You're losing your hair and don't know what to try anymore. Between the marketing promises of cosmetic brands, Pinterest recipes, and contradictory advice from those around you, it's hard to know what actually works — and especially, what science actually proves.
Good news: medical research has made great progress on this question. 8 nutritional actives now have solid clinical evidence to support hair quality, limit hair loss, and promote regrowth. Bad news: no dietary supplement works miracles, and some of the most popular ones (like biotin alone) are actually less effective than you've been led to believe.
In this article, we break down the 8 actives proven by meta-analyses from 2018-2024, with exact figures, PubMed DOIs, and the limitations of each study. By the end, you'll know exactly what to take, at what dosage, and for how long.
Keratin • Biotin — 30 capsules
Cynatine® HNS (patented keratin) + biotin + zinc. Triple proven action: hair, skin, nails. Visible results in 30 days.
View Keratin • Biotin →
Sublimateur® — 60 capsules
Sulfur-containing amino acids (L-cystine, methionine) + B vitamins + minerals + plant extracts. Complete beauty ritual for hair, skin, and nails.
View Sublimateur® →Iron deficiency ultra-common: according to Dugan et al. 2021 in Anaesthesia, 12 to 18% of healthy women are iron deficient, the leading cause of hair loss in women.
Vitamin D and alopecia: according to Chen et al. 2023 in Journal of Cosmetic Dermatology (meta-analysis of 23 studies, 3,374 patients), people experiencing hair loss have vitamin D levels 7.3 ng/mL lower and 3 times more deficiency vs. healthy population.
Collagen and skin: according to de Miranda et al. 2021 in International Journal of Dermatology (meta-analysis of 19 RCTs, 1,125 participants), 90 days of hydrolyzed collagen significantly improve skin elasticity and hydration — favorable conditions for hair follicles.
Biotin alone = myth: according to Patel et al. 2017 in Skin Appendage Disorders, biotin only works in people with actual deficiency. A complete formula (biotin + keratin + zinc) is significantly more effective.
- Why your hair is really falling out (the 6 real causes)
- The 8 science-proven actives: overview
- Active #1 — Biotin: the underrated vitamin (and its true place)
- Active #2 — Zinc: the mineral of keratinization
- Active #3 — Iron / Ferritin: the #1 deficiency in women
- Active #4 — Vitamin D: the solar hormone of the follicle
- Active #5 — Marine collagen: the scalp matrix
- Active #6 — Patented hydrolyzed keratin: the promise and the science
- Active #7 — Sulfur-containing amino acids (cysteine, methionine)
- Active #8 — Ashwagandha: stress-related hair loss
- For men: androgenetic alopecia and DHT
- How to combine these actives: 3 to 6 month protocol
- Self-test: what is the cause of your hair loss?
- Personalized decision table
- FAQ — All your questions about hair loss
Why your hair is really falling out (the 6 real causes)
Hair loss is never without cause. Science identifies 6 main mechanisms that often accumulate: chronic stress, nutritional deficiencies (iron, zinc, vitamin D, biotin), hormonal upheavals (post-partum, perimenopause, contraception), genetic predisposition (androgenetic alopecia), underlying diseases (thyroid, autoimmune diseases), and physiological seasonal hair loss (spring and autumn). Before searching for the "right magic pill," you must identify your dominant cause.
Normal hair loss is approximately 50 to 100 hairs per day — this is physiological renewal. Beyond that, and especially if hair loss lasts more than 3 months, it is calledtelogen effluvium and it becomes relevant to seek the underlying cause.
1. Chronic stress: the forgotten cause
Cortisol (stress hormone) disrupts the hair cycle by shortening the growth phase (anagen) and pushing follicles into the shedding phase (telogen). In practical terms, intense stress (bereavement, burnout, surgery, infection, COVID, childbirth) typically triggers massive hair loss… 2 to 3 months after the event. This is the delay between the forced shift to telogen and the actual hair shedding.
2. Nutritional deficiencies
4 main deficiencies are involved in hair loss: iron (especially in menstruating women), zinc, vitamin D and biotin (more rarely). According to Zhang et al. 2021 in Obesity Surgery, a meta-analysis of 18 studies (n=2,538) confirms that low levels of zinc, ferritin, and folic acid are significantly associated with hair loss after bariatric surgery—a study model that amplifies what we observe in real life among undernourished individuals or those in caloric restriction.
3. Hormonal upheavals
- Postpartum : hair loss begins 2 to 4 months after delivery and can last 6 to 12 months. This is physiological shedding (hairs maintained in anagen during pregnancy shift to telogen all at once).
- Perimenopause / menopause : decreased estrogen and slight relative increase in testosterone weakens the female hair follicle.
- Stopping or changing contraception : abrupt change in the hormonal environment that can trigger telogen effluvium.
- Thyroid dysfunction : hypo- or hyperthyroidism alter the hair cycle (to be detected through routine TSH testing).
4. Genetic predisposition (androgenetic alopecia)
<<<31>>> Androgenetic alopeciaalopécie androgénétique is the most common form of lasting hair loss. It affects 80% of men during their lifetime (often from age 25-35) and approximately 30 to 40% of women after menopause, in a more diffuse form. According to York et al. 2020 in Expert Opinion on Pharmacotherapy, the only truly proven treatments to date are finasteride (5-alpha-reductase inhibitor) and topical minoxidil—prescription medications that dietary supplements cannot replace.
5. Underlying diseases
Lupus, rheumatoid arthritis, alopecia areata (round bald patches), celiac disease, chronic inflammatory bowel diseases, severe anemia… All these conditions can cause hair loss. Medical evaluation is necessary in case of persistent hair loss beyond 3 months, especially if accompanied by other symptoms (extreme fatigue, pain, digestive disorders, distinct patches).
6. Seasonal hair loss
In spring and especially inautumn, many people experience more pronounced hair loss for 4 to 6 weeks. This is physiological (a legacy of mammals' seasonal cycles) and generally reversible without treatment. Do not confuse this with pathological hair loss.
The 8 science-proven active ingredients: overview
Here are the 8 nutritional active ingredients with the strongest scientific documentation against hair loss and to support hair quality. Each is supported by at least one meta-analysis or randomized controlled trial published on PubMed between 2017 and 2024. They do not work the same way or for the same profiles — the rest of the article details for each active ingredient the exact evidence, the target population, the effective dose and the validated synergies .
Before reviewing each active ingredient in detail, here is the summary grid for an immediate overview. The 8 active ingredients are ranked by strength of scientific evidence, from most proven to most contextual:
Note thatno single active ingredient works in isolation at 100%. Science shows that the most effective approaches are those that combine multiple complementary actives, targeted at the dominant cause (stress, deficiency, hormones, genetics). This is the approach of complete formulas such as Keratin • Biotin (Cynatine® HNS + biotin + zinc) or Sublimateur® (sulfur-containing amino acids + B vitamins + minerals + plant extracts).
Let us now detail each active ingredient, with precise figures, PubMed DOIs and usage contexts.
Biotin (vitamin B7): marketing promise vs scientific reality
The most publicized active ingredient on the market — but not for the reasons you think.
According to Patel et al. 2017 in Skin Appendage Disorders, biotin (vitamin B7 or B8) has a documented effect only in individuals with prior deficiency. For the vast majority of adults with normal nutrition, biotin alone does not provide clinically proven benefit. Its value comes mainly from its combination with other active ingredients (keratin, zinc) in complete formulas.
The authors identified 18 reported cases of biotin use for hair and nail growth. In all cases, patients receiving biotin supplementation presented with an underlying condition affecting hair or nail growth (acquired or hereditary biotin deficiency, brittle nail syndrome, unmanageable hair). All cases showed clinical improvement. The authors conclude that despite the commercial popularity of biotin, evidence of its efficacy in healthy individuals remains insufficient.
Patel DP, Swink SM, Castelo-Soccio L. Skin Appendage Disorders 2017;3(3):166-169. DOI: 10.1159/000462981
Why biotin is everywhere on the market
Biotin is a water-soluble B-group vitamin (B7 or B8). It plays a role in protein metabolism, including keratin which makes up hair and nails. This biochemical mechanism is the foundation of all hair marketing: "biotin = building block of keratin = stronger hair".
The problem is that biotin deficiency is extremely rare in the general population. Biotin is naturally produced by our gut microbiota and is present in many foods (egg yolks, liver, nuts, yeast, legumes). Except in special cases (genetic disease, chronic alcoholism, prolonged antibiotic treatment, severely unbalanced diet), you are probably not deficient.
When biotin really works
Biotin makes a clear difference in 3 contexts:
- Documented biotin deficiency (biotinidase deficiency, alcohol dependence syndrome, prolonged anticonvulsant treatments)
- Fragile and brittle nails (brittle nail syndrome) — stronger evidence than for hair
- In synergy with other active ingredients in a complete formula: this is exactly the principle of Keratin • Biotin by Nutrition•pro which combines Cynatine® HNS (patented keratin) + biotin + zinc, with clinically tested effects over 30 days
Effective dose
RCTs use doses of 300 µg to 5 mg/day. Beyond that, no additional documented benefit — and risk ofinterfering with laboratory tests (particularly thyroid levels, troponin, hormones). If you are taking biotin and need to have blood work done, stop taking it at least 48 to 72 hours before.
Zinc: the mineral of keratinization
Essential enzymatic cofactor for keratin synthesis and hair follicle cell division.
According to Zhang et al. 2021 in Obesity Surgery, a meta-analysis of 18 studies on 2,538 patients confirms a significant association between low serum zinc levels and hair loss (SMD -1.13, p = 0.05). Zinc is an essential enzymatic cofactor for keratinization and cell proliferation of the hair follicle. Recommended dose: 8 to 15 mg/day for 3 months.
The pooled analysis of 18 studies (n=2,538) shows that the incidence of hair loss after bariatric surgery is 57% (95% CI 42-71%). Low serum zinc levels (SMD -1.13; 95% CI -2.27 to 0.01; p = 0.05), folic acid (SMD -0.88; p < 0.0001), and ferritin (SMD -0.22; p = 0.01), but not serum iron or vitamin B12, are significantly associated with post-surgical hair loss. Hair loss is more frequent in young women.
Zhang W, Fan M, Wang C, Mahawar K, Parmar C, Chen W, Yang W. Obesity Surgery 2021;31(6):2649-2659. DOI: 10.1007/s11695-021-05311-2
Why zinc is so important for hair
Zinc acts at multiple levels in hair biology:
- Synthesis of structural proteins (keratin, collagen) — it is a cofactor for more than 300 enzymes, many of which are involved in protein production
- Cell division of the hair bulb — the hair follicle is one of the fastest-renewing structures in the body, requiring regular zinc intake
- Hormonal regulation — zinc modulates the enzyme 5-alpha-reductase which converts testosterone to DHT (involved in androgenetic alopecia)
- Scalp healing — useful in cases of chronic inflammation or seborrheic dermatitis
Effective dose and at-risk profiles
EFSA official recommendations are 10 mg/day for women and 12 mg/day for adult men. In case of hair loss, the therapeutic dose ranges from 15 to 30 mg/day for 3 months, to be taken away from meals rich in calcium (the two minerals compete for absorption).
Zinc deficiency risk profiles : vegetarians/vegans (zinc from plant sources is less bioavailable), people after bariatric surgery, chronic alcoholics, athletes (heavy perspiration), pregnant or nursing women, elderly people with malabsorption. The Zinc Nutrition•pro is a targeted option at 15 mg per capsule. It is also present in the formula Keratin • Biotin for complete hair/nails/skin synergy.
Iron / Ferritin: the #1 deficiency in women experiencing hair loss
A major cause often overlooked — blood work mandatory before any anti-hair loss protocol.
According to Dugan et al. 2021 in Anaesthesia, 12 to 18% of apparently healthy women are iron deficient, primarily due to unidentified heavy menstrual bleeding. Among the symptoms: fatigue, brain fog, and hair loss. Iron supplementation improves oxygen consumption and physical performance, independent of hemoglobin levels. Ferritin testing is essential for any woman with persistent hair loss.
This narrative review reveals that anemia is common, particularly in women, and that its most frequent underlying cause — iron deficiency — is often overlooked. Population screening shows that iron deficiency affects 12 to 18% of "fit and healthy" women, with heavy menstrual bleeding being the most common cause. Reported symptoms range from fatigue to brain fog, hair loss, and pica (craving to eat ice). Experiments demonstrate that reduced physical performance is related to iron deficiency independent of hemoglobin levels, and that iron supplementation improves oxygen consumption and physical fitness.
Dugan C, MacLean B, Cabolis K, Abeysiri S, Khong A, Sajic M, Richards T. Anaesthesia 2021;76 Suppl 4:56-62. DOI: 10.1111/anae.15432
The key role of iron in the hair cycle
Iron is essential forDNA synthesis and therefore cell division — a process that occurs at exceptional speed in the hair bulb (faster than in blood cells!). When iron reserves (measured by ferritin) decline, the body prioritizes vital functions (oxygen transport) at the expense of hair, which enters the shedding phase (telogen).
The blood work to request
If you are a woman experiencing persistent hair loss (> 3 months), ask your doctor for blood work including at minimum: ferritin (iron reserve, earlier indicator than hemoglobin), hemoglobin, serum iron, transferrin saturation coefficient, and ideally TSH (thyroid), vitamin D and zinc.
Ferritin should be above 50 ng/mL to support healthy hair growth (above 70 ng/mL is the ideal target for women with hair loss). Below 30 ng/mL, the effect on hair is generally marked.
Food sources and supplements
Heme iron (red meat, organ meats, seafood) is significantly better absorbed than non-heme iron (legumes, spinach, whole grains). For vegetarians and vegans, combining non-heme iron sources with vitamin C (acerola, orange, kiwi, bell pepper) doubles absorption.
The Organic Spirulina Nutrition•pro provides bioavailable iron and B vitamins as a natural dietary supplement. In cases of confirmed deficiency, medical iron supplementation (often prescribed) is necessary — dietary supplements alone are insufficient for true iron deficiency anemia. Never take iron supplements without prior blood work : excess iron is toxic.
Vitamin D: the solar hormone that drives hair follicle health
Meta-analysis of 23 studies on 3,374 patients — 3 times higher deficiency rate in hair loss cases.
According to Chen et al. 2023 in Journal of Cosmetic Dermatology, a meta-analysis of 23 studies comparing 3,374 hair loss patients to 7,296 healthy controls shows that patients with non-scarring alopecia (androgenetic, areata, female pattern, telogen effluvium) have significantly lower vitamin D levels (-7.29 ng/mL on average) and 3 times higher vitamin D deficiency rates (OR 3.11). Vitamin D supplementation and monitoring can help in the treatment of these alopecias.
The meta-analysis included 3,374 patients with non-scarring alopecia and 7,296 healthy controls, drawn from 23 studies. Patients with non-scarring alopecia showed decreased serum 25(OH)D levels (weighted mean difference −7.29 ng/mL; 95% CI −9.21 to −5.38) and increased incidence of vitamin D deficiency (OR 3.11; 95% CI 2.29 to 4.22) compared to healthy controls. The authors conclude that vitamin D supplementation and screening for vitamin D deficiency may be beneficial in the treatment of non-scarring alopecias.
Chen Y, Dong X, Wang Y, Li Y, Xiong L, Li L. Journal of Cosmetic Dermatology 2023;23(4):1131-1140. DOI: 10.1111/jocd.16093
Why vitamin D acts on hair
Vitamin D is actually an hormone, not simply a vitamin. It binds to specific receptors (VDR — Vitamin D Receptor) present notably in hair follicles. These receptors play a key role in the hair cycle : initiation of the anagen phase (growth), cellular differentiation of keratinocytes in the bulb, and local immune regulation.
When vitamin D levels are low (which is common in France, especially in winter and in people with limited sun exposure), hair follicles enter the growth phase less readily and remain in telogen longer. Result: diffuse shedding, thinner hair, slowed growth.
What level to aim for and how to supplement
The blood level of 25-OH-vitamin D to target for hair health is above 30 ng/mL (75 nmol/L), ideally between 40 and 60 ng/mL. In France, winter and urban lifestyle often bring this level below 20 ng/mL in adults.
Recommended supplementation: 1,000 to 2,000 IU/day of vitamin D3 (the most active form) for maintenance, or 4,000 IU/day in case of proven deficiency, under medical supervision. The Multivitamins & Minerals Nutrition•pro provides vitamin D in a complete formula also covering zinc, biotin and other key micronutrients for hair.
To learn more about essential vitamins to supplement during winter, see our article Essential vitamins to face winter.
Marine collagen: the matrix of the scalp
19 RCTs, 1,125 participants — proven efficacy on skin, favorable environment for hair follicles.
According to de Miranda et al. 2021 in International Journal of Dermatology, a meta-analysis of 19 RCTs on 1,125 participants (95% women, 20 to 70 years old) shows that daily intake of hydrolyzed collagen for 90 days significantly improveshydration,elasticity and reduces wrinkles vs placebo. Indirectly, by improving the quality of the dermis and the extracellular matrix of the scalp, collagen creates a favorable environment for the anchoring and nourishment of hair follicles.
This meta-analysis included 19 double-blind, placebo-controlled randomized studies on 1,125 participants aged 20 to 70 years (95% women). The pooled analysis of studies shows favorable results of hydrolyzed collagen supplementation compared to placebo in terms of skin hydration, elasticity and wrinkles. Improvements in hydration and elasticity are also confirmed in the subgroup meta-analysis. The authors conclude that ingestion of hydrolyzed collagen for 90 days is effective in reducing skin aging, decreasing wrinkles and improving elasticity and hydration.
de Miranda RB, Weimer P, Rossi RC. International Journal of Dermatology 2021;60(12):1449-1461. DOI: 10.1111/ijd.15518
Why marine collagen indirectly helps hair
Hair grows from a follicle anchored in the dermis — the deep layer of skin composed mainly of collagen. When the quality of the dermis deteriorates (aging, hormonal decline, repeated UV exposure, oxidative stress), the anchoring of the follicle and its blood supply become weakened. The hair then grows thinner, shorter, more fragile.
Furthermore, hydrolyzed marine collagen provides key amino acids (glycine, proline, hydroxyproline) which are also used in the synthesis of keratin. Indirectly, it is a useful raw material for hair metabolism.
Format and effective dosage
Effective RCTs use 5 to 10 g/day of hydrolyzed marine collagen for at least 90 days. Marine collagen (fish skin) is better absorbed than bovine collagen thanks to shorter peptides.
Nutrition•pro offers 3 formats to choose from according to your preference:
- Marine collagen Naticol® + hyaluronic acid — 120 capsules : discreet format, ideal to get started
- Marine collagen Naticol® powder — 300 g : best quantity/price ratio, to mix into yogurt, smoothie or hot beverage
- Marine collagen Naticol® to drink — 20 shots (grape flavor) : convenient travel-friendly format, ready-to-use
To learn more about optimal dosage and collagen quality criteria, see our article Marine collagen: what is the optimal daily dosage?.
Patented hydrolyzed keratin: the promise and the science
The flagship active ingredient in hair marketing — but not all keratins are created equal.
Keratin is the main structural protein of the hair (90% of the fiber). As a dietary supplement, its effectiveness depends entirely on its form and its bioavailability. Cheap powdered keratins (often from non-hydrolyzed animal sources) are barely absorbed by the intestines. Patented hydrolyzed keratins such as Cynatine® HNS are pre-digested into low molecular weight peptides, much better assimilated by the body.
The honest scientific angle on oral keratin
Let's be clear: keratin taken orally does not directly rebuild the hair fiber. Like any ingested protein, it is broken down into peptides and then amino acids by digestion. These amino acids are then redirected according to the body's priority needs — and hair is never a metabolic priority.
The real benefit of hydrolyzed keratin comes from 3 mechanisms:
- Targeted supply of sulfur-containing amino acids (cysteine, methionine) which are the main building blocks of endogenous keratin that you manufacture yourself
- Bioactivity of peptides derived from hydrolysis, which can modulate hair follicle cell signaling
- Synergy with other active ingredients in a complete formula: keratin + biotin + zinc = triple action on hair synthesis
Cynatine® HNS: the best-documented patented keratin
Cynatine® HNS is a patented soluble keratin, extracted from sheep wool through a gentle process that preserves disulfide bonds and original structure. It has undergone proprietary clinical testing demonstrating improvements in hair density, shine, and strength over 30 to 90 days.
This is precisely the form found in Keratin • Biotin by Nutrition•pro, combined with highly bioavailable biotin and zinc — a synergistic combination that covers both assimilable keratin intake, its vitamin cofactors, and its mineral cofactor.
For women seeking a more comprehensive approach (hair + skin + nails + sulfur amino acids via L-cystine), the Sublimator® is a relevant alternative, with a more complete formula also integrating B vitamins and plant extracts.
Sulfur amino acids: the true building blocks of your keratin
L-cystine, methionine, thiamine — the essential precursors documented in telogen effluvium.
According to Addor et al. 2018 in Clinical, Cosmetic and Investigational Dermatology, a clinical study over 180 days in women with telogen effluvium shows significant improvement in hair loss, volume, density, shine, and strength with combined formulas containing keratin and collagen amino acids, zinc, biotin, iron, and vitamins. Hengl et al. 2018 in J Photochem Photobiol B confirm the key role of L-cystine and thiamine for keratinocyte proliferation.
This clinical study compared the efficacy of two nutritional supplements as monotherapy for telogen effluvium in adult women over 180 days. Clinical evaluations demonstrated significant clinical improvement (p < 0.05) across evaluated parameters: hair loss, hair volume, density, shine, and strength. Digital trichoscopy showed significant improvement in the group containing zinc, biotin, iron, vitamins A, C, E, B complex, folic acid, magnesium, and keratin and collagen amino acids (+11.09%).
Sant'Anna Addor FA, Donato LC, Melo CSA. Clinical, Cosmetic and Investigational Dermatology 2018;11:431-436. DOI: 10.2147/CCID.S173082
Why sulfur amino acids are essential
The keratin produced by your body is rich in two sulfur-containing amino acids: cysteine and methionine. These two amino acids form the disulfide bonds that give hair fiber its strength and elasticity. Without sufficient intake, your hair becomes finer, more brittle, and grows more slowly.
The L-cystine (dimeric form of cysteine) is the most studied form. Hengl et al. 2018 demonstrated that it increases keratinocyte proliferation 3-fold in cell culture, and protects these cells from UV damage — a protective effect in addition to the structural effect.
Food sources and supplements
The foods richest in sulfur amino acids are: eggs (especially the yolk), fatty fish, lean meats, legumes (particularly soy), pumpkin and sunflower seeds, cruciferous vegetables (broccoli, cabbage). Strict vegan diets or very low-calorie diets may be deficient in them.
As a supplement, the Sublimateur® by Nutrition•pro provides sulfur amino acids through a complete formula combining L-cystine, B vitamins (including biotin), minerals and plant extracts. This is the recommended option for women experiencing telogen effluvium or seeking a comprehensive hair/skin/nail approach.
Ashwagandha: hair loss linked to chronic stress
If cortisol is making your hair fall, the most studied adaptogen may be your angle of attack.
According to Arumugam et al. 2024 in Explore, a meta-analysis of 9 RCTs on 558 patients confirms that ashwagandha reduces the perceived stress scale PSS by -4.72 points and serum cortisol by -2.58 µg/dl vs placebo. Now cortisol is directly implicated in telogen effluvium : it shortens the growth phase and precipitates follicles into shedding. For women experiencing hair loss linked to burnout, chronic overwork, or post-COVID, ashwagandha attacks the root of the problem.
The authors report a significant effect of ashwagandha formulations on the perceived stress scale (PSS, mean difference -4.72; 95% CI [-8.45 to -0.99]), Hamilton's anxiety scale (HAS, mean difference -2.19), and serum cortisol levels (mean difference -2.58 µg/dl) compared to placebo. Adverse effects associated with ashwagandha are limited. The authors conclude a beneficial effect on stress and anxiety.
Arumugam V, Vijayakumar V, Balakrishnan A, et al. Explore (NY) 2024;20(6):103062. DOI: 10.1016/j.explore.2024.103062
The link stress → cortisol → hair loss
During intense or chronic stress, cortisol rises and remains elevated. Now cortisol acts directly on the hair cycle in 3 ways:
- Shortening of the anagen phase (active hair growth, normally 2 to 6 years)
- Precipitation into telogen phase (hair enters "shedding" mode prematurely)
- Inflammation of the hair follicle (disruption of blood supply and nourishment to the bulb)
This is why massive hair loss typically occurs 2 to 3 months after a major stressful event (bereavement, burnout, COVID, childbirth, surgery). At that point, acting on cortisol through an adaptogenic plant like ashwagandha can make a real difference.
How to use ashwagandha for hair
Effective dose: 600 mg/day of standardized KSM-66® extract (the most studied extract), for 8 to 12 weeks minimum. Take in the evening with dinner to target evening cortisol and sleep. Quality sleep is also crucial for hair regeneration — it is at night that the hair follicle is most active.
To learn more about the proven benefits of ashwagandha, see our complete guide 10 science-backed benefits. Product: Ashwagandha KSM-66® Nutrition•pro.
For men: androgenetic alopecia and DHT (and the limitations of supplements)
According to York et al. 2020 in Expert Opinion on Pharmacotherapy,male androgenetic alopecia affects up to 80% of men during their lifetime. It is hair loss linked to DHT which progressively miniaturizes follicles. The only treatments truly proven at a large scale remain prescription medications: finasteride (5-alpha-reductase inhibitor) and topical minoxidil. Dietary supplements can support the overall condition but do not replace these treatments in cases of established baldness.
This clinical review concludes that androgenetic alopecia progresses over time. Although currently available medical treatments such as finasteride and minoxidil are effective in stopping disease progression, they allow only partial regrowth at best. Early treatment allows for more optimal results. Non-pharmacological approaches such as PRP (platelet-rich plasma) can be considered in patients resistant to medical treatment. Saw palmetto (Serenoa repens) is cited among complementary approaches being explored.
York K, Meah N, Bhoyrul B, Sinclair R. Expert Opinion on Pharmacotherapy 2020;21(5):603-612. DOI: 10.1080/14656566.2020.1721463
What supplements can actually do for men
Dietary supplements (keratin, biotin, zinc, collagen) do not stop established androgenetic alopecia. What they can do:
- Optimize the quality of remaining hair (thickness, shine, strength)
- Limit associated telogen effluvium (stress, nutritional deficiencies)
- Support the results of medical treatment (finasteride/minoxidil) by providing optimal nutritional support
In case of early onset androgenetic alopecia in a young man (before age 35, receding hairline, thinning crown), consult a dermatologist quickly. Finasteride and minoxidil are all the more effective when prescribed early — waiting 10 years means missing the optimal window of action.
Useful synergies for men
For men who want comprehensive hair support + vitality, several relevant synergies:
- Keratin • Biotin for scalp health
- Zinc for 5-alpha-reductase regulation
- Ashwagandha for cortisol (which worsens hair loss during chronic stress)
- Multivitamins & Minerals to cover all micronutrients
How to combine these actives: 3 to 6 month protocol
No supplement takes effect in less than 3 months — this is the duration of a complete hair cycle. The right protocol depends on your dominant profile: chronic stress (ashwagandha + magnesium + keratin), nutritional deficiency (blood test + targeted supplementation iron/zinc/vit D + multivitamins), post-partum/perimenopause hormonal (collagen + sulfur-containing amino acids + biotin), androgenetic (dermatology consultation + finasteride/minoxidil + nutritional support).
The bare minimum: 3 months, otherwise nothing
The hair cycle lasts 2 to 6 years in the growth phase (anagen), 2 to 3 weeks in the transition phase (catagen), then 2 to 3 months in the shedding phase (telogen). A hair you see falling out today left the anagen phase 2 to 3 months ago. Conversely, a hair regrowing today has just entered anagen — it won't be visible until after several centimeters of growth, or 3 to 6 months minimum.
Consequence: any anti-hair loss protocol requires patience. The first signs of decreased shedding often appear between 6 and 12 weeks. The first signs of visible regrowth (restored density) take 4 to 6 months. If you stop a supplement after 4 weeks because "it's not working," it's mechanically impossible that it could have worked.
Profiles and recommended protocols
"Chronic stress / post-COVID / burnout" profile
Hair loss appearing 2 to 3 months after a major stressful event, typical telogen effluvium.
Ashwagandha KSM-66® 600 mg/day in the evening + Magnesium bisglycinate 300 mg/day + Keratin • Biotin 1 capsule/day for a minimum of 3 months. If hair loss persists after 3 months, add Sublimateur® to reinforce sulfur-bearing amino acids.
Profile "Suspected Nutritional Deficiency"
Chronic fatigue, brain fog, brittle nails in addition to hair loss. Woman with heavy periods, vegetarian, restrictive diet.
Step 1: blood work (ferritin, TSH, vitamin D, zinc, CBC). Step 2: targeted supplementation based on results. In the meantime: Multivitamins & Minerals + Keratin • Biotin + Organic Spirulina for natural iron + Organic Acerola for vitamin C (iron absorption cofactor). For a minimum of 3 months, then repeat blood work.
Multivitamins & Minerals · Organic Spirulina · Organic Acerola · Keratin • Biotin
Profile "Hormonal — Postpartum / Perimenopause / Pill Discontinuation"
Massive hair loss 2-4 months after childbirth, or progressive loss after age 45 with diffuse thinning.
Sublimateur® 1 capsule/day (sulfur-bearing amino acids + B vitamins) + Marine Collagen Naticol® 5-10 g/day (skin matrix + amino acids) + Keratin • Biotin as a complement. Course of 4-6 months as the postpartum hair cycle lasts up to 12 months.
Sublimateur® · Marine Collagen Naticol® powder · Keratin • Biotin
Profile "Androgenetic Alopecia" (Primarily Men, Postmenopausal Women)
Hair progressively thinning, receding temples deepening (men) or center part widening (women).
Step 1: dermatological consultation. Step 2: if AGA confirmed, medical treatment (finasteride and/or minoxidil by prescription). Step 3: nutritional support — Keratin • Biotin + Zinc (role in 5-alpha-reductase) + Multivitamins to optimize medical treatment results.
Mistakes to Avoid
- Stopping Before 3 Months thinking that "it's not working" — that's mechanically impossible, the hair cycle doesn't respond faster
- Taking 10 Supplements at Once without logic — a targeted protocol with 3-4 active ingredients is more effective than scattered supplementation
- Supplementing with Iron Without Blood Work — excess iron is toxic, never take iron without ferritin testing
- Neglecting External Factors — 7-8 hours of sleep, sufficient protein intake (1 g/kg/day minimum), stress management, limiting aggressive chemical treatments and straightening
- Relying on supplements to treat AGA — they can support, not replace medical treatment
Self-test: what is causing your hair loss?
Check the statements that apply to you. The dominant profile that emerges will guide you toward the protocol best suited to your situation.
Personalized decision table
IF / THEN summary based on 8 studies in the guide — to decide quickly based on your situation.
FAQ — All your questions about hair loss
How much hair do we normally lose per day?
It is physiological to lose between 50 and 100 hairs per day. This is the normal renewal of the scalp (approximately 100,000 hairs in total). Hair loss becomes concerning when it exceeds 100 hairs/day persistently for more than 3 months, or when it is accompanied by visible thinning of scalp areas, widening of the parting or recession of the hairline.
How long does it take for an anti-hair loss supplement to take effect?
The hair cycle lasts 3 to 6 months. No dietary supplement can produce visible results in less than 3 months — it's mechanically impossible, as hair only grows approximately 1 cm/month on average. The first signs of reduced hair loss generally appear between 6 and 12 weeks. Real regrowth (restored density) takes a minimum of 4 to 6 months. Patience is essential.
Is biotin alone sufficient against hair loss?
No. According to Patel et al. 2017 (Skin Appendage Disorders), biotin has a documented effect only in people with a real biotin deficiency, which is rare in the general population. For the majority of hair loss cases, you must combine multiple active ingredients: keratin + biotin + zinc in a complete formula (such as Keratin • Biotin), with if needed a supplement of sulfur-containing amino acids, marine collagen and correction of underlying deficiencies.
What is the best form of keratin in dietary supplements?
The patented hydrolyzed keratin Cynatine® HNS is the best absorbed and most documented form. Extracted from sheep's wool through a gentle process that preserves disulfide bonds, it is pre-digested into low molecular weight peptides for optimal absorption. This is the form used in Keratin • Biotin by Nutrition•pro, combined with biotin and zinc. Cheap unhydrolyzed keratin powders are poorly absorbed and poorly effective.
When should you see a doctor for hair loss?
Consult a dermatologist without delay in case of:
• Sudden and massive hair loss (handfuls of hair in the brush or shower)
• Clear alopecic patches without hair (suspected alopecia areata, autoimmune disease)
• Itching, redness, pain of the scalp
• Persistent hair loss beyond 3 months despite an appropriate nutritional protocol
• Young man with early androgenetic alopecia (finasteride and minoxidil prescribed early are significantly more effective)
• Associated symptoms : extreme fatigue, suspected thyroid disorders, digestive issues
Why am I losing my hair after childbirth?
This is what is calledpostpartum telogen effluvium. During pregnancy, elevated estrogen levels artificially keep your hair in the growth phase (anagen) — you lose very little hair. After childbirth, the sharp drop in estrogen shifts all these hairs maintained in anagen to the shedding phase (telogen) simultaneously, resulting in massive hair loss 2 to 4 months after delivery. Good news: it is physiological and reversible. Recovery takes 6 to 12 months. Sublimateur® and marine collagen can support regrowth.
Is there a risk to taking iron as a supplement?
Yes, this is very important. Never take iron supplementation without prior blood work. Excess iron is toxic to the liver and can worsen certain conditions (hemochromatosis, for example). Ask your doctor for ferritin testing (reserves), serum iron, transferrin, and its saturation coefficient. If ferritin is low, your doctor will prescribe the appropriate dose. For gentle, natural dietary support without risk, organic spirulina provides bioavailable iron at a moderate dose.
Is seasonal hair loss (autumn/spring) concerning?
No, it is a normal physiological phenomenon. In spring and especially in autumn, many people notice more pronounced shedding for 4 to 6 weeks. This is a legacy of seasonal cycles in mammals, generally reversible without treatment. A preventive course of Keratin • Biotin or Sublimateur® during this period can limit the extent of shedding, though it is not essential. If shedding persists beyond 8 weeks or worsens, do not attribute it to the season and investigate another cause.
Can androgenetic alopecia be treated with dietary supplements alone?
No. According to York et al. 2020, only pharmacological treatments (finasteride oral and minoxidil topical) have solid evidence of efficacy in slowing the progression of androgenetic alopecia. Dietary supplements (keratin, biotin, zinc, collagen) can support the foundation and optimize the results of medical treatment, but cannot replace it. The earlier AGA is addressed, the better the results. Consult a dermatologist at the first signs (receding hairline, thinning crown, widening part line).
What is the difference between Keratin • Biotin and Sublimateur®?
Keratin • Biotin : targeted hair fiber formula with Cynatine® HNS (patented hydrolyzed keratin) + biotin + zinc. Ideal for structural reinforcement of hair and nails. 30-capsule format for 1 month of treatment.
Sublimateur® : more comprehensive feminine formula with sulfur amino acids (L-cystine, methionine) + B vitamins + minerals + plant extracts. A more holistic approach for periods of fatigue, stress, and hormonal changes. 60-capsule format for 2 months.
The two are complementary and often prescribed together for hormonal hair loss (postpartum, perimenopause) to combine fiber support (Keratin) and building blocks (Sublimateur®).
Does marine collagen really make hair grow?
Indirectly, yes. According to de Miranda et al. 2021 (meta-analysis of 19 RCTs, 1,125 participants), 90 days of hydrolyzed collagen improves skin elasticity and hydration. Hair grows from a follicle anchored in the dermis — when dermis quality improves, follicle anchoring and nutrition also improve. Additionally, collagen provides amino acids (glycine, proline, hydroxyproline) that can be used indirectly in keratin synthesis. The effect on hair is more subtle than the effect on skin, but real over 3-6 months.
Can multiple anti-shedding supplements be combined at the same time?
Yes, it is even often recommended to combine mechanisms of action. Coherent combinations:
• Hormonal profile : Sublimateur® + Marine collagen + Keratin • Biotin
• Stress profile : Ashwagandha + Magnesium + Keratin • Biotin
• Deficiency profile : Multivitamins + Spirulina + Acerola + Keratin • Biotin
Avoid combining 10 supplements at once without logic: a targeted protocol with 3-4 complementary actives is more effective than scattered supplements. Also be careful of duplicates (for example: zinc in Keratin • Biotin + isolated zinc = possible excess).
Are there any contraindications to hair loss supplements?
Yes, several precautions to follow depending on the active ingredients:
• Pregnancy / breastfeeding : no ashwagandha. Multivitamins and collagen acceptable under medical advice.
• Autoimmune diseases (lupus, MS, rheumatoid arthritis, Hashimoto) : no ashwagandha (immune stimulation).
• Hyperthyroidism or levothyroxine use : no ashwagandha without medical advice (thyroid effect).
• Hemochromatosis or elevated ferritin : no iron supplementation.
• Fish allergy : no marine collagen.
• Anticoagulants : caution with evening primrose/borage oil.
In case of doubt or ongoing medical treatment, consult your doctor.
Should an external hair care routine (shampoo, serum) be combined with supplements?
Yes, the approach is more complete when combining theinside (dietary supplements that nourish the hair follicle) and theoutside (scalp and hair fiber care). External tips: avoid washing too frequently (ideally 2-3 times per week maximum), opt for gentle sulfate-free shampoos, massage your scalp 2-3 minutes daily to stimulate microcirculation, limit aggressive chemical coloring and straightening treatments, space out hot styling tools and high-temperature blow-drying. A weekly hair oil treatment can also protect and nourish the hair fiber.
What tests should I ask my doctor for in case of persistent hair loss?
The basic blood work to request for persistent hair loss (> 3 months):
• Ferritin (iron stores — aim for > 50 ng/mL, ideal > 70)
• Hemoglobin and CBC (complete blood count)
• TSH (thyroid — between 0.5 and 2.5 mIU/L)
• 25-OH-Vitamin D (target > 30 ng/mL)
• Serum zinc
• Vitamin B12 and folate (if vegetarian/vegan or suspected deficiency)
Depending on the context, the doctor may also request: estradiol and FSH (if menopause suspected), testosterone and SHBG (if hyperandrogenism), ferritin and CRP (if inflammation), thyroid antibodies (if Hashimoto).
- Androgenetic Alopecia (AGA)
- The most common form of permanent hair loss, linked to genetic sensitivity of the hair follicle to dihydrotestosterone (DHT). Affects up to 80% of men during their lifetime and 30-40% of women after menopause. Recognizable by its pattern: receding hairline and vertex hair loss in men, widening of the parting in women.
- Telogen Effluvium
- Diffuse hair shedding (without patches), where an abnormally high number of hairs prematurely enter the telogen phase (shedding). Typical causes: major stress, childbirth, fever, surgery, nutritional deficiency. Reversible in 3 to 6 months if the cause is identified and treated.
- Anagen / Catagen / Telogen Phase
- The 3 phases of the hair cycle. Anagen = active growth (2 to 6 years). Catagen = transition (2-3 weeks). Telogen = resting then shedding (2-3 months). At any given time, approximately 85% of your hair is in anagen and 10-15% in telogen.
- Ferritin
- Protein that stores iron in the body. It is the most sensitive marker of iron reserves, well before hemoglobin. To support hair growth, ferritin should be above 50 ng/mL, ideally between 70 and 100 ng/mL in women.
- Keratin
- Fibrous protein rich in sulfur-containing amino acids (cysteine, methionine), comprising 90% of the hair fiber, epidermis and nails. Its structure relies on disulfide bonds that give it strength and elasticity. The best-studied oral form is Cynatine® HNS, patented hydrolyzed keratin.
- Hair Follicle
- Skin structure at the base of the hair, anchored in the dermis. Contains the bulb (where cells divide to produce hair), the dermal papilla (which supplies nutrients via blood vessels) and the sebaceous gland. The follicle progressively miniaturizes in androgenetic alopecia.
- DHT (Dihydrotestosterone)
- Active metabolite of testosterone produced by the enzyme 5-alpha-reductase. Responsible for progressive miniaturization of hair follicles in androgenetic alopecia. Finasteride blocks 5-alpha-reductase and reduces DHT production, thus slowing hair loss.
- Patel DP, Swink SM, Castelo-Soccio L. A Review of the Use of Biotin for Hair Loss. Skin Appendage Disorders 2017;3(3):166-169. DOI : 10.1159/000462981
- Zhang W, Fan M, Wang C, Mahawar K, Parmar C, Chen W, Yang W. Hair Loss After Metabolic and Bariatric Surgery: a Systematic Review and Meta-analysis. Obesity Surgery 2021;31(6):2649-2659. DOI : 10.1007/s11695-021-05311-2
- Dugan C, MacLean B, Cabolis K, Abeysiri S, Khong A, Sajic M, Richards T. The misogyny of iron deficiency. Anaesthesia 2021;76 Suppl 4:56-62. DOI : 10.1111/anae.15432
- Chen Y, Dong X, Wang Y, Li Y, Xiong L, Li L. Serum 25 hydroxyvitamin D in non-scarring alopecia: A systematic review and meta-analysis. Journal of Cosmetic Dermatology 2023;23(4):1131-1140. DOI : 10.1111/jocd.16093
- de Miranda RB, Weimer P, Rossi RC. Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis. International Journal of Dermatology 2021;60(12):1449-1461. DOI : 10.1111/ijd.15518
- Sant'Anna Addor FA, Donato LC, Melo CSA. Comparative evaluation between two nutritional supplements in the improvement of telogen effluvium. Clinical, Cosmetic and Investigational Dermatology 2018;11:431-436. DOI : 10.2147/CCID.S173082
- Hengl T, Herfert J, Soliman A, Schlinzig K, Trüeb RM, Abts HF. Cystine-thiamin-containing hair-growth formulation modulates the response to UV radiation in an in vitro model for growth-limiting conditions of human keratinocytes. Journal of Photochemistry and Photobiology B 2018;189:318-325. DOI : 10.1016/j.jphotobiol.2018.09.005
- Arumugam V, Vijayakumar V, Balakrishnan A, Bhandari RB, Boopalan D, Ponnurangam R, Sankaralingam Thirupathy V, Kuppusamy M. Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis. Explore (NY) 2024;20(6):103062. DOI : 10.1016/j.explore.2024.103062
- York K, Meah N, Bhoyrul B, Sinclair R. A review of the treatment of male pattern hair loss. Expert Opinion on Pharmacotherapy 2020;21(5):603-612. DOI : 10.1080/14656566.2020.1721463
