Biotin, or vitamin B7, is an essential, water-soluble vitamin that plays a critical role in the metabolism of fats, carbohydrates, and proteins. While it's found in many common foods and is even produced by intestinal bacteria, making a deficiency uncommon, certain populations are far more susceptible. These at-risk groups face potential health complications if the condition is not identified and treated early.
Genetic causes of biotin deficiency
Inborn errors of metabolism are among the most significant causes of biotin deficiency. These genetic disorders impair the body's ability to utilize or recycle biotin, leading to a functional deficiency regardless of dietary intake.
Biotinidase deficiency (BTD)
This rare, inherited disorder is the most common cause of genetic biotin deficiency. BTD affects the body's ability to produce the enzyme biotinidase, which is needed to free biotin from proteins so the body can reuse it.
- Profound BTD: Characterized by less than 10% of normal enzyme activity, profound BTD typically appears in early infancy and can cause serious neurological and dermatological issues if untreated. Symptoms include seizures, developmental delays, hypotonia (weak muscle tone), hair loss, and rashes. Thanks to universal newborn screening in many countries, this condition is often detected and managed with lifelong biotin supplementation before irreversible damage occurs.
- Partial BTD: With 10% to 30% of normal enzyme activity, individuals may have milder or no symptoms, but they can still develop problems during times of stress, like illness or infection.
Holocarboxylase synthetase deficiency (HCSD)
Another inherited disorder, HCSD, affects the enzyme responsible for binding biotin to carboxylase enzymes, which are vital for metabolism. Infants with HCSD often present with severe metabolic problems, seizures, and developmental delays within the first few months of life. Similar to BTD, treatment involves high doses of biotin.
Pregnancy and lactation
During pregnancy, the body's demand for nutrients increases dramatically. Studies show that up to one-third of pregnant women develop a marginal biotin deficiency, even with normal dietary intake. The clinical significance of this is still being researched, but there are concerns that it may pose a risk to fetal development. Likewise, plasma and breastmilk biotin concentrations can decrease in lactating women, requiring higher intake. Healthcare providers often recommend ensuring adequate intake through diet or prenatal supplements to mitigate this risk.
Lifestyle and dietary factors
Certain lifestyle choices can significantly impact biotin levels by interfering with absorption or metabolism.
Chronic alcoholism
Individuals with long-term alcohol use disorder are at an elevated risk. Alcohol can interfere with the intestinal absorption of biotin and other B vitamins. Studies have shown that a considerable percentage of people with chronic alcoholism have low biotin levels.
Excessive consumption of raw egg whites
Raw egg whites contain a protein called avidin that binds to biotin, preventing its absorption in the digestive tract. While consuming a few raw eggs won't cause a problem, excessive consumption over a long period can lead to deficiency. The avidin is neutralized by heat, so cooked eggs do not pose this risk.
Prolonged malnutrition
In regions with limited food availability, severe malnutrition can lead to nutritional biotin deficiency. Similarly, individuals on very restrictive, long-term diets that exclude biotin-rich foods may also be at risk.
Medical conditions and interventions
Several medical factors can disrupt the body's biotin balance.
Medications
- Anticonvulsants: Long-term use of certain anti-seizure medications, including phenytoin, phenobarbital, and carbamazepine, can accelerate biotin catabolism and inhibit its absorption, leading to lower biotin levels.
- Antibiotics: Prolonged courses of antibiotics can disrupt the balance of gut bacteria responsible for producing biotin, potentially leading to a deficiency.
- Isotretinoin: This acne medication has also been linked to reduced biotin levels.
Other medical interventions
- Total Parenteral Nutrition (TPN): Patients receiving long-term TPN without proper biotin supplementation are at a high risk of developing a deficiency. Modern hospital protocols typically include biotin in TPN formulas to prevent this.
- Gastrointestinal Disorders: Conditions that affect nutrient absorption in the intestines, such as Crohn's disease or short gut syndrome, can also increase the risk of biotin deficiency.
Comparing major risk factors
| Risk Factor | Primary Cause | Affected Population | Severity Potential |
|---|---|---|---|
| Genetic Disorders | Defective enzymes (biotinidase, HCS) preventing biotin recycling. | Newborns, infants, and children. | High; can cause irreversible neurological damage if untreated. |
| Pregnancy | Increased metabolic demands. | Pregnant and lactating women. | Marginal; potential risk for fetal development. |
| Chronic Alcoholism | Impaired intestinal absorption. | Individuals with alcohol use disorder. | Moderate; can lead to long-term deficiency. |
| Excessive Raw Eggs | Avidin binding to biotin. | Individuals on specific raw egg-heavy diets. | Moderate; reversible upon changing dietary habits. |
| Medications | Interference with absorption or metabolism. | Individuals on long-term anticonvulsants or antibiotics. | Variable; can be managed with supplementation. |
| Parenteral Nutrition | Absence of oral food intake and supplementation. | Patients on long-term IV feeding. | High; requires medical supervision and supplementation. |
Conclusion
While a severe biotin deficiency is a rare occurrence in the general population, it is a serious health concern for specific at-risk groups. The most common causes are rare genetic disorders, such as biotinidase deficiency, which is identified through newborn screening. Other populations at increased risk include pregnant women, those with chronic alcoholism or gastrointestinal disorders, and individuals on certain long-term medications or intravenous feeding. For these individuals, early identification and management are key to preventing the dermatological and potentially irreversible neurological consequences of deficiency. For further reading on biotin and other nutrients, the NIH Office of Dietary Supplements provides a helpful fact sheet.
Biotin-rich foods to consider
- Eggs (cooked)
- Organ meats (like liver)
- Nuts (e.g., almonds, peanuts) and seeds
- Salmon
- Spinach
- Sweet potatoes
- Mushrooms
- Whole grains
These foods can help maintain adequate biotin levels in most people. However, for those in the high-risk groups mentioned, dietary changes alone may not be sufficient, and a healthcare provider should be consulted.
