Which vitamin deficiency actually causes hair loss? A dermatologist’s guide

Table of Content:
Amino acids | Vitamin A | Vitamin B | Vitamin C | Vitamin D | Vitamin E | Iron | Omega-3 | Selenium | Zinc | Can too many vitamins cause hair loss? | Can I take pre-natal vitamins for hair loss?

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Hair loss or hair thinning can be influenced by various factors; however, the school of thought that people are missing key nutrients in their diet is becoming a thought of the past. Key nutrients for maintaining healthy hair include vitamin D, iron, zinc, biotin (Vitamin B7), vitamin A, vitamin E, vitamin C, omega-3 fatty acids, protein, and B vitamins. 

Insufficient levels of these nutrients certainly can contribute to hair problems, such as hair loss, brittle hair, or weak hair. However, there are many other factors and underlying health conditions, such as genetics, hormonal imbalances, medications, that also play a role in hair issues. 

A dermatologist’s general hair loss workup generally only includes checking for levels of vitamin D and Iron (Fe) unless their suspicion for other nutrient deficiencies is high. It tends to be exceedingly rare with modern diets and many fortified foods to become deficient in vitamins such as biotin or amino acids which are the building blocks of protein. 

If you suspect nutrient deficiencies may be a factor, consult a healthcare professional for proper evaluation and guidance on dietary changes or supplements to address the problem.

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What vitamin and nutrient deficiencies contribute to hair loss?

Amino acids and hair 

Dr. Ben Williams, dermatologist, says that amino acids play somewhat of a role in hair health, and their deficiency can contribute to hair loss and other hair-related problems since they are the building blocks of proteins and hair is primarily composed of a protein called keratin¹. However, if protein deficiencies are truly real, people often have many other issues of varying severity other than their hair loss.

Amino acids are obtained primarily from the proteins we consume in our diet. Sources of protein include lean meats, poultry, fish, eggs, dairy products, legumes, and nuts. One of the best sources are eggs since they are considered a “complete protein” containing 100% of the necessary amino acids. 

• Amino acids are essential for the synthesis of proteins, including keratin. Hair is made up of approximately 95% keratin, and having a sufficient supply of amino acids is necessary for the growth, repair, and maintenance of hair strands.²
• Amino acids also contribute to the structural integrity of hair, making it strong, flexible, and resistant to damage. The amino acids cysteine and methionine, in particular, are important for the formation of disulfide bonds, which give hair its strength and elasticity.
• Amino acids are involved in the hair growth cycle by promoting the development and health of hair follicles. Inadequate amino acid intake can lead to disruptions in the hair growth cycle and contribute to hair thinning and loss.

Vitamin A and hair loss

Dr. Williams says that vitamin A is essential for maintaining healthy hair, but this can be achieved by having a well-rounded diet that includes foods like carrots, sweet potatoes, spinach, and other fruits and vegetables rich in beta-carotene. 

He also added that the excessive intake of preformed vitamin A (retinol) from animal sources and supplements should be avoided as consuming too much vitamin A can lead to a condition called hypervitaminosis A. Hypervitaminosis A can result in hair loss, as well as other health issues such as dry skin, dizziness, nausea, and more. 

• Vitamin A is necessary for the proper functioning of hair follicles. It helps in the production of sebum, an oily substance that moisturizes the scalp and keeps hair healthy. Adequate sebum production ensures that hair follicles stay lubricated and do not become dry or damaged.
• Vitamin A has antioxidant properties that can protect hair follicles and scalp cells from oxidative stress and damage caused by free radicals. This protection helps maintain the health of the hair follicles.
• While vitamin A is essential, excessive intake can have adverse effects on hair and overall health³. 

Vitamin B and hair loss

Vitamin B complexes (including vitamin B1, B2, B3, B5, B7, B9 and B12) play a role in hair health, and its deficiency can contribute to hair loss or hair-related problems⁴. 

Vitamin B1 (Thiamine)

Thiamine supports the overall health of hair follicles by aiding in the production of energy for the cells in the hair follicles. It helps maintain the proper functioning of the scalp’s cells and promotes hair growth. Deficiencies are rare and usually only seen in chronic alcohol use.

Vitamin B2 (Riboflavin)

Riboflavin is involved in the metabolism of proteins, fats, and carbohydrates, which are vital for hair growth. It helps ensure that the hair follicles receive the necessary nutrients and energy.

Vitamin B3 (Niacin)

Niacin improves blood circulation to the scalp, ensuring that hair follicles receive an adequate supply of oxygen and nutrients. This helps promote healthy hair growth and may contribute to thicker hair.

Vitamin B5 (Pantothenic Acid)

Pantothenic acid is important for hair health because it helps with the production of coenzyme A, which is involved in various metabolic processes, including the synthesis of fatty acids and proteins. These processes are crucial for maintaining strong and healthy hair.

Vitamin B7 (Biotin)

Biotin is one of the most well-known B vitamins for hair health. It plays a key role in the synthesis of keratin, a protein that makes up the structure of hair. Biotin deficiency can lead to hair thinning, hair loss, and brittle hair. Biotin is one of the most commonly confused supplements as being truly useful for hair loss. I only recommend biotin to people suffering from brittle hair or nail syndrome. 

Vitamin B9 (Folic acid)

Folic acid is essential for cell growth and repair, and indirectly supports hair health by contributing to the maintenance of healthy hair follicles and promoting blood circulation to the scalp. While folic acid deficiency can potentially contribute to hair problems, it is relatively rare in well-nourished individuals.

Vitamin B12 (Cobalamin)

Vitamin B12 supports the health of red blood cells, which transport oxygen and nutrients to the hair follicles. Adequate B12 levels are necessary for preventing hair follicle damage and promoting hair growth⁵.

Vitamin C (ascorbic acid) and hair

Dr. Williams that vitamin C is essential for overall health, including the health of your hair. While it may not directly prevent hair loss, vitamin C plays an important role in maintaining the overall condition of your hair and supporting a healthy scalp, however, its overall role in hair loss is likely minimal. 

• Vitamin C is crucial for the synthesis of collagen, a protein that provides structure to the hair, skin, and nails. Collagen helps maintain the integrity and strength of hair follicles and the hair shaft itself.
• As an antioxidant, vitamin C helps protect hair follicles and the scalp from oxidative stress and free radical damage. This protection can help maintain a favorable environment for hair growth.
• Vitamin C enhances the absorption of the iron found in plant-based foods and supplements.⁶

Vitamin D and hair loss

Vitamin D deficiency is associated with various hair-related issues as vitamin D plays an essential role in supporting the immune system, regulating cell growth, and maintaining overall health and well-being.

• Vitamin D is essential for the proper functioning of hair follicles, which are responsible for hair growth. It helps regulate the hair growth cycle and may promote the growth of new hair follicles.⁷
• Vitamin D may also help in regulate hormones in the body, including those involved in hair growth. Hormonal imbalances can contribute to hair loss, so maintaining appropriate hormone levels through vitamin D is beneficial⁸
• A deficiency in vitamin D can weaken the immune system, potentially leading to conditions like alopecia areata, an autoimmune disorder that causes hair loss.⁹
• Vitamin D has anti-inflammatory properties, and inflammation in the scalp can contribute to hair loss. Adequate levels of vitamin D may help reduce inflammation in the hair follicles and scalp.
• Vitamin D aids in the absorption of calcium, which is important for hair structure and strength. A deficiency in calcium can lead to brittle hair¹⁰.

Vitamin E and hair

While Vitamin E plays a role in overall skin and hair health, its deficiency does not have a direct impact on hair loss. However, this is how Vitamin E supports hair growth:

• Vitamin E contributes to maintaining a healthy scalp by reducing oxidative stress and inflammation. 

• Vitamin E supports overall cardiovascular health, which indirectly benefits the hair by promoting better blood circulation. 
• Vitamin E is known for its moisturizing properties. When applied topically, it can help improve the moisture retention of hair and prevent dryness and breakage, particularly in individuals with dry or damaged hair.

Iron deficiency and hair loss

Iron deficiency can play a significant role in hair loss, and it is one of the most common nutritional factors associated with hair problems. This predominantly affects younger women.

• Insufficient iron levels can lead to a reduced supply of oxygen to the hair follicles impairing their ability to function optimally.
• Hair follicles have a growth cycle that includes a growth phase (anagen), a transitional phase (catagen), and a resting phase (telogen) before the hair falls out and new hair begins to grow. Iron deficiency can disrupt this cycle, causing more hair follicles to enter the telogen (resting) phase prematurely. This results in increased shedding and can lead to noticeable hair thinning or hair loss.
• Iron deficiency can also affect the quality and strength of the hair shaft itself which  may result in hair becoming brittle, dry, and more prone to breakage.¹¹

Omega-3 fatty acids and hair 

Dr. Williams says that omega-3 fatty acids are a type of polyunsaturated fat that can play a role in promoting hair health and potentially preventing hair loss. They  are primarily found in fatty fish (such as salmon, mackerel, and sardines), flaxseeds, chia seeds, and walnuts. Many people also take omega-3 supplements like fish oil capsules to ensure an adequate intake.

• Omega-3 fatty acids help maintain a healthy scalp by reducing inflammation¹². A balanced scalp environment is essential for optimal hair growth, as excessive inflammation can contribute to hair loss conditions like alopecia areata or dandruff.
• Research shows that omega-3 contributes to the health and strength of the hair. They help keep the hair moisturized and prevent it from becoming dry and brittle, reducing the risk of breakage and hair loss¹³.
• Omega-3 fatty acids support overall cardiovascular health, which indirectly benefits the hair by promoting better blood circulation. Improved circulation ensures that hair follicles receive an adequate supply of oxygen and nutrients, facilitating healthy hair growth¹⁴.
• Omega-3s have anti-inflammatory properties, which can help reduce inflammation in hair follicles and potentially alleviate conditions that cause hair loss related to inflammation¹⁵.

Selenium and hair loss

Selenium is a trace mineral that plays a role in overall health, and its deficiency can potentially contribute to hair loss. 

• Selenium functions as antioxidants in the body and antioxidants help protect cells, including those in hair follicles, from oxidative damage caused by free radicals which is important for overall hair follicles health.
• Selenium contributes to proper thyroid function which is crucial for overall metabolic processes and hair growth. Thyroid imbalances, whether due to selenium deficiency or other factors, can lead to hair problems, including hair loss.
• Selenium also plays a role in supporting the immune system. A healthy immune system is important for maintaining the overall health of the scalp and hair follicles.

Zinc and hair loss

Zinc is an essential mineral that plays a significant role in hair health, and its deficiency has also been linked to hair and scalp problems. 

• Zinc is involved in the growth and repair of hair follicles. Adequate zinc levels are necessary for the proper functioning of hair follicles and to promote healthy hair growth.
• Zinc helps regulate various hormones in the body, including those related to hair growth and hair loss. Imbalances in these hormones can contribute to hair problems.
• Zinc supports immune function, and a strong immune system is essential for overall health, including the health of hair follicles. Zinc deficiency can lead to other health conditions that may result in hair loss.
• Zinc helps in the regulation of sebum production, which is the natural oil that moisturizes the scalp and hair. An imbalance in sebum production can lead to conditions like dandruff or an overly oily scalp, which can affect hair health.

Can too many vitamins cause hair loss?

Dr. Williams says that indeed, an excessive intake of certain vitamins, particularly fat-soluble vitamins like vitamin A and vitamin E, can potentially lead to hair loss. This condition is often referred to as vitamin toxicity or hypervitaminosis.  It is even the reason why people may develop hair loss from drugs like isotretinoin (Accutane). This tends to be a self-limited side effect that resolves once the drug is stopped.

Can you take prenatal vitamins for hair growth?

Yes, some people take prenatal vitamins for hair growth because they contain key nutrients like biotin, folic acid, and iron that can promote hair health. However, folic acid deficiency causing hair loss is generally not recognized as a contributing factor to hair loss considering the liver can store about a 3 month supply of folate.

Are the same vitamins that are good for hair, also good for the skin?

Dr. Williams says that many vitamins that are beneficial for hair health also have positive effects on the skin. For example, vitamin A supports both skin and hair cell growth and repair, while vitamin C and vitamin E are antioxidants that help protect the skin from oxidative damage and promote collagen production, benefitting both skin elasticity and hair strength. Biotin, a B-vitamin, is known to support healthy skin and nails in addition to hair. Similarly, vitamin D helps maintain skin health and has many other important functions within the body.

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