Biotin used to be referred to as vitamin B7 or vitamin H, but nowadays it is just called biotin. Like the other B vitamins, it plays an important role in energy production and metabolism. (1) Although it is widely believed to improve skin, nails, and hair, there is currently little evidence to support this. Biotin deficiencies can indeed cause hair thinning and skin problems, but fortunately, these are very rare, as a varied diet usually provides enough of it to prevent severe deficiencies. (2)  

High-dose supplementation has been studied in connection with blood sugar and insulin problems, where it has been shown to be effective in humans in combination with chromium. (5, 6) It has also been tried in other diseases, such as multiple sclerosis, but it hasn't produced outstanding results on this front. Biotin is extremely safe, even high doses (200 mg/day, 10000 times the required intake) do not cause overdose symptoms.  

How much biotin do we need? 

The daily requirement for biotin has been set at a mere 30 micrograms, and for children, as with other vitamins, a fraction of this on the basis of body weight. (2) Fortunately, most people who eat a balanced, mixed diet consume more biotin than this, so deficiencies are very rare and mainly limited to special cases. In such cases, problems mostly occur with the absorption and utilization of biotin. (3)  

Egg whites contain a substance called avidin, which inhibits the absorption of biotin, but fortunately, it breaks down when exposed to heat, so heat-treated eggs should not cause a problem. (1) Small amounts of biotin are synthesized by our gut flora, but the bacteria need it, too, so a deficiency will harm our gut flora. (7).

Sources of biotin 

Biotin is found in many foods, the best food sources are liver and other animal products, but sweet potatoes and almonds are also good sources of plant biotin. (2) 

10 dkg of liver provide the total daily intake, while 20 dkg of other meats, fish, and eggs, combined with potatoes, are needed. In a balanced, mixed diet, it is therefore unlikely to be deficient, although some factors may interfere with its absorption, and in such cases, biotin supplementation may be necessary. 

Biotin can also be found in food supplements, so most multivitamins and B-complex products also contain biotin in the form of d-biotin, which is well absorbed and well utilized. As with other B vitamins, biotin can be absorbed by passive diffusion at high concentrations, which is good news as supplementation can help to correct rare problems that can lead to biotin deficiency. 

When might we need a higher biotin intake? 

There are a few cases that indicate biotin supplementation in high dosage.  

Excessive alcohol consumption can also be problematic in this regard: alcohol inhibits the function of many B vitamins, and reduces the absorption of biotin through the intestinal wall, among other things, along with many digestive diseases. The solution may be to supplement at higher doses. 

In some people, a genetic disorder causes the biotidinase enzyme to not work properly, so the body cannot recycle biotin, and absorbs it more poorly, as well. In such cases, high doses of biotin supplementation should be started in childhood to address the problem.  

What are the benefits of biotin supplementation? 

Higher intakes of biotin may have beneficial effects: it is found in many supplements and other products because of its supposed beneficial effects on skin, nails, and hair.  

Animal studies suggest that biotin is beneficial for insulin sensitivity and blood glucose, as a key enzyme, glucokinase, does not function properly in its absence. (4) Human studies with chromium have shown that co-supplementation of 2 mg of biotin per day in combination with chromium significantly improved blood glucose levels and insulin sensitivity in type 2 diabetics in several studies. (5,6) Both fasting and food-induced blood glucose elevations were significantly reduced, as were HbA1C and triglycerides, which are also important indicators of blood glucose problems. This combination has also been shown to successfully reduce cardiovascular risk in other studies. (8,9)

[The cover photo of this note shows chicken liver. 100 grams contain 130 μg of vitamin B7, which is more than four times the recommended daily intake.]

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