• by: Fondazione Valter Longo
  • August 3rd, 2022

Vitamin H, also known as biotin, is a water-soluble vitamin, meaning it is part of that group of water-soluble vitamins, which cannot be accumulated in the body. For this reason, it is important to take it every day with a varied and balanced diet. Biotin participates in several biological processes that are fundamental for our well-being.


Biotin plays a role as a coenzyme. It is particularly useful for the proper functioning of the carboxylase enzymes, involved in cellular reactions and metabolism. For this reason, biotin is essential for cell functioning, growth, and development in the body. Furthermore, it plays an important role in the metabolism of carbohydrates, proteins, and lipids. Assimilated through food, it is also minimally produced by some bacteria in our intestines.

Useful for the health of skin, nails, and hair, vitamin H strengthens and improves tissue appearance, acts on sebaceous production both in the skin and in the scalp, and prevents hair loss.

It is also important for the normal functioning of the nervous system in adults, children, and also in the fetus, where it takes part in the embryonic development of the whole organism too. As far as the cardiovascular system is concerned, biotin keeps blood glucose and cholesterol levels stable.


The recommended daily intake varies greatly based on age, gender, and other conditions, starting from 7 μg in children, reaching 30 μg in adults. Dosage increases during pregnancy and breastfeeding up to 35 7 μg.

A deficiency may be due to malnutrition or rapid weight loss, as well as the use of a nasogastric tube in hospitalized people for a long time. Prolonged use of antibiotics or the presence of diabetes can also cause reduced assimilation of biotin.

Possible symptoms of vitamin H deficiency are varied: tiredness, fatigue, sleepiness, muscle aches, night cramps, itching in the legs and arms, skin problems (dermatitis, dryness and reddish flaking around the nose, eyes, and mouth), in children seborrheic dermatitis, brittle nails, thinning hair, and losing its natural color, up to hair loss (from baldness to alopecia), depressive symptoms, or nervous exhaustion.

Since it is present in many foods, both vegetable and animal ones, it is difficult to run into a deficiency of vitamin H. In case of deficiency, however, it is important to supplement it, especially for women during pregnancy and in other specific cases (such as hair loss, fragile nails, seborrheic dermatitis, and mild depression). It is essential to always contact a doctor and/or a nutritionist to be prescribed an adequate supplement and the right doses based on individual needs. Conversely, an excess could show signs of toxicity.


Biotin is present in various foods, both of animal and vegetable origin, many of which are also sources of essential minerals such as calcium and magnesium.

The main sources of bioavailable vitamin H are products of animal origin, especially liver, chicken, and eggs. Beware, however, of excessive consumption of raw and/or soft-boiled eggs, since in this case the biotin binds to a protein (avidin) present in raw egg white, which could make this precious vitamin unavailable. Cooking, on the other hand, denatures the avidin. Biotin is also found in milk and cheese. Good source of this vitamin is fish.

Even products of plant origin can be a source of biotin, although absorption from these foods is limited by their low bioavailability. We find vitamin H in whole grains (wheat and rice), legumes (lentils and peas), fresh fruits and vegetables (cauliflower, lettuce, and carrots), nuts, and mushrooms. Biotin, like many other group B vitamins, is also found in brewer’s yeast.

It is important to know that biotin, to be assimilated correctly, requires that those foods containing it (even in the bioavailable form of animal origin) are completely digested. As a matter of fact, it is often carried by residues of the amino acid lysine that require digestive enzymes (peptidase pancreatic).


Biotin is stable at room temperature. It does not require refrigeration, and it is not destroyed by cooking. However, its absorption may depend on the type of cooking. For example, the amount of biotin that is absorbed by eggs changes depending on whether they are cooked or raw. Raw eggs contain a protein called avidin, which binds to biotin and makes it nearly impossible to absorb. Cooking the egg leads to distorting or destroying avidin and releasing biotin, promoting its absorption in the digestive tract. In fact, once biotin is released from avidin, almost 100% of it is absorbed.


  • Vitamine – Informazioni generali – EPICENTRO (last viewed 02/07/2022)

  • Vitamine – Studi – EPICENTRO (last viewed 02/07/2022)

  • LARN – Livelli di assunzione di riferimento per la popolazione italiana: VITAMINE. Fabbisogno medio (AR); valori su base giornaliera – Società Italiana di Nutrizione Umana-SINU, 2014 (last viewed 02/07/2022)

  • Vitamin and Mineral Supplement Fact Sheets – NIH National Institute of Health (last viewed 02/07/2022)

  • Biotin – NIH National Institute of Health (last viewed 02/07/2022)



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