Your hair, skin and nails are built from what you eat (and you are probably missing something)
90% of the dry weight of your hair is keratin. Your nails are keratin. The outer layer of your skin is keratin. And keratin is built from sulphur amino acids - cystine and methionine - that you can only get from what you eat. If the bricks are missing, the factory turns out defective parts: thin hair, splitting nails, and skin that has lost its texture.
The "beauty" supplement market is one of the most saturated and confusing out there. Biotin here, collagen there, strawberry-flavoured "hair gummies" that deliver more sugar than nutrients. But behind the noise there is real biochemistry. Your hair, skin and nails need specific raw materials, and science knows what they are.
Let's separate what works from what is marketing. What these tissues really need, why they sometimes fail, and what makes sense to supplement.
In this guide
How your body builds hair, skin and nails
Hair, nails and the outermost layer of skin (epidermis) share a structural protein: keratin. They are fast-renewal tissues, meaning your body produces them constantly. An active hair follicle builds hair 24 hours a day. Nails grow about 3 mm per month. The epidermis renews every 28-40 days.
And to build all that, raw materials are needed. Keratin is a protein rich in disulfide bonds (sulphur bridges between amino acid chains). Those bonds give it stiffness, resistance and structure. Without enough sulphur, keratin is weak. Hair that breaks. Nails that split into layers. Skin that loses firmness.
The key sulphur amino acids are L-cystine (two cysteine molecules joined by a disulfide bond) and L-methionine (essential amino acid, cysteine precursor). The body cannot make methionine, it must come from the diet. If protein intake is low or the diet is unbalanced, hair and nails are the first to show the deficit, because the body prioritises vital organs.
But keratin is not built from amino acids alone. It needs cofactors: zinc (for cell division in the follicle matrix), selenium (for antioxidant protection of the follicle), biotin (enzyme cofactor in keratin synthesis), B vitamins (energy metabolism of follicle cells) and vitamin C (collagen synthesis in the dermis surrounding the follicle).
The hair cycle has three phases: anagen (growth, 2-7 years), catagen (transition, 2-3 weeks) and telogen (rest and shedding, 2-4 months). Under normal conditions, 85-90% of your follicles are in the anagen phase. When there is a nutritional deficit, severe stress or hormonal changes, an abnormally high percentage of follicles enter the telogen phase simultaneously (telogen effluvium), and the shedding becomes visible 2-3 months after the triggering event.
The deficits that affect hair, skin and nails the most
Not everything that happens to your hair is genetic. In fact, a significant proportion of hair, skin and nail problems have a nutritional component that can be corrected. The best-documented deficits are:
Zinc. Involved in DNA synthesis and cell division, essential processes for fast-renewal tissues like the hair follicle. Zinc deficit is associated with telogen effluvium and with hair pigmentation changes. EFSA has approved the claim that zinc contributes to the maintenance of hair, nails and skin under normal conditions.
Biotin (vitamin B7). Cofactor of carboxylases, enzymes involved in amino acid metabolism and fatty acid synthesis. Its deficit causes dermatitis, alopecia and nail fragility. Rare on a normal diet, but more common in pregnant women, smokers and people who consume large amounts of raw egg white (avidin inactivates biotin).
Selenium. Protects the hair follicle from oxidative stress. Both deficit and excess can cause hair loss, so dosage matters. EFSA recognises its contribution to the maintenance of hair and nails under normal conditions.
Iron. Not in this formula (and rightly so: iron should only be supplemented with bloodwork confirming the deficit), but it is one of the most frequent causes of diffuse hair loss in premenopausal women. If you suspect iron deficit, request ferritin in your blood test before taking anything.
Protein and sulphur amino acids. Very low-calorie diets, poorly planned vegetarian diets or low-protein intakes may not cover cystine and methionine needs. Hair is the first thing to suffer when protein intake drops.
8 signs that your hair, skin or nails need attention
The ingredients science backs (and what each one does)
If you recognise several of the above signs and there is no dermatological diagnosis explaining them, the nutritional component is worth exploring. A specific supplement can make a visible difference in weeks.
A good nutricosmetic supplement is not just "biotin". It is a formula that covers the entire keratin production chain: sulphur amino acids + enzyme cofactors + supporting vitamins + antioxidant protection.
Sulphur amino acids: the raw material
L-cystine (180 mg): two cysteine molecules joined by a disulfide bond. It is the most abundant amino acid in keratin. It directly delivers the sulphur that forms the disulfide bridges giving structure and resistance to hair and nails.
L-methionine (120 mg): essential amino acid the body converts into cysteine. It is also a precursor of SAMe (S-adenosylmethionine), a methyl donor molecule with functions throughout cellular metabolism.
L-taurine (110 mg): amino acid with antioxidant and osmoregulatory function in the hair follicle. In vitro studies suggest taurine protects the follicle from oxidative stress and may prolong the anagen phase.
MSM (180 mg): methylsulfonylmethane, a source of bioavailable organic sulphur. It supplies the sulphur needed to form the disulfide bridges of keratin and collagen.
Keratin (60 mg)
Direct supply of hydrolysed keratin. It provides keratin peptides the body can use as substrate for the synthesis of new hair and nails.
Cofactors and vitamins
Each nutrient plays a specific role in the keratin production chain and in maintaining the skin barrier. The table summarises the doses included and the claims approved by EFSA:
| Nutrient | Amount/dose | Function in hair/skin/nails | EFSA claim |
|---|---|---|---|
| Biotin | 450 mcg (900% NRV) | Enzyme cofactor in keratin synthesis | - |
| Zinc | 10 mg (100% NRV) | Cell division in the hair follicle | Maintenance of hair, nails and skin |
| Selenium | 55 mcg (100% NRV) | Antioxidant protection of the follicle | Maintenance of hair and nails |
| Vitamin C | 80 mg (100% NRV) | Collagen synthesis in the dermis | Normal collagen formation for skin |
| Vitamin A | 800 mcg (100% NRV) | Epidermal cell differentiation | - |
| Vitamins B2, B3, B6 | 100% NRV each | Cellular energy metabolism | B2 and niacin: maintenance of skin |
How to choose a beauty supplement with judgement
The market is full of hair supplements containing token doses of biotin and little else. Here is what really matters:
Sulphur amino acids, not just vitamins. A supplement that only has biotin and zinc without cystine or methionine is like putting fuel in without having an engine. Biotin is the cofactor, but the amino acids are the actual raw material for keratin. Without them, biotin has nothing to work on.
Relevant doses of zinc and selenium. Not 10% of the NRV, but 100%. These minerals are involved in follicle cell division and in its antioxidant protection. If the dose is token, the effect will be too.
Keratin in the formula. Direct supply of keratin peptides saves the body a metabolic step. Not all supplements include it.
Realistic patience. Hair grows 1 cm per month. You will not see miracles in two weeks. The minimum window to assess a hair supplement is 3 months, ideally 4-6 months for density. Nails respond a bit faster (6-8 weeks) and skin is the first to improve (3-4 weeks).
If you also want to cover the deep dermis and the joints, combining Hair & Skin Support with hydrolysed collagen covers both fronts: keratin (epidermis, hair, nails) + collagen (dermis, joints). They are complementary, not redundant.
Hair & Skin Support
L-cystine + L-methionine + MSM + keratin + biotin 900% + zinc + selenium + vitamins A, B2, B3, B6, C. Complete formula for hair, skin and nails.
Hair & Skin Support - Vittalogy
Sulphur amino acids + Keratin + Biotin + Zinc + Selenium + Vitamins
120 vegetable capsules - 2 months - ISO 22000 & GMP
View Hair & Skin SupportFrequently asked questions
Does biotin really make hair grow?
If you have a biotin deficit, yes. If your levels are normal, taking more biotin will not speed up growth. Biotin is a cofactor, not a miracle ingredient. It works when it is part of a complete formula with the sulphur amino acids that are the actual raw material for keratin.
Can supplements stop hair loss?
If the loss is due to a nutritional deficit (iron, zinc, biotin, protein) or stress-related telogen effluvium, supplementation can significantly improve it. If it is androgenetic alopecia, supplements do not stop it on their own but can improve hair quality. A dermatological diagnosis before supplementing is the smartest move.
What are sulphur amino acids for in a hair supplement?
They are the building blocks of keratin. L-cystine forms the disulfide bonds that give structure to hair and nails. L-methionine is its essential precursor. MSM provides additional bioavailable sulphur. Without these amino acids, the keratin produced is of lower quality.
How long does it take to notice the effect?
Skin is usually the first (3-4 weeks). Nails improve in 6-8 weeks. Hair takes longer because it grows 1 cm per month: changes in thickness and quality show at 2-3 months, and in density at 4-6 months. There are no shortcuts.
Is it the same as taking collagen?
No. Collagen is the protein of the deep dermis and joints. Keratin is the protein of hair, nails and the epidermis. They are different structures. Hair & Skin Support covers keratin, collagen covers the dermis. They are complementary.
Can I take Hair & Skin Support together with other supplements?
Yes. It is compatible with collagen, magnesium, omega-3, vitamin D and probiotics. The combination with collagen is especially good for a complete inside-out beauty approach.
Sources and scientific references
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[2] Patel DP, Swink SM, Castelo-Soccio L. A Review of the Use of Biotin for Hair Loss. Skin Appendage Disord. 2017;3(3):166-169. - PubMed 28879195
[3] Goluch-Koniuszy ZS. Nutrition of women with hair loss problem during the period of menopause. Prz Menopauzalny. 2016;15(1):56-61. - PubMed 27095961
[4] Guo EL, Katta R. Diet and hair loss: effects of nutrient deficiency and supplement use. Dermatol Pract Concept. 2017;7(1):1-10. - PubMed 28243487
[5] Rushton DH. Nutritional factors and hair loss. Clin Exp Dermatol. 2002;27(5):396-404. - PubMed 12190640
[6] Trost LB, Bergfeld WF, Calogeras E. The diagnosis and treatment of iron deficiency and its potential relationship to hair loss. J Am Acad Dermatol. 2006;54(5):824-44. - PubMed 16635664
[7] Regulation (EC) 432/2012. Zinc: maintenance of hair, nails and skin. Selenium: maintenance of hair and nails. Vitamin C: normal collagen formation for skin. Riboflavin and niacin: maintenance of skin. EUR-Lex. - eur-lex.europa.eu
[8] Trueb RM. The impact of oxidative stress on hair. Int J Cosmet Sci. 2015;37 Suppl 2:25-30. - PubMed 26574298
[9] Naziroglu M, Kokcam I. Antioxidants and lipid peroxidation status in the blood of patients with alopecia. Cell Biochem Funct. 2000;18(3):169-73. - PubMed 10965636
[10] Harries MJ, Trueb RM, Tosti A, et al. How not to get scar(r)ed: pointers to the correct diagnosis in patients with suspected primary cicatricial alopecia. Br J Dermatol. 2009;160(3):482-501. - PubMed 19120338