Last updated: August 27, 2021

You have read that L-cysteine can strengthen your immune system and that it detoxifies the body through the sulphuric acid it releases? That L-cysteine provides stability and strength in the hair and nails because it is a natural protein building block and helps to build up the structural proteins of the connective tissue? But you are not convinced of its effect and would like to know more about its intake, scientific background and the necessary criteria for buying L-cysteine? Then you have come to the right place.

We are pleased that you have found your way to our L-cysteine test 2021. We will provide you with all the information you need about L-cysteine. You will not only learn why this α-amino acid is said to have healing effects, but also learn something about the amino acid, L-cysteine, itself.




Summary

  • Even though L-cysteine is a relatively unknown supplement, some beneficial healing effects of L-cysteine have been shown. These include, for example, the positive influence on the stability of hair and nails, the strengthening of the immune system and the protection of the digestive system.
  • You can take L-cysteine in the form of powder or capsules. While the powder can taste a little bitter when dissolved in liquid, the capsules are tasteless and should be swallowed with the help of liquid.
  • Even if no side effects have been observed when taking L-cysteine, the dosage and intake should be discussed with your pharmacist or family doctor.

The Best L-Cysteine: Our Picks

Guide: Questions you should ask yourself before buying L-cysteine

In order to inform you comprehensively about the effectiveness of L-cysteine and to give you an understanding of the current state of science, we have summarised all the important information for you in the following sections.

What is L-cysteine and how does it work?

L-cysteine is a non-essential amino acid and thus one of the building blocks needed for protein synthesis. It contains sulphur in the form of a thiol group (-SH) at the end of its side chain. The -SH group is responsible for the amino acid's high reactivity and is therefore responsible for many of its biological functions in humans (1).

L-cysteine is a very important source of sulphur for the human body.

It is responsible for the formation of proteins such as creatine and insulin and has the function of stabilising the structure by building sulphur bridges.

L-Cystein-1

L-cysteine helps to strengthen and strengthen hair and nails.
(Image source: Flickr.com / Megan Olson)

One of the most important functions L-cysteine has is glutathione production, which is one of the most powerful antioxidants in our bodies. L-cysteine has several specific functions that can positively affect our body and health.

Regulation of immune system activity

It has been reported that L-cysteine can regulate the activity of the immune system by promoting changes in the production of its effector molecules, as is the case with IL-17. IL-17 is a cytokine produced mainly by some T cells, called Th17 cells, which act on epithelial cells and fibroblasts as well as other cells of the immune system.

It has also been shown that the administration of NAC can improve graft-free survival in patients with acute liver failure unrelated to paracetamol by some margin when administered in the early stages of hepatic encephalopathy. This effect is due to the regulation of IL-17 production, which is closely related to the progression of encephalopathy (2).

Antioxidants Role

L-cysteine acts as a precursor for the synthesis of glutathione, an important antioxidant. The reduced form of glutathione plays an essential role in defending against damage caused by oxidative stress. This property is based on the ability of L-cysteine to neutralise reactive particles that can damage cells and tissues.

Therefore, dietary supplementation with L-cysteine restores the synthesis of glutathione in cases where it has been compromised, improving the redox balance and promoting the reduction of oxidative stress (1).

Mucolytic function

L-cysteine causes a decrease in the viscosity of mucus secretions, facilitating their elimination. Bronchial secretions contain high concentrations of mucoproteins.

The decrease in viscosity caused by L-cysteine is mainly due to the breaking of the disulphide bonds of the mucoproteins, resulting in fragmentation of the chains of mucins, immunoglobulins and serum albumin present in the mucous secretion (3).

Hair and nail strengthening

Mixtures enriched with L-cysteine strengthen the hair and your nails. Keratin is one of the most abundant proteins in the skin, hair and nails and contains high levels of L-cysteine as a component.

L-cysteine forms disulphide bridges that give keratin strength and stability. Consequently, the use of L-cysteine promotes the repair of structural lesions and slows down hair loss in patients(4).

Protection of the digestive system

In the case of cancer of the upper gastrointestinal tract, excessive alcohol consumption can play a major role in its development as it is exposed to acetaldehyde, which is carcinogenic to humans.

In this sense, taking L-cysteine reduces the concentration of acetaldehyde in saliva, thereby reducing the exposure of the gastrointestinal tract to this compound and consequently the risk of cancer (5).

Where is L-cysteine found?

L-cysteine is the main source of sulphur in our diet and it is found in almost all proteins. It is found in all kinds of animal meats, but also in legumes, nuts and soy products.

The following list gives you an overview of the cysteine content and refers to 100 g of the respective food:

Product L-cysteine/100g
Soybeans, dried 655 mg
Sunflower seeds 451 mg
Peas, dried 373
Pork 242 mg
Chicken breast 222 mg
Walnut 208 mg

What are the side effects of taking L-cysteine?

No real incompatibilities or negative side effects have yet been researched with L-cysteine, but there is a study that advises that L-cysteine should not be taken at the same time as a cough suppressant.

In the form of N-acetylcysteine (NAC), cysteine promotes the formation of secretions and thus the loosening of mucus. In the case of coughs, it is therefore taken as a medicine to loosen the cough. In this case, cough suppressants(antitussives) should not be taken. Except in this case, L-cysteine is well-tolerated and can be taken on a permanent basis after consultation with the doctor due to a regulated dosage (6).

Decision: What types of L-cysteine are there and which one is right for you?

Since L-cysteine is processed into powder, you can distinguish between the dosage forms in which you buy it or whether you opt for vegan L-cysteine. Basically, a distinction can be made between these three (most common) types of L-cysteine:

  • L-cysteine capsules
  • L-Cysteine Powder
  • Vegan L-Cysteine

By the way, the vegan variant is available in both forms of administration We will explain the advantages and disadvantages of the three variants in more detail in the next few paragraphs.

What distinguishes L-cysteine capsules and what are their advantages and disadvantages?

There are different ways to take L-cysteine, and one of them is through capsules. By taking capsules, you will not have a problem with the taste of L-cysteine, because the capsule dissolves in your stomach and the powder does not come into contact with your taste buds.

L-Cystein-2

Very often, L-cysteine is packaged in white or clear capsules, which allows for tasteless ingestion and longer shelf life.
(Image source: Flickr.com /Chupacabra Viranesque)

One of the advantages of L-cysteine in capsules is that they have a much longer shelf life than powdered L-cysteine in an open package. Because the capsules are vacuum-packed, unlike the open packaging, they do not come into contact with the air and other things that can affect the shelf life.

Also, the dosage of the capsules is always accurate and constant, so you never have to worry about taking the right amount of L-cysteine because each capsule has the exact and same amount of L-cysteine in it.

Many people who do not deal with capsules or tablets on a daily basis will share the same problem with each other and that is that they have problems swallowing.

Even if the capsules are not too big, taking them can be a struggle, even with liquid.

The capsules always have an exact amount of L-cysteine in them, some see this as an advantage but it can also be a disadvantage if your doctor or pharmacist prescribes/recommends an amount where you have to split the capsules.

Once the L-cysteine capsules reach your stomach, they need time to dissolve, enter your system and finally work.

Advantages
  • Have no taste of their own due to encapsulation
  • Shelf life several months
  • More precise dosage
Disadvantages
  • Capsules can be difficult to swallow
  • Not divisible
  • Takes longer to work

What distinguishes L-cysteine powder and what are its advantages and disadvantages?

One of the great advantages of L-cysteine powder is that you can dose your own intake. Because the powder is not sealed in capsules in constant amounts, you can measure out how much you want to take yourself, which can be an advantage if your doctor prescribes an amount you can't take in capsule form.

For L-cysteine users who have problems swallowing capsules, the powder is ideal because it can be easily mixed with liquid and then consumed. If you can't handle the taste of L-cysteine, you can also mix the powder with a juice that reduces or even eliminates the L-cysteine taste.

The L-cysteine powder also enters your stomach immediately after consumption and is in your system faster because it simply does not have to dissolve like the capsule.

When travelling or on the road, the powder is at a disadvantage compared to the capsules. When carrying the powder, you have to have the whole L-cysteine container and measuring utensils with you and you can't just take the amount of capsules you need.

The taste of L-cysteine powder can also be a problem, even if you mix it with juice, the taste may well still come through and consumption is therefore prevented.

Advantages
  • Self-dosing
  • Can be consumed in liquid
  • After consumption immediately in your stomach
Disadvantages
  • Not easily transported
  • Taste can be problematic

What makes L-Cysteine Vegan special and what are its advantages and disadvantages?

Many supplement consumers don't understand what the difference is between normal and vegan supplements. Many are not aware that there are other additives in their supplements that they do not know how they affect their bodies. Vegan L-Cysteine does not contain any unwanted additives that can have a negative effect on your body.

The vegan way with L-cysteine is ideal for allergy sufferers who often have problems with other supplements and their additives. With vegan L-cysteine, you don't have to worry about consuming it.

But vegan L-cysteine also has its disadvantages, which it shares with many other vegan supplements and foods. Vegan L-cysteine is a lot more expensive in powder and capsule form than the non-vegan L-cysteine. You therefore need to know where your priorities lie.

Because vegan L-cysteine does not contain any additives, it has a shorter shelf life and you need to consider how much you are buying to use before it expires and goes bad.

Advantages
  • No unwanted additives
  • ideal for allergy sufferers
Disadvantages
  • More expensive
  • shorter shelf life

Buying criteria: You can use these factors to compare and evaluate L-cysteine

When buying L-cysteine, you can look at various aspects, such as:

By making the right choice for you, you can save money and also ensure that you don't give your body anything it doesn't need. Therefore, always look for high quality and ask to see the manufacturer's certificates if necessary.

Dosage

There are no special studies on the exact dosage of L-cysteine. L-cysteine is used to cover the daily requirement as well as in the prevention and therapy of diseases. As a food supplement to cover the daily requirement, 0.5 - 1.5 g of L-cysteine per day are used.

In chronic patients, the synthesis of L-cysteine may be limited and people with chronic diseases may therefore often need higher amounts of L-cysteine than normal, for example up to 1g three times a day for a month.

However, as there is no standard recommended dosage yet, your dosage should be discussed with an expert, i.e. pharmacist or doctor.

Stock up

L-cysteine capsules in particular can often be bought in large stock packs, which will be much cheaper for you because the capsules have a very long shelf life and do not go bad. However, if you want to try the product first, we advise you to buy a smaller pack so as not to waste too much.

The shelf life of the products can also differ. If you rarely want to take L-cysteine in powder form, a particularly large package is not necessarily advisable. Because of the packaging of the powder, it does not have as long a shelf life as L-cysteine in capsule format.

Interesting facts about L-cysteine

What happens when I overdose on L-cysteine?

If you are dealing with L-cysteine and take it frequently, you must be aware that it can have effects on your body if an L-cysteine intake is overdosed. A distinction is made between acute and permanent overdose.

Effects of acute overdose

If you take too high a dose, you may experience acute symptoms of fatigue, nausea and dizziness. If you notice these symptoms, the daily dose should be reduced. L-cysteine administration can reduce the insulin concentration in the blood, so that diabetics may need to adjust their antidiabetic dosage.

If you are L-cysteine deficient, giving L-cysteine can induce a state of euphoria. This can often be the case with cancer patients, among others, who suffer from frequent severe L-cysteine deficiency.

Effects of permanent overdose

A permanent overdose of L-cysteine supplements can lead to the formation of kidney and bladder stones, which can be extremely painful when they are eliminated.

In addition, overuse of L-cysteine can be crucial in disrupting the insulin action in your body; and it can also lead to deficiencies in trace elements such as cobalt, copper or manganese.

Picture source: Minaeva/ 123rf.com

References (6)

1. Plaza, N., García-Galbis, M., Martínez-Espinosa, R (2018). Fasst die neuesten Erkenntnisse über die Verwendung der Aminosäure l-Cystein durch Ernährung, Nahrungsergänzungsmittel oder Medikamente zusammen, um die menschliche Gesundheit zu verbessern oder bestimmte Krankheiten zu behandeln.
Source

2. Stravitz R.T., Sanyal A.J., Reisch J., Bajaj J.S., Mirshahi F., Cheng J., Lee W.M. (2013)
Source

3. Samuni Y., Goldstein S., Dean O.M., Berk M. (2013). Regulation der Aktivität des Immunsystems N-Acetylcystein (NAC) verbessert das transplantatfreie Überleben bei Patienten mit akutem Leberversagen ohne Acetaminophen (ALF) in frühen Stadien der hepatischen Enzephalopathie. Die Mechanismen dieses Nutzens sind nicht bekannt.
Source

4. Petri H., Pierchalla P., Tronnier H (1990) Das Wachstum und die Qualität der Haare wurden nach viermonatiger Behandlung mit Pantogar, einer anderen Verschreibung (Verum-2) und Placebo bei 60 Patienten mit diffusem Effluvium capillorum und agnogenen strukturellen Veränderungen der Haare untersucht.
Source

5. Salaspuro V., Hietala J., Kaihovaara P., Pihlajarinne L., Marvola M., Salaspuro M. (2002).
Source

6. Iyer SS, Accardi CJ, Ziegler TR, Blanco RA, Ritzenthaler JD, Rojas M, Roman J, Jones DP.
Source

Why you can trust me?

Effects of the Usage of l-Cysteine (l-Cys) on Human Health
Plaza, N., García-Galbis, M., Martínez-Espinosa, R (2018). Fasst die neuesten Erkenntnisse über die Verwendung der Aminosäure l-Cystein durch Ernährung, Nahrungsergänzungsmittel oder Medikamente zusammen, um die menschliche Gesundheit zu verbessern oder bestimmte Krankheiten zu behandeln.
Go to source
Effects of N‐acetylcysteine on cytokines in non‐acetaminophen acute liver failure: potential mechanism of improvement in transplant‐free survival
Stravitz R.T., Sanyal A.J., Reisch J., Bajaj J.S., Mirshahi F., Cheng J., Lee W.M. (2013)
Go to source
The chemistry and biological activities of N-acetylcysteine
Samuni Y., Goldstein S., Dean O.M., Berk M. (2013). Regulation der Aktivität des Immunsystems N-Acetylcystein (NAC) verbessert das transplantatfreie Überleben bei Patienten mit akutem Leberversagen ohne Acetaminophen (ALF) in frühen Stadien der hepatischen Enzephalopathie. Die Mechanismen dieses Nutzens sind nicht bekannt.
Go to source
The efficacy of drug therapy in structural lesions of the hair and in diffuse effluvium--comparative double blind study
Petri H., Pierchalla P., Tronnier H (1990) Das Wachstum und die Qualität der Haare wurden nach viermonatiger Behandlung mit Pantogar, einer anderen Verschreibung (Verum-2) und Placebo bei 60 Patienten mit diffusem Effluvium capillorum und agnogenen strukturellen Veränderungen der Haare untersucht.
Go to source
Removal of acetaldehyde from saliva by a slow-release buccal tablet of L-cysteine
Salaspuro V., Hietala J., Kaihovaara P., Pihlajarinne L., Marvola M., Salaspuro M. (2002).
Go to source
Cysteine redox potential determines pro-inflammatory IL-1beta levels.
Iyer SS, Accardi CJ, Ziegler TR, Blanco RA, Ritzenthaler JD, Rojas M, Roman J, Jones DP.
Go to source
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