Biotin, also called vitamin B7 or vitamin H, is an essential, water-soluble vitamin that plays a key role in metabolizing fats, carbohydrates, and amino acids. The nutrient is relatively stable and easily accessible, but some people cannot process it, and this results in a range of health problems. Biotin deficiency is a rare condition that affects mental, physical, and psychological processes and requires a quick response before it cascades into something more serious.

Dietary Causes of Biotin Deficiency

People limit or adjust their food intake for many reasons, and certain long-term diets can lead to biotin deficiency. For example, those who consume large amounts of raw egg whites for long periods may become deficient. Raw eggs whites contain avidin, a protein that binds irrevocably to biotin and simply carries it through the body until it is eliminated in urine. Antibiotics can also cause deficiencies because they kill both unhealthy and healthy bacteria in the gut; the healthy kind naturally produces biotin. People being fed through an IV are also prone to this deficiency.

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Lifestyle Causes

Smoking is one lifestyle choice that can lead to biotin deficiency. One study shows that women who smoke are more likely to experience biotin catabolism. This breakdown of vitamin B7 results in biotin depletion and increased production of byproducts excreted in urine. Excessive alcohol intake can also reduce biotin levels in the blood, and tests suggest liquor inhibits biotin absorption in the small and large intestines.

smoking chronic alcohol Terroa / Getty Images



Phenylketonuria is an inherited genetic disorder that renders the body incapable of metabolizing the essential amino acid phenylalanine. As a result, the amino acid builds up in the blood to toxic levels and causes intellectual disability, mental disorders, and even heart problems. Studies show that in children with phenylketonuria, the biotin recycling process is impaired, resulting in lower biotinidase activity and seborrheic dermatitis, a common skin condition.

phenylketonuria phenylalanine amino acid Hailshadow / Getty Images


Biotin Deficiency and Skin

Biotin deficiency causes skin infections that can manifest in various ways. It can cause erythematous dermatitis; blood flow increases to address injury or inflammation, causing redness of the skin and mucous membranes. Skin lesions caused by biotin deficiency can contain the pathogen Candida albicans, which is behind many fungal infections including genital yeast.

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Hair Loss and Brittle Nails

Hair roots are comprised of protein cells, and blood vessels transport food to the roots, creating more cells. As this process continues, hair is pushed through the skin. Nails operate similarly, using the protein keratin to harden the nail cells as the old ones are pushed out from the root bed. Biotin deficiency interrupts amino acid metabolism, leading to partial or complete hair loss and brittle nails.

hair loss brittle nails Sittisak Therdbaramee / Getty Images



Myelin is a layer of insulation surrounding nerve fibers; it is made from proteins and fats that allow quick transmission of impulses. Damage to the myelin in turn damages peripheral nerves and slows down these impulses, which is what happens to people with multiple sclerosis. Biotin deficiency causes paresthesia: random, abnormal skin sensations, such as tingling, prickling, or burning.

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Effect on the Immune System

Dendritic cells are the sentinels of the immune system. They initiate the immune response by examining, converting, and presenting antigens in a way the body's T cells can recognize. Research suggests that biotin deficiency stimulates cytokines, which promote inflammation in the body and may contribute to certain inflammatory disorders, such as chronic obstructive pulmonary disease and asthma.

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Biotinidase Deficiency

There are two types of biotinidase deficiency, a genetic disorder that prevents the body from recycling biotin: partial and profound. Partial biotinidase deficiency is the milder form, causing symptoms such as skin problems, alopecia, and candidiasis. The profound type prompts these symptoms, affects balance and causes developmental delays and seizures. One in 61,000 people has a partial deficiency, while one in 140,000 has the more severe form. Left undiagnosed, biotin and biotinidase deficiencies can be life-threatening.

biotinidase enzyme seizures Gilnature / Getty Images


BTD Gene Mutation

A mutation of the BTD gene, which provides instructions for the creation of biotinidase enzymes, prevents the body from breaking down proteins and creating free biotin. Free biotin activates another set of enzymes called carboxylases that aid metabolism. Biotinidase deficiency presents within a few months of birth or during childhood. To diagnose it, specialists can conduct newborn screening and genetic tests.

BTD gene carboxylases Christoph Burgstedt / Getty Images


Treatment Options

Doctors who suspect biotin deficiency may take a patient's family history and do a blood test. For treatment, they may recommend over-the-counter biotin supplements and foods rich in biotin, such as nuts, salmon, and meat. Cooked eggs, especially the yolk, are on the list of biotin-rich foods, because cooking breaks down 60 to 70 percent of the avidin, leaving more free biotin. For those with diagnosed biotinidase deficiency, a consistent diet and supplementation of five to ten milligrams of biotin daily are required to avoid or mitigate complications.

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