New Considerations for Biotin Use in Hair Disorders
Figure 1. Central Centrifugal Cicatricial Alopecia.
Biotin has been highly commercialized in the past decade, with consumer sales steadily increasing from July 2014 to June 2017.1,2 Its increased popularity is likely due to media attention promoting its use (still mostly unsubstantiated) in hair and nail growth, as well as its documented health benefits in biotinidase deficiency, propionic acidemia, diabetes, lipid disorders, diabetic peripheral neuropathy, and secondary, progressive multiple sclerosis (MS).3-11
Regardless of whether individuals are using biotin for cosmetic or therapeutic purposes, the literature is clear that many of them are ingesting more than the daily value of 30 mcg4,12 set by the FDA in 2016. The commercial availability of biotin in doses ranging from 30 to 10,000 mcg makes supraphysiologic dosing possible.1 Manufacturers are not required to list biotin on their label unless the product has been fortified with it, although the FDA will require all food products and dietary supplements to list the daily value for biotin on their labels by January 2020.
Currently, however, there is no recommended daily intake for biotin, nor a tolerable upper intake level, the maximum amount at which a supplement can be taken without any adverse health effects. However, according to the Office of Dietary Supplements website, “high biotin intakes, and potentially even intakes greater than the AI, [adequate intake] may pose another type of health risk.13 Supplementing with biotin beyond recommended intakes can cause clinically significant falsely high or falsely low laboratory test results.”
In November 2017, the FDA issued a statement cautioning the public on the harmful effects of high-dose biotin on laboratory testing.14,15 According to the report, serum biotin interferes with certain laboratory tests, causing falsely low- or high-test results; this poses a threat to patient safety. There has been at least 1 reported death as a consequence of biotin interference, in which falsely low troponin levels in a patient delayed care.14
The prevalence of high-dose biotin use has dramatically increased over the past 3 years and will likely continue, placing patients at risk for erroneous endocrine (thyroid-stimulating hormone [TSH], human chorionic gonadotropin [HCG]) and cardiac (N-terminal prohormone of brain natriuretic peptide [NT-proBNP], troponin T) testing.5,16 The effect of biotin on laboratory results is a direct consequence of its interference in the biotin-streptavidin immunoassay employed by most reagent manufacturers. Clinicians should be aware of these effects in order to adequately evaluate inaccurate laboratory results in the setting of increased biotin use among the general population.
Biotin: The Vitamin
Biotin is a water-soluble B vitamin, also known as vitamin H, vitamin B7, and coenzyme R, that serves as a co-factor for 5 carboxylases.17-19 It is responsible for fatty acid metabolism, gluconeogenesis, and catabolism of branched chain amino acids.17-19 Intestinal bacteria synthesize biotin, thus providing an endogenous source. Biotin can also be found exogenously in soybeans, butter, peas, sunflower seeds, lentils, peanuts, walnuts, pecans, and eggs.
Biotin is currently marketed as a supplement for hair and nail growth. It is sold in different formulations, from beauty supplements to multivitamins, and is available in stores and online. Most hair, nail, and skin supplements contain 5000 to 10,000 mcg of biotin, while multivitamins range in their dosing from 30 to over 300 mcg.1,4
Biotin’s small molecular size and ability to attach to a variety of functional groups have proven useful in the in vitro diagnostic industry. Additionally, biotin’s affinity for streptavidin has been exploited for use as an immobilizing system in protein analysis. The biotin-streptavidin interaction has, and continues to be, used by most reagent manufacturers in immunoassays that measure TSH, HCG, NT-proBNP, and troponin T.
Figure 2. Localized alopecia areata.
Use in Hair and Nail Disorders
Biotin has been purported to help in hair and nail disorders for decades; however, no randomized controlled trial has proven its efficacy in these conditions.20 A recent study reviewing its efficacy in hair and nail disorders found 18 reported cases.20 The cases were a combination of acquired and congenital biotin deficiencies, predominantly congenital type (eg, biotinidase or holocarboxylase synthetase deficiency). All 18 cases involved patients with underlying pathology for poor hair or nail growth—each of whom demonstrated improved clinical outcomes with biotin use.20 Each case varied in the time needed for clinical improvement and administered biotin dose.20 These findings suggest that biotin deficiency is relatively uncommon, or at least discordant with the number of consumers purchasing biotin supplements.
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