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What is biotin?

Biotin Poached Egg

Biotin is a B-complex vitamin required for all organisms!

Biotin is a water soluble vitamin, generally classified as a B-complex vitamin and is required by all organisms. It is obtained from food however most foods are poor sources of biotin, so a low intake is common (exceptions are biotin-rich foods such as egg yolk, kidney, liver and some cheeses). Scientists have also discovered that a portion of the biotin we use comes from the intestinal flora (such as E coli and bifidobacteria) found in a healthy human gut.

Biotin deficiency

Biotin deficiency was once thought to be rare because such small amounts are required and clinical signs of deficiency are non-specific. However, recent findings are shifting the clinical outlook for biotin deficiency.

Biotin deficiencies of various degrees have been shown to develop in normal pregnancies and in patients on long-term anticonvulsant therapy. Symptoms of biotin deficiency include; hair loss, red scaly rash around the nose, mouth and genital area, brittle nails, Candida dermatitis, unusual odour to the urine, immune deficiencies and muscle weakness. Some neurological symptoms of deficiency reported in adults have also included depression, lethargy, hallucination and numbness and tingling of the extremities. Individuals with hereditary disorders of biotin metabolism resulting in functional biotin deficiency have evidence of impaired immune system function, including increased susceptibility to bacterial and fungal infections.

Carboxylases catalyses

In its physiologically active form biotin is attached at the active site of four important enzymes, these are known as carboxylases. Each carboxylase catalyses an essential metabolic reaction in the body, including:

  • The binding of bicarbonate to acetyl-CoA to form malonyl-CoA. Malonyl-CoA is required for the synthesis of fatty acids.
  • Gluconeogenesis (i.e. the formation of glucose from a source other than carbohydrates, for example amino acids and fats).
  • A vital step in the metabolism of leucine (an essential amino acid).
  • Essential steps in the metabolism of amino acids, cholesterol, and odd chain fatty acids.

DNA replication and transcription

Biotin may also play a role in DNA replication and transcription, via the biotinylation of histones. Histones are proteins that bind to DNA and package it into compact structures to form chromosomes. The attachment of biotin to another molecule, such as a protein, is known as biotinylation. Biotinidase (the enzyme which “recycles” biotin) has recently been shown to catalyse the biotinylation of histones, leading to the suggestion of a possible role of biotin in DNA replication and transcription. The mineral magnesium is important to biotinidase activity. This means that people with low magnesium may be more prone to see signs of biotin deficiency.

Oral antibiotics and their impact on Biotin

Biotin is the B-complex vitamin most dramatically affected by oral antibiotics. This is because the bacteria of a healthy gut can produce biotin (as stated above), adding significantly to the dietary supply. Thus antibiotics can disrupt the biotin produced in the gut and unfortunately dietary sources are not generally adequate to compensate for this loss. Additionally, vitamin B6 inadequacy, which is often seen in Pyrroluria and ASD patients (among others), may make it difficult for the intestinal flora to produce biotin. Also, because children with ASD frequently have problems with dysbiosis and diarrhoea, intestinal microbes may not be able to produce enough biotin from food. The reduced transit time may make it difficult for intestinal cells to absorb adequate biotin from food or flora. This problem of reduced absorption would be shared by other vitamins and minerals as well.

Dosing recommendations

We see quite a wide range of dosing recommendations at Kingsway – from 200mcg to as high as 10,000mcg (10mg) daily. However, the most common strengths we see are between 1,000 – 3,000mcg (1 – 3mg) daily. Susan Costen Owens, autism researcher from the Husson Science Research Institute USA, uses doses as high as 10 – 40mg/day to treat biotinidase deficiency.

Biotin is not known to be toxic. Toxicity has not been reported with daily oral doses of up to 200mg, used to treat hereditary disorders of biotin metabolism and biotin deficiency.

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