Updated: November 2025

Your evidence-based guide to choosing a keratin supplement that actually works, understanding what matters, and avoiding wasted money on inferior products

You've decided to try a keratin supplement. Good decision. But now you're facing a bewildering array of options, price points, and marketing claims.

Some say "pure keratin." Others boast "hydrolysed" formulas. A few claim "clinically proven." And you're wondering: are these differences real, or just marketing?

Here's the truth: not all keratin supplements are created equal. The quality, bioavailability, and effectiveness vary dramatically. Choosing the wrong supplement means wasting money on a product that won't deliver results.

Choosing the right one means seeing measurable hair, skin, and nail improvements within 90-180 days.

Let's break down exactly what separates an effective keratin supplement from an expensive placebo.

The Most Critical Factor: Bioavailability

Before you look at anything else, understand this one concept: bioavailability determines whether your body can actually use the keratin.

Why Bioavailability Matters

Your digestive system is sophisticated but selective. It can't absorb all proteins equally. Standard keratin has essentially zero bioavailability, meaning your body literally cannot break it down or utilize it.

This is why most cheap keratin supplements don't work. They contain keratin, but your body can't absorb it.

Bioavailable vs. Non-Bioavailable Keratin

Standard Keratin (Non-Bioavailable):

• Intact protein molecules too large to absorb

• Your digestive system passes it through unchanged

• You get no benefit

Digestible Functional Keratin™ (Bioavailable):

• Hydrolysed into free amino acids and small peptides

• Your body recognises and absorbs these components

• Achieves 91% bioavailability to human keratin

• Clinical studies prove measurable results

The difference: Standard keratin is like trying to absorb a brick. Functional Keratin™ is like absorbing pre-digested amino acids. Your body knows exactly what to do with it.

How to Identify Bioavailable Keratin

Look for:

• Digestible Functional Keratin™ or hydrolysed keratin with over 80% free amino acids

• Clinical studies demonstrating bioavailability

• Specific percentages mentioned (like 91% bio-identical to human keratin)

• Third-party testing verifying absorption rates

Avoid:

• "Pure keratin" with no mention of bioavailability

• Supplements that don't specify processing method

• Products without clinical backing

Key Ingredients: What Works Together

Quality keratin supplements don't contain keratin alone. They contain a synergistic blend of complementary ingredients.

The Star Ingredient: Digestible Functional Keratin™

The primary active ingredient providing bioavailable keratin your body can actually use

What it does: Provides 91% bio-identical keratin for rebuilding hair structure, strengthening nails, and improving skin elasticity

Supporting Cast: Essential Co-Ingredients

Biotin (Vitamin B7):
A B vitamin that activates your body's keratin production pathways

What it does: Tells your body to make more keratin while the supplemented Functional Keratin™ provides the structural support

Vitamin C:
An antioxidant that supports collagen synthesis

What it does: Protects your hair and skin from oxidative damage while supporting the connective tissue that anchors hair follicles

Vitamin E:
A fat-soluble antioxidant protecting cell membranes

What it does: Shields hair from environmental damage (UV, pollution, heat) and supports scalp health

Zinc:
A mineral essential for hair tissue growth and repair

What it does: Supports hair follicle health, reduces inflammation, and prevents hair loss from deficiency

Iron:
Critical for oxygen transport to hair follicles

What it does: Ensures hair follicles receive adequate oxygen and nutrients to maintain the growth phase

Folic Acid (Folate):
A B vitamin supporting cell division and DNA synthesis

What it does: Helps hair follicles divide and grow new hair cells while improving blood flow to the scalp

Red Flags: Ingredients That Shouldn't Be There

• Excessive fillers: Look at the ingredient list. If there are more fillers than active ingredients, it's low quality

• Artificial additives: Dyes, artificial flavours, artificial sweeteners indicate low-quality manufacturing

• Unknown proprietary blends: If you can't see exact ingredient amounts, the company might be hiding weak formulations

Bioavailability: Hydrolysed Keratin vs. Digestible Functional Keratin™

This distinction is crucial and often misunderstood.

Standard Hydrolysed Keratin

Hydrolysed keratin has been broken down into smaller molecules, which is better than standard keratin but still not optimal.

Issues:

• Varies dramatically in quality depending on hydrolysis method

• Some hydrolysis processes damage the protein structure

• Bioavailability can be unpredictable

• Loss of key amino acids (especially cysteine) during hydrolysis

Digestible Functional Keratin™

Uses patented technology that breaks keratin into free amino acids while preserving structural integrity

Advantages:

• 91% bioavailability to human keratin

• Preserves critical amino acids like cysteine

• Consistent, predictable bioavailability

• Clinically proven effectiveness

The difference: Digestible Functional Keratin™ isn't just "more hydrolysed." It uses patented processing that preserves what makes keratin work while ensuring absorption.

Quality Standards: What to Verify

Third-Party Testing

This is non-negotiable for a quality supplement.

Look for verification that:

• The product contains what the label claims (potency)

• No contaminants are present (purity)

• Heavy metals are within safe limits (safety)

• Manufacturing followed proper protocols (quality assurance)

Common third-party testers:

• NSF Certified

• USP Verified

• ConsumerLab tested

• UL (Underwriters Laboratories)

If a supplement doesn't mention third-party testing, that's a red flag.

Clinical Research

Look for supplements with peer-reviewed clinical studies backing their claims.

Questions to ask:

• Has this specific supplement been studied in humans?

• Were studies double-blind and placebo-controlled?

• Were results published in credible medical journals?

• Are results replicable?

Example of credible research:
Functional Keratin™ has peer-reviewed clinical studies showing 43% reduction in hair loss, 17.61% improvement in hair cortex integrity, and 10.1% increase in skin elasticity within 60 days.

Generic "keratin supplements" rarely have this level of evidence.

Source and Sustainability

Where does the keratin come from? This matters.

Best sources:

• New Zealand sheep wool (highest keratin concentration due to climate)

• Regeneratively farmed sources (humane, sustainable)

• Traceable supply chains

Lower quality sources:

• Industrial farmed wool (lower keratin concentration)

• Poultry feathers (lower bioavailability)

• Unknown origin

Dosage: Getting the Right Amount

The Right Amount Matters

Taking too little won't produce results. Taking too much won't speed results and increases side effect risk.

Standard effective dosage:
400-500mg of Digestible Functional Keratin™ daily is considered safe and effective

Why this amount:
This dosage provides enough bioavailable keratin for your body to use effectively while staying within safe limits

Timing for Maximum Absorption

Take with food, preferably meals containing fat:
Fat-soluble nutrients absorb better with dietary fat. Taking your keratin supplement with lunch or dinner (rather than on an empty stomach) improves absorption

Consistency Is Everything

Take it daily without missing days

Results appear within 90-180 days with consistent daily use. Missing days delays results.

Minimum duration: Most experts recommend at least 90-180 days of consistent use to see full benefits

This aligns with your hair's natural growth cycle. Hair grows slowly (about half an inch per month), so visible improvements take time.

Brand Reputation and Customer Reviews

Credible Sources for Information

Trustworthy review sources:

• Peer-reviewed medical journals (PubMed, PMC)

• Healthcare provider recommendations

• Third-party testing sites

• Verified customer reviews (not anonymous testimonials)

Red flags in customer reviews:

• Generic testimonials ("this changed my life!") without specifics on how or why

• All 5-star reviews (unrealistic)

• Reviews you suspect are paid, meaning they seem too good to be true or there's multiple that all sound the same 

• Reviews that seem copied or repetitive

Questions to Research

Before buying, search for:

• "Brand name keratin supplement clinical studies"

• "Brand name keratin supplement side effects"

• "Brand name keratin supplement reviews consumer reports"

• "Brand name keratin supplement third party tested"

What you find (or don't find) tells you about the product's credibility.

Safety Considerations

Who Should Consult a Healthcare Provider First

Before starting any supplement, consult your healthcare provider if you:

• Have existing medical conditions

• Take medications (especially blood thinners)

• Are pregnant or breastfeeding

• Have known allergies to any ingredient

• Are planning surgery (some supplements interact with anaesthesia)

Potential Side Effects

Quality keratin supplements like Functional Keratin™ are well-tolerated with minimal side effects.

Occasional side effects (usually temporary):

• Mild digestive adjustment in first few days

• Rare allergic reactions to specific ingredients

Stop immediately and consult a healthcare provider if you experience:

• Severe allergic reactions

• Unexplained symptoms

• Interactions with medications

Interactions with Medications

Keratin supplements are generally safe with most medications.

However, discuss with your healthcare provider if you take:

• Blood thinners (warfarin, aspirin)

• Thyroid medications

• Iron supplements (timing matters for absorption)

Storage and Shelf Life

• Store in a cool, dry place away from direct sunlight

• Check expiration dates before use

• Don't use supplements beyond their expiration date

Comparing Options: Quality Tiers

Red Flags: What to Avoid

These indicate a low-quality supplement:

• No mention of bioavailability or processing method

• No third-party testing verification

• Unsubstantiated health claims ("guaranteed to grow hair")

• Extremely cheap price (quality costs money)

• No ingredient transparency (won't list exact amounts)

• Claims to work in days or weeks instead of realistic expectations

• Only anonymous testimonials, no verified buyers

• No clinical research

• Pressure to buy, fear marketing

• Unknown brand with no verifiable information, i.e. brand owner / Founders hidden

The Bottom Line: What Actually Matters

In order of importance:

1. Bioavailability: The keratin must be in a form your body can absorb (Digestible Functional Keratin™)

2. Clinical Evidence: The product should have peer-reviewed studies proving effectiveness (43% hair loss reduction is gold standard)

3. Third-Party Testing: Verification that the product contains what it claims and is contaminant-free

4. Quality Ingredients: Supporting nutrients (biotin, vitamin C, zinc, iron) that complement the keratin

5. Transparent Sourcing: You should know where the keratin comes from and how it's processed

6. Reasonable Price: You get what you pay for. Premium quality costs more, but it delivers results

7. Realistic Timeline: Expect 90-180 days minimum to see results

A supplement that checks all these boxes will deliver measurable improvements in hair strength, skin elasticity, and nail health.

A supplement that lacks most of these is likely a waste of money.

References and Further Reading

• The Effects of Oral Keratin Supplementation - PMC - Research on bioavailability and hair health

• Effect of keraGEN IV Keratin Oral Supplementation - Lincoln Agritech - Clinical study showing 43.1% hair loss reduction

• keraGEN IV Clinical Study - Keraplast - Comprehensive peer-reviewed research on hair structure improvement

• Hair Loss: Causes and Prevention - American Academy of Dermatology - Professional guidelines on understanding hair loss

• Supplement Quality and Safety - FDA - Government standards for dietary supplements

• Why New Zealand Keratin Is Superior - Kiri10 - Deep dive into Functional Keratin™ sourcing and extraction

• KiriGlow Keratin Supplement - Kiri10 - Clinically-formulated keratin supplement with third-party testing

• Understanding Supplement Labels - ConsumerLab - How to read and interpret supplement labels