Biotin (B7)

Water-soluble · carboxylases

What does Biotin (B7) do in your body?

A coenzyme for enzymes that process fats, carbohydrates and amino acids. Popular for hair and nails, but evidence there is thin.

What does Biotin (B7) do?

Helps carboxylase enzymes in fatty-acid synthesis, glucose production and amino-acid breakdown.

Where does Biotin (B7) act in the body?

Liver and every cell's mitochondria.

Which foods contain Biotin (B7)?

Eggs (cooked), organ meats, salmon, seeds, nuts, sweet potato.

How much Biotin (B7) do adults need?

Adequate Intake: 30 mcg for adults. No upper limit set.

What happens with too little Biotin (B7)?

Rare; can cause hair thinning and scaly rash. Regularly eating raw egg whites can block biotin absorption.

Can you get too much Biotin (B7)?

No toxicity known, but high-dose supplements can make some lab tests wrong (including thyroid and heart tests). Tell your clinician if you take them.

What does Biotin (B7) interact with?

Interferes with many lab tests that use biotin–streptavidin technology.

What is known and unknown about Biotin (B7)?

Evidence that biotin improves hair or nails in people without deficiency is limited.

Evidence & sources

• High-dose biotin supplements can cause falsely high or low results on some lab tests. Evidence: regulatory. Known: FDA safety communication after reported incidents, including a missed heart attack diagnosis. Unknown: Which tests and doses are affected varies by lab. Source: US FDA, Biotin interference with laboratory tests — safety communication (2017, updated 2019).

Connected topics

• Energy Metabolism
• Egg
• Thyroid

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General education only, not medical advice. Drafted Oct 2026 · pending qualified expert review.