Biotin (Vitamin B7): What It Does, Where to Get It and When Supplements Make Sense

Biotin, also known as vitamin B7 or vitamin H, belongs to the B-complex family. It has become famous thanks to shampoos, gummies and capsules promising better hair and nails, yet its real role in the body is both broader and more modest than the marketing suggests. Here is a clear, practical look at what it does, where to find it and when a supplement may be worth considering.

What biotin does in the body

Biotin works as a coenzyme, meaning it helps certain enzymes do their job. It takes part in the processing of carbohydrates, fats and proteins, supporting normal energy metabolism. It is also involved in making fatty acids and in the breakdown of some amino acids.

Because it is water-soluble, the body does not store much of it, and the excess is mostly lost in urine. That is why a regular intake from food matters.

What about hair, skin and nails?

This is where expectations run highest. Biotin contributes to the normal maintenance of hair and skin, and a true shortage can cause hair thinning, dry skin and brittle nails. However, in people who already get enough, the evidence that extra biotin makes hair grow faster or nails grow stronger is limited. It is not a treatment for baldness and it is not a guaranteed fix.

If you are noticing significant hair loss, it is wiser to look for the cause with a doctor or dermatologist. Stress, low iron, thyroid problems and hormonal changes are common culprits.

Food sources of biotin

Biotin occurs in many everyday foods, so a varied diet usually covers it. Good sources include:

• Cooked eggs, especially the yolk;
• Liver and other organ meats, in moderation;
• Oily fish such as salmon and sardines;
• Nuts and seeds, including almonds, walnuts and sunflower seeds;
• Legumes such as beans, chickpeas and lentils;
• Sweet potatoes, mushrooms, avocado and cauliflower;
• Whole grains and dairy products.

One curious detail: raw egg white contains a protein called avidin, which binds biotin and makes it harder to absorb. Cooking the egg neutralises it. Regularly eating large amounts of raw egg whites is not a good idea.

When a deficiency can happen

Biotin deficiency is uncommon in people who eat a varied diet. It can appear in particular situations, such as:

• heavy, long-term alcohol use;
• pregnancy and breastfeeding, when needs may rise;
• some medicines, such as certain anti-seizure drugs taken for a long time;
• conditions that reduce nutrient absorption in the gut;
• rare inherited disorders such as biotinidase deficiency, usually picked up by newborn screening.

Possible signs include hair loss, a scaly rash around the mouth or eyes, fatigue and tingling in the hands and feet. Since these symptoms are non-specific, please do not assume biotin is the problem on your own. Speak with your doctor.

Supplements: what to know

Biotin supplements often contain doses far above what food provides. They are generally well tolerated, but there is one important warning: high doses can interfere with blood tests, skewing results for hormone panels, thyroid tests and even cardiac markers, which may lead to misleading readings. If you take biotin, always tell your doctor and ask whether you should pause it for a few days before blood work.

It is also sensible to check with a doctor or pharmacist before starting, particularly if you are pregnant, breastfeeding, taking regular medication or due for routine tests.

The short version

1. Biotin is key to energy metabolism and is found in many foods.
2. A varied diet usually meets your needs.
3. For hair and nails, supplements have no guaranteed effect if you are not deficient.
4. Always mention supplements to your healthcare team because of lab tests.