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Vitamin B7 Vitamin B7, also known as biotin, vitamin H or vitamin B8, is a water-soluble vitamin, required by all organisms. There are eight different forms of biotin, but only one of them, D-biotin, occurs naturally and has full vitamin activity. Biotin can only be synthesized by bacteria, molds, yeasts, algae, and by certain plant species (1, 2). VITAMIN B7 // BIOTIN Health functions https://twitter.com/NutriFacts_DSM Nutri-Facts (EN) @NutriFacts_DSM Welcome to NUTRI-FACTS, a high-quality information source about vitamins, carotenoids and other micronutrients for consumers, healthcare professionals and media Kaiseraugst, Switzerland nutri-facts.org Joined September 2011 In humans, vitamin B7 (biotin) is the coenzyme attached at the active site of five enzymes known as ‘carboxylases’ (3). The attachment of biotin to another molecule, such as a protein (e.g. histone), is known as ‘biotinylation’. Each carboxylase catalyzes an essential metabolic reaction required for the synthesis of fatty acids, the formation of glucose from sources other than carbohydrates (e.g., amino acids), the catabolism of leucine (an essential amino acid), and the metabolism of certain amino acids, cholesterol, and certain fatty acids (4). Evidence indicates that biotinylation of histones plays a role in regulating DNA replication and gene expression (‘transcription’) as well as cell division (‘proliferation’) and other cellular responses (5, 6, 7). The European Food Safety Authority (EFSA), which provides scientific advice to assist policy makers, has confirmed that clear health benefits have been established for the dietary intake of biotin (vitamin B7) in contributing to: normal macronutrient metabolism; normal energy yielding metabolism; the maintenance of normal skin and mucous membranes; the normal function of the nervous system; the maintenance of normal hair; normal psychological functions. VITAMIN B7 // BIOTIN Disease risk reduction Birth defects Research indicates that vitamin B7 (biotin) is broken down more rapidly during pregnancy and that biotin nutritional status declines during the course of pregnancy (6, 8, 9). Although the level of biotin depletion is not severe enough to cause diagnostic signs or symptoms, such observations are sources of concern because biotin deficiency without clinical signs or symptoms (‘subclinical’) has been shown to cause birth defects in several animal species (10). Currently, it is estimated that at least one third of women develop marginal biotin deficiency during pregnancy (11). Indirect evidence also suggests that marginal biotin deficiency causes birth defects in humans. The potential risk for abnormal development of the embryo or fetus (‘teratogenesis’) from biotin deficiency makes it prudent to ensure adequate biotin intake throughout pregnancy. Since pregnant women are advised to consume supplemental vitamin B9 (folic acid) prior to and during pregnancy to prevent neural tube defects, it would be easy to consume supplemental biotin (at least 30 mcg/day) in the form of a multivitamin that also contains at least 400 mcg folic acid. Toxicity at this level of biotin intake has never been reported (see Safety). VITAMIN B7 // BIOTIN Other Applications Please note: Any dietary or drug treatment with high doses of micronutrients may override the body's own control mechanisms; therefore, micronutrient therapies may be associated with potential side effects and toxicities. High-dosed micronutrients should not be used without medical supervision. Diabetes mellitus Research suggests that vitamin B7 (biotin) can improve glucose utilization, which is impaired in diabetes mellitus. Several mechanisms could explain a possible blood glucose-lowering effect of biotin: as a cofactor of enzymes required for fatty acid synthesis, biotin may increase the utilization of glucose for fat synthesis. Biotin has been found to stimulate a liver enzyme (‘glucokinase’) that increases synthesis of glycogen, the storage form of glucose. Biotin has also been found to stimulate the secretion of insulin in the pancreas of rats, which also has the effect of lowering blood glucose (12). An effect on cellular glucose transporters (GLUT) is under investigation. In one human study, blood vitamin B7 (biotin) levels were significantly lower in 43 patients with type 2 diabetes than in non-diabetic control subjects, and lower fasting blood glucose levels were associated with higher blood biotin levels. After one month of biotin supplementation (9,000 mcg/day), fasting blood glucose levels decreased by an average of 45% (13). In contrast, a study in ten type 2 diabetics and seven non-diabetic controls reported that biotin supplementation (15,000 mcg/day) for 28 days did not decrease fasting blood glucose levels in either group (14). Additionally, a few studies have shown that co-supplementation with biotin and chromium picolinate, used to prevent or treat chromium deficiency, may be a beneficial therapy in patients with type 2 diabetes (15, 16, 17, 18). However, several studies have reported that administration of chromium picolinate alone improves glycemic control in diabetic subjects (19). Reductions in blood glucose levels were found in seven type 1 diabetics after one week of supplementation with 16,000 mcg of biotin daily (20). Presently, studies of the effect of supplemental biotin on blood glucose levels in humans are extremely limited, highlighting the need for further research. Brittle fingernails Three uncontrolled trials examining the fingernail strengthening effects of vitamin B7 (biotin) supplementation (2.5 mg/day for up to six months) in women with brittle fingernails have been published (22, 23). In two of the trials, subjective evidence of clinical improvement was reported in 67–91% of the participants available for follow-up at the end of the treatment period (22). One trial that used scanning electron microscopy to assess fingernail thickness and splitting found that fingernail thickness increased by 25% and splitting decreased after biotin supplementation (23). Although the results of these small uncontrolled trials suggest that vitamin B7 (biotin) supplements may be helpful in strengthening brittle nails, larger placebo-controlled trials are needed to assess efficacy. Hair loss There are no published scientific studies that support the claim that high-dose vitamin B7 (biotin) supplements are effective in preventing or treating hair loss in men or women. Cradle cap Infants who don't have enough biotin often develop a scaly scalp condition, known as ‘cradle cap’ (seborrheic dermatitis). Although no studies have confirmed that biotin supplements given in formula or breast milk effectively treat cradle cap, there are individual reports of some improvement with this treatment (24). Nutri-Facts (EN) @NutriFacts_DSM Welcome to NUTRI-FACTS, a high-quality information source about vitamins, carotenoids and other micronutrients for consumers, healthcare professionals and media Kaiseraugst, Switzerland nutri-facts.org Joined September 2011