Biotin deficiency – symptoms, causes, and effective supplementation methods

If you observe excessive hair loss, brittle nails, and dull, rough skin, it’s time to take a look at your diet and check if the cause isn’t biotin – or rather, its deficiency. This is a B vitamin with an undeniable role in the proper functioning of the body. Where does our body get it from, and who is at risk of its deficiency?

The role of biotin in the body

Biotin (vitamin B7) is a water-soluble B-group vitamin that acts as a coenzyme in key metabolic reactions. It participates in the metabolism of carbohydrates, fats, and amino acids, supporting the activity of enzymes responsible, among others, for fatty acid synthesis, gluconeogenesis, and leucine metabolism. Thanks to this, it influences the proper functioning of the nervous system, energy level stability, and the condition of tissues with high renewal dynamics, such as skin, hair, and nails. Biotin also plays a role in regulating gene expression and maintaining the integrity of the skin barrier, which explains its importance for healthy skin appearance and adnexa¹.

What are the symptoms of biotin deficiency?

Biotin deficiency, though relatively rare, can lead to a series of non-specific yet characteristic symptoms. The most commonly observed include brittle and split nails, excessive hair loss, dry and flaky skin, a feeling of chronic fatigue, and metabolic disorders. These symptoms result from impaired processes of fatty acid and keratin synthesis – the protein that builds hair and nails – as well as less efficient energy acquisition at the cellular level. Insufficient biotin can also disrupt the functioning of the nervous system, contributing to weakness, concentration problems, or mood swings.

What causes biotin deficiency?

Potential causes of low biotin levels include:

• long-term use of antibiotics (affecting the gut microbiota),
• restrictive elimination diets,
• excessive consumption of raw egg whites (containing avidin, which binds biotin)
• certain gastrointestinal diseases that impair nutrient absorption.

How to supplement biotin deficiency?

Natural sources of biotin in the diet

The primary way to supplement biotin is a diet based on foods naturally rich in this vitamin. The most important sources include egg yolks, liver, nuts (especially almonds and walnuts), seeds, legumes, whole-grain cereals, and some vegetables, including cauliflower and broccoli.

Biotin absorption can be impaired by the presence of avidin – a protein found in raw egg white that binds biotin and prevents its absorption; however, heat treatment deactivates this effect. The condition of the gut microbiota is also important, as intestinal bacteria participate in the synthesis of small amounts of biotin – long-term antibiotic therapy or intestinal diseases can therefore limit its availability.

Biotin supplementation – when and in what dose

In situations where diet proves insufficient or when factors increasing demand occur, biotin supplementation may be justified. Doses in supplements most often range from 30 to 100 µg per day, which corresponds to the physiological needs of adults. In clinical and supplementary practice, higher doses are also encountered, but their use should be justified by higher demand or a clear deficiency and limited in time due to problems associated with too long supplementation at this level². Biotin is sometimes combined with other B vitamins (as in the case of Best B-Complex), zinc, selenium, or silicon, which can support metabolic processes and skin and adnexa regeneration, although it does not replace addressing the primary cause of the deficiency.

How long does it take to replenish biotin deficiency?

The time needed to correct biotin deficiency varies and depends on several key factors. With mild deficiency and proper absorption, the first metabolic effects may appear after several weeks, while improvement in hair, skin, and nail condition usually requires at least 2-3 months. This process can be slowed down in the case of absorption disorders, chronic intestinal diseases, long-term stress, use of certain medications, or persistent deficiencies of other micronutrients. Conversely, a balanced diet, good digestive tract condition, and regular supplementation promote faster normalization of biotin levels and resolution of symptoms.

Groups at increased risk of biotin deficiency

Individuals particularly susceptible to biotin deficiency are those with limited intake of this vitamin, impaired absorption, or increased metabolic demand. Groups at increased risk include:

• people following elimination diets or diets with limited diversity, including plant-based diets, if they do not include sufficient plant sources of biotin; during the initial period of changing the eating pattern, the body may not receive the amount of biotin corresponding to its needs. A similar mechanism applies to people consuming very low-calorie diets long-term, where the overall intake of micronutrients is often insufficient;
• people with digestive system disorders, such as inflammatory bowel diseases or malabsorption syndromes, because biotin is absorbed in the small intestine, and its availability also depends on the condition of the gut microbiota. Long-term antibiotic therapy can limit the endogenous production of biotin by intestinal bacteria, which, with low dietary intake, contributes to the gradual development of deficiency³;
• people who smoke and regularly consume alcohol in larger doses. Similar to the previous example, here the deficiency is caused by a combination of impaired normal gut microbiota function and impaired biotin absorption from the diet. The problem may be exacerbated by tissue hypoxia resulting from respiratory system dysfunction.

Furthermore, groups requiring special attention include individuals in states of increased metabolic demand, such as pregnancy and lactation, as well as those chronically exposed to stress or taking certain medications affecting the metabolism of B vitamins. In these cases, biotin deficiency does not result from a single factor, but from the overlapping mechanisms of limited supply, increased consumption, and less efficient utilization of the vitamin by the body.

Bibliography:

• X.Jin, Biotin (Vitamin B7) – Oral Biotin Supplementation for Keratin Synthesis, Barrier Integrity, and Beauty-From-Within Support, 2025 [access:https://www.researchgate.net/publication/396144252_Biotin_Vitamin_B7_-_Oral_Biotin_Supplementation_for_Keratin_Synthesis_Barrier_Integrity_and_Beauty-From-Within_Support]
• A. A. Sanosi, High-Dose Biotin Supplementation Exacerbates Chronic Migraine: A Case Report, International Medical Case Reports Journal, 2025.
• E. Belda, L. Voland, V.Tremaroli et al., Impairment of gut microbial biotin metabolism and host biotin status in severe obesity: effect of biotin and prebiotic supplementation on improved metabolism, British Society of Gastroenterology, no. 71/2022, vol.12.