Category Archives: Cysteine

Can Increasing Glutathione Improve Symptoms of Schizophrenia?

Can glutathione help schizophrenia? Schizophrenia, a psychological disorder characterized by impairment in a person’s ability to think clearly and manage emotions, is believed to affect an estimated 300,000 Canadians. Worldwide, up to 0.7 per cent of individuals are diagnosed with the mental disorder. Even Vincent Van Gogh, the artist who created the famous “The Starry Night” painting, suffered from schizophrenia.

Symptoms can include paranoia, delusions, disorganized speech and thought process and auditory hallucinations. Individuals living with schizophrenia may encounter significant social or occupational difficulties. It is believed the disorder is caused by a combination of genetic and environmental factors. One of the biological factors may be due to low levels of the tripeptide glutathione.

In a study conducted at the University of Lausanne in Switzerland, researchers looked at a precursor of glutathione, N-acetyl-cysteine, to see if it would improve neural synchronicity. Previous studies revealed that irregularities in neural connectivity leads to the symptoms expressed in schizophrenics.

For the double-blind, randomized trial researchers Cristian Carmeli, Maria Knyazeva, Michel Cuenod and Kim Do examined whether treatment with glutathione precursor N-acetyl-cysteine would improve EEG synchronization in schizophrenic patients. Eleven patients with a history of schizophrenia participated in the study.

One group received glutathione precursor N-acetyl-cysteine for two months as part of their treatment and placebo for the second half of treatment. Another group was given the placebo treatment first for two months and then the glutathione precursor N-acetyl-cysteine treatment for the two months after. All participants remained on their usual antipsychotic medication throughout the trial. EEG recordings were done before treatment, at the crossover and at the end of the trial.

The effects of the glutathione precursor in neural synchronicity

At the end of the experiment, the researchers found that glutathione precursor N-acetyl-cysteine significantly increased EEG synchronization, especially in the clusters located over the parieto-temporal, right temporal and right prefrontal lobes. The researchers believe that with treatment of glutathione precursor N-acetyl-cysteine, negative symptoms of schizophrenia will improve along with reduced side-effects of antipsychotics.

Based on these results they’re hopeful that the precursor to glutathione, N-acetyl-cysteine, has huge potential to be used towards treatment for schizophrenia.


Amino Acids: Taurine Essential For Brain Development

An interesting study of human brain cells highlights the crucial role the amino acid taurine has on the development of our brains. This amino acid is vital for optimal development of newborn and infant brains.

Taurine is an important inhibitory neurotransmitter. It’s essential for our cardiovascular function, and the development and function of our central nervous system. Every human needs taurine, adults and babies. Adults metabolize taurine from cysteine, using vitamin B6. High levels of B6 are found in shellfish, such as oysters and clams. It’s also present in meat and fish proteins.

Newborns get their taurine from breast milk, and taurine has been added to many infant formulas.

The role of taurine for optimal brain development has been studied in animal trials. Taurine increases the proliferation of neural stem cells in embryonic and adult rodent brains. But what about humans?

Researchers Hernández-Benítez R, Vangipuram SD, et al, from the Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico, developed a study of taurine’s effect on cell numbers in human neural precursor cells, which are stem cells.

Neural precursor cells can become neurons (nerve cells), and can also become the two other main cell types in the nervous system. They can also be cultured in the laboratory, so have great potential for a variety of transplant treatments.

Effect of Taurine on human brain development

The researchers in this human cell study used neural precursor cells from three fetal brains (14-15 weeks of gestation). The cells were cultured, and then tested with taurine. After four days of culture, taurine induced an impressive increase of neural precursor cells: an increase of up to 188%. Taurine also dramatically increased the percentage of neurons formed: up to 480% in the best case.

These results show the positive effect taurine has on the formation and development of the brain.


Anti-Inflammatory Effect of Amino Acids Cysteine, Glycine and Histidine

Inflammation in the body is like fire in the veins! But can inflammation be “cooled off” by the amino acids cysteine, glycine, and histidine? Inflammation is characterized as the bodily response of vascular tissues to unsafe stimuli. 

Such stimuli may include pathogens, irritants or damaged cells. Symptoms can vary in cases of inflammation, but the most common signs are redness, heat, swelling, pain, and loss of function in the affected area.

Because inflammation is a discomfort that affects a majority of the population at one time or another, researchers at Yamaguchi University Graduate School of Medicine in Japan set out to examine the anti-inflammatory effects of the amino acids cysteine, glycine and histidine.

Researchers S. Hasegawa, et al., report that nuclear factor-kappa B is a system that regulates endothelial activation. They explain that nuclear factor-kappa B is induced by tumor necrosis factor-alpha in vascular endothelial cells, and it is this process that can lead to inflammation and disorders such as atherosclerosis.

The researchers wanted to test the anti-inflammatory effects in coronary endothelial cells since results from previous studies ended inconclusively. They hypothesize that amino acids cysteine, glycine and histidine would produce inhibitory effects on nuclear factor-kappa B activation in human coronary arterial endothelial cells.

The effect of amino acids cysteine, glycine and histidine on inflammation in endothelial cells

For the study Hasegawa et al. took human coronary arterial endothelial cell cultures and treated them with either alanine, cysteine, glycine and histidine amino acids. They stimulated the cultures with 2 ng/mL of tumour necrosis factor-alpha before taking out nuclear extracts to determine their concentrations of proteins and nuclear factor-kappa B.

They found that without treatment, the cultures showed significant activation of nuclear factor-kappa B. But with pretreatment of cysteine, glycine and histidine, nuclear factor-kappa B activation was inhibited significantly in the coronary endothelial cells. Alanine did not have an effect on the activation, demonstrating no anti-inflammatory properties.

Overall, cysteine showed the most inhibiting effects out of the tested amino acids at any concentration. They also found that the amino acids inhibited E-selectin expression, a cell adhesion molecule that plays an important role in inflammation.

Based on these results, the researchers conclude that cysteine, glycine and histidine can help reduce inflammation to the endothelial cells.


L-methionine Supplements for HIV or Immune-Compromised Patients

A study from South Africa has investigated the effects of L-methionine supplements for HIV or immune-compromised patients, with positive results.

Human immunodeficiency virus (HIV) is a major global public health issue. Over 25 million people have died from HIV in the past 30 years, and more people are being diagnosed every day. According to the World Health Organization, there were about 34 million people living with HIV in 2011. HIV, in a matter of a decade, can develop into AIDS, which is the most advanced form of HIV.

HIV causes the immune system to fail, which means life-threatening infections and cancers can develop. The virus affects T cells in the immune system, leading to declines in the amounts of these vital cells.  HIV specifically affects CD4 T cells, white blood cells which are an essential part of the immune system.  If untreated, HIV causes the amount of CD4 cells to drop to a critically low level. Immunity is lost.

There’s no cure for HIV, but the virus can be treated with antiretroviral drugs. These are widely available in North America, but in Africa, where most of the new cases are diagnosed, fewer people have access. Research into boosting the immune system, therefore, is a growing field.

R Van Brummelen and D du Toit, researchers with the Tshwane University of Technology, Gezina, South Africa, developed a clinical study to test L-L-methionine supplements. Would the amino acid improve the immune system of HIV infected patients?

L-methionine, one of the sulfur-containing amino acids, is important for many bodily functions.  It converts to L-cysteine in the body, when it becomes a vital antioxidant, scavenging damaging free radicals and boosting the immune system.

L-methionine tested as immune supportive supplement

The researchers designed a double-blind, placebo-controlled study. HIV patients were given either L-methionine supplements, or a placebo. Treatments continued for six months, then the patients were tested.

Results were statistically significant. In the L-methionine supplement group, CD4 counts showed a decreased level of decline, meaning the HIV was not destroying as many of these crucial cells in the immune system.

Additionally, there were no serious side effects from the treatment.

The researchers concluded that L-methionine supports the immune system, and can play a role in the treatment of immune-compromised patients.


Homocysteine, Cysteine, and Colorectal Cancer

Researchers investigated the link between levels of plasma homocysteine and colorectal cancer in postmenopausal women. Will the results shed light on the risk of developing this cancer?

Colorectal cancer—also known as bowel cancer–is a cancer of the colon (large intestine) or rectum. It’s the third most common cancer diagnosed in men and women, and the second leading cause of cancer-related death when statistics for both sexes are combined.

Improved screening techniques have led to the death rate dropping for colorectal cancer. The polyps which form in the early stages can be removed before they develop into cancers, and early detection also means much better prognosis. All cancers are easier to treat when they are detected early.

But better understanding of colorectal cancer is an important topic of research. And new screening techniques could help diagnose the disease even earlier.

JW Miller, SA Beresford, et al, researchers at the Department of Medical Pathology and Laboratory Medicine, University of California, USA, developed a study to assess the links between the amino acids homocysteine, cysteine, and the incidence of colorectal cancer in postmenopausal women.

Homocysteine is a non-protein amino acid. It’s similar in formula to cysteine, though homocysteine is biosynthesized in our bodies, from the amino acid methionine. It can also be converted into methionine or cysteine with the aid of B-vitamins. We also get cysteine from food, especially high-protein foods like meat, cheese, and eggs.

High levels of homocysteine have been linked to cardiovascular disease. Would they also be linked to colorectal cancer?

Results of homocysteine, cysteine, and colorectal cancer trial

The trial found some significant results. High levels of homocysteine were associated with proximal colon tumors, though not distal or rectal tumors.

They concluded that high plasma homocysteine levels are associated with an increased risk of colorectal cancer. High levels of cysteine indicate a decreased risk.


Table of Amino Acid Abbreviations

Students and teachers come together with terms like “Amino acid abbreviations” – but scientists use these abbreviated forms to refer to the 20+ names of amino acids as well.

Amino acids are the building blocks of proteins, and they can be gotten from food. Before we get into the amino acid abbreviations you may want to know that there are two main types of amino acids (with a few exceptions)…

Essential and Non-essential amino acids

Essential amino acids does not mean they are “essential” as in necessary… it simply means that they can only be gotten from the food you eat so must be included through diet or dietary supplementation. Protein foods like meats (beef, chicken, pork, etc.) and eggs, as well as fish, are excellent sources of amino acids. Many meat-eating Americans actually eat an overabundance of protein compared with what the human body requires, which can lead to acidity (which leads to disease), cardiovascular and other diseases.

Non-essential amino acids are those that your body can produce naturally. Occasionally, someone is born with a deficiency in their body’s ability to produce the amino acids necessary for proper functioning, leading to diseases or disorders where people have trouble breaking down certain amino acids. An example of the latter is Maple Syrup Urine Disorder (MSUD) which is what newborn babies are screened for soon after birth.

There are 22 different amino acids in all (some of them semi-essential), but about 20 of them are more common. Their names, 3-letter, and 1-letter amino acid abbreviations follow.

Table of amino acid abbreviations

Amino Acid












Aspartic acid






Glutamic acid













































Aspartic acid or Asparagine



Any amino acid



Termination codon


For more information on amino acid abbreviations or more detailed information on amino acids in general, please see other articles at the Amino Acid Information Center. There are also many excellent resources on the Internet or in encyclopedias.


Can Autistic Children Benefit From Glutathione Supplements?

Autism is a developmental disorder that is characterized by failure to relate to others, impairment in communication, intolerance of change, and repetitive and ritualistic behaviour. Some studies have shown that individuals diagnosed with autism spectrum disorder also have comparatively lower glutathione levels than the average developing child — about 20 to 40% lower. Also, their levels of oxidized glutathione are higher.

In a study conducted by Genetic Consultants of Dallas in Texas, researchers Janet Kern, David Geier, James Adams, Carolyn Garver, Tapan Audhya and Mark Geier tested whether glutathione supplements would benefit transsulfuration metabolites in autistic children.

Studies have shown that children diagnosed with autism spectrum disorder have irregularities in transsulfuration metabolites, which affects the production of glutathione. The researchers hope that by examining the effects of two commonly used supplements for autism, transdermal glutathione and oral glutathione,that their results would lead to a better comprehension of treatment in increasing glutathione levels.

Glutathione is a tripeptide that is made up of amino acids glycine, cysteine and glutamic acid. A few of its many functions is DNA and protein synthesis and repair, transport of amino acids, and enzyme regulation. Because of it’s antioxidant properties, glutathione can prevent peroxides and free radicals from damaging important cells, making it important for immune functioning.

The Effects of Glutathione Supplements on Transsulfuration Metabolites

For the experiment, the researchers used 26 children with autism and divided them into two groups. One group would receive transdermal glutathione while the other group would receive oral glutathione. The treatment lasted over a period of eight weeks.  The researchers monitored side-effects and levels of glutathione, oxidized glutathione, taurine, sulfate, and cysteine.

At the end of the trial, Kern, et al., found that the oral glutathione group exhibited significant increases in plasma reduced glutathione. Both treatment groups also demonstrated significant increases in levels of plasma sulfate, cysteine and taurine. Oxidized glutathione showed little change in the groups.

Based on these results, the researchers believe that both forms of glutathione supplements, oral and transdermal, can benefit children with autism by increasing transsulfuration metabolites. They suggest additional studies be done in order to investigate the potential of glutathione supplements for management of autism symptoms.


Sulfur-Containing Amino Acids Cysteine and Methionine

The two main sulfur-containing amino acids are cysteine and methionine; however, there are other sulfur-containing amino acids as well. Both cysteine and methionine are nonpolar as well as hydrophobic, with methionine being extremely hydrophobic as far as amino acids go. Methionine is also found inside proteins, and cysteine is often found there too. There are some other fascinating things about these two (and other) sulfur-containing amino acids.

Aside from methionine and cysteine being most popularly known, other commonly known sulfur-containing amino acids include homocysteine and taurine. The last two are not incorporated into proteins, however. According to the authors at the Journal of Nutrition (JN), the “difference accounts for some of the distinctive properties of the sulfur-containing amino acids. Methionine is the initiating amino acid in the synthesis of virtually all eukaryotic proteins … [and if] exposed, are susceptible to oxidative damage. Cysteine, by virtue of its ability to form disulfide bonds, plays a crucial role in protein structure and in protein-folding pathways.”

The authors of JN discuss a number of these sulfur-containing amino acids—methionine, cysteine, taurine, homocysteine, and the lesser known S-adenosylmethionine.

Importance of sulfur-containing amino acids

Although cysteine and methionine are the primary sulfur-containing amino acids due to being two of the 22 common amino acids that are incorporated within proteins, both taurine and homocysteine are also important for physiological function. So why is sulfur in amino acids since most aminos are made of carbon, oxygen, hydrogen, and nitrogen? Because, says JN, oxygen and sulfur both belong to ‘Group 6’ of the Periodic Table of Elements, so are “capable of making similar covalent linkages” with a critical difference that sulfur has a low electronegativity (oxygen has the second lowest electronegativity). So if oxygen replaces the sulfur it would “result in a much less hydrophobic amino acid.”

Furthermore, substituting oxygen for sulfur—causing oxidation—in sulfur-containing amino acids (including in the more rare S-adenosylmethionine) can have effects in methionine residues where the surface is exposed, causing an oxidation-reduction cycle, imparing the activity of “methionine sulfoxide reductase and the subsequent accumulation of methionine sulfoxide residues [that] are associated with age-related diseases, neurodegeneration, and shorter lifespan.”

Lastly taurine, as one of the more remarkable sulfur-containing amino acids, has very high concentrations within muscle tissues and utilizes a wide variety of functions. Taurine is, says JN, the “most abundant free amino acid in animal tissues [even though it] accounts for only 3% of the free amino acid pool in plasma, it accounts for 25%, 50%, 53%, and 19%, respectively, of this pool in liver, kidney, muscle, and brain.” It is also one of the most necessary sulfur-containing amino acids for cats and results retinal degeneration in kittens if the mothers are not fed a taurine-rich diet. Taurine is also found in human mother’s milk and is added to many infant formulas because it helps with eyesight.

So all in all, sufur-containing amino acids are necessary for proper health of both animals and humans in the proper biological functioning and growth, as well being associated with some diseases and anti-aging and neurological issues.


Selenium and Selenocysteine and Health

Selenium is a nonmetal element on the periodic table (between sulfur and tellurium), while Cysteine is a semi-essential amino acid. But when Selenium performs its biological functions, it does so through selenoproteins. Selenoproteins have selenium in them as the form of the 21st amino acid, selenocysteine (also called Sec), which is a cysteine analog. Selenocysteine is encoded by the UGA codon (one of three) in mRNA translation for non-selenoprotein genes. Selenocysteine is a proteinogenic amino acid.

Unlike the 20 regular amino acids (both essential and non-essential) selenocysteine is biosynthesized on its tRNA from the amino acid serine. Interestingly, there are 25 selenoproteins, like selenocysteine and selenomethionine (the latter of which replaces methionine amino acid residues, and is sometimes randomly substituted for methionine), which are encoded in our human genome.

Study on selenium and selenocysteine on health

Selenocysteine, according to S Kurokawa and MJ Berry, in their publication titled Selenium. Role of the essential metalloid in health discuss selenocysteine and its role in health. They say that selenocysteine (Sec) is described as “having stronger nucleophilic and electrophilic properties than cysteine, and Sec is present in the catalytic site of all selenoenzymes. Most selenoproteins, whose functions are known, are involved in redox systems and signaling pathways. However, several selenoproteins are not well characterized in terms of their function.”

Even though selenium can be considered toxic if the dose is too high, it is still required for health purposes in the bigger picture, selenocysteine notwithstanding. According to the researchers the selenium field (which includes the selenoproteins, and selenomethionine, etc.) has “grown dramatically in the last few decades, and research on selenium biology is providing extensive new information regarding its importance for human health.”

Selenocysteine, itself, is a building block of selenoproteins, contains selenium, and is present in several enzymes such as glutathione peroxidases, glycine reductases, methionine-R-sulfoxide reductase B1 (SEPX1), and so on). Glutathione and glycine are standard amino acids.

The biochemist, Theresa Stadtman (married to Earl R. Stadtman) at the National Institutes of Health, discovered selenocysteine.


Health Benefits – Amino Acids

Amino acids provide certain health benefits to the human body. They are the building blocks of proteins and help the body’s metabolic functions. Of the 22 amino acids known to science, only 9 are considered to be essential to the human body, with some sources claiming the number is 10.

List of amino acids include Essential, Non-essential, and Conditionally Essential

To avoid amino acid deficiencies and to experience optimum health you must consume the essential amino acids since they cannot be produced by the body. Some medical professionals, like Naturopath Dr. Eliezer Ben-Joseph, who advises his patients and the public on alternative health matters through his Natural Solutions Radio show, suggest a list of 10 amino acids to include in your diet, which include: Arginine, Histidine, Methionine, Threonine, Valine, Isoleucine, Lysine, Phenylalanine, Tryptophan, and Leucine.

10 of the remaining 22 non-essential amino acids, which your body can manufacture on its own include Alanine, Asparagine, Aspartic Acid, Cysteine, Glutamine, Glutamic Acid, Glycine, Proline, Serine, and Tyrosine. Dr. Ben-Joseph suggests that if you are stressed or have a disease then these amino acids are “conditionally essential”: Arginine, Glycine, Cystine, Tyrosine, Proline, Glutamine, and Taurine.

Amino acids help build cells and repair tissues as well as create antibodies to ward off viruses and bacteria. Additionally, they help with enzymes and they body’s hormonal system. Dr. Ben-Joseph suggests these 8 amino acids provide these health benefits:

Tryptophan: is a natural relaxant, alleviates insomnia, and reduces anxiety/depression

Lysene: helps the body absorb calcium

Methionine: supplies sulfur to help hair, nails, and skin

Histidine: repairs tissue, good for digestion/ulcers, blood pressure, nerves, sexual function

Phenylalanine: aids the brain to produce Norepinephrine, which helps the brain and nerve cells

Valine: calms emotions, helps with mental vigor and coordination of the muscles

Leucine & Isoleucine: helps the body manufacture other necessary biochemical components

You can never be certain that you are getting enough of the aminoc acids that your body needs.  It may be a good idea to incorporate amino acid dietary supplements in your health regimen.  Each one serves a different function so it is important to ensure your body obtains the necessary nutrients.  As with anything else, be sure to check with your doctor before taking amino acid supplements or any dietary supplements.