Biotin: its role in DNA, diet and health
What it found
Biotin is needed for many body processes, and people get it from food and gut bacteria.
The exact amount people need is still uncertain.
What they found
Studies in people
Supplements for hair and nails
Biotin supplements are promoted for hair, skin and nail health, but only limited clinical evidence supports these claims.
High doses
Doses up to 10 mg a day are added to hair, nail and skin supplements. Doses up to 300 mg a day are used for people with biotinidase deficiency or multiple sclerosis.
Animal and lab studies
Biotin and bacteria
In lab tests, biotin helped some bacteria grow, including tuberculosis bacteria. Blocking biotin production weakened several harmful bacteria.
Other findings
What biotin does
Biotin helps break down fats, amino acids and make glucose. It also plays a role in DNA copying and gene control.
Where biotin comes from
Humans cannot make biotin. They get it from food like egg yolk, liver and some vegetables, or from gut bacteria.
How much is needed
The exact amount of biotin people need is not known. Recommended intake for different ages ranges from 5 to 35 micrograms a day.
What the authors conclude
“The exact human requirement of biotin is not known; therefore, the average intake (AI) is calculated based on the average biotin intake by the healthy population, and the recommended AI of biotin is 30–40 µg/d for men and women”
Also in their conclusions
- They say the exact human requirement of biotin is not known.
- They note that biotin supplements promote hair, skin and nail health, but only limited clinical evidence supports these claims.
- They highlight the need to address key findings and limitations in biotin research.
How it was done
The biotin market is growing, so the authors wanted to review what is known and what is still unclear about biotin.
They reviewed existing research on biotin, from how it is made in cells to its use in supplements.
What it can’t tell you
- This is a review of many studies, not a new experiment. It cannot show cause and effect.
- The exact amount of biotin people need is still uncertain.
- Most of the findings on bacteria and cells may not apply to people.
Who paid
- Conflicts
- Declaration of competing interest The authors declare no conflict of interest.
- Authors work at
- University of Copenhagen, Denmark; University of Liverpool, UK
The paper
- Title
- Biotin: DNA to diet
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Karalia S, Meena VK (2025). Biotin: DNA to diet. The Journal of nutritional biochemistry. doi:10.1016/j.jnutbio.2025.110081Free full textPubMed 40854404DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error