound healing. However, taking extra zinc without a deficiency may not help. Moreover, excessive zinc can cause copper deficiency.

Can a lack of protein cause hair loss?

Yes. Severe protein deficiency, inadequate calorie intake, rapid weight loss, or malnutrition may disrupt the hair cycle and trigger diffuse shedding.

Biotin and Hair Supplements

Does biotin really help hair grow?

Biotin may help when a true deficiency exists. However, most people are not biotin deficient. Therefore, high-dose biotin does not usually create new hair growth by itself.

Can hair supplements cause hair loss?

Yes. Excessive intake of selenium, vitamin A, and some other nutrients can contribute to hair loss. Furthermore, taking several overlapping products may raise your total dose without you realising it.

Can too many vitamins cause hair loss?

Yes. Excess vitamin A and selenium are recognised causes of hair loss. In addition, excess iron, zinc, or vitamin E can cause harmful effects. Therefore, supplements should match a confirmed need.

Can biotin interfere with blood tests?

Yes. High-dose biotin can interfere with some thyroid, hormone, and cardiac blood tests. Therefore, tell your doctor and laboratory staff that you take biotin and follow their instructions before testing.

Testing, Treatment and Recovery

Should I get blood tests before taking hair supplements?

Testing is often a safer starting point than guessing. Depending on your history, a clinician may consider a full blood count, iron studies, ferritin, thyroid markers, vitamin D, vitamin B12, zinc, or other targeted tests.

What ferritin level is needed for hair growth?

There is no single ferritin level that guarantees hair growth for every person. Laboratories use different reference ranges, and inflammation can change ferritin. Therefore, a clinician should interpret it with your symptoms and other iron results.

How long does hair take to recover after correcting a deficiency?

Hair recovery often takes several months because follicles grow in cycles. However, the exact timeline depends on the deficiency, its severity, the type of hair loss, and whether another condition is also present.

What if my blood tests are normal but I am still losing hair?

Normal nutrient results do not rule out genetic pattern hair loss, thyroid disease, hormonal changes, medication effects, autoimmune hair loss, scalp inflammation, traction, stress-related shedding, or other causes. Therefore, a hair and scalp assessment may help identify the next step.

When should I see a professional?

Seek help for sudden or severe shedding, bald patches, scalp pain, redness, scaling, scarring, a widening part, a receding hairline, or hair loss that continues despite correcting a confirmed deficiency.

Conclusion: Can Nutritional Deficiencies Cause Hair Loss?

Nutritional deficiencies can contribute to hair loss. However, taking every available supplement is not the answer. Instead, identify what is actually low, investigate why it is low, and correct it with appropriate food, treatment, or supplementation.

Iron, zinc, biotin, protein, and vitamin D are commonly reviewed when nutrition-related hair loss is possible. In addition, vitamin C, vitamin E, selenium, vitamin B12, and other nutrients may matter in specific circumstances. However, evidence varies, and excessive supplementation can create new problems.

If shedding continues, do not assume that nutrition is the only cause. Genetics, hormones, thyroid disease, stress, illness, medication, rapid weight loss, autoimmune conditions, and scalp inflammation may also contribute.

Next step: If you are unsure where to begin, find a trichologist near you for a hair and scalp assessment. Then discuss appropriate laboratory testing with a qualified healthcare professional.

Disclaimer: This content is for general informational and educational purposes only. It is not medical advice and should not replace consultation with a qualified healthcare professional. Do not begin, stop, or change iron, vitamin D, zinc, selenium, biotin, or other supplements without appropriate guidance. Seek professional care for sudden, severe, patchy, painful, inflamed, scarring, or persistent hair loss.

References

1. ^ Review of nutritional factors and hair loss
2. ^ Nutritional factors in hair and scalp health
3. ^ Vitamin D deficiency: symptoms, causes, and treatment
4. ^ Micronutrients and hair-loss research
5. ^ Vitamin deficiencies associated with hair loss
6. ^ Iron, vitamins, minerals, and hair-loss evidence
7. ^ Zinc and other micronutrients in hair loss
8. ^ Healthdirect: Zinc deficiency
9. ^ Biotin and hair-loss evidence (2017-06-14)
10. ^ Vitamin deficiencies and hair loss overview
11. ^ NIH Office of Dietary Supplements: Biotin fact sheet
12. ^ Vitamin C, vitamin E, and hair-health evidence
13. ^ Nutritional deficiencies linked to hair loss (2023-09-25)
14. ^ Selenium balance and hair-loss evidence