L-Cystine: Benefits, Side Effects & Dosage

What Is L-Cystine? 

L-cystine, also known as cystine, is an oxidized union of two molecules of simpler forms. The cysteine amino acid links two cysteine residues with a bond that pertains to amino acids. (x) Cysteine and cystine are very similar. One can turn one into the other and vice versa. Cystine acts as an antioxidant and prevents radiation in skeletal tissues and skin. (x) It also helps your body heal burns and wounds and breaks down illness-related mucus deposits. (x)

Recent research has sought to determine the viability of cystine in alternatives to antibiotics and environmentally safe insecticides. (x) In the latter case, this research has found that cystine-stabilized peptides — short chains of amino acids — have helped recently made insecticides degrade in the environment after effectively killing the crop pests. 

History of L-Cystine 

English chemist and physicist William Hyde Wollaston discovered cystine in 1810. He is also renowned for finding the chemical elements palladium and rhodium (x). In 1899, eighty years after cystine’s discovery, researchers recognized cystine as a protein derivative after extracting it from a cow’s horn. (x

Sources of L-Cystine 

Cystine is a nonessential amino acid. That means the body produces its supply of it. In your body, cystine occurs naturally and abundantly in skin, hair and connective tissues. It’s also in the horn and wool of animals. (x) Even though it’s a nonessential amino acid, you can consume more of it by eating more whole grains, dairy products and eggs.

Discovering the benefits of this valuable compound may compel you to take L-cystine. Before starting any new supplement, it’s best to check with your medical provider and see if it works for your body. 

Benefits of L-Cystine & L-Cysteine 

L-cystine and its cousin, L-cysteine (coming in both NAC and HCL forms), have a wide range of benefits. A 2009 article written by Dr. Paul Millea for the journal American Family Physician supports supplemental cysteine’s applications in the treatments of:


Preventive and Adjutant Treatment for COVID-19 

Oral administration of NAC as a preventive measure for exposure to SARS-CoV-2 carriers received support through clinical tests. Administered NAC orally, IV, or inhaled as an additive treatment when patients have mild to severe COVID-19 symptoms is worth promoting as a cost-effective measure. 

The reason for NAC as a potential treatment or a preventive measure is two-fold. The first is the supplements help relieve congested lungs by lowering the development of mucus in the respiratory system. Second, it’s a potent antioxidant source to treat the oxidative stress areas in your body based on glutathione synthesis to reverse the oxidation. (x

More Benefits Combining Cystine and Cysteine 

Both cystine and cysteine can help modulate the immune system. (x). Cystine reduces into cysteine, and cysteine helps the body make GHS. GHS supports the immune system by protecting cells from oxidative stress and fighting inflammation. (x) Supplementing these amino acids should help supply enough GHS when the body needs to kick its immune system into gear.

Cystine and its analog cysteine may help support postoperative recovery, heart health, cognitive functioning, memory and focus, and they may even reverse hair loss

The decrease in insulin resistance for type 2 diabetes is another combined benefit. (x) And research has suggested that cysteine improves the body’s insulin sensitivity, regulating blood sugar. It means it may help treat your diabetes, too. (x)

Research suggests that supplemental cysteine as an antioxidant may help treat thalassemia (a blood disorder that causes cellular damage by forming reactive oxygen species) by lowering oxidative stress in the body (x). 

Supplemental cysteine may also help prevent chronic obstructive pulmonary disease (COPD) and contrast-induced kidney damage during X-rays. (x) According to a study published in the Archives of Iranian Medicine, it could also help ease cravings in people with methamphetamine dependencies. (x

Benefits of L-Cystine 

So why should you care about cysteine? The benefits of the amino acid are extensive and apply to many health concerns that may help your body, such as:

  1. Look Younger as You Age

Well, GHS levels in the body decline during aging, and one study suggests that taking supplemental cysteine can help the elderly maintain healthy amounts of GHS. (x) Cysteine helps your body make collagen (which many consider the glue that holds your body together) and keeps skin elastic. (x) So, if you want to increase the amount of cysteine and GHS in your body, take more cystine.

  1. Potent Antioxidant 

For starters, the supplement acts as an antioxidant and protects tissues from pollution and radiation. In cells, cystine reduces back into cysteine, an ingredient for making essential biomolecules such as proteins and glutathione (GHS), a potent antioxidant. (x)

Long-term supplementation of cystine delays loss of muscle mass as you age. Studies show oxidative stress increases as you age and causes osteoporosis, loss of bone-related to aging. Based on findings from scientific research performed on old mice, they administered for six months cystine. Its antioxidant properties slowed down the decline of age-related skeletal muscle loss. (x)

  1. Postoperative Recovery

A study published in SpringerPlus in 2013 showed that postoperative patients treated with cystine suppressed:

  • Resting energy expenditure (the amount of energy consumed at rest)
  • Body temperature, which increases in response to inflammation
  • Neutrophil and lymphocyte counts, which increase in response to illness, injury and bodily stress in general
  • Levels of interleukin 6 (IL-6), a marker of inflammation (x)
  1. Lung Health

As a supportive treatment for respiratory tract infections, supplemental cysteine gives antioxidant protection to the lungs and helps the body break down mucus. (x) It does this by breaking the mucoproteins’ disulfide bonds, which further break down mucins, serum albumin, and immunoglobulins present in the mucus. It helps you breathe better when you have inflamed airways.

  1. Heart Health

Cysteine helps support healthy hearts, boosts athletic performance, and reduces the exercise-induced oxidative damage that intense training causes (x). It may also reduce the risk of stroke in women and men, alleviate arterial stiffness, and reduce blood pressure (x).

One study supports NAC’s being used to relieve the adverse effects of diabetes on the cardiovascular system since diabetic patients leading cause of death is heart failure. The report identifies the potential of the supplement being cardioprotective by preventing oxidative damage with a diabetic heart. (x)

  1. Cognitive Health

Studies show that supplemental cysteine may improve memory and learning deficits, reduce anxiety and support motor coordination. To add, it may help treat Alzheimer’s disease, a major neurodegenerative illness, and a common cause of dementia. (x) Evidence shows that taking supplemental cysteine reduces oxidative stress, alleviating age-related inflammation and possibly Alzheimer’s disease.

  1. Hair Growth

Despite it being a mild, benign condition, alopecia (hair loss) significantly relates to emotional and physical stress, likely caused by environmental issues, watching the news media, and even childbirth. A study used a combination of retinol, L-cystine and gelatin. During the investigation, they measured the density of the hair before and after. In the end, the group who took these supplements orally noticed an overall improvement in their hair growth. (x)

Also, the overproduction of a potent androgen called dihydrotestosterone (DHT) causes alopecia. Cysteine helps by accelerating alpha-keratin production, an abundant hair protein. It sped up alpha-keratin production, strengthens hair follicles, thus slowing down and eventually preventing further hair loss. By forming disulfide bridges, cysteine provides keratin rigidity and strength. (x)

  1. Anti-Cancer Attributes

Excessive alcohol drinking can cause cancer to develop in the upper gastrointestinal tract because of exposure to acetaldehyde, a cancer-causing component. L-cystine consumption lowers acetaldehyde concentration in saliva, reducing the exposure to the upper tract, thus lowering the chances of cancer. (x)Studies have also supported cystine’s involvement with the arrest of tumor growth. Cystine helps the body absorb glutathione synthesis, which is essential for cellular protection from oxidative stress while maintaining cystine. (x

L-Cystine Benefits

L-Cystine Dosage 

It is best to take 500 milligrams (or a 1/3 teaspoon) one to three times daily. Of course, if a doctor suggests otherwise, it is wise to follow their instructions. It’s best to see your physician before starting any new supplement. Also, be sure to talk to your doctor if you’re pregnant or nursing. 

Where to Buy L-Cystine?

You can purchase L-cystine at BulkSupplements.com. The company is an industry-leading manufacturer and distributor of pure dietary supplements. BulkSupplements.com is not just a consumer brand. It also supplies pure ingredients to other food and supplement brands to make their products. All products at BulkSupplements.com are manufactured and tested according to current and proper manufacturing practices. 

Are you interested in trying L-cystine? Contact BulkSupplements.com to place an order.

L-Cystine Side Effects 

Common side effects of taking cystine include stomach pain, nausea, vomiting, wheeziness, runny nose and mouth inflammation. Side effects are possible with a standard daily dose of 1.5 grams. These include:

  1. Stomach Pain

This common side effect may precede feelings of nausea and vomiting. Sometimes diarrhea and stomach cramps can follow, too. To counter these symptoms, take cystine with plenty of food and water to avoid irritating the gastrointestinal tract.

  1. Nausea and Vomiting

Nausea is a common side effect of taking cystine on an empty stomach. It is also a common side effect for people with preexisting gastrointestinal upsets. Take cystine with food and lots of water to counter nausea and vomiting.

  1. Allergic Reactions

Allergic reactions to cystine are possible. A response may manifest all over the body as irritated, itchy, peeling patches of skin. If patches persist or swell, or if itching intensifies, talk to your doctor. 

The Bottom Line 

Many consider L-cystine and its cousin, L-cysteine, leading supplements supporting memory and cognition, heart health, lung health, skin health and the immune system. Those recovering from surgery may also significantly benefit from taking them. Cysteine and cystine are very similar. One can turn one into the other and vice versa. 

Many people in the scientific community support using NAC as a preventive and additional treatment for COVID-19. The supplement contains L-cysteine but relates to L-cystine since they help each other once in your body.  

Follow dosage based on your doctor’s recommendation. Shared side effects of taking cystine include stomach pain, vomiting, nausea, runny nose, wheeziness and mouth inflammation. 

Although substantial evidence supports these supplements’ efficacy on health, the scientific community warmly encourages further research into them.

The statements in this article have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.

Author: James D