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.
Progressive multiple sclerosis (MS) is considered an autoimmune demyelination disorder causing severe neurological disabilities in humans. It is characterized by progressive degeneration of the myelin sheath surrounding axons and neuronal loss in the brain and spinal cord (49). Mitochondrial dysfunction and chronic demyelination lead to virtual hypoxia and may be partly responsible for the progressive axonal degeneration in not-active MS (49, 50). Biotin plays a major role in the intermediary metabolism and fatty acid synthesis (required for myelin formation), therefore it has been hypothesized that it might be beneficial for limiting or reversing MS-associated functional impairments (49). An uncontrolled, non-blinded pilot study in 23 patients with progressive MS found that high doses of biotin (100-600 mg/day) might sustain clinical improvements in 5 (out of 5) patients with progressive visual loss and 16 (out of 18) patients with partial paralysis of the limbs after a mean 3 months following treatment onset (48). In addition, the results from a multi-centre, randomized, placebo-controlled trial in 154 subjects with progressive MS showed that 13 out of 103 patients receiving daily oral biotin (300 mg) for 48 weeks achieved sustained reversal of MS-related disability and the high dose was well tolerated. In comparison, none of the 51 placebo group patients showed significant clinical improvements (50). Two ongoing trials are evaluating the effect of high-dose biotin supplementation in the treatment of MS (see trials NCT02220933 and NCT02220244 at www.clinicaltrials.gov).
Research suggests that biotin can improve glucose utilization, which is impaired in type 2 diabetes mellitus (T2DM). Several mechanisms could explain a possible blood glucose-lowering effect of biotin: as a cofactor of carboxylases that catalyse the synthesis of fatty acids, biotin may enhance the the de-novo fat synthesis from glucose . Biotin has been found to induce a liver enzyme (‘glucokinase’) that increases synthesis of glycogen, the storage form of glucose (45). It was also shown that biotin can stimulate the secretion of insulin in the pancreas of rats, which attenuates the blood glucose lowering (glucose homeostasis) (12).
In one human study, blood 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 mg/day), fasting blood glucose levels decreased by an average of 45% (13).
In contrast, a study in 10 type 2 diabetics and 7 non-diabetic controls reported that biotin supplementation (15 mg/day) for 28 days did not decrease fasting blood glucose levels in either group (14).
Furthermore, a few studies showed that combined supplementation of 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, it has been reported that administration of chromium picolinate alone improves glycemic control in diabetic subjects (19).
An early human study found reductions in blood glucose levels in 7 type 1 diabetics after one week of supplementation with 16 mg of biotin daily (20). Presently, studies investigating the effect of supplemental biotin on blood glucose and lipid levels in humans are extremely limited, highlighting the need for further research.
Three uncontrolled trials examining the fingernail strengthening effects of biotin supplementation (2.5 mg/day for up to 6 months) in women with brittle fingernails have been published (22, 23, 62). 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 (62).
Although the results of these small uncontrolled trials suggest that biotin supplements may be helpful in strengthening brittle nails, larger placebo-controlled trials are needed to assess efficacy.
There are no published scientific studies that support the claim that high-dose biotin supplements are effective in preventing or treating hair loss in men or women (54, 55).
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).
Authored by Dr Peter Engel in 2010, reviewed and revised by Ines Warnke on 28.06.2017