Biotin, also known as vitamin H or B7, and often grouped with the B-complex vitamins, is a water-soluble vitamin that can be produced by bacteria in the body and which is present in numerous foods.
Recommended intake of biotin
The Adequate Intake (AI) for biotin is 30 micrograms per day for adults over 18 years of age. Biotin deficiency is rare in humans due to its wide distribution in foods and the ability of gut bacteria to synthesize biotin typically in excess of requirements.
The most common cases of biotin deficiency that have been reported are in pregnant women, patients receiving prolonged parenteral (intravenous) nutrition, infants consuming breast milk containing low amounts of biotin and in patients with impaired biotin absorption due to an inflammatory bowel disease or other GI tract disorder.
Biotinidase deficiency is another cause of biotin deficiency. This autosomal recessive metabolic disorder means that the body does not produce sufficient amounts of the enzyme required to release biotin from proteins in the diet during digestion or from normal protein turnover in the cell.
Around 1 in 60,000 newborns have profound (less than 10% of normal enzyme activity) or partial (10-30% of normal enzyme activity) biotinidase deficiency.
Long-term use of anti-seizure medications such as phenobarbital, phenytoin, or carbamazepine can also reduce blood levels of biotin.
Biotin supplements are available, and those with biotinidase deficiency are usually given a starting dose of 5-10 mg a day. For those without this genetic condition, it is usually preferable to try to first obtain sufficient biotin from the diet as this can also help enhance the intake of other beneficial nutrients which work alongside biotin.
Isolating specific nutrients in supplement form does not provide the same health benefits as consuming the nutrient from a whole food that also contains a variety of other nutrients. As such, it makes sense to focus on obtaining daily biotin requirements from foods and to only resort to supplements as a backup where necessary.
Possible health benefits of consuming biotin
Biotin is an essential nutrient for the metabolism of fats, carbohydrates, and protein. It is a coenzyme for carboxylase enzymes, which are involved in the synthesis of fatty acids, isoleucine, and valine (amino acids), and in gluconeogenesis.
Mild biotin deficiency is often seen during pregnancy and poses a risk for abnormal development of the fetus. Since folic acid supplementation is recommended both before and during pregnancy, it is sensible to obtain a multivitamin with at least 30 micrograms of biotin per day in addition to folic acid to decrease the risk for deficiency.
Biotin has been shown to improve nail strength and durability of fingernails in several small-scale studies. One study showed a 25% increase in thickness and a decrease of splitting with biotin supplementation.3 Another trial reported an improvement in nail strength for up to 91% of participants.4
Lower blood glucose
Promising results have been seen in several studies testing biotin’s ability to lower blood glucose in both type 1 and type 2 diabetics. In animal studies, biotin was shown to stimulate the secretion of insulin from the pancreas and subsequently lower blood glucose. More studies need to be conducted before biotin’s effects on blood sugar can be confirmed.
Biotin may also help reduce the risk of nerve damage in people with diabetes. This is because it is necessary for the activity of pyruvate carboxylase, without which high levels of pyruvate and aspartate may arise, adversely affecting nerves.
Foods sources of biotin
Eggs are rich in biotin – one large egg contains 13-25 micrograms.
Foods that are rich in biotin include baker’s yeast, wheat bran, organ meats, eggs, and oysters.
Care should be taken, however, with the consumption of raw eggs as these contain a protein called avidin that inhibits the absorption of biotin. Excessive consumption of egg whites has been known to cause biotin deficiency.
- Liver, cooked: 27-35 micrograms
- Egg, large, cooked: 13-25 micrograms
- Salmon, 3 ounces, cooked: 4-5 micrograms
- Raspberries, 1 cup: 0.2-2 micrograms.
Many foods, such as fruits and vegetables, contain a small amount of biotin.
Potential health risks of consuming biotin
Large doses of biotin have no known toxic effects.