How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Biotin (vitamin B8)
B vitamin sold for hair and nails. No randomised trial has tested its effect on hair, and it can distort numerous blood tests.
Benefits
- Brittle nails: 63% of the 35 patients taking it saw their nails improve (retrospective study, without placebo)
- Fragile hair or nails linked to a disease: improvement in the 18 published cases compiled by a review; no sufficient evidence in healthy people
- Associated with chromium picolinate in 447 poorly controlled type 2 diabetics: HbA1c down by 0.54% more than with placebo
- At a high dose (61.4 µmol per day for 28 days), triglycerides and VLDL lower in type 2 diabetics and people with high triglycerides
Precautions
Biotin skews numerous blood tests: in 6 healthy adults, 10 mg per day for 7 days skewed 9 of the 23 assays studied. One patient thus presented false Graves' disease results, which returned to normal upon stopping biotin. In a survey, 7.7% of patients interviewed at consultation were taking it, and 7.4% of samples taken in the emergency department contained enough to skew certain tests. Inform your doctor and the laboratory before a blood test. For troponin, the heart attack marker, the risk of a false result was deemed extremely low in two patient cohorts. Also worth knowing: no randomized trial has tested biotin on hair loss or quality in humans, and its popularity far exceeds the evidence. In progressive multiple sclerosis, the first trial was positive, but the large phase 3 trial (642 patients) showed no effect on disability or walking. Diabetes trials test biotin with chromium, which makes it impossible to know which of the two acts.
Recommended dosage
2 mg per day, with chromium picolinate, in diabetes trials; no dose tested in a controlled trial for hair or nails.
How to take it
- For whom: the only controlled trials involve patients (type 2 diabetes, multiple sclerosis); for hair and nails, there are only published cases and a retrospective study.
- Hair loss: a study in women complaining of it finds a biotin deficiency in 38% of them, and advises against taking any without a demonstrated deficiency.
- Dose: 2 mg per day, combined with chromium picolinate, in the two diabetes trials (43 and 447 patients).
- Very high dose: 100 mg three times a day in trials on progressive multiple sclerosis, a medical treatment with no effect on disability in the large trial of 642 patients.
- Before a blood test: 10 mg per day for 7 days was enough to skew 9 of the 23 assays tested in healthy adults; biotin is rapidly eliminated from the body, says the AACC guide.
- Timing and meals: no study in this file compares the timing of intake nor intake during a meal.
Did you know?
In the first trial on progressive multiple sclerosis, 12.6% of patients on a very high dose of biotin (300 mg per day) saw their disability decrease, compared to none on placebo. The subsequent trial, four times larger, found nothing.
What the studies say
This phase 3, randomized, double-blind, placebo-controlled study evaluated the efficacy and safety of high-dose biotin (100 mg, three times daily) in 642 patients with progressive multiple sclerosis. The study showed no significant improvement in disability or walking speed compared to placebo. In addition, biotin led to inaccurate laboratory results and is therefore not recommended for the treatment of progressive multiple sclerosis.
Cree BAC, Cutter G, Wolinsky JS, Freedman MS, Comi G, Giovannoni G, Hartung HP, Arnold D, Kuhle J, Block V, Munschauer FE, Sedel F, Lublin FD, SPI2 investigative teams. — The Lancet. Neurology (2020) — View the source study
Pairs well with
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more