Biotin Deficiency: What Kind of Deficiency Does Eating Raw Eggs Cause?

December 28, 2025 •

3 min read

According to the U.S. Food and Drug Administration (FDA), consuming raw or undercooked eggs poses a risk of Salmonella infection, which affects thousands of people each year. A related, but less common, concern is what kind of deficiency does eating raw eggs cause, namely the water-soluble vitamin B7, or biotin.

Quick Summary

The protein avidin in raw egg whites binds to biotin, preventing its absorption and causing a potential deficiency. This risk is amplified by the more immediate danger of Salmonella contamination in unpasteurized eggs. Cooking eggs denatures avidin and eliminates bacteria, making them safer and more nutritious.

Key Points

Biotin Deficiency: The protein avidin in raw egg whites binds to biotin (Vitamin B7), preventing its intestinal absorption.
Requires High Consumption: A biotin deficiency from raw eggs is rare and typically only occurs with long-term, excessive consumption of raw egg whites, not from occasional consumption.
Salmonella is a Bigger Concern: The immediate and more common risk of eating raw eggs is food poisoning from Salmonella bacteria, which can be life-threatening for high-risk individuals.
Cooking Eliminates Risks: Heat from cooking denatures the avidin protein, making biotin available for absorption, and kills any harmful Salmonella bacteria.
Vulnerable Groups Should Avoid Raw Eggs: Young children, older adults, pregnant women, and people with compromised immune systems should never consume raw or undercooked eggs due to the high risk of severe illness.
Cooked Eggs Are More Bioavailable: Studies show that protein from cooked eggs is absorbed much more efficiently by the body than protein from raw eggs.

The Avidin-Biotin Connection

While eggs are a fantastic source of many nutrients, including biotin found in the yolk, the white of a raw egg contains a protein called avidin. Avidin has a remarkable ability to bind tightly to biotin, forming a complex that the body cannot break down or absorb. The biotin-avidin complex passes harmlessly through the digestive system, preventing the body from utilizing the vitamin. For this reason, historically, a severe biotin deficiency caused by excessive raw egg consumption was termed "egg white injury". Cooking eggs denatures the avidin protein, effectively destroying its ability to bind to biotin and rendering the nutrient fully available for absorption.

Symptoms of a Biotin Deficiency

While a severe biotin deficiency is rare for most people, it can occur in individuals who consume large quantities of raw egg whites over extended periods. The signs and symptoms often develop gradually and can be non-specific, making diagnosis challenging.

Symptoms of a biotin deficiency include:

Dermatological Issues: Scaly, red rashes around the eyes, nose, and mouth (known as "biotin-deficient facies"), and generalized skin infections.
Hair Problems: Thinning hair or complete hair loss (alopecia).
Nail Brittleness: Brittle, thin, or ridged nails.
Neurological Problems: In severe cases, symptoms can include depression, lethargy, hallucinations, and numbness and tingling in the extremities (paresthesia). Infants might show signs of developmental delay, seizures, and hypotonia (weak muscle tone).
Metabolic Abnormalities: Problems with fat and carbohydrate metabolism, which can lead to fatigue, nausea, and lack of appetite.

The More Serious Risk: Salmonella Contamination

Although a biotin deficiency is a potential long-term risk of eating large amounts of raw egg whites, the immediate and more prevalent danger is food poisoning from Salmonella bacteria. Salmonella is a type of harmful bacteria that can be present inside or on the surface of an egg. This risk is present regardless of the egg's origin and can cause severe illness.

Salmonella infection, or salmonellosis, can cause a variety of unpleasant symptoms that typically appear within 12 to 72 hours of exposure. For most healthy individuals, the illness passes within a few days, but it can be dangerous for vulnerable populations.

High-risk groups who should strictly avoid raw eggs include:

Young children
Pregnant women
Older adults
Individuals with compromised immune systems (e.g., cancer, HIV/AIDS, diabetes, or transplant patients)

Comparison Table: Raw vs. Cooked Eggs


Feature	Raw Eggs	Cooked Eggs
Biotin Absorption	Reduced due to avidin binding in the white	Enhanced; avidin is denatured by heat
Protein Absorption	Reduced, approximately 50-60% absorbed	Higher, approximately 90% absorbed
Salmonella Risk	High, especially if not pasteurized	Very low, as heat kills the bacteria
Risk Groups	Dangerous for children, pregnant women, elderly, and immunocompromised	Safe for all populations when properly cooked

How to Minimize Risks

For those who prefer a runny yolk, or for recipes that traditionally use raw eggs (like homemade mayonnaise or Caesar dressing), there are steps to reduce the risk of illness. Using pasteurized eggs is the most effective way to eliminate the danger of Salmonella, as they have been treated with heat to destroy harmful bacteria. Proper food handling and storage are also critical. For further safety guidelines, consult the U.S. Food and Drug Administration's page on egg safety, as linked at.

Conclusion

While raw eggs do not directly cause a nutrient deficiency in the typical consumer, prolonged and excessive intake of raw egg whites can lead to a rare biotin deficiency due to the presence of the protein avidin. The most significant health risk associated with eating raw eggs is the potential for contracting a Salmonella infection, which can cause severe food poisoning. For optimal nutrition and safety, especially for vulnerable populations, cooking eggs thoroughly is the recommended method. Cooking not only eliminates the risk of bacterial contamination but also improves the absorption of both protein and biotin.

Frequently Asked Questions

Raw egg whites contain a protein called avidin, which binds to biotin (Vitamin B7) in the digestive tract. This binding prevents the body from absorbing the biotin, potentially leading to a deficiency if a large quantity of raw eggs is consumed over a long period.

No, a biotin deficiency from eating raw eggs is very rare. It would require consuming excessive amounts of raw egg whites, possibly dozens a day, over many months to cause a clinical deficiency in a healthy person.

The most serious and immediate risk of eating raw eggs is contracting a Salmonella infection. Salmonella is a bacteria that can cause food poisoning, leading to symptoms like diarrhea, fever, and abdominal cramps.

Yes, cooking eggs effectively prevents biotin deficiency. The heat denatures the avidin protein, destroying its ability to bind with biotin and allowing the vitamin to be fully absorbed by the body.

While the overall nutritional content is similar, cooked eggs offer better bioavailability. Studies have shown that the body absorbs significantly more protein from cooked eggs compared to raw eggs.

Certain groups are at a higher risk of severe illness from Salmonella and should always avoid raw eggs. These include young children, pregnant women, older adults, and individuals with weakened immune systems.

To safely use eggs in recipes that call for raw eggs, such as homemade mayonnaise or certain dressings, you should use pasteurized eggs. Pasteurization heats the eggs to kill harmful bacteria without cooking them.