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Vitamin B7 (Biotin)

Biotin is more than skin-deep -- it helps all the way down to the cellular level. Learn everything you need to know about biotin in this week's feature of the Vitamin, Minerals, and Supplements Series!

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What is vitamin B7 ?

Vitamin B7, better known as biotin, is renowned for its role in keeping hair and nails healthy. It was even called vitamin H initially, based on the German words for hair and skin.

However, healthy individuals should be getting enough biotin in a balanced diet, and little research supports its use as a supplement to promote hair or nail growth. What most people don’t know is that biotin is essential to many processes involved in normal metabolism.

The word “biotin” comes from the Greek “biotos”, meaning life or sustenance. Many B vitamins are crucial to life, but biotin especially is important during pregnancy and embryonic growth. Organs including your skin, eyes, liver, and nervous system can’t function properly without it.

What does the body use biotin for?

Biotin has multiple crucial roles in the human body. It helps assist in the process of breaking down fats, carbohydrates, and proteins from the food we eat. In other words it is a micronutrient that helps metabolize macronutrients.

Another amazing activity of biotin is its ability to help in the process of regulating cell signals and genetic activity. In other words. Biotin is more than skin-deep -- it helps all the way down to the cellular level.

Recommended Amounts

Dietary Reference Intakes (DRIs)

The amount of vitamin B7 recommended for daily intake is based on the Adequate Intake (AI) level. This is the level assumed adequate to meet nutritional needs. An AI is established when there is not enough evidence for a Recommended Dietary Allowance, or RDA.

Helpful terms to know

  • Recommended Dietary Allowance (RDA): covers the needs of 97-98% of individuals in a group; the average amount of a nutrient a healthy person should consume daily. Vary by gender, age, and whether a woman is pregnant or breastfeeding. Developed by the Food and Nutrition Board at the Institutes of Medicine (IOM) of the National Academies.

  • mcg = micrograms

  • Adequate Intake (AI): recommended daily intake of a nutrient; established by Institute of Medicine (IOM) to meet or to exceed the needed amount to maintain adequate nutrition for most people in a particular stage of life or gender group; established when not enough evidence is available to determine the RDA


In the United States, biotin deficiency is rare. Most people in the western population get about 35-70 mcg/day from their diet, which is more than adequate.

Who is at risk for a biotin deficiency?

Certain populations may run the risk of a biotin deficiency.

The following conditions may increase the need for vitamin B6:

  • Individuals with alcoholism

  • Pregnant women

  • Congenital lack of biotinidase

  • Inflammatory bowel disorders

  • Smoking

  • Antibiotics or other medications

  • High intakes of avidin

Biotin Deficiency During Pregnancy

According to recent studies, biotin is broken down at an increased rate during pregnancy. Marginal deficiency, in other words mild or slight deficiencies, occur in 50% of cases despite having a normal dietary intake.

About Avidin

Avidin is a protein found in the following foods:

  • Raw eggs

  • Mayonnaise

  • Caesar dressing

  • Eggnog

If you regularly eat these foods in high amounts, you might want to reconsider. Avidin is a protein found in raw eggs, and it binds to biotin. This can result in biotin absorption in the gastrointestinal (GI) tract being prevented.

When you cook eggs, avidin is broken down by the heating process. Cooked eggs can be a great source of biotin, so if you are looking to up your biotin intake it might be worth the switch from raw eggs to cooked.


Biotin deficiency was first observed in rats, and then in human studies where similar symptoms resulted. Potential symptoms of a biotin deficiency include:

  • Neuromuscular dysfunction

  • Alopecia

  • Dermatitis

Brittle nails, scaly rashes, and thinning hair are signs of a biotin deficiency. Since biotin is involved in so many functions of the body, high cholesterol or heart problems may also indicate a deficiency. Remember, deficiency of biotin is rare and research has not promoted biotin use to restore hair loss, nail health, or skin health.

Biotin can be used for specific dermatological conditions, but it is not often expressly indicated for the uses that popular beauty products claim on their product’s bottles. Often, a balanced diet can be the best thing for hair, skin, and nail health.


Even with high intakes, biotin has not been shown to be toxic to humans. Excess amounts of this vitamin leave the body through the urine, since biotin is a water-soluble vitamin.

There is not a toxic limit or upper limit (UL) established for biotin, and most people report tolerating biotin supplements well. However, some people report having nausea, cramping, diarrhea, or digestive discomfort associated with biotin supplementation.


Excess biotin can produce a false positive in lab tests for thyroid disease. Be sure to mention to your healthcare team any supplements you take, especially if thyroid conditions are likely to be the diagnosis.

How To Determine Biotin (Vitamin B7) Levels

Few tests are available that are reliable indicators of biotin status. Like other water-soluble vitamins, blood work and urine analysis can give clinicians an idea of biotin intake. However, these indicators do not decrease sufficiently in people with marginal deficiencies to be detected.

These tests should be run under direct medical supervision. Ask your doctor and dietitian for more information. Your vitamin status can be assessed through measurement of the following:

  • Serum Biotin Status

    • Healthy Adults: 133-329 pmol/L

  • Urine

    • Healthy Adults: 18-127 nmol/24 hours

    • Abnormally low excretion of biotin is an indicator of deficiency

Due to some of the limitations of these tests, multiple exams and tests should be performed in order to establish a true deficiency.

Sources of Vitamin B7

Biotin is found in many foods, including both animal and plant products. It is produced also by the bacteria in the gut and in breastmilk.

How stable is biotin?

The stability of biotin is excellent, especially in dry products. In strong acids, biotin is unstable. In other words, evidence indicates that in foods, biotin shows good stability.

Losses of 10-15% biotin occur during the processing of evaporated and powdered milk. Biotin is fairly stable to air, daylight, and heat but destroyed by ultraviolet (UV).

Studies show pharmaceutical liquid losses of up to 12% and changes in pH after 1 year at room temperature. Essentially, this means it is important to follow recommended expiration dates and when in doubt, reach out to the manufacturer and request information about shelf life.

Supplementation & Treatment with Vitamin B6

Uses & Treatment

In most individuals, supplementation of biotin is most likely unnecessary. Supplemental vitamin B7 can be prescribed for a few reasons, under appropriate medical direction and supervision following medical diagnosis and prescription, for the following:

  • Dermatological conditions (i.e. acne)

  • Hypoglycemia

  • Hyperlipidemia

  • Glucose control


Hair and Nail Health

The majority of research finds that people taking biotin had an underlying cause for poor hair or nail growth that wasn’t a biotin deficiency. However, most cases also show improvement upon supplementation. This means that eating a balanced diet to meet biotin needs, and supplementing under proper medical supervision, may cause improvements in overall health.

Reducing the Risk of Side Effects

Taking supplements with food can help to lessen the side effects. It’s always a good idea to talk with your dietitian or doctor if you are confused about potential risks, benefits, proper dosage, or absorption. Also, be sure to follow the directions on the label unless expressly directed otherwise by your health provider.

The Bottom Line

Although most people are likely meeting their biotin needs, biotin in supplement form is extremely well-tolerated. Although studies show it doesn’t quite elicit the hair and nail growth properties popular brands may claim, biotin can be used under the supervision of your healthcare provider to improve certain dermatological conditions or correct deficiencies due to other circumstances, such as pregnancy.


FREE Patient Resources

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Products for Professionals

Blanking on biotin? It's hard to keep track of all the vitamins! With this easy to navigate 5-page guide, never forget the facts again! With purchase, a high-quality PDF file will be available for download. Turn it into posters, handouts, and even more. It's simply the best way to brush up on biotin before meeting with a patient!





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Onder AB, Guven S, Demir S, Mentese A, Guvendag Guven ES. Biotin deficiency in hyperemesis gravidarum. J Obstet Gynaecol. 2019;39(8):1160-1163. doi:10.1080/01443615.2019.1604640

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Piraccini BM, Berardesca E, Fabbrocini G, Micali G, Tosti A. Biotin: overview of the treatment of diseases of cutaneous appendages and of hyperseborrhea. G Ital Dermatol Venereol. 2019;154(5):557-566. doi:10.23736/S0392-0488.19.06434-4

PubChem. Biotin (Compound). National Institutes of Health. 2021.

Saleem F, Soos MP. Biotin Deficiency. In: StatPearls. Treasure Island (FL): StatPearls Publishing; April 20, 2020.

Stevens CJ. Health Benefits of Biotin. Healthline. 2019.

The Nutrition Source. Biotin -- Vitamin B7. Harvard School of Public Health. 2021.


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