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Skin, Hair & Nails

CUTIZANA

£29.95

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Cutizana is the 10,000mg liquid collagen supplement for radiant skin, fabulous hair and strong nails.

  • 10,000mg of marine collagen per serving
  • Nutrients to support collagen, keratin and elastin
  • Delicious berry flavour
  • Beats all tablet and sachet supplements
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As we age, our body’s own production of collagen declines and this is where Cutizana steps in.

“Cutis sana” means healthy skin and Cutizana is packed with more marine collagen and nutrients than collagen supplements which are twice the price.

The nutrients are dissolved in liquid which means that Cutizana has more nutrients than any tablet supplement where nutrients are compressed.  In fact, one tasty serving of Cutizana is the equivalent of twenty 500mg collagen tablets.

  • 10,000mg Hydrolyzed Collagen 1 & 3
  • Hyaluronic Acid
  • Silica & Gluconate
  • Vit B7 (Biotin) B5, B6, B12
  • Vit C

Combining additional nutrients with 10,000mg of collagen, Cutizana also delivers far more than sachet collagen supplements, and all at an affordable price.

The nutrients in Cutizana are fully supported by scientific papers, see the ingredients tab for information and references to 41 published research articles.

Why Cutizana?

Cutizana contains a10,000mg of type 1 and 3 marine collagen whose amino acids  are used in the proteins collagen, elastin and keratin.   Made from amino acids, collagen is the most abundant protein in the human body.

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A quick clarification, hydrolyzed collagen or collagen peptides?  The two are exactly the same, just different words.  Hydrolyzed collagen or collagen peptides is simply collagen which has been broken down so that the amino acids can be dissolved and thus be available and easily absorbed by the body.
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Collagen, elastin and keratin proteins are the building blocks of our skin, hair and nails and all of the amino acids in these proteins are found in Cutizana.

  • Collagen is made of glycine, proline, alanine, and hydroxyproline.
  • Elastin is made of glycine, proline, alanine, leucine, and valine.
  • Keratin is made of methionine, cysteine, and cystine.

SKIN

Human skin is made of three layers;  epidermis, dermis and subcutis.  The outer protective epidermis layer is made from keratin which gives the skin its rigidity.  It takes roughly five weeks for new cells to reach the skin surface.

The middle layer is the dermis.  The dermis is made of collagen (75-85%) and elastin and together they give the skin its firmness and elasticity.  Lower levels of collagen production as we age and low levels of elastin cause the skin to wrinkle and sag.

The third layer of the skin is the hypodermis or subcutis and this houses the sweat glands and a layer of fat for insulation and energy storage, whilst providing cushioning against knocks and bumps.

HAIR

95% of human hair is made of keratin. Whilst keratin is extremely strong and rigid if thick, when it is fine it has great flexibility.  Keratin is made up of amino acids and cysteine is a key amino acid in the production of keratin for healthy hair.  Diet and environment can affect the hair and whilst products can be used on our hair, the starting point for healthy hair comes from the inside.

NAILS

Fingernails are also made from keratin which gives them their strength and resilience.  Interesting fact, keratin is the substance found in the horn of the rhinoceros.

PLUS+

In addition to a large supply of collagen, Cutizana also provides other nutrients:

Hyaluronic acid – Found in the the epidermis and dermis, hyaluronic acid helps to keep our skin moist by trapping water molecules.  Drinking enough water is of course a key foundation of maintaining healthy skin.
Silica – Required for the formation of collagen as well as some enzymes that enhance skin strength and elasticity.  It is also used in nails.
Copper – Used in the production of collagen and elastin.
Vitamin C – Necessary for collagen and elastin production, it is a powerful antioxidant which protects cells from damage caused by “free radicals”.
Vitamin B5, B6, B7 (biotin), B12 – B vitamins are water-soluble.  This means that our bodies do not store them. B12 helps with hair colour, B7 deficiency can cause brittle nails, B6 helps with collagen formation and B5 supports hair colour and hair growth.

How to take Cutizana

Cutizana comes in a single, delicious berry-flavoured serving and can be taken neat or diluted with water.  You can even put it in your smoothie.  Once opened, store in the fridge.

Cutizana can be taken with Vitaliti and or Cartonica.

Each 500ml bottle is a 20 day supply.

Money Back Guarantee

We offer a 60 day money back guarantee on single bottles. That allows you to take Cutizana and in the unlikely event you feel it has not helped you to let us know.

The guarantee is on single bottle purchases, the return rate for all of our products is under 1%.

About Clinic Nutrition

At Clinic Nutrition we aim to simplify the choice for you by delivering nutrient-packed, delicious tasting supplements that are a pleasure to take, without ever being over-priced to match a hype.  We supply liquid supplements to medical clinics and hair and beauty centres.

Allergen Advice: Contains extracts from fish. See label image for full list of ingredients.
Not suitable for vegetarians.

See and feel the difference with Cutizana.

Cutizana Nutrients

Below is an explanation of the function of each of the nutrients in Cutizana with 41 references and links to scientific research papers.

– Hydrolyzed Collagen Types 1 & 3
– Hyaluronic Acid (Vegan, Sodium Hyaluronate)
– Silica (Silicone Dioxide)
– Copper (as Gluconate)
– Vitamin C (L-Ascorbic Acid)
– Vitamin B5 (Pantothenate)
– Vitamin B6 (Pyridoxine HCL)
– Vitamin B7 (Biotin)
– Vitamin B12 (Methylcobalamin)

For reference collagen, elastin and keratin are made from amino acids and these are the amino acids found in each body area:

Skin: Serine, Glycine, Alanine, Citrulline, Threonine, Histidine, Aspartic acid, Valine, Ornithine, Arginine, Isoleucine, Lysine, Leucine, Tyrosine, Glutamic acid, Proline, Phenylalanine

Hair: Alanine, Arginine, Aspartic acid, Cysteine, Glutamic acid, Glycine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Proline, Serine, Threonine, Tyrosine, Valine

Nails: Arginine, Histidine, Lysine

COLLAGEN & AMINO ACIDS

L-glycine

It is the most abundant amino acid in collagen. About 33% of the collagen molecule is glycine. (1)

Skin

Glycine helps prevent unwanted skin darkening (hyperpigmentation) by blocking the enzymes necessary for the production of melanin. (2) That way, it helps keep your skin lighter and smooth. Besides, it is a critical component of the skin’s moisture retention system.

Hair

Glycine is one of the amino acids that make hair keratin. Its deficiency has been linked to about 15% of all cases of baldness in men. (3)

L-proline

L-Proline and hydroxyproline contribute to about 23% of the collagen molecule. (1) They protect collagen against breakdown by proteolytic enzymes.

Skin

Proline protects your skin against UV rays and helps prevent premature skin ageing. (4) Besides, by increasing collagen production, they promote wound healing.

Hair

Proline deficiency is present in about 25% of all cases of baldness in women and 24% in men.  (3)

L-alanine

Alanine is found in both human skin and hair.

Skin

Alanine is a critical component of collagen. Its major role in the skin is to prevent the loss of water from the skin surface. Thus, sufficient alanine is key to preventing dryness and related skin problems, such as irritation.

Hair

Over 90% of men and women with thinning hair have alanine deficiency. (3)

L-glutamic acid

The body uses glutamic acid to produce proline and hydroxyproline. Both proline and hydroxyproline are the major constituents of collagen.

Skin

As a precursor of proline and hydroxyproline, glutamic acid is key to protecting the skin from the sun’s harmful UV rays.

Hair

Proline is necessary for keeping your hair strands strong. Proline deficiency is one of the causes of excessive hair loss and baldness in both men and women.

L-arginine

Arginine is one of the major components of structural proteins that make your skin, hair, and nail. The body uses arginine to produce proline and glutamate.

Skin

Arginine promotes wound healing and increases the production of collagen. (4) Supplementation with arginine, along with leucine and glutamine, improves skin texture, especially in women. (5)

Hair

Arginine is a powerful antioxidant with anti-ageing properties. It protects your hair against oxidative stress caused by colouring agents and bleach. (6)

Nail

A 6-week supplementation with arginine improves nail growth and hardness. (7)

L-aspartic acid or Aspartate

Unlike D-aspartic acid, L-aspartic acid is involved in the synthesis of structural proteins in the skin and hair.

Skin

The body uses aspartate to produce other amino acids – lysine, methionine, threonine, and isoleucine. (8) All these amino acids are essential for maintaining skin health and preventing UV-induced skin damage.

 Hair

Deficiency of any of the four amino acids – lysine, methionine, threonine, and isoleucine – can cause excessive hair loss in both men and women.

L-serine

Skin

Serine helps prevent the loss of moisture from the skin surface. That way, it hydrates the skin and prevents dryness – major cause of irritation.

Hair

Serine deficiency has been linked to hair thinning and baldness in both men and women.

L-lysine

L-lysine is found in the skin, hair, and nail.

Skin

Lysine is one of the building blocks of collagen. Deficiency of lysine can delay wound healing. (9) Lysine, along with zinc and herbs, can help treat facial cold sores. (10)

Hair

Lysine and iron therapy can help women with excessive hair loss. (11) Over half of people with telogen effluvium (TE) may have lysine deficiency. (7) TE causes temporary hair loss associated with stress or shock.

Nail

The body needs lysine to use. (12) Biotin (also called vitamin B7) is essential for nail growth and strength.

L-leucine

Leucine is a component of elastic. Elastin is a protein that makes your skin elastic. Low elastin levels cause wrinkles and sagging.

Skin

Supplementation with leucine, arginine, and glutamine improves skin texture and appearance. (5)

Hair

Leucine deficiency is common in women with hair loss and those with stress-related hair loss. (3)

L-valine

Like leucine, valine is one of the building blocks of elastin – a protein that gives your skin elasticity.

Skin

When you are valine deficient, you cannot produce enough elastin. Low elastin levels are a major cause of wrinkles and saggy skin.

Hair

Valine deficiency is commonly seen in men and women with baldness and those with stress-related hair loss. (3)

L-threonine

Skin

Threonine prevents the loss of moisture from your skin. Thus, supplementing with threonine can be an effective measure to prevent skin dryness.

Hair

Threonine deficiency may cause excessive hair loss. Likewise, some people with stress-related hair loss may have low levels of this amino acid.

L-phenylalanine

Phenylalanine is required for the synthesis of tyrosine. Tyrosine is used to make melanin – a pigment that gives your hair, skin, and eyes their natural colour.

Skin

Phenylalanine is essential for normal skin and hair colour. People with loss of skin colour (vitiligo) may benefit from phenylalanine supplementation. (13)

Hair

Phenylalanine deficiency may cause hair loss in some people. However, this is uncommon.

L-isoleucine

Skin

Isoleucine is used as a skin conditioning agent in many cosmetics. It is required for wound healing and may help people with eczema. (14, 15)

Hair

Isoleucine deficiency is common in people with excessive hair loss.

L-hydroxylysine

Hydroxylysine contributes to 1% of collagen. During collagen synthesis, lysine is converted to hydroxylysine in the presence of iron, oxygen, and vitamin C.

Skin

L-hydroxylysine is key to skin wound healing. (16)

L-methionine

Methionine improves the elasticity of skin and hair. Moreover, it makes your nails strong. As an antioxidant, methionine is revered for slowing down the aging process. (17)

Skin

Methionine is required for the synthesis of keratin. Keratin is a protein that protects the skin against damage by external stressors.

Methionine prevents the loss of moisture from the skin surface. Due to its powerful antioxidant activity, methionine protects the skin against the sun’s harmful UV rays.

Hair

Methionine deficiency is known to cause hair loss. Supplementation with methionine can prevent hair loss by increasing the absorption of zinc and selenium. (17)

L-histidine

Histidine is one of the three amino acids found in human nails.

Skin

Histidine is a potent antioxidant. It protects the skin from the harmful UV radiation.

Besides, histidine supplementation improves skin hydration and reduces itching in some forms of severe eczema. (18)

 Hair

Histidine deficiency is commonly seen in people with thinning hair.

Nail

Histidine deficiency can cause anaemia, which is one the reasons for brittle nails and vertical ridges on the nails. (19)

L-tyrosine

Tyrosine is required for melanin production. Melanin is a pigment that gives your hair, skin, and eyes their natural colour.

L-cysteine

Skin

Cysteine is a component of the skin’s hydration system and keratin. Thus, it helps your skin stay hydrated and intact. Besides, the antioxidant property helps protect your skin against damage by the UV rays.

 Hair

L-cysteine strengthens the hair strands and prevents hair loss. ( 20) Cysteine deficiency causes brittle hair. (21)

OTHER INGREDIENTS

Hyaluronic Acid

Hyaluronic acid (HA) is a critical component of the skin. It is found in both epidermis and dermis – the two layers of the skin above the subcutaneous tissues.

HA helps keep your skin moist by trapping water molecules in epidermis and dermis. UV exposure breaks down HA, which leads to dehydration and loss of elasticity. Furthermore, oral HA helps reduce wrinkles and skin roughness. (22)

According to a recent study, supplementation with HA improves hair appearance and texture. (23) Likewise, in another study, people taking HA with collagen reported strong, smooth and firm nails. (24)

Silica (Silicon Dioxide)

Silica is required for the synthesis of collagen as well as some enzymes that enhance skin strength and elasticity. (25) High levels of silica in the hair are shown to prevent hair loss and promote brightness.

Silica deficiency can cause soft and brittle nails. Notably, it may increase the risk of nail infections.

Copper (as Gluconate)

Copper is an essential nutrient for humans. It is a crucial nutrient required for the production of collagen and elastin. (26) Thus, taking copper can help reduce fine lines and wrinkles.

Copper deficiency may cause hair loss in some people. It is because copper plays a critical role in the production of cells that regulate hair growth. (27,28)

When taken with iron, zinc and amino acids, copper can make your nails strong, smooth, and shiny. (29)

Vitamin C (L-Ascorbic Acid)

Vitamin C has powerful antioxidant and skin-rejuvenating properties. As an antioxidant, it protects the cells from harmful chemical species called free radicals.

Vitamin C increases the production of collagen and elastin and helps maintain skin’s natural lipids. (30) Moreover, it is required for wound healing.

Because vitamin C is necessary for collagen production, its deficiency can cause hair loss and premature hair ageing. Furthermore, vitamin C promotes the absorption of iron from the food you eat. Iron is essential for hair growth.

Vitamin C deficiency can cause your nails to grow slowly and become brittle. (31)

Vitamin B5 (Pantothenate)

Vitamin B5 is a water-soluble vitamin. Your body uses this vitamin to make blood cells and release energy from the food you eat.

Pantothenate prevents premature greying of hair, promotes natural hair colour, and supports hair growth. (32) Due to its skin-softening and anti-inflammatory properties, pantothenate helps reduce acne lesions by as much as 67%. Moreover, pantothenate is used to promote nail growth. (33,34)

Vitamin B6 (Pyridoxine HCL)

This water-soluble B vitamin is required for protein, glucose, and fat metabolism. Besides, your body needs pyridoxine to make blood cells and neurotransmitters. The human body does not produce vitamin B6. Thus, you need to get it from your food or supplement.

Pyridoxine is essential for making collagen – a major component of the skin. Thus, the vitamin is crucial for maintaining healthy skin. (35,36) Its deficiency can lead to skin rashes, cracked lips, swollen tongue, and weakened immune system. Thankfully, taking a supplement can help clear the skin-associated symptoms. (37)

Vitamin B7 (Biotin)

Biotin is required for the metabolism of carbohydrates, fatty acids, and amino acids. A deficiency of biotin can cause skin rashes, brittle nails, and hair loss.

Biotin supplementation is effective in treating brittle splitting nails, hair loss, and premature greying of hair. (38,39,)

Studies show that biotin can reduce the production of sebum, an oily substance produced by the sebaceous glands. Thus, biotin can be used to control conditions caused by excessive sebum, such as dandruff and acne. (40)

Vitamin B12 (Methylcobalamin)

In humans, vitamin B12 deficiency can cause many skin and nail disorders. These include darkened skin, painful lumps on the skin, and nail streaks. (41)

Vitamin B12 is essential for maintaining your natural hair colour. Its deficiency may cause premature greying or whitening. (39)

References

1 Adrian Barbul, Proline Precursors to Sustain Mammalian Collagen Synthesis, The Journal of Nutrition, Volume 138, Issue 10, October 2008, Pages 2021S–2024S

2 Ishikawa M, Kawase I, Ishii F. Glycine inhibits melanogenesis in vitro and causes hypopigmentation in vivo. Biol Pharm Bull. 2007 Nov;30(11):2031-6. doi: 10.1248/bpb.30.2031. PMID: 17978471.

3 Gowda D, Premalatha V, Imtiyaz DB. Prevalence of Nutritional Deficiencies in Hair Loss among Indian Participants: Results of a Cross-sectional Study. Int J Trichology. 2017;9(3):101-104. doi:10.4103/ijt.ijt_48_16

4 Park K. Role of micronutrients in skin health and function. Biomol Ther (Seoul). 2015;23(3):207-217. doi:10.4062/biomolther.2015.003

5 Takaoka M, Okumura S, Seki T, Ohtani M. Effect of amino-acid intake on physical conditions and skin state: a randomized, double-blind, placebo-controlled, crossover trial. J Clin Biochem Nutr. 2019;65(1):52-58. doi:10.3164/jcbn.18-108

6 Oshimura E, Ino M. Effects of arginine on hair damage via oxidative coloring process. J Cosmet Sci. 2004;55 Suppl:S155-70. PMID: 15645092.

7 Mohamed Z. Gad, Anti-aging effects of l-arginine, Journal of Advanced Research, Volume 1, Issue 3, 2010, Pages 169-177,

8 Bender, D.A. (2012). Amino Acids Synthesized from Aspartate: Lysine, Methionine (and Cysteine), Threonine and Isoleucine. In Amino Acid Metabolism, D.A. Bender (Ed.).

9 Guo S, Dipietro LA. Factors affecting wound healing. J Dent Res. 2010;89(3):219-229. doi:10.1177/0022034509359125

10 Singh BB, Udani J, Vinjamury SP, Der-Martirosian C, Gandhi S, Khorsan R, Nanjegowda D, Singh V. Safety and effectiveness of an L-lysine, zinc, and herbal-based product on the treatment of facial and circumoral herpes. Altern Med Rev. 2005 Jun;10(2):123-7. PMID: 15989381.

11 Rushton DH. Nutritional factors and hair loss. Clin Exp Dermatol. 2002 Jul;27(5):396-404. doi: 10.1046/j.1365-2230.2002.01076.x. PMID: 12190640.

12 Bistas KG, Tadi P. Biotin. [Updated 2021 Jul 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-.

13 National Center for Biotechnology Information (2021). PubChem Compound Summary for CID 6140, Phenylalanine. Retrieved August 23, 2021

14 National Center for Biotechnology Information (2021). PubChem Compound Summary for CID 6306, l-Isoleucine.

15 Marseglia A, Licari A, Agostinis F, et al. Local rhamnosoft, ceramides and L-isoleucine in atopic eczema: a randomized, placebo controlled trial. Pediatr Allergy Immunol. 2014;25(3):271-275. doi:10.1111/pai.12227

16 Medscape. Skin Wound Healing. Author: Patrick E Simon, MD; Chief Editor: Arlen D Meyers, MD, MBA

17 National Center for Biotechnology Information (2021). PubChem Compound Summary for CID 6137, Methionine. Retrieved August 23, 2021

18 Michael Rothkopf, Results of Histidine (His) Supplementation in a Case of Severe Nummular Eczema (NE), Current Developments in Nutrition, Volume 4, Issue Supplement_2, June 2020, Page 1141,

19 Vera-Aviles, M.; Vantana, E.; Kardinasari, E.; Koh, N.L.; Latunde-Dada, G.O. Protective Role of Histidine Supplementation Against Oxidative Stress Damage in the Management of Anemia of Chronic Kidney Disease. Pharmaceuticals 2018, 11, 111.

20 Clemente Plaza N, Reig García-Galbis M, Martínez-Espinosa RM. Effects of the Usage of l-Cysteine (l-Cys) on Human Health. Molecules. 2018;23(3):575. Published 2018 Mar 3. doi:10.3390/molecules23030575

21 Hosking A, -M, Juhasz M, Atanaskova Mesinkovska N: Complementary and Alternative Treatments for Alopecia: A Comprehensive Review. Skin Appendage Disord 2019;5:72-89. doi: 10.1159/000492035

22 Papakonstantinou E, Roth M, Karakiulakis G. Hyaluronic acid: A key molecule in skin aging. Dermatoendocrinol. 2012;4(3):253-258. doi:10.4161/derm.21923

23 Guaitolini E, Cavezzi A, Cocchi S, Colucci R, Urso SU, Quinzi V. Randomized, Placebo-controlled Study of a Nutraceutical Based on Hyaluronic Acid, L-carnosine, and Methylsulfonylmethane in Facial Skin Aesthetics and Well-being. J Clin Aesthet Dermatol. 2019;12(4):40-45.

24 Aguirre A, Gil-Quintana E, Fenaux M, Erdozain S, Sarria I. Beneficial Effects of Oral Supplementation With Ovoderm on Human Skin Physiology: Two Pilot Studies. J Diet Suppl. 2017 Nov 2;14(6):706-714. doi: 10.1080/19390211.2017.1310781. Epub 2017 Apr 21. PMID: 28429999.

25 Araújo LA, Addor F, Campos PM. Use of silicon for skin and hair care: an approach of chemical forms available and efficacy. An Bras Dermatol. 2016;91(3):331-335. doi:10.1590/abd1806-4841.20163986

26 Borkow G. Using Copper to Improve the Well-Being of the Skin. Curr Chem Biol. 2014;8(2):89-102. doi:10.2174/2212796809666150227223857

27 Kil MS, Kim CW, Kim SS. Analysis of serum zinc and copper concentrations in hair loss. Ann Dermatol. 2013;25(4):405-409. doi:10.5021/ad.2013.25.4.405

28 Ryan R. Driskell, Carlos Clavel, Michael Rendl, Fiona M. Watt; Hair follicle dermal papilla cells at a glance. J Cell Sci 15 April 2011; 124 (8): 1179–1182. doi: doi.org/10.1242/jcs.082446

29 Sparavigna A, Tenconi B, La Penna L. Efficacy and tolerability of a biomineral formulation for treatment of onychoschizia: a randomized trial. Clin Cosmet Investig Dermatol. 2019;12:355-362. Published 2019 May 13. doi:10.2147/CCID.S187305

30 Pullar JM, Carr AC, Vissers MCM. The Roles of Vitamin C in Skin Health. Nutrients. 2017;9(8):866. Published 2017 Aug 12. doi:10.3390/nu9080866

31 Scheinfeld N, Dahdah MJ, Scher R. Vitamins and minerals: their role in nail health and disease. J Drugs Dermatol. 2007 Aug;6(8):782-7. PMID: 17763607.

32 Goluch-Koniuszy ZS. Nutrition of women with hair loss problem during the period of menopause. Prz Menopauzalny. 2016;15(1):56-61. doi:10.5114/pm.2016.58776

33 Yang M, Moclair B, Hatcher V, et al. A randomized, double-blind, placebo-controlled study of a novel pantothenic Acid-based dietary supplement in subjects with mild to moderate facial acne. Dermatol Ther (Heidelb). 2014;4(1):93-101. doi:10.1007/s13555-014-0052-3

34 Oh SJ, Kim JE, Ko JY, Ro YS. Therapeutic Efficacy of Combination Therapy Using Oral Cyclosporine with a Dietary Supplement (Pantogar®) in Twenty-Nail Dystrophy. Ann Dermatol. 2017;29(5):608-613. doi:10.5021/ad.2017.29.5.608

35 Prasad R, Lakshmi AV, Bamji MS. Impaired collagen maturity in vitamins B2 and B6 deficiency–probable molecular basis of skin lesions. Biochem Med. 1983 Dec;30(3):333-41. doi: 10.1016/0006-2944(83)90025-x. PMID: 6651795.

36 Kato N. (2012) Role of vitamin B6 in skin health and diseases. In: Preedy V.R. (eds) Handbook of diet, nutrition and the skin. Human Health Handbooks no. 1, vol 2. Wageningen Academic Publishers. https://doi.org/10.3920/978-90-8686-729-5_4

37 Inubushi T, Takasawa T, Tuboi Y, Watanabe N, Aki K, Katunuma N. Changes of glucose metabolism and skin-collagen neogenesis in vitamin B6 deficiency. Biofactors. 2005;23(2):59-67. doi: 10.1002/biof.5520230201. PMID: 16179747.

38 Colombo VE, Gerber F, Bronhofer M, Floersheim GL. Treatment of brittle fingernails and onychoschizia with biotin: scanning electron microscopy. J Am Acad Dermatol. 1990 Dec;23(6 Pt 1):1127-32. doi: 10.1016/0190-9622(90)70345-i. PMID: 2273113.

39 Almohanna HM, Ahmed AA, Tsatalis JP, Tosti A. The Role of Vitamins and Minerals in Hair Loss: A Review. Dermatol Ther (Heidelb). 2019;9(1):51-70. doi:10.1007/s13555-018-0278-6

40 Piraccini BM, Berardesca E, Fabbrocini G, Micali G, Tosti A. Biotin: overview of the treatment of diseases of cutaneous appendages and of hyperseborrhea. G Ital Dermatol Venereol. 2019 Oct;154(5):557-566. doi: 10.23736/S0392-0488.19.06434-4. PMID: 31638351.

41 Brescoll J, Daveluy S. A review of vitamin B12 in dermatology. Am J Clin Dermatol. 2015 Feb;16(1):27-33. doi: 10.1007/s40257-014-0107-3. PMID: 25559140.