(Source: SaluGenecists, Inc.)
Biotin, the least well known of the B-complex vitamins, was originally referred to as vitamin H. Biotin was discovered in the late 1930s and early 1940s when researchers found that chicks fed diets high in raw egg whites would consistently develop skin rashes while also losing the hair around their eyes; when egg yolks were added to their diets, the chicks symptoms disappeared. The reason for this phenomenon is as follows not only are egg yolks one of the densest sources of dietary biotin but raw egg whites contain a glycoprotein called avidin that can bind with biotin and prevent its absorption.
Physiological functions of biotin
- Contributes to healthy skin through supporting proper fat production
- Participates in the efficient use of sugar
- Maintains an energy supply in nerve cells
Physiological events that may signal a need for greater biotin intake
- Skin-related problems, including seborrheic dermatitis and cradle cap
- Hair loss
- Lack of good muscle tone or coordination
- Muscle cramps
Functions of biotin
Biotin is integral to energy production since it is involved in the metabolism of both glucose and fat. In sugar metabolism, biotin participates in moving the sugar molecule from its initial stages of processing to its conversion into usable chemical energy. Therefore, muscle cramps and pains that are related to physical exertion, which may be the result of the bodys inefficient use of sugar as an energy source, may signal a biotin deficiency. Biotins role in fat metabolism is discussed below under the subsequent subheading Fatty acid synthesis.
Fatty acid synthesis
A link between biotin and skin health has been established since many of the classic biotin deficiency symptoms involve skin-related problems. The oft-cited reason for the biotin-skin link is biotins role in fatty acid synthesis.
Biotin is required for the function of acetyl Co-A carboxylase, an enzyme that puts together the building blocks for production of fats. Since the membrane of all cells must contain the proper fat components to function properly, the correct and efficient fat production processes are critical for the health of all cells.
Fat production is especially critical for skin cells since they replicate quickly and are in contact with the outside environment, therefore serving as an efficient selective barrier. When a biotin deficiency impairs cellular fat component production, skin cells are among the first cells to manifest problems.
In infants, the most common biotin deficiency symptom picture involves the condition known as cradle cap, a dermatitis (skin condition) where crusty whitish/yellowish patches appear around the infants scalp, head, eyebrows and the skin behind the ears. In adults, biotin deficiency manifests in an equivalent skin condition known as seborrheic dermatitis that can occur in many different locations on the skin.
Nervous system activity support
Since the nervous system relies upon energy production from glucose and fat and biotin plays a critical role in energy metabolism from these compounds, this nutrient also plays an important role in maintaining the integrity of the nervous system. Nerve-related symptoms that have been linked to biotin deficiency include seizures, ataxia (lack of muscle coordination) and hypotonia (lack of good muscle tone).
A variety of factors can contribute to a deficiency of biotin. While poor dietary intake of biotin-containing foods can lead to deficiency, inadequate intake of vitamin B5 (pantothenic acid) can lead to a functional biotin deficiency since these nutrients jointly participate in a variety of metabolic processes. Since intestinal flora can produce biotin under appropriate conditions, intestinal problems that lead to disturbed floral balance (dysbiosis) can deprive the body of this endogenous source of biotin. Since raw egg whites contain avidin, a glycoprotein that binds to biotin and prevents its absorption, eating them can contribute to a biotin deficiency (cooking the eggs will deactive avidins ability to bind biotin).
The most common biotin deficiency-related symptoms are skin-related conditions such as cradle cap in infants and seborrheic dermatitis in adults. Nervous system-related problems are the second most common type of deficiency symptoms; these include seizures, lack of muscle coordination (ataxia) and lack of muscle tone (hypotonia). In addition, since the body needs biotin to efficiently use sugar as fuel, muscle pains and cramps caused by physical exertion may be symptomatic of a biotin deficiency. Hair loss may also be a caused by inadequate levels of biotin.
Despite the clinical use of biotin in doses as high as 60 miligrams per day over extended periods of times, there have been no reports of biotin toxicity in the research literature. In 1998, when the Institute of Medicine at the National Academy of Sciences reviewed research on biotin they concluded that excessive intake from foods or supplements was not associated with any adverse effects and therefore they did not establish a Tolerable Upper Intake Level (UL) for this nutrient.
Cooking, Storage and Processing
Although biotin is relatively stable even when exposed to heat, light and oxygen, acidic environments can cause it to denature. Eggs are a good source of biotin, but they must be cooked in order for absorption to take place. This is because in raw eggs, biotin is bound to avidin, a glycoprotein molecule, that prevents its absorption. Heating the eggs allows the biotin and avidin to separate.
Drug & Nutrient Interactions
Interactions between medications and biotin
Medicines that can compromise biotin absorption include:
- Anticonvulsant drugs like carbamazepine
Biotin and vitamin B5 (pantothenic acid) have a synergistic relationship as many of the bodys metabolic reactions that require biotin also require B5.
Health conditions that require special emphasis on biotin
Individuals who have the following health conditions should pay special attention to their biotin status:
- Alopecia (hair loss)
- Ataxia (lack of muscle coordination)
- Chronic diarrhea
- Cradle cap
- Crohns disease
- Hypotonia (lack of good muscle tone)
- Inflammatory bowel syndrome
- Irritable bowel syndrome
- Seborrheic dermatitis
- Ulcerative colitis
Forms in Dietary Supplements
D-biotin, the only known metabolically active form, is the one found in virtually all dietary supplements.
Excellent sources of biotin include carrots, romaine lettuce, Swiss chard and tomatoes. Very good sources include almonds, cabbage, cauliflower, eggs, cucumber and onions.