What Does Ingesting Keratin Do? Supplements, Digestion, and Effects

November 16, 2025 •

5 min read

The human body cannot properly digest natural keratin found in sources like hair and feathers due to its tough, insoluble structure. Consequently, ingesting keratin in its raw form provides no nutritional benefit and may pose certain health risks.

Quick Summary

Ingesting unaltered keratin is not digestible by humans and can lead to digestive issues. Bioavailable, hydrolyzed keratin in supplements may support hair, skin, and nail health.

Key Points

Indigestible Protein: Natural keratin from sources like hair or nails is not digestible by humans and provides no nutritional benefit.
Hydrolyzed Keratin: Supplements use hydrolyzed (broken down) keratin peptides, making them bioavailable and absorbable by the body.
Supports Keratin Production: Ingested keratin supplements provide the amino acid building blocks that the body can use to naturally synthesize its own keratin.
Potential Benefits: Research suggests bioavailable keratin supplements may improve hair strength, brightness, and nail hardness, while also benefiting skin elasticity.
Digestive Risks: Ingesting large quantities of undigested keratin can lead to the formation of hairballs (trichobezoars) and potential digestive blockages.
Balanced Diet is Key: Eating a diet rich in protein, biotin, and vitamins A and C is crucial for supporting the body's natural keratin production.
Oral vs. Topical: Ingesting supplements differs from topical keratin treatments, which temporarily smooth hair from the outside and can contain harmful chemicals like formaldehyde.

Understanding Keratin: The Indigestible Protein

Keratin is a fibrous, structural protein that provides strength to our hair, skin, and nails. It is remarkably tough and highly resistant to digestive enzymes, including those found in the human stomach. If a human were to ingest a large quantity of natural, unprocessed keratin—such as swallowing hair—their body would be unable to break it down. Instead, the hair would simply pass through the digestive system largely unchanged. In some severe cases, this can lead to a condition known as trichobezoar, where a hairball forms in the stomach or intestines, potentially causing a blockage and requiring medical intervention.

The Science Behind Hydrolyzed Keratin Supplements

Given the body's inability to absorb raw keratin, how can oral keratin supplements be effective? The answer lies in the manufacturing process. Companies use a process called hydrolysis to break down the large keratin protein molecules into smaller, more bioavailable peptides. These smaller pieces can be readily absorbed by the body's digestive system. The source of this keratin is often animal by-products like sheep's wool or poultry feathers.

Once absorbed, these peptides and amino acids can then be used by the body's cellular processes. The key distinction is that the body is not absorbing a full keratin protein, but rather the building blocks that it can then utilize for various functions, including potentially synthesizing its own keratin.

The Reported Benefits of Keratin Supplements

Scientific research, particularly on hydrolyzed forms of keratin, suggests a number of potential benefits, primarily for hair, skin, and nail health. A study published in the Journal of Cosmetic Dermatology demonstrated that oral supplementation with a natural, hydrolyzed keratin led to significant improvements in the appearance of facial skin, hair, and nails in adult women.

Hair Health

Keratin supplements may improve hair health in several ways:

Increased Strength and Elasticity: By providing the necessary building blocks, supplements can help strengthen hair strands, making them more resistant to breakage. One study showed a significant improvement in hair strength after 90 days of supplementation.
Enhanced Shine and Luster: Many users report that their hair appears brighter and glossier, which is thought to result from the reinforcement of the hair cuticle.
Reduced Hair Loss: By strengthening hair from the root, some studies have noted a reduction in hair loss among participants.

Nail Health

For nails, which are also primarily composed of keratin, the benefits of supplementation can be particularly noticeable:

Improved Hardness: Research has shown that supplements can significantly increase nail hardness, making them less brittle and prone to breakage.
Smoother Appearance: In addition to strength, supplements may improve the overall smoothness and appearance of nails.

Skin Health

Supplementing with hydrolyzed keratin can also impact skin health:

Increased Elasticity and Firmness: The supplement can help support the skin's structural proteins, leading to a measurable increase in elasticity and firmness.
Reduced Wrinkle Depth: Studies have reported a progressive reduction in the depth and area of wrinkles in participants using keratin supplements.
Deep Skin Moisturization: Supplementation has been shown to improve deep skin moisturization, contributing to a healthier, more hydrated complexion.

The Role of Diet vs. Supplements

While supplements offer a direct route for delivering bioavailable keratin peptides, the most sustainable and fundamental way to support your body's keratin production is through a nutrient-rich diet. The body synthesizes keratin from amino acids, a process that requires a balanced intake of protein, vitamins, and minerals.

Foods that support natural keratin production include:

Eggs: A great source of protein and biotin, a key nutrient for keratin synthesis.
Salmon: Rich in protein, biotin, and omega-3 fatty acids, which promote healthy hair growth.
Sweet Potatoes: High in provitamin A, essential for promoting keratin synthesis and maintaining skin health.
Garlic and Onions: Contain N-acetylcysteine, which the body converts into L-cysteine, an amino acid found in keratin.
Kale: Provides provitamin A and vitamin C, supporting both keratin and collagen production.

This approach ensures that your body has a consistent supply of the raw materials it needs to produce and maintain its own keratin from the inside out.

Oral vs. Topical Keratin: What's the Difference?

It is crucial to understand that oral supplements and topical keratin treatments work in fundamentally different ways. The benefits of one do not necessarily translate to the other. Here is a comparison:


Feature	Oral Keratin Supplement (Hydrolyzed)	Topical Keratin Treatment (Salon/At-Home)
Mechanism	Delivers bioavailable peptides and amino acids internally to support the body's natural keratin synthesis.	Applies a keratin solution externally to the hair cuticle, using heat to seal it in and fill gaps.
Primary Effect	Supports overall hair, skin, and nail health from the inside out, potentially improving structure and appearance over time.	Primarily affects hair appearance, resulting in smoother, shinier, and less frizzy hair for a temporary period (up to several months).
Ingredients	Bioavailable keratin peptides, often combined with other vitamins and minerals.	Keratin protein combined with other chemicals; some formulations may contain formaldehyde, a known carcinogen.
Duration of Effect	Requires consistent, long-term use to see and maintain results.	Temporary, with effects lasting only as long as the treatment remains on the hair.
Application	Ingested as a capsule, tablet, or powder.	Applied directly to hair by a professional stylist or at home, often involving heat styling.

Conclusion: The Final Verdict on Ingesting Keratin

Ingesting keratin is a complex topic with a clear distinction between natural and supplemented forms. It is established that consuming raw, natural keratin, such as hair, is not digestible and can be dangerous. The human digestive system simply lacks the enzymatic capability to break down its tough fibrous structure. However, oral supplements that contain hydrolyzed keratin have shown promising results in clinical studies, suggesting they can deliver the necessary amino acids to support the body's own keratin production for healthier hair, skin, and nails. For optimal results, these supplements should be considered as a supportive measure alongside a balanced, nutrient-rich diet. The choice between oral supplementation and topical treatments depends on the desired outcome, as they address cosmetic and systemic needs differently. Ultimately, for those seeking to enhance their health from the inside, supporting the body’s natural keratin synthesis through diet and targeted supplements is the most effective approach.

The Effects of an Oral Supplementation of a Natural Keratin on Skin, Hair, and Nails

Frequently Asked Questions

No, the human body cannot digest or absorb natural keratin. It is a tough, insoluble protein that is resistant to digestive enzymes and passes through the system without being broken down.

Swallowing small, individual hairs is generally harmless, but consuming a large amount can be dangerous. The undigested hair can accumulate in the stomach or intestines and form a hairball (trichobezoar), which can cause blockages and requires medical attention.

Keratin supplements contain hydrolyzed, or broken-down, keratin. This process reduces the large protein into smaller peptides and amino acids that the body can easily absorb and use as building blocks for its own keratin production.

Clinical studies on hydrolyzed keratin supplements have shown potential benefits, including increased hair strength and brightness, improved nail hardness, reduced hair loss, and enhanced skin elasticity and moisturization.

The best way to naturally boost keratin production is by eating a balanced diet rich in protein and nutrients essential for its synthesis, such as biotin, vitamin A, and vitamin C. Good sources include eggs, salmon, sweet potatoes, and kale.

Keratin supplements are generally considered safe for most people, though some may experience mild side effects like digestive upset. Using supplements with independent verification (like USP or NSF) ensures ingredient accuracy. People with kidney disease should consult a doctor.

Ingesting and topically applying keratin have different effects. Oral supplements work internally to provide building blocks for natural production, while topical treatments only affect the external hair shaft. The best approach depends on whether you seek systemic health benefits or temporary cosmetic improvements.

There is no known risk of overdosing on the amount of keratin typically found in regulated supplements, as excess protein is generally processed and excreted by the body. However, people with specific health conditions, like kidney disease, should always consult a doctor before taking supplements.