Biotin is a B vitamin also known as vitamin H or B-7. Biotin helps convert carbohydrates into glucose, which the body uses for energy. It also helps the body process fats and protein, and the nervous system to function. B complex vitamins are needed for healthy skin, hair, eyes, and for liver functioning.
Biotin is available in small amounts in some foods. Additionally, the microbiome, which is the bacterial population living in the intestines, makes biotin. Similar to all B vitamins, biotin is water-soluble. That means it dissolves in the water inside the body and cannot be stored.
People with health conditions that impact how the body absorbs nutrients, or who are on certain medications, can be at risk of developing biotin deficiency. Biotinidase deficiency (BTD) is the most common cause of biotin deficiency. BTD is a rare inherited disorder where the body is not able to use biotin and leads to biotin deficiency. It is caused by a mutation in the BTD gene. This gene instructs the body on how to make the enzyme biotinidase, which the body needs to extract biotin from food. BTD affects approximately one in 60,000 new-born babies.
Babies with BTD tend to start showing symptoms of the condition in the first weeks or months of life. The most common symptoms include hypotonia or weak muscles, seizures, alopecia or hair loss, eczema, and developmental delay.
Factors that put people at risk of developing biotin deficiency include being on parenteral nutrition, which means being fed intravenously, for long periods; taking anti-seizure medication over a long period, which can lower the body’s biotin levels; taking antibiotics over a long period, as these can destroy the biotin-producing bacteria in the gut; having a condition, such as Crohn’s disease, that makes it hard for the gut to absorb nutrients; having excessive exposure to alcohol, which inhibits biotin absorption.
Symptoms of biotin deficiency start gradually and can build up over time. These symptoms can include thinning hair, progressing to loss of hair across the body, and a scaly, red rash around body openings, including the eyes, nose, mouth, and anus. Conjunctivitis can also develop. Adults with biotin deficiency may suffer seizures, skin infections, brittle nails, as well as neurological problems, such as depression, lethargy, hallucinations, and paraesthesia (pins and needles) in the extremities.
While symptoms of BTD may disappear with medical assistance, a person may need to take biotin for the rest of their life.