Energy And Resistance

Cistina: What It Is, What It Serves for, Benefits and Side Effects

Cystine is an amino acid, one of the few that contains sulfur, which is not essential, that is, it can be synthesized by the body from other molecules. However, cystine is also obtained from feed, being present in eggs, meats, dairy products and whole grains. Consumption as a dietary supplement has also increased greatly as the benefits of cysteine ​​become better known. We will understand in this article what is the use of cysteine, its main benefits and also its side effects.

What exactly is cystine?

Cystine is, in fact, made up of two cysteine ​​molecules, and one form can be converted into another by the organism as needed, and cystine is considered the stable form of cysteine. Hence it frequently refers to cystine or cysteine ​​as synonyms.

The term L-cysteine ​​is also frequently used since it designates the isomeric form L, which is biologically active. The other isomer of cysteine, and many other amino acids, is indicated by the letter D. Isomeric forms are molecules with the same chemical constitution, but with different spatial arrangements, in this case, by changing only the positions of the bonds to one of the carbons, called asymmetric carbon or chiral.

Cystine as food supplements

Cystine is widely used as a nutritional supplement in the form of acetylcysteine ​​(NAC) or L-cysteine, because cysteine ​​is more easily absorbed by the body than cystine. In addition excess cystine has been associated with a rare disease that causes the accumulation of cystine crystals, forming renal stones, Therefore, it is also possible to use supplementation in the form of cysteine, although the two molecules are easily interconverted by body. The N-acetyl form is used to improve the body's absorption of the molecule. The recommended daily dose of L-cysteine ​​is between 250mg and 1500mg.

Sources of cystine in food

Food sources rich in cystine, or cysteine, include foods high in protein, such as meat, poultry, eggs, fish and dairy products, vegetable sources include sunflower seed, Soy. Broccoli, red and yellow peppers, onions and garlic also contains the amino acid, however in smaller amounts.

What is Cystine for?

Amino acids are the building blocks of proteins. In turn proteins are responsible for all enzymatic activity in the body, by complex chemical reactions, metabolism, cell signaling, immune system, and are important structural components for all tissues and organs, such as muscles, heart, bones, skin, connective tissue. etc.

Cystine is equally important in the synthesis of glutathione, its lack being a limiting factor for the synthesis of the molecule by the body. Glutathione is an important endogenous antioxidant, able to neutralize free radicals are constantly generated by metabolic activity and promote detoxification of the liver, a metabolically very active.

  • Glutathione - What It Is, What It Serves For, Rich Foods And Supplement
  • Methionine - What It Is, What It Serves For, Rich Foods And Supplement
  • Fattening Pantogar?
  • Differences Between Essential and Non-Essential Amino Acids

Acetylcysteine ​​is often used in the treatment of overdoses of acetaminophen, which causes many liver damage, besides protecting against the damages of the cigarette consumption and the excess alcohol intake, being effective in the prevention of the hangover.

Glutathione may also be found in foods, but ingested glutathione is not harnessed for endogenous synthesis. The body needs the amino acids glutamate, glycine and cysteine ​​for its production.

Cystine supplementation is also used to improve the health of the skin and hair, as an agent anti-aging, stimulating collagen synthesis and healing, as well as in the treatment of arthritis rheumatoid.

Committed health states, stress, intense physical exertion, and gastrointestinal illnesses may increase the need for cystine.

Benefits of Cystine / Cysteine ​​- What is it for?

Let's now look at the key properties of cysteine ​​for health and fitness and consumer tips.

1) Antioxidant and detoxifying action

The antioxidant activity of glutathione is dependent on the chemical action of the cysteine ​​sulfur-containing group, the which makes the availability of cysteine ​​a critical factor for the production and effectiveness of glutathione. Thus, cysteine ​​levels are limiting factors on the speed and amount of glutathione produced by the body.

In the absence of cysteine, low levels of glutathione will lead to non-repair of oxidative damage and may have serious consequences, especially hepatic.

The endogenous cysteine ​​synthesis occurs as part of another amino acid, methionine, which is an essential amino acid, ie it is only purchased from the feed. The synthesis only occurs when there is availability of folic acid, vitamin B6 and B12, so lack of these nutrients may also imply in cysteine ​​deficiency. Foods rich in methionine include meats and poultry, fish, eggs, dairy products, quinoa, sesame seeds, Brazil nut, among others. However, methionine can also be converted to homocysteine, a blood parameter that has been considered a risk factor for the development of atherosclerosis. Therefore, methionine supplementation is contraindicated.

In this way the intake of cysteine ​​as a food supplement is a safer source than methionine for maintain adequate levels of glutathione and consequently the effectiveness of the body.

The lack of glutathione may further contribute to the development of dementia and multiple sclerosis by the deficiency in removing toxins from the body.

2) Immune system support and inflammatory processes

Because it plays a key role in the formation and action of glutathione, cystine assists in the maintenance of the defense system, inhibiting inflammation and stimulating production of leukotrienes, substances that act in the defense exerted by the macrophages, that are cells of the immune system very important in the defense against organisms invaders.

A 2009 study demonstrated that in addition to reducing oxidative stress, cysteine ​​is able to reduce the inflammatory process in individuals with some type of disease, promoting an acceleration of the cure without effects collaterals.

3) Improvement of skin and hair

Cystine is very present in alpha-keratin, the basic building protein of nails, hair and skin. The adequate supply of cysteine ​​guarantees the raw material for the body to synthesize alpha-keratin in adequate amounts to maintain its health and vitality.

In addition, cysteine, along with vitamins E and C and selenium, helps protect the skin by keeping activated and preventing the damaging action of ultraviolet rays on cellular DNA, which can lead to cancer. skin.

L-cysteine ​​may also be useful in the treatment of some types of acne. One of them when acne treatment with benzoyl peroxide causes even more inflammation, a combination of L-cysteine ​​with alpha-lipoic acid reduces the redness and itching of the pimples. The other in the case of acne induced by high levels of testosterone due to polycystic ovary syndrome, in which cysteine ​​makes skin cells more sensitive to estrogen and less testosterone.

Since cystine is not the only factor that interferes with skin health and attachments, the important thing is always maintain a rich diet in all nutrients, including proteins, minerals and vitamins.

4) Fighting Osteoporosis

Osteoporosis is a serious disease that occurs primarily in the elderly leading to the resorption of bone tissue, which leads to loss of bone density and high risk of fractures.

Cysteine ​​supplementation has been shown to be useful in the treatment of osteoporosis mainly in elderly women. Research has indicated a decrease in the activity of osteoclasts, the cells responsible for the reabsorption of bone tissue and an increase in collagen synthesis, minimizing two important factors for the osteoporosis.

5) Gain of muscle mass

Like all amino acids, cysteine ​​is one of the building blocks of proteins. Muscles, in turn, are basically made up of protein fibers. Thus, adequate supply of cysteine ​​also aids in gaining muscle mass and strength, being much used by athletes and fitness enthusiasts alike.

Other benefits of Cystine

L-cysteine ​​is also important in lipid metabolism and is an essential molecule in the construction and maintenance of cell membranes and myelin sheaths that surround the axon of the neurons and ensure nerve transmission proper. Cell membranes and myelin sheath protect against external damage and the action of free radicals. Thus, L-cysteine ​​may be an ally in the prevention of degenerative diseases such as Parkinson's.

Cysteine ​​can also neutralize copper poisoning and protect cells against other harmful substances from smoking.

Another important action would be on muscle recovery after physical exertion and tissue after injuries or surgeries.

The body also uses cysteine ​​to produce taurine, another amino acid.

N-acetylcysteine ​​helps in the amelioration and breakdown of phlegm and mucus in diseases such as bronchitis, cystic fibrosis and allergies. The collagen fibers that maintain mucus viscosity, bind through sulfur-containing points in their amino acids, in the presence of free cysteine, the sulfur binds to it, breaking the fibers and reducing their adhesion the others. This makes elimination easier.

Side effects of cystine

Despite all the benefits already mentioned above, high doses of cystine / cysteine ​​can be dangerously harmful, causing many side effects. Let us understand next what they would be. Generally, the dose of 400 mg of L-cysteine ​​daily is enough to see the benefits, while more than 1500 mg can start to see some side effect. It is worth mentioning that the supplement is considered safe and its side effects are rare. Side effects are most noticeable when the consumption goes from 7000 mg per day, in which case it can be toxic.

Possible Side Effects

Some common effects associated with cysteine ​​supplementation are considered mild when ingested doses are recommended. They are diarrhea, vomiting, nausea, nausea, stomach pain, body aches, and generalized gastrointestinal discomfort. These effects can be minimized by ingesting a good amount of water.


Some people may be allergic to some types of cysteine-containing supplements by forming large amounts of homocysteine. The allergy presents as swelling, rashes, alteration of the heart beat and respiratory difficulty and is considered a serious condition and must receive medical attention urgently.

Interaction with drugs

Cysteine ​​supplements may also cause interaction with certain medications such as:

  • ACE inhibitors, which are used in the treatment of high blood pressure;
  • prednisone, which is an anti-inflammatory of the corticosteroid class;
  • cyclophosphamide, used in the treatment of some types of cancer and autoimmune diseases;
  • nitroglycerin and isosorbide, which are drugs used to treat angina.

So if you use any medicine, you need to see a doctor to check any type of interaction before starting any type of cystine supplementation.

Homocysteine ​​production

As already mentioned, high doses of L-cysteine ​​can be converted to homocysteine, which is a risk factor for the development of atherosclerotic disease, with plaque formation in the arteries that block the passage of blood, causing problems cardiovascular diseases.

Lack of cystine

In the rare cases where cystine deficiency occurs, swelling, lethargy, skin lesions, immunity and susceptibility to damage caused by toxins from the metabolism of substances by the liver and free.

Since cystine supplementation, both in the form of L-cysteine ​​and N-acetyl-cysteine, can also risk, the important thing is always to have the medical opinion before starting treatment with this type of supplement.

Additional references

  1. Aminoacids Studies. L-cysteine.
  2. LifeExtension - Foundation for Longer Life. The Overlooked Compound That Saves Lives.
  3. Nutritional Supplements. Benefits of L-cysteine ​​- Using NAC for Better Breathing, Clearer Skin and More.

Do you think about taking cystine supplements for any of the benefits listed above? Was it recommended by a professional? Comment below!

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