Biotin or Vitamin H: what it is, what it does and when to take it

Biotin, or vitamin H, is known for its healthy action on skin and hair, but also for a regular functioning of the nervous system and metabolism.

What is it

Biotin (or vitamin H) is a water-soluble vitamin that belongs to the group of B vitamins.

Its functions are essentially metabolic: specifically, this micronutrient contributes to the formation of fatty acids (the fundamental components of lipids) and facilitates the metabolism of amino acids (the structural units of proteins) and the transformation of carbohydrates.

Our body needs it for the functioning of its cells, but also for the growth and development of some skin appendages (especially those with a high cell turnover such as hair, skin and nails).

Unfortunately, however, the human body is not able to synthesize it independently, nor can it store it in the liver (where fat-soluble vitamins, such as A and D, are accumulated).

For this reason, to ensure sufficient quantities to meet daily needs, it is important to take it from the outside, choosing the right foods and, if necessary, resorting to supplements.

Food sources

Produced to a small extent also by intestinal bacteria, biotin is present in various foods such as yeast, calf liver and, as we have seen, egg yolk. It is also found in milk and its derivatives (especially cow’s milk, and then yogurt and cheese), in dried fruit and seeds (such as sunflower seeds), in cereals (such as wheat and brown rice), in legumes (especially lentils), in some vegetables (peas, carrots, lettuce, cauliflower) and in mushrooms.

The daily requirement of this vitamin can therefore be satisfied by including in your diet foods that derive from both animals and plants. Many of these are also sources of minerals important for the functioning of the body, such as calcium and magnesium.

It is, however, good to remember that biotin binds to a protein present in the egg white, avidin, which removes it from intestinal absorption; Therefore, care must be taken because excessive consumption of raw or soft-boiled eggs in the daily diet (and in particular raw egg white) could make biotin taken with the diet unavailable. Cooking the egg, on the other hand, denatures avidin, and this eliminates its negative effect on biotin absorption.

It was precisely the interaction between these substances to bring to light the existence of biotin: in fact, some researchers, led by the biochemist Margaret Averil Boas, have noticed that mice fed only with raw egg white undergo hair loss and alterations of skin and growth.

Subsequently, it was discovered that the phenomenon responsible for this association is the interaction between two compounds: biotin and avidin.

Subsequently, biotin has been given several names: for this reason, it can happen to hear about this molecule calling it vitamin I, vitamin B7, vitamin B8 or, as mentioned, vitamin H.

Biotin activity

Biotin plays the role of coenzyme.

Coenzymes are organic substances with a rather simple chemical composition, but a complex structure. Their fundamental role is to make possible the action of enzymes, i.e. proteins that act as accelerators of biological reactions.

In the case of biotin, all this means that its availability is important for the functioning of several enzymes (for example, some ATP-dependent carboxylases). These enzymes are involved in the metabolism of fats and carbohydrates and in several other reactions that take place in the body’s cells.

It is useful for the health of the skin and hair. In the latter case it is often recommended together with the intake of folic acid (vitamin B9).


Biotin deficiency (just like that of another very common trace element, vitamin B5 or pantothenic acid) is quite rare as it is a very common vitamin among foods, and the body’s need is very low.

Some conditions, however, increase the risk of finding yourself struggling with insufficient levels of this nutrient, and therefore some may benefit from taking a dietary supplement.

Biotin deficiency may be due to a congenital defect in the enzyme biotidinase (the enzyme that makes it available to the body) but more often it is associated:

  • pregnancy,
  • breastfeeding,
  • alcohol abuse,
  • excessive consumption of antibiotics or anticonvulsants,
  • to gastrointestinal disorders such as Crohn’s disease.

But biotin values can also be altered by long-term use of a nasogastric tube, or for nutritional reasons (for example following a state of malnutrition or rapid weight loss).

It also seems that diabetes can also lead to insufficient levels of this vitamin. Finally, biotin deficiency has also been associated with smoking and eating 2 or more raw egg whites per day for several months.

Unfortunately, there are no laboratory tests that can reliably detect biotin deficiency. For this, to recognize this type of problem, it is necessary to rely solely on the analysis of the presence of its possible symptoms.

Lack of biotin is reported by skin disorders (especially dry desquamative dermatitis) and alopecia (especially baldness), by a general sense of fatigue and drowsiness along with muscle pain.

In addition, in the absence of adequate amounts of biotin, hair can thin and lose its natural color, while the thickness of the nails can shrink causing them to weaken and break. Skin irritations are characterized by reddish scales concentrated mainly around the eyes, nose and mouth.

Not even the nervous system is spared, and in addition to the sense of tiredness and skin problems you can find yourself struggling with the symptoms of depression or exhaustion, with hallucinations and with tingling in the arms and legs.

When to take biotin

The intake of biotin is used both for the treatment of its deficiencies and to prevent them, but not only.

This vitamin is, in fact, proposed to combat hair loss, nail fragility, mild depression and, in childrenseborrheic dermatitis (an inflammation of the skin that mainly affects the face, scalp and sternum); But it would also seem to be indicated in pregnancy and in the treatment of diabetes.

In particular, biotin, when taken in combination with zinc – a micronutrient known for its antioxidant and protective properties  would help fight hair loss.

The available scientific evidence indicates that the intake of this vitamin is most likely an effective strategy to prevent or treat any deficiencies.

On the other hand, there are more doubts about its effectiveness in case of seborrheic dermatitisand especially in case of diabetes. In fact, although some studies have indicated that the administration of biotin combined with chromium (a mineral of which there are some traces in the human body) could reduce the level of sugar in the blood, the data collected are not sufficient to show that this improvement should be attributed to biotin alone.

Recommended doses

The daily requirement for biotin is very low and studies have not shown a recommended intake level.

More specifically, according to the revision of the Larn (Reference intake levels of nutrients and energy for the Italian population) definitively published by the Italian Society of Human Nutrition (Sinu) in 2014, the intake of adequate biotin varies depending on the growth phase referred to.

Infants 6-12 months 7 μg
Children-adolescents 1-3 years 10 μg
4-6 years 15 μg
7-10 years 20 μg
Males 11-14 years 25 μg
15-17 years 30 μg
Females 11-14 years 25 μg
15-17 years 30 μg
Males > 18 years 30 μg
Females > 18 years 30 μg

However, it is good to keep in mind that the most appropriate dosage depends not only on age but also on other factors, such as health status or other conditions.

In addition, the Larn themselves recall that during pregnancy and lactation the adequate intake of biotin rises further up to 35 μg per day.

Biotin products taken orally are considered safe for most people, as long as they are taken at recommended dosages.

Their intake seems to have no contraindications even during pregnancy and breastfeeding, but even in these periods it is essential to use them by following the recommendations about the quantities to be taken.

Joycelyn Elders is the author and creator of EmpowerEssence, a health and wellness blog. Elders is a respected public health advocate and pediatrician dedicated to promoting general health and well-being.

The blog covers a wide range of topics related to health and wellness, with articles organized into several categories.

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