Biotin is involved in the metabolism of both sugar and fat. In sugar metabolism, biotin helps move sugar from its initial stages of processing on to its conversion into usable chemical energy. For this reason, muscle cramps and pains related to physical exertion, which may be the result of the body’s inability to use sugar efficiently as fuel, may signal a biotin deficiency. The role of biotin in fat metabolism is discussed below under the heading “Synthesis of Fat (Fatty Acids).”
One of the least well-known of the B-complex vitamins, biotin was originally referred to as “vitamin H.” Biotin was discovered in late 1930s and early 1940s research when chicks fed diets high in raw egg white consistently developed skin rashes and lost the hair around their eyes. When egg yolk was added to the chicks’ diet, these symptoms disappeared.
Today, we know why. Researchers have identified a substance in raw egg white – a sugar and protein-containing molecule (glycoprotein) called avidin – that can bind together with biotin and prevent its absorption. Food scientists have also identified the egg yolk as one of the most dense sources of biotin in the diet.
Vitamin B7; Vitamin H; Coenzyme R; Biopeiderm
244.31 g mol−1
Appearance White crystalline needles
Solubility in water
22 mg/100 mL
Synthesis of Fat (Fatty Acids)
Many of the classic biotin deficiency symptoms involve skin-related problems, and the role of biotin in fat synthesis is often cited as a reason for this biotin-skin link. Biotin is required for function of an enzyme in the body called acetyl Co-A carboxylase. This enzyme puts together the building blocks for the production of fat in the body. Fat production is critical for all cells in the body since the membranes of all cells must contain the correct fat components to function properly. Fat production is especially critical for skin cells since they die and must be replaced very rapidly, and also because they are in contact with the outside environment and must serve as a selective barrier. When cellular fat components cannot be made properly due to biotin deficiency, skin cells are among the first cells to develop problems. In infants, the most common biotin-deficiency symptom is cradle cap – a dermatitis (skin condition) in which crusty yellowish/ whitish patches appear around the infant’s scalp, head, eyebrows and the skin behind the ears. In adults, the equivalent skin condition is called seborrheic dermatitis, although it can occur in many different locations on the skin.
Skin-related problems, including cradle cap in infants and seborrheic dermatitis in adults, are the most common biotin deficiency-related symptoms. Hair loss can also be symptomatic of biotin deficiency. Nervous system-related problems provide the second most common set of biotin-related symptoms, including seizures, lack of muscle coordination (ataxia), and lack of good muscle tone (hypotonia). Muscle cramps and pains related to physical exertion can be symptomatic of biotin deficiency, reflecting the body’s inability to use sugar efficiently as a fuel.
What are toxicity symptoms for biotin?
Reports of biotin toxicity have not surfaced in the research literature, despite the use of biotin over extended periods of time in doses as high as 60 milligrams per day. For this reason, in its 1998 recommendations for intake of B-complex vitamins, the Institute of Medicine at the National Academy of Sciences chose not to set a tolerable upper limit (UL) for intake of biotin.
Biotin may play a role in the prevention and/or treatment of the following health conditions:
• Hair loss (alopecia)
• Intestinal imbalances, including inflammatory bowel syndrome, irritable bowel syndrome, Crohn’s disease, ulcerative colitis, and chronic diarrhea
• Neuromuscular-related conditions, including seizures, ataxias (movements characterized by lack of muscle coordination), and hypotonias (posture and movement characterized by lack of muscle tone)
• Skin conditions, including cradle cap in infants and seborrheic dermatitis in adults
• Pregnancy, as there is an increased demand for nutrients placed upon the mother by the growing fetus.