ONCE › Ingredients › Biotin
Hair & nails
Biotin
What it is
Biotin is a B vitamin involved in keratin production, the protein that makes up hair and nails.
Why it is in ONCE DUSK
It is the ingredient most associated with hair and nail supplements, and also the one most often abused with a number chosen to look impressive on a label.
Why this dose
2,500 mcg is the dose used in the nail research. It is deliberately NOT 10,000 mcg. High dose biotin is well documented to interfere with laboratory blood tests, including thyroid and troponin assays, which is a real clinical problem rather than a theoretical one. DUSK holds the studied dose and stops there.
Held deliberately below the lab-assay interference threshold. Do not increase.
How it works with the rest of the formula
Biotin works on keratin, and zinc is involved in the same structural proteins, which is why they sit together in the hair and nails group along with copper. None of the three is dosed at a headline-grabbing number, and that is deliberate.
What to look for on any label
This is the ingredient where a bigger number is a warning sign rather than a selling point. Megadose biotin, meaning 5,000 to 10,000 mcg, is documented to interfere with laboratory blood tests including thyroid and troponin assays. Troponin is the test used to diagnose a heart attack. That is a genuine clinical problem, and a brand printing 10,000 mcg on the front is optimising for the label rather than for you.
Biotin helps if you are short of it. If you are not deficient, the evidence that more biotin produces more hair is weak. Tell your doctor you take it before any blood work.
Questions
Why only 2,500 mcg of biotin and not 10,000?
2,500 mcg is the dose used in the nail trials. Megadose biotin is documented to interfere with lab blood tests including thyroid and troponin assays. DUSK stays at the studied dose deliberately.
Does biotin interfere with blood tests?
High dose biotin does. It is a recognised clinical issue. DUSK is held below the interference threshold, but tell your doctor about any supplement before blood work.
Does biotin actually grow hair?
It helps if you are deficient. If you are not, the evidence is weak. Any brand promising hair growth from biotin alone is overselling it.
Related actives
Biotin is one of 19 actives in one scoop.ONCE DUSK · night time beauty + rest · every milligram printedThese statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This page is educational and is not medical advice. If you are pregnant, nursing, or taking prescription medication, speak to your doctor first.