What is Keratin?

Keratin is the tough, fibrous protein that forms the structural backbone of your hair, nails, and skin's outer surface. Because raw keratin is not digestible, supplement manufacturers use a process called hydrolysis to break it into smaller peptides that the body can actually absorb and put to use. Once absorbed, these peptides give your body the building blocks it needs to repair and reinforce keratin-based tissues.

How does Keratin work?

When you take hydrolyzed keratin orally, the peptides are absorbed through the gut and delivered via the bloodstream to hair follicles, nail beds, and skin. There, they provide amino acids — especially cysteine — that are the raw material your body uses to synthesize new keratin. Cysteine is critical because it forms the disulfide bonds that give keratin its strength and resilience. Supplementing these peptides essentially tops up the supply your body needs to produce stronger, thicker hair and nails.

What forms does Keratin come in?

Oral capsules and powders deliver keratin systemically for hair, nail, and skin support from the inside out. Topical keratin products (shampoos, treatments) coat the hair shaft to temporarily smooth and protect but do not penetrate the follicle or alter growth biology. Salon keratin treatments work similarly — they bond to the hair surface using formaldehyde or safer alternatives but are cosmetic rather than therapeutic.

Where it comes from:

Keratin supplementation is a relatively modern development emerging from the early 2000s, driven by the cosmetics and nutraceutical industries. The challenge for decades was making keratin bioavailable — the protein is inherently resistant to digestion. Advances in enzymatic hydrolysis and solubilization technology (notably Cynatine, developed in New Zealand) made oral supplementation viable and opened the door to clinical research.

What does Keratin help with?

• Hair thinning and shedding: Hydrolyzed keratin provides cysteine-rich peptides that feed hair follicles the amino acids they need to produce stronger, denser strands. Clinical trials using Cynatine HNS have shown meaningful reductions in daily hair loss and improvements in overall hair volume within 90 days of consistent use.
• Brittle or weak nails: Nails are made almost entirely of hard keratin, so when keratin building blocks are in short supply, nails become thin, peel, and break easily. Supplementing with hydrolyzed keratin replenishes these building blocks, and studies have shown measurable improvements in nail hardness and reduced breakage within 6 to 8 weeks.
• Dull, damaged, or frizzy hair: Hair that has been damaged by heat, chemicals, or environmental stress loses its keratin structure, leaving the surface rough and porous. Keratin supplements help the body rebuild that structure from within, improving shine, smoothness, and manageability over time.
• Slow nail growth: Adequate keratin protein availability supports the active growth cells at the nail matrix. Users and clinical participants have reported faster nail growth alongside improved strength when supplementing with hydrolyzed keratin over a 12-week period.
• Dry or rough skin texture: Keratin is one of the key proteins in the skin's outer barrier, helping it retain moisture and resist environmental damage. Hydrolyzed keratin supplements have been linked to modest improvements in skin hydration and smoothness, particularly in the hands and face.
• Hair breakage and split ends: Breakage happens when the disulfide bonds holding keratin fibers together are weakened. Cysteine from hydrolyzed keratin helps the body rebuild these bonds, reducing mid-shaft breakage and improving overall hair tensile strength.
• Weak hair after chemical or heat damage: Chemical treatments and excessive heat disrupt the protein matrix of hair. Oral keratin supplements support follicle-level protein synthesis so that new hair growing in is structurally stronger, even if existing damaged strands still need time to grow out.
• Skin elasticity and firmness: Keratin contributes to the skin's structural integrity alongside collagen and elastin. Early research suggests that keratin peptides may support skin resilience and reduce roughness, though this is less studied than the hair and nail benefits.

What can Keratin help prevent?

• Progressive nail brittleness in individuals with low dietary protein intake
• Hair shaft damage from ongoing heat or chemical exposure (when used concurrently)

Which foods are rich in Keratin?

Keratin itself is not found in food — dietary proteins are broken down into amino acids before absorption, and no food delivers pre-formed keratin peptides. However, eating protein-rich foods high in cysteine and sulfur-containing amino acids gives your body the raw materials to synthesize its own keratin. Top supportive foods include: (1) Eggs — especially egg whites, which are one of the richest sources of cysteine; (2) Lean poultry like chicken and turkey, which supply complete protein with good sulfur amino acid content; (3) Beef and lamb, which provide both cysteine and methionine needed for keratin synthesis; (4) Legumes such as lentils and black beans, which offer plant-based protein and sulfur compounds; (5) Sunflower seeds and pumpkin seeds, which are concentrated sources of cysteine-rich protein. Ensuring adequate overall protein intake (at least 0.8g per kg of body weight) is the most important dietary step to support keratin production naturally.

What are the side effects of Keratin?

• Mild nausea or stomach discomfort at higher doses
• Bloating or gas, especially when starting supplementation
• Rare allergic reactions in individuals sensitive to wool or poultry proteins (source-dependent)
• Topical salon keratin treatments carry separate concerns: formaldehyde-based products can cause eye, nose, and throat irritation with repeated professional exposure

Good to know:

Hydrolyzed keratin is considered very safe for most adults. It is derived from natural animal protein sources and has a strong tolerability profile in clinical studies, with no serious adverse events reported in trials.

How much Keratin should you take?

• Recommended daily: 500 mg to 1,000 mg of hydrolyzed keratin per day (clinical trials typically use 500 mg of Cynatine HNS daily)
• Best time of day: No strict timing requirement — morning or midday works well for most people
• With or without food: Take with food to improve tolerability and support amino acid absorption alongside dietary protein
• Time to effect: 4 weeks for early changes in shedding; 8 to 12 weeks for visible hair, nail, and skin improvement
• How long to take it: Best results come from consistent daily use for at least 90 days. Long-term supplementation is generally safe; benefits may diminish if discontinued, as the body's keratin synthesis returns to its baseline rate.