Biotin: Hair, Skin, and Nails — Science-Based Guide

What is biotin and why is it popular?

Biotin (vitamin B7, formerly known as vitamin H) is a water-soluble B vitamin needed for various metabolic processes. It has become one of the most popular beauty supplements, especially for strengthening hair, skin, and nails.

Biotin is found naturally in many foods: eggs (especially yolks), nuts, sweet potatoes, spinach, broccoli, and whole grains.

Biotin's roles in the body:

• Fatty acid synthesis
• Amino acid metabolism
• Gluconeogenesis (glucose production)
• Keratin production (hair, skin, nails)
• Gene expression regulation

Does biotin really help with hair loss?

This is the most popular question about biotin and the answer is nuanced.

Important distinction:

• Biotin deficiency → biotin definitely helps
• Adequate biotin levels → benefit is limited

Biotin deficiency causes:

• Hair loss and thinning
• Brittle nails
• Reddish, scaly skin (especially around nose and mouth)

Patel et al. (2017) — review of 18 studies:

• All cases of hair growth improvement had an underlying biotin deficiency or a condition affecting biotin absorption
• In people with healthy biotin levels, additional biotin showed no convincing hair growth improvement

Who is at risk of biotin deficiency:

• Pregnant and breastfeeding women (deficiency in 50% of pregnant women)
• Alcoholism
• Long-term antibiotic use
• Certain genetic conditions (biotinidase deficiency)
• People consuming large amounts of raw egg whites (avidin binds biotin)
• Inflammatory bowel disease patients

What do studies say about nail strengthening?

For nails, biotin evidence is stronger than for hair.

Colombo et al. (1990):

• 2.5mg biotin daily for 6 months
• Nail thickness increased by 25%
• 63% of participants reported stronger nails

Hochman et al. (1993):

• Biotin supplementation improved brittle and splitting nails
• 3 to 6 months of use needed to see results

Nail growth is slow (3-6mm per month), so results appear only after several months.

Does biotin affect skin and skin health?

Biotin deficiency causes characteristic skin appearance:

• Perioral dermatitis (reddish skin around mouth)
• Seborrheic dermatitis
• Dry and scaly skin

Biotin supplementation helps these symptoms when deficiency is present.

Important skin connections:

• Biotin supports keratin production — skin's primary structural protein
• Supports fatty acid synthesis — needed for skin barrier function
• Improves skin problems when deficiency is present

What is the correct biotin dose and what are the risks?

Dosing Table

WARNING: Biotin affects blood tests!

This is critically important knowledge:

• Biotin at high doses (>1000mcg) interferes with immunoassays
• Can give false-positive results on thyroid tests
• Can give false-negative results on troponin tests (heart attack)
• FDA issued a warning (2017)

What to do:

• Stop biotin 48-72 hours before blood tests
• Inform your doctor about biotin use
• Especially important for thyroid, cardiac, and hormone tests

Side Effects

• Biotin is generally very safe (water-soluble, excess excreted in urine)
• Rarely: acne at high doses (may interfere with B5 absorption)
• Digestive issues (rare)

Explore our biotin selection and find the right product.

Summary

Biotin is a beneficial supplement, especially for deficiency:

• Nails: Strengthens nails (stronger evidence)
• Hair: Helps with deficiency, limited benefit at normal levels
• Skin: Effective for deficiency symptoms
• Dose: 2500-5000mcg for hair and nails
• WARNING: Stop 48-72h before blood tests!
• Time: Results in 3-6 months

Read more: Biotin: A Science-Based Guide

References

1. Patel DP, Swink SM, Castelo-Soccio L. (2017). A review of the use of biotin for hair loss. Skin Appendage Disorders, 3(3), 166-169.
2. Zempleni J, Wijeratne SSK, Hassan YI. (2009). Biotin. BioFactors, 35(1), 36-46.
3. Hochman LG, Scher RK, Meyerson MS. (1993). Brittle nails: response to daily biotin supplementation. Cutis, 51(4), 303-305.
4. Colombo VE, Gerber F, Bronhofer M, Floersheim GL. (1990). Treatment of brittle fingernails and onychoschizia with biotin: scanning electron microscopy. Journal of the American Academy of Dermatology, 23(6), 1127-1132.
5. Mock DM. (2017). Biotin: from nutrition to therapeutics. The Journal of Nutrition, 147(8), 1487-1492.