Cysteine (L-cysteine): what it is, properties, formula, where it occurs

Cysteine is one of the amino acids responsible for the production of collagen.

AuthorLudwik Jelonek

Natu.Care Editor

Ludwik Jelonek is the author of more than 2,500 texts published on leading portals. His content has found its way into services such as Ostrovit and Kobieta Onet. At Natu.Care, Ludwik educates people in the most important area of life - health.

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Reviewed byIlona Bush

Verified by an expert

Reviewed byIlona Bush

Master of Pharmacy

Ilona Krzak obtained her Master of Pharmacy degree from the Medical University of Wrocław. She did her internship in a hospital pharmacy and in the pharmaceutical industry. She is currently working in the profession and also runs an educational profile on Instagram: @pani_z_apteki

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Edited byBart Turczynski

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Fact-checkingEmilia Moskal

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Emilia Moskal specialises in medical and psychological texts, including content for medical entities. She is a fan of simple language and reader-friendly communication. At Natu.Care, she writes educational articles.

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Cysteine (L-cysteine): what it is, properties, formula, where it occurs

10 July, 2024

Reviewed by10 January, 2024

Updated by12 January, 2024

Fact-checking08 January, 2024

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13 min

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Cysteine is an inconspicuous amino acid that supports skin health, detoxifies the body and regulates metabolism. Although the human body produces it on its own it is worth considering supplementation in some cases.

Check out the most important information about cysteine prepared together with Ilona Krzak, MSc pharmacy.

From this article you will learn:

What is cysteine and how it differs from L-cysteine.
What is cysteine?
What functions cysteine has in the body.
What it does.
How to dose it and which products it is found in.
How to dose it.

See also:

What is cysteine?

Cysteine is a amino acid that has many functions in the body. It is important for the formation of proteins, including keratin, which is responsible for the condition of hair, skin and nails. Additionally, cysteine is involved in the production of one of the most important antioxidants in the body - glutathioneand.

Cysteine is an endogenous amino acid, i.e. one that the body can produce on its own. Nevertheless, during certain metabolic diseases or inflammatory conditions, the demand for cysteine increases. In such cases, supplementation withand may be beneficial (and sometimes even necessary).

Cysteine versus L-cysteine - what's the difference?

Cysteine and L-cysteine are actually the same amino acid. The prefix "L-" is used to describe the specific orientation of the molecule.

Molecules of many amino acids - including cysteine - occur in two mirrored forms known as isomers. Isomers are molecules that have the same composition but differ in the arrangement of their atoms. In the case of amino acids, these two isomers are called 'L' and 'D'and.

We can compare this to human hands. Both are relatively the same, have similar functions, and similar capabilities. However, when you want to superimpose one on top of the other, you will notice that they occur in a mirror image.

When we talk about cysteine in a biological context, we usually mean L-cysteine. It is the one that is biologically active and therefore responsible for the vast majority of functions in the body. There is also D-cysteine, which, however, does not have many beneficial properties and is therefore usually not studied by specialistsand.

What formula does cysteine have?

The chemical formula of cysteine is: C3H7NO2S. This amino acid contains three carbon atoms (C), seven hydrogen atoms (H), one nitrogen atom (N), two oxygen atoms (O), and one sulfur atom (S)and.

Structurally, cysteine is an amino acid with a thiol group (consisting of a sulphur atom and a hydrogen atom) that allows specific structures (disulphide bridges) to form. And these are crucial for the stability of protein structuresand.

The sulphur atoms in cysteine have the ability to break down the glycoproteins of mucus into smaller molecules and to liquefy it and reduce its viscosity, which greatly facilitates expectoration without additional secretion production. This function is used in mucolytic drugs.

Ilona Krzak Master of Pharmacy

. .

Are N-acetylcysteine (NAC) and cysteine the same substance?

No, N-acetylcysteine (NAC) and cysteine are not the same substance, although they are closely related. Cysteine is an amino acid that occurs naturally in the human body. N-acetylcysteine (NAC), on the other hand, is a derivative of cysteine. It has been modified by the addition of an acetyl group (CH3CO), which increases its stability and bioavailability to the bodyand.

NAC is a popularly used dietary supplement due to its antioxidant capacity. Additionally, it is converted to cysteine in the body, increasing the concentration of this amino acid.

Cysteine is being studied for its effect on the risk of later cancer.

Ilona Krzak Master of Pharmacy

. .

What cysteine is for - action and properties

Cysteine is an amino acid that significantly affects the functioning of the human body. Its unique properties affect skin health, metabolic processes and the body's ability to fight toxins.

How exactly does cysteine work?

Promotes skin health

Cysteine is one of the main components of keratin, which is responsible for the condition of the skin, hair and nails. Keratin is the structural protein that gives strength and forms the structure of these elements. Adequate amounts of cysteine in the body, supports healthy levels of keratin, which in turn has a positive effect on the appearance ofand.

Additionally, cysteine has antioxidant properties, which are responsible for protecting the skin from harmful environmental factors such as UV rays and pollution .

Cysteine also affects the synthesis of glutathione - one of the body's most powerful antioxidants. Glutathione helps neutralise oxidative stress, which contributes to skin ageing. As a result, it increases the skin's resistance to damage and slows down the ageing processand.

Promotes detoxification of the body

The aforementioned glutathione (a powerful antioxidant) not only supports skin health, but also aids detoxification of the body. Because of its ability to neutralise free radicals and other harmful substances, it is called the master of detoxificationand.

The cysteine also owes its detoxifying properties to its sulphur atoms. These attract heavy metals such as mercury and lead, which helps to remove them from the body .

Glutathione destroys free radicals, but it also guards the detoxification of the body during drug use. After poisoning with paracetamol - a popular painkiller - it is not uncommon to administer acetylcysteine to regenerate glutathione and enhance its detoxifying action.

Ilona Krzak Master of Pharmacy

. .

Regulates metabolism

Cysteine is an essential component of many enzymes and hormones that are intimately involved in normal metabolism.

It participates in the metabolic cycle, which helps to properly absorb and process nutrients. Among other things, it is thanks to cysteine that the body can metabolise fats, proteins and carbohydrates efficiently, which translates into the correct production of energyand.

Additionally, cysteine also plays an important role in the production of taurine, an amino acid essential for the proper functioning of the nervous and muscular systems. Taurine is also involved in many other metabolic processes, including blood sugar regulation and water-electrolyte balance.

You could say that cysteine is such a 'metabolic base' - like flour for bread.

Ilona Krzak Master of Pharmacy

Improves immunity

Cysteine is particularly important for the production of antibodies. And it is these that are responsible for recognising and combating dangerous pathogens. What's more, cysteine supports the maintenance of a normal concentration of T lymphocytes, which are an important part of the immune systemand.

Responsible for insulin production

Cysteine is involved in the production of insulin, the hormone that regulates glucose (sugar) levels in the blood. It forms so-called disulphide bridges - specific connections that stabilise the three-dimensional structure of the protein. Without correctly formed disulphide bridges, insulin would not be able to do its job. The result would be fluctuations in blood sugarand.

Research shows that L-cysteine supplementation alleviates symptoms of chronic atrophic gastritis and can be used as a maintenance treatment in patients with this condition.

Ilona Krzak Master of Pharmacy

. .

Cysteine - dosage

The dosage of cysteine depends on a number of factors, such as age, health status, lifestyle or the goal you want to achieve with supplementation. The optimum dosage may therefore vary from person to person, so it is always advisable to consult your doctor or pharmacist.

General recommendations, however, suggest that a typical serving of a dietary supplement containing cysteine should be between 100 and 500 mg per day. In some cases - under the care of a doctor - this dose may be increasedand.

Where is L-cysteine found in food?

Although cysteine is an endogenous amino acid, i.e. the body is able to produce it on its own, it is a good idea to supply it from the diet too. In the table below, you will find 10 good sources of cysteine and its content per 100 grams of product.

Source	Cysteine content per 100 gand
Sunflower seeds	383 mg
Pork chops	350 mg
Beef .	345 mg
Chicken breast	336 mg
Tuna	321 mg
Egg	292 mg
Swiss cheese	290 mg
Lentils	118 mg
Low-fat yoghurt	52 mg

Cysteine - supplementation

L-cysteine supplementation is most commonly used to support various bodily functions, such as detoxification, antioxidant production and immune system protection. Cysteine is well absorbed and safe for most people, although it is always advisable to consult with a doctor.

Who should consider cysteine supplementation?

Cysteine supplementation is usually recommended for people who want to improve their overall health, support detoxification of the body or improve immune system function. Who in particular should consider taking this amino acidand?

People exposed to oxidative stress. Cysteine is a precursor to glutathione, one of the most powerful antioxidants. People who are exposed to high oxidative stress, such as by a polluted environment, may want to consider cysteine supplementation.
People with weak immunity. Cysteine supports the proper functioning of the immune system. Therefore, people who struggle with frequent infections should consider its supplementation
People wishing to improve the condition of their skin, hair and nails. Cysteine is a key component of keratin, the protein that builds skin, hair and nails. Its supplementation may therefore help to improve the appearance of these elements.

Best supplements with cysteine

Best for hair

Glow Stories

5.0

Active ingredients: bamboo shoot extract, Quatrefolic®, L-Methionine, L-cysteine, vitamin E, vitamin A, niacin (vitamin B3), vitamin B6, vitamin B2 (riboflavin), biotin, zinc, copper
Form: capsules
Dose: 1 capsule per day
Sufficient for: 60 days

See price

Product description

A dietary supplement containing vitamins, minerals and plant extracts thatósupport the skinóhand, hair and nails. The product is especially distinguished by the form of folate – it is Quatrefolic, whichós absorbed very well and is natural.

In addition to valuable vitamins and minerals, such as vitamin A, E, B3, B2 and biotin, the formula contains bamboo shoot extract, whichóry further enhances your beauty.

Pros and cons

In addition to valuable vitamins and minerals, such as vitamin A, E, B3, B2 and biotin, the formula contains bamboo shoot extract, whichóry further enhances your beauty.

Additional information

In addition to valuable vitamins and minerals, such as vitamin A, E, B3, B2 and biotin, the formula contains bamboo shoot extract, whichóry further enhances your beauty.

10 ingredients

YANGO, More Hair™

4.8

Main active ingredients: L-cysteine, L-methionine, zinc, selenium, biotin, copper, iron, vitamin B12, nettle, sabal palm
Form: capsules
Dose: 1 capsule per day
Sufficient for: 90 days

See price

Product description

Synergistic combination of 10 ingredientsós: vitamins, mineralsós, amino acidsós and plant extractsós for healthy hairós. This product is recommended to support the treatment of hair lossó

Pros and cons

Synergistic combination of 10 ingredientsós: vitamins, mineralsós, amino acidsós and plant extractsós for healthy hairós. This product is recommended to support the treatment of hair lossó

Additional information

Synergistic combination of 10 ingredientsós: vitamins, mineralsós, amino acidsós and plant extractsós for healthy hairós. This product is recommended to support the treatment of hair lossó

Patented extract

ALLDEYNN VITAROSE

4.7

Major ingredients: extracts from vegetables, fruitsós, vitamins, minerals, amino acids
Form: tablets
Packaging: 120 tablets
Dose: 4 tablets daily
Sufficient for: 30 days

See price

Product description

A comprehensive set of valuable vitamins and mineralsów specially formulated for women of all ages to support their health and beautiful appearance. Contains Oxxynea® – a patented natural plant extract whichóry contains a blend of 22 fruitsóy and vegetables.

Oxxynea® is rich in polyphenols, anthocyanins, carotenoids and vitamins. In addition, VITAROSE contains a valuable composition of ingredientsós to support the condition and appearance of the skinós, hairós, nails, as well as immunity, digestive system, nervous system and well-being.

Pros and cons

Additional information

User review

Cysteine - side effects

Cysteine is safe, however - as with any supplement - it can cause some side effects. What are the most common side effects?

Gastrointestinal problems.

It is a very rare side effect.

Side effect .	What are the characteristics of and
Gastrointestinal problems .	Gastrointestinal problems such as nausea, vomiting, heartburn or abdominal pain. They occur particularly frequently when the supplement is consumed on an empty stomach.
Allergic reactions .	Slightly less frequent allergic reactions may occur. Symptoms then include itching, rash, trouble breathing or swelling of the face and throat. If symptoms flare up or do not go away after stopping the supplement, see your doctor. There is no need to take the supplement.
Fatigue	This is a very occasional side effect of cysteine supplementation. Nonetheless, it can occur when the body is unable to assimilate it properly. Fatigue

In addition to this, cysteine can also interact with certain drugs, such as nitroglycerine. Therefore, if you are taking any drugs, check with your doctor before starting supplementation.

Cysteine - reviews

I have been using Cysteine as a supplement for about 6 months and have noticed a significant improvement in my hair. They are now shinier and stronger.

Wioletta35 years old

Cysteine has worked fantastically on my skin. After several months of use, my complexion became smooth and radiant.

Katarzyna30 years old

A friend recommended cysteine to me for immune system support. Since I started using it I get sick less often, and even if I do, the sickness passes more quickly.

Jan58 years old

I have tried cysteine, but unfortunately I have not noticed any significant change. Maybe it works better in others, but I haven't noticed any benefit.

Monica32 years old

I was taking cysteine, but after a few days I started to feel nauseous. Maybe it wasn't because of it, but to be safe I stopped supplementation.

Beata40 years old

Summary

Cysteine is an endogenous amino acid that has many functions in the body.
The chemical formula of cysteine is: cysteine.
The chemical formula of cysteine is: C3H7NO2S.
The chemical formula of cysteine is.
N-acetylcysteine (NAC) is a derivative of cysteine, popularly used as a supplement.
Cysteine has a positive effect on skin health, detoxification of the body, normal metabolism, immunity and insulin production.
The dosage of cysteine depends on a number of factors, but a typical serving is between 100 and 500 mg per day.
Cysteine is found in many foods, such as sunflower seeds, meat and eggs.
Cysteine supplementation is used to support the immune system or detoxify the body, among other things.
Cysteine supplementation is used to support the immune system or detoxify the body.
Supplementation with cysteine can lead to some side effects, such as gastric problems, allergic reactions or unusual tiredness.
Opinions on cysteine supplementation vary, with some people appreciating its effects on hair or skin condition, while others feel no significant change.

FAQ

Glycine + cysteine - how do they work?

Glycine and cysteine are amino acids with key functions in the body. Cysteine is essential for the production of glutathione, which neutralises free radicals, reducing oxidative stress. Glycine supports the nervous system, affecting the ability to concentrate and improving sleep quality. Consuming them together can effectively support the body's detoxification and overall health.

Can L-cysteine be harmful?

L-cysteine is generally safe for healthy individuals. However, like any supplement, it can lead to unwanted side effects such as stomach problems, allergic reactions or feelings of severe fatigue.

Also, it may interact with some medications. Its use in such cases should therefore always be consulted with a physician.

In what forms are supplements with cysteine available?

Supplements with cysteine are available in several forms. The most common form is capsules and tablets, which are easy to dose and take. Another form is a powder, which can be added to food or drinks.

Outside of this, you can also find cysteine as part of multi-ingredient supplements to boost hair, skin and nail health. An example of such a supplement is Glow Stories from Natu.Care.

What is the price of cysteine supplements?

The price of cysteine supplements can vary considerably depending on the brand, the form of the supplement or the number of servings per packet. Usually, however, the price of supplements with this ingredient is within the range of 20 to 100 PLN.

Please note that the price of supplements with cysteine can vary significantly depending on the brand.

Remember that the cost does not always reflect the quality of the product, so it is worth paying attention to the purity of the composition and the reputation of the manufacturer before purchasing.

Is L-cysteine only found in meat products?

No, although meat and livestock products are rich sources of cysteine, an amino acid you can also find this in some plant sources. Examples include sunflower seeds and lentils.

Who is at risk of cysteine deficiency?

Cysteine is an amino acid endogenous, meaning that the human body can produce it on its own. Nevertheless, during certain metabolic diseases or inflammatory conditions, the need for it increases. In such cases, it is worth considering reasonable supplementation.

Does cysteine affect the skin ageing process?

Yes. Cysteine plays an important role in skin ageing. It is a precursor to glutathione, one of the most important antioxidants in the body. Glutathione helps neutralise oxidative stress, which causes skin ageing. As a result, cysteine can help increase the skin's resistance to damage and slow down the ageing process.

Sources

See all

Clemente Plaza, N., Reig García-Galbis, M., & Martínez-Espinosa, R. M. (2018). Effects of the Usage of l-Cysteine (l-Cys) on Human Health. Molecules, 23(3), Article 3. https://doi.org/10.3390/molecules23030575

Correia, M. J., Pimpão, A. B., Fernandes, D. G. F., Morello, J., Sequeira, C. O., Calado, J., Antunes, A. M. M., Almeida, M. S., Branco, P., Monteiro, E. C., Vicente, J. B., Serpa, J., & Pereira, S. A. (2022). Cysteine as a Multifaceted Player in Kidney, the Cysteine-Related Thiolome and Its Implications for Precision Medicine. Molecules (Basel, Switzerland), 27(4), 1416. https://doi.org/10.3390/molecules27041416

Duperray, J., Sergheraert, R., Chalothorn, K., Tachalerdmanee, P., & Perin, F. (2022). The effects of the oral supplementation of L-Cystine associated with reduced L-Glutathione-GSH on human skin pigmentation: A randomized, double-blinded, benchmark- and placebo-controlled clinical trial. Journal of Cosmetic Dermatology, 21(2), 802-813. https://doi.org/10.1111/jocd.14137

Eriksson, C. J. P., Metsälä, M., Möykkynen, T., Mäkisalo, H., Kärkkäinen, O., Palmén, M., Salminen, J. E., & Kauhanen, J. (2020). L-Cysteine Containing Vitamin Supplement Which Prevents or Alleviates Alcohol-related Hangover Symptoms: Nausea, Headache, Stress and Anxiety. Alcohol and Alcoholism (Oxford, Oxfordshire), 55(6), 660-666. https://doi.org/10.1093/alcalc/agaa082

Jain, S. K., Micinski, D., & Parsanathan, R. (2021). L-Cysteine Stimulates the Effect of Vitamin D on Inhibition of Oxidative Stress, IL-8, and MCP-1 Secretion in High Glucose Treated Monocytes. Journal of the American College of Nutrition, 40(4), 327-332. https://doi.org/10.1080/07315724.2020.1850371

Jiao, N., Wang, L., Wang, Y., Xu, D., Zhang, X., & Yin, J. (2022). Cysteine Exerts an Essential Role in Maintaining Intestinal Integrity and Function Independent of Glutathione. Molecular Nutrition & Food Research, 66(3), e2100728. https://doi.org/10.1002/mnfr.202100728

Marino, S. M., & Gladyshev, V. N. (2010). Cysteine function governs its conservation and degeneration and restricts its utilization on protein surfaces. Journal of Molecular Biology, 404(5), 902-916. https://doi.org/10.1016/j.jmb.2010.09.027

McPherson, R. A., & Hardy, G. (2011). Clinical and nutritional benefits of cysteine-enriched protein supplements. Current Opinion in Clinical Nutrition and Metabolic Care, 14(6), 562-568. https://doi.org/10.1097/MCO.0b013e32834c1780

Raghu, G., Berk, M., Campochiaro, P. A., Jaeschke, H., Marenzi, G., Richeldi, L., Wen, F.-Q., Nicoletti, F., & Calverley, P. M. A. (2021). The Multifaceted Therapeutic Role of N-Acetylcysteine (NAC) in Disorders Characterized by Oxidative Stress. Current Neuropharmacology, 19(8), 1202-1224. https://doi.org/10.2174/1570159X19666201230144109

Schwalfenberg, G. K. (2021). N-Acetylcysteine: A Review of Clinical Usefulness (an Old Drug with New Tricks). Journal of Nutrition and Metabolism, 2021, 9949453. https://doi.org/10.1155/2021/9949453

Tenório, M. C. dos S., Graciliano, N. G., Moura, F. A., Oliveira, A. C. M. de, & Goulart, M. O. F. (2021). N-Acetylcysteine (NAC): Impacts on Human Health. Antioxidants, 10(6), Article 6. https://doi.org/10.3390/antiox10060967

Yoon, S. J., Combs, J. A., Falzone, A., Prieto-Farigua, N., Caldwell, S., Ackerman, H. D., Flores, E. R., & DeNicola, G. M. (2023). Comprehensive Metabolic Tracing Reveals the Origin and Catabolism of Cysteine in Mammalian Tissues and Tumors. Cancer Research, 83(9), 1426-1442. https://doi.org/10.1158/0008-5472.CAN-22-3000

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