Radiance & Glow

About biotin

A B vitamin your body cannot make for itself. It switches on five enzymes — the ones that build fats, break down protein, and make glucose between meals.

Running low shows up as a scaly rash around the eyes, nose and mouth, thinning hair that can include eyebrows and eyelashes, low mood, tiredness and pins and needles. Most people eating normally do not run low: gut bacteria make some, and your body recycles what it has.

Who is more likely to be low

• Crohn’s, colitis, celiac disease, or any gut condition that affects absorption
• Bowel surgery, including weight-loss surgery, or a shortened bowel
• Long or repeated courses of antibiotics — some of your biotin comes from your own gut bacteria
• A disturbed gut microbiome for any other reason, including after illness
• Regular alcohol — it blocks the same transporter that absorbs biotin
• Getting older, as absorption generally becomes less efficient
• Pregnancy, where low levels are common even on a normal diet
• Smoking, which speeds up how fast biotin is broken down
• Some anti-seizure medicines — carbamazepine, phenytoin, phenobarbital
• Isotretinoin and some other long-term medicines
• Long-term tube or drip feeding that does not include biotin
• Chronic kidney disease or dialysis
• A rare inherited fault in the enzyme that recycles biotin — screened for at birth in the US since the 1980s

What the evidence shows

If you are low, replacing biotin works — the skin and hair recover. If you are not low, the evidence that extra biotin improves hair, skin or nails is thin: the main review found 18 reported cases, nearly all in people who were deficient. We would rather tell you that than sell you a promise. If you think you may be low, ask us to measure it.