Hair loss and brittle nails: understanding the hair cycle

BIOLOGYST · Cellular beauty & glow

Hair loss and brittle nails: understanding the hair cycle

Hair, nails: what science really says, and how to act from within.

You find it in your brush, in the shower, on your pillow. Your nails break at the slightest effort. You feel like your hair is thinning, that the volume isn't there anymore. These signs are often trivialized, and yet, they provide information about the state of your inner biology.

Hair loss and brittle nails are almost never a surface problem. They are signals that your hair follicles and nail matrices are lacking something essential: sulfur amino acids, structural minerals, enzymatic cofactors. These are parameters that can be identified, ideally with a healthcare professional.

I. Your hair is alive, and it follows a precise cycle

The hair cycle in 3 phases

Each hair goes through three successive phases, in an immutable order:

When the cycle gets disrupted: excessive shedding

Excessive hair loss is when more than 100 to 150 hairs fall out per day persistently, when density visibly decreases, or when the anagen phase shortens and hair grows back thinner and shorter than before.

There are several types of hair loss, but the most common among women are:

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II. Keratin: what is your hair really made of?

Keratin makes up 95% of your hair

Keratin is a fibrous protein that constitutes the essential structure of hair and nails. It is not a single molecule, but a network of intertwined proteins, held together by very strong chemical bonds, notably disulfide bridges, which are bonds between sulfur atoms.

It is precisely for this reason that sulfur amino acids—cysteine and methionine—play a central role in hair biology. Without them, the body cannot produce strong keratin. And without strong keratin, the hair fiber is fragile, brittle, and downy.

Why oral keratin has been re-evaluated

For a long time, experts believed that keratin taken orally was simply degraded into amino acids in the intestine, with no particular benefit for hair. Recent research has completely nuanced this view.

The key is the hydrolyzed form: when keratin is fragmented into small peptides (hydrolyzed keratin), available studies describe fragments that partially survive digestion, pass into the bloodstream, and are distributed to keratin-rich tissues: hair follicles, nail matrix, skin. The authors report that they not only provide sulfur amino acids but also biosynthesis signals described as stimulating keratinocytes.

“Hair is built from the inside. Topical keratin stays on the surface: it’s the oral route that research is exploring to reach the root.”

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III. The micronutrients that make the difference

Zinc: the conductor of hair growth

Zinc is the most studied trace element in hair loss. It is involved in more than 300 enzymatic reactions, several of which directly concern folliculogenesis (hair follicle formation) and keratinization. Zinc contributes to the maintenance of normal hair and nails.

Mechanistically, the literature describes zinc's involvement in the regulation of 5α-reductase, the enzyme that converts testosterone into DHT, the molecule associated with follicle miniaturization in androgenetic alopecia. It is also a cofactor of superoxide dismutase (SOD) and helps protect cells against oxidative stress.

Iron: the fuel for follicles

The hair follicle is one of the fastest dividing tissues in the body, so it needs high amounts of oxygen, transported by iron via hemoglobin. Even a slight iron deficiency (low ferritin without anemia) is described in the literature as potentially shortening the anagen phase and leading to diffuse hair loss.

Published data describe it as the most common deficiency in women of childbearing age and the primary nutritional cause of female hair loss. Iron helps reduce fatigue, contributes to normal oxygen transport in the body, and to normal cognitive function.

Silicon: the forgotten beauty mineral

Silicon is little known to the general public, but it contributes to the structure of the extracellular matrix that surrounds and supports the hair follicle. It is part of the composition of collagen and elastin fibers, and available studies describe a role in the mechanical resistance of the hair fiber and nail plate, as well as in the hydration retention of keratinocytes.

Bamboo extract is the most concentrated plant source of bioavailable silicon: up to 70% of its dry matter is composed of silicon dioxide.

Selenium: the antioxidant guardian of the follicle

Selenium is the essential cofactor of glutathione peroxidase: the antioxidant enzyme that protects hair follicle cells against oxidative damage. Without selenium, the follicle is particularly vulnerable to oxidative stress generated by inflammation, pollution, and UV radiation. Selenium contributes to the maintenance of normal hair and nails and to protecting cells from oxidative stress.

A selenium deficiency is associated with a degradation of hair quality: finer, more fragile, more prone to breakage, as well as changes in pigmentation.

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IV. Hair Nail Regenesis: the formula dedicated to your hair and nails

Hair Nail Regenesis is the BIOLOGYST formula designed for hair and nails. It combines the most scientifically documented active ingredients, in carefully studied dosages, and covers every link in the chain studied by research: keratin structure, supply of sulfur amino acids, minerals and vitamins.

Cynatine® HNS · 500 mg: patented hydrolyzed keratin

The most documented hydrolyzed keratin. Cynatine® HNS is a highly bioavailable hydrolyzed keratin, derived from New Zealand sheep's wool processed cold (Keratec process). According to the supplier's work, its peptide structure allows it to partially survive digestion, be absorbed into the bloodstream, and distribute to hair follicles and the nail matrix. It provides sulfur amino acids involved in keratin synthesis (notably cysteine, serine, glutamic acid); the authors describe a stimulation of keratinocyte activity.

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L-Cysteine · 200 mg

Direct precursor of keratin disulfide bonds. L-cysteine is the most abundant sulfur amino acid in hair keratin: it represents approximately 14% of the hair's amino acid composition. It is involved in the formation of disulfide bonds which give hair its mechanical resistance. It is also the direct precursor of glutathione, a molecule that cells produce themselves and that research describes as central to their defense system.

L-Methionine · 50 mg

Essential sulfur amino acid, not synthesizable by the body. Methionine is an essential amino acid: the body cannot produce it; it must be supplied through diet or supplementation. It is the precursor of cysteine via the methylation cycle. It also participates in the synthesis of creatine and carnitine, and in DNA methylation in follicle cells. Available studies link methionine deficiency to a slowdown in keratinization.

Bamboo extract · 150 mg (of which silicon: 112 mg)

Strengthening the structural matrix of the follicle and nail. Bamboo extract standardized in organic silicon is the most concentrated plant source of bioavailable silicon. Silicon participates in the synthesis of collagen and elastin fibers that form the architecture of the hair follicle and nail plate. Available studies describe an improvement in the mechanical resistance of hair and its elasticity, as well as a reduction in the porosity of the fiber that promotes breakage.

Zinc + Selenium + Iron · Zinc: 10 mg (100% NRV) · Selenium: 50 µg · Iron: 7 mg

Mineral trio for hair growth and protection. Zinc: contributes to the maintenance of normal hair and nails; it regulates 5α-reductase, participates in keratinocyte proliferation, and helps protect cells from oxidative stress via SOD. Selenium: a cofactor of glutathione peroxidase, it contributes to the maintenance of normal hair and nails and to the protection of cells from oxidative stress. Iron: essential for bulb oxygenation and the duration of the anagen phase; it helps reduce fatigue. Its deficiency is the number one nutritional cause of female hair loss.

Vitamin E + B Vitamin Complex + A · Vit. E: 14.4 mg (120% NRV) · B complex including biotin

Antioxidant protection and support for follicular metabolism. Vitamin E helps protect cells from oxidative stress, especially the lipid membranes of follicle cells exposed to peroxidation. Biotin (vitamin B8) contributes to the maintenance of normal hair: it is the cofactor of enzymes that synthesize fatty acids and proteins in hair, and its deficiency is a classic factor of hair fragility. Vitamins B5, B6 and B9 contribute to normal energy metabolism and reduce fatigue, and participate in the cellular metabolism of the follicle as well as melanin production.

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In summary

Hair loss and brittle nails are almost never inevitable. They are signals that your hair follicle is lacking raw materials: hydrolyzed keratin, sulfur amino acids, zinc, iron, silicon. Deficiencies often invisible in conventional blood tests, but very real.

Hair Nail Regenesis acts on the entire chain: Cynatine® HNS provides hydrolyzed keratin, L-cysteine and L-methionine provide the sulfur building blocks, bamboo supports the structure, zinc, selenium and iron support follicle growth and protection. All supported by clinical studies.

A three-month course: that's the length of a complete hair cycle.

Frequently Asked Questions

How much hair loss is normal per day?

Losing 50 to 100 hairs per day is normal: this is the natural rotation of the hair cycle. Excessive hair loss is defined as consistently losing more than 100 to 150 hairs per day, or when hair regrowth is visibly thinner and shorter than before.

Does oral keratin really reach the hair?

In hydrolyzed form, yes: small peptides partially survive digestion, enter the circulation, and redistribute to keratin-rich tissues. Glynis's study (2012, n=50, 90 days) reported a 33% reduction in hair loss and a 47% greater tensile strength compared to placebo.

What is the primary nutritional cause of hair loss in women?

Iron deficiency. Rushton's study (2002) on 194 women with diffuse hair loss showed that 72% of them had low ferritin (< 40 ng/mL) despite normal hemoglobin. Iron helps reduce fatigue and is essential for bulb oxygenation.

How long does it take to see a change?

Allow 6 to 8 weeks for hair and 4 to 6 weeks for nails, with 3 capsules per day with a meal. A minimum 3-month course is recommended, as the hair cycle extends over 3 to 6 months.

What active ingredients does Hair Nail Regenesis contain?

Cynatine® HNS 500 mg (patented hydrolyzed keratin), L-cysteine 200 mg, L-methionine 50 mg, bamboo extract 150 mg (of which 112 mg silicon), zinc 10 mg, selenium 50 µg, iron 7 mg, vitamin E 14.4 mg and a complex of B vitamins including biotin. Further analyses of active ingredients are available in the active ingredients blog and in the BIOLOGYST Journal.