Hair health is often seen as an indicator of overall well-being. While factors such as age, genetics, hormones, and medication can affect hair, nutrition plays a key role throughout life. All vital amino acids (vitamins) are essential nutrients that the body needs to maintain overall health, and hair health, in particular. A complete absence of any vitamin will lead to illness and even death. However, outside of undeveloped countries, extreme diets, and specific diseases, vitamin deficiency severe enough to cause disease is very rare, and this includes hair loss.
Menstruating women who do not consume enough iron-containing foods are often iron deficient and should supplement, and people who live in cloudy locations should assume they are deficient in Vitamin D and supplement accordingly. Most vitamins are readily available in our diets, and inexpensive oral supplements can be used to ensure adequate levels are available for our bodily functions. Excess intake of vitamins can cause disease states as well or is eliminated from the body unused, so in spite of the availability of heavily promoted nutrient supplements claiming to improve hair growth and quality, the consumer should be cautious and seek the most cost-effective options.
This article explores the role of various vitamins and minerals in promoting hair growth and thickness, examining the scientific evidence, natural sources, recommended intake, and potential risks associated with supplementation.
Hair loss, also called alopecia, is a common condition that can cause emotional distress. Hair loss can be a normal part of the aging process, but it can also result from a range of other causes and contributors.
Androgenetic alopecia, telogen effluvium, and alopecia areata are types of nonscarring hair loss, meaning when the hair falls out there is no damage to the hair follicle or scalp itself (no "scarring"). Hair regrowth is possible with time and appropriate treatment.
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A variety of vitamins and minerals play a role in new hair growth. They also strengthen your immune system, which is necessary for healthy hair. Consuming adequate vitamins and minerals is important to preventing and managing hair loss. However, if blood tests show that you have certain vitamin or mineral deficiencies, your doctor may recommend supplements.
Biotin is a critical vitamin for healthy hair growth, and deficiency will lead to thinning hair. However, biotin deficiency is very rare and almost always associated with an inherited disorder called biotinidase deficiency. Biotin deficiency has never been reported in healthy individuals with a normal diet, and there is no evidence that biotin supplements will help grow hair in the absence of a documented deficiency. Acquired biotin deficiency may occur with raw egg consumption, alcohol use disorder, pregnancy, and isotretinoin and antibiotic use. Notably, excess biotin intake may interfere with a number of important lab tests, including thyroid and other hormone tests such as pregnancy tests.
Natural Sources: Biotin deficiency is very rare because biotin is found in eggs, liver, wheat and oat cereals, several vegetables, rice, and dairy products, so even vegetarians and vegans can fulfill their body’s need for this vitamin.
Recommended Daily Intake: The FDA does not have a recommended daily allowance (RDA) for biotin. However, most sources state that a daily intake of 30 mcg is sufficient to prevent deficiency. Biotin remains commonly recommended by hair loss specialists at doses up to 5,000 mcg.
Excess Intake Risks: There are no reports of biotin toxicity even at very high doses of 100,000 mcg per day. However, there is also no evidence to support such doses for the treatment of hair loss or any other condition.
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Vitamin D is essential for creating the cells that develop into hair follicles. It also supports healthy bones and your immune system. Vitamin D plays an important role in healthy hair development as well as in many other physiologic processes, so deficiency may have detrimental effects. However, exactly how deficiency impairs hair growth is unknown. There are reports in the literature of successful hair regrowth after correcting Vitamin D deficiency, but in areas such as the northeast US, where Vitamin D deficiency is very prevalent, supplements rarely bring clinical benefits. Hair loss specialists who regularly screen for Vitamin D levels help patients attain normal levels for all of its potential benefits.
Natural Sources: Dietary Vitamin D is most easily obtained through fortified foods such as milk, yogurt, orange juice, and cheese, in fatty fish including sardines, salmon and tuna, and in egg yolks and mushrooms. The prevalence of Vitamin D deficiency suggests that most people do not consume adequate dietary Vitamin D, nor have sufficient sun exposure for adequate skin conversion of Vitamin D.
Recommended Daily Intake: Most experts recommend a daily Vitamin D intake of 2,000-5,000 IU for adults, and checking Vitamin D blood levels at least annually in order to make appropriate adjustments in intake. Severe deficiency can be treated with high-dose prescription strength Vitamin D for short periods of time.
Excess Intake Risks: Severe Vitamin D deficiency is defined as blood levels of 20 ng/ml or less, mild deficiency at 30-50 ng/ml, and normal levels at 50-70 ng/ml. Levels above 80ng/ml are excessive, and severe toxicity, known as hypervitaminosis D or vitamin D intoxication occurs at levels above 150 ng/ml. This would require extremely high daily doses over a long period, with symptoms including bone pain and kidney problems, such as the formation of calcium stones. Progression to confusion, apathy, recurrent vomiting, abdominal pain, and dehydration may occur if supplements are not stopped.
Vitamin A is an essential nutrient critical to normal vision, gene expression, reproduction, embryonic development, growth, and immune function. All cells need vitamin A to grow, including hair-the fastest-growing organ in the body. Vitamin A also helps skin glands produce sebum to moisturize the scalp and keep hair healthy. Therefore, a diet lacking or over-supplying vitamin A can lead to hair loss. Both deficiencies and excess levels can contribute to disease states, and for hair, in particular, deficiency can lead to follicular hyperkeratosis. Vitamin A is part of a family of compounds including retinal, retinol, retinoic acid and carotenoids. Vitamin A deficiency is rare outside of developing countries and is unlikely to play a role in hair loss for the majority of patients. Notably, high intake of Vitamin A during pregnancy may be associated with birth defects. Excessive intake of vitamin A can lead to increased hair loss. And consuming too much vitamin A is toxic.
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Natural Sources: Vitamin A is found in a variety of meats, fish and vegetables, including carrots, salmon, kale, sweet potatoes, spinach, dried apricots, broccoli, butter, butternut squash, cantaloupe, mango, red bell pepper, goat cheese, peas, cow’s milk, tomato, beef liver, pumpkin, eggs and grapefruit. Sweet potatoes, carrots, pumpkins, spinach, and kale are rich in beta-carotene, a precursor of vitamin A. This vitamin can also be found in dairy products, eggs, cod liver oil, and can be supplemented through dietary supplements. In addition, Vitamin A is fat soluble and extensively stored in the liver, so for most people even prolonged periods of inadequate intake will not lead to clinical deficiency.
Recommended Daily Intake: The Recommended Dietary Allowance (RDA) for vitamin A is 900 micrograms (mcg) retinol activity equivalents (RAE) per day for men and 700 mcg RAE per day for women. This is equivalent to 3,000 international units (IU) for men and 2,333 IU for women.
Excess Intake Risks: Vitamin A toxicity is rare, with the most severe examples occurring after ingestion of polar bear liver, which can be fatal. Excess supplementation over 10,000 IU per day may produce symptoms including blurred vision, nausea, vomiting, dizziness and headache, nervous system effects, liver abnormalities, fatigue, muscle weakness, bone and skin changes and others. The adverse effects of both acute and chronic toxicity are reversed after consumption is stopped.
Vitamin C is necessary to absorb iron from your diet. Vitamin C is another essential nutrient required for the biosynthesis of collagen, L-carnitine, and certain neurotransmitters, and is also involved in protein metabolism. Collagen and other proteins are important for healthy hair growth. Vitamin C helps the absorption of plant-based iron, another important nutrient for healthy hair growth. Vitamin C is a powerful antioxidant that protects against oxidative stress from free radicals, which can hinder hair growth. Furthermore, the body requires vitamin C to produce collagen, an important part of hair structure. Severe Vitamin C deficiency produces scurvy, a life-threatening disease that includes follicular hyperkeratosis and corkscrew hairs. Interestingly, smokers have impaired Vitamin C absorption and need greater dietary intake.
Natural Sources: Natural sources of Vitamin C include all citrus fruits, red and green bell peppers, tomatoes, broccoli, brussels sprouts, potatoes, spinach, green peas, cantaloupe and strawberries. Strawberries, bell peppers, guavas, and citrus fruits are excellent sources of vitamin C.
Recommended Daily Intake: The RDA for Vitamin C is 90 mg daily for men and 75 mg daily for women, with higher intake during pregnancy and lactation.
Excess Intake Risks: Excess Vitamin C intake does not generally cause toxicity, but can result in gastrointestinal distress, insomnia, headaches and rarely kidney stones. Most excess Vitamin C is excreted unmetabolized in the urine.
Vitamin E is an antioxidant that can prevent oxidative stress. Vitamin E is best known for its role as an antioxidant and ability to reduce oxidative stress. Oxidative stress plays a role in many disease states and occurs naturally in the body as well as externally from environmental factors. In a study, subjects suffering from hair loss experienced a 34.5% increase in hair growth after taking vitamin E for 8 months, while the placebo group only saw a 0.1% increase. While its direct role in hair growth is poorly characterized, adequate intake of Vitamin E is beneficial and important for overall health.
Natural Sources: Natural sources of Vitamin E include wheat germ oil, avocados, almonds, mangos, sunflower seeds, peanut butter, bell peppers, fish and some meats. Sunflower seeds, almonds, spinach, and avocados are good sources of vitamin E. However, rather large quantities of these foods would be required to satisfy daily needs, such as five avocados or ten mangos daily, so oral supplements are a simpler method of maintaining adequate daily intake.
Recommended Daily Intake: The RDA for Vitamin E is 15 mg (22.5 IU) daily for men and women.
Excess Intake Risks: Toxic doses of Vitamin E begin at 20 times the RDA and may produce symptoms including nausea, diarrhea, stomach cramps, tiredness, dizziness, blurred vision and headache.
Folic Acid is a B vitamin and is one of the few vitamins that have a very specific potential benefit for hair growth in that it helps regulate keratin production, which is the primary protein of the hair shaft. A deficiency of Folic Acid may lead to thinning of the hair shafts as well as overall hair loss. However, there is little evidence that Folic Acid supplementation produces clinical benefits in most patients with hair loss. Individuals at greater risk of Folic Acid deficiency include those with alcohol use disorder, pregnant women, and those with malabsorptive disorders.
Natural Sources: Natural sources of Folic Acid include vegetables (especially dark green leafy vegetables), fruits and fruit juices, nuts, beans, peas, seafood, eggs, dairy products, meat, poultry, and grains. Spinach, liver, asparagus, and Brussels sprouts are among the foods with the highest folate levels.
Recommended Daily Intake: The RDA of Folic Acid is 400 mcg for both men and women, with higher intake during pregnancy and lactation.
Excess Intake Risks: Excess folic acid is excreted in urine. A high folate intake can mask vitamin B-12 deficiency until its neurological effects become irreversible. Other rare side effects include stomach upset, nausea, diarrhea, irritability, confusion, behavior changes, skin reactions and seizures.
Other group B vitamins help produce red blood cells, carrying oxygen and nutrients to the scalp and hair follicles. These processes are vital for hair growth. Group B vitamins can be obtained from various foods, including whole grains, almonds, meat, fish, seafood, and dark green vegetables. The only source of vitamin B12 is animal products, so if you are vegetarian, consider taking vitamin B12 supplements. Additionally, B vitamins can also be supplemented through dietary supplements.
Iron is responsible for carrying oxygen to your hair follicles so your hair can grow. Iron supplements may be recommended if you have hair loss as well as iron deficiency that is confirmed by laboratory tests. The most common nutritional deficiency in the world is iron deficiency, and iron deficiency is common in women with hair loss. Iron helps red blood cells carry oxygen to cells. This makes it an important mineral for various body functions, including hair growth. Iron deficiency leading to anemia is common among women and is a major cause of hair loss. However, the association between hair loss and low serum ferritin levels remains controversial. While testing for and correcting iron deficiency is always prudent, significant improvement in hair loss in these individuals cannot be assured.
Natural Sources: Iron is found in many natural sources, including meat, fish, poultry, fruits, vegetables, grains, and more. To boost iron intake, consider incorporating iron-rich foods such as clams, eggs, red meat, spinach, and lentils into your diet. Iron can also be supplemented through dietary supplements.
Recommended Daily Intake: The RDA for all age groups of men and postmenopausal women is 8 mg/day; the RDA for premenopausal women is 18 mg/day.
Excess Intake Risks: The upper limit for safe iron intake is 45 mg per day for adults. Excess iron is deposited in organs throughout the body and can cause organ damage due to the formation of reactive oxygen species. The liver, heart and endocrine glands are the most notable organs with iron deposition. Extremely high doses can cause organ failure, coma, convulsions and death.
Zinc plays a crucial role in hair tissue growth and repair, and helps keep the sebaceous glands around the hair follicles functioning properly. Zinc is an essential trace element, and severe zinc deficiency is associated with hair loss in infants with poor nutrition, malabsorption conditions, alcohol use disorder and pregnancy. Hair loss is a common symptom of zinc deficiency. The role of zinc in most forms of hair loss is poorly established, and supplements do not reliably result in hair growth in most individuals.
Natural Sources: Natural sources of zinc include oysters, meat, eggs, fish, nuts and dark chocolate. It's better to obtain zinc from natural food sources like oysters, beef, spinach, wheat germ, pumpkin seeds, and lentils.
Recommended Daily Intake: The RDA for adults is 8 mg/day for women and 11 mg/day for men.
Excess Intake Risks: Excess zinc intake symptoms include nausea, vomiting, loss of appetite, abdominal cramps, diarrhea and headaches. Excessive supplementation can lead to hair loss, so it's better to obtain zinc from natural food sources
Magnesium is a mineral that plays a role in the functioning of enzymes involved in DNA and RNA synthesis, as well as in cell replication. Thus, it helps support normal hair shaft growth. Magnesium is also involved in the production of proteins including keratin, the primary component of the hair shaft. While magnesium deficiency is suspected as playing a role in hair loss and some forms of gray hair, strong evidence is lacking. Most people get enough magnesium from their diet and do not need to take supplements.
Natural Sources: Magnesium is found in many plant and animal foods, including bananas, leafy green vegetables, fruits, beans, soy products, seafood and dairy.
Recommended Daily Intake: The RDA of magnesium for adults is 400-420 mg per day for men and 310-320 mg per day for women.
Excess Intake Risks: Magnesium toxicity is rare with symptoms including irregular heartbeat, low blood pressure, confusion, slowed breathing, coma and death.
Vitamins and supplements may support hair growth by providing essential nutrients that might be missing from your diet. While individual results vary, products rich in vitamins B, C, and D, iron, zinc, and omega-3 fatty acids have been linked to healthier hair. It’s important to choose products based on scientific research and to have realistic expectations about their effectiveness.
With rare exceptions noted in this discussion, the availability of vitamins and minerals in a varied and healthy diet makes supplementation unnecessary for most individuals. When supplements are desired, there are many choices for multivitamins or individual vitamins that are readily available and inexpensive. There are also several heavily marketed “hair loss” supplements that are very expensive and that lack scientific credibility. The reader is cautioned to be skeptical of these products.
Vitamins and supplements work differently depending on their ingredients and mechanisms. For example, some address nutrient deficiencies, such as biotin, zinc, and iron, that may be causing hair loss or thinning. Other supplements work by promoting the growth phase of hair. Ingredients like marine-based complexes, seen in Viviscal, or collagen peptides provide the building blocks for keratin production, the primary protein in hair.
Certain botanicals and antioxidants, like horsetail extract or vitamin C, may also support hair health by reducing oxidative stress, which can damage follicles.
It’s important to note that not all supplements or ingredients are backed by strong scientific evidence, and their effectiveness can vary from person to person. Setting realistic expectations and consulting a healthcare professional can help ensure safe and effective use.
Hair growth supplements and vitamins can cause side effects, especially if taken in high doses or by individuals with sensitivities. Common issues include:
Long-term use of some supplements, particularly those with high doses of specific nutrients, may also elevate risks of chronic conditions like diabetes or cardiovascular issues.
It’s essential to follow dosing recommendations and consult a healthcare professional, especially if you’re taking other medications or have underlying health conditions.
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