Cysteine is a sulfur-containing, conditionally-essential amino acid. Cysteine has six major functions: 1) incorporation into amino acid sequences of proteins where cysteine promotes protein structure by sulfhydryl bonding and are used throughout the body; 2) rate-limiting precursor for glutathione synthesis; 3) precursor for taurine (used in bile formation and nerve function); 4) source of sulfate for connective tissue synthesis; 5) source of pyruvate for energy or glucose production; and 6) neurotransmitter.
When cells have cysteine, they are able to manufacture the most important antioxidant in our body called glutathione. As a component of glutathione, cysteine functions include being a powerful antioxidant, detoxification agent, component of some prostaglandins, and an amino acid transporter across membranes. Formation of cysteine from homocysteine is one pathway to reduce homocysteine levels. Low levels of cysteine may reduce our ability to prevent free radical damage and may result in impaired function of the immune system.
Cysteine Deficiency:
Cysteine deficiencies identified by inherited metabolic disorders or reduced levels in body fluid have been associated with: 1) impaired antioxidant defenses; 2) decreased ability to metabolize drugs or toxic compounds; 3) depressed immune functions; 4) some psychoses; and 5) homocystinemia.
Patients with rheumatoid arthritis, hypertension, and smokers have reduced levels of cysteine in fluids and tissues. Clinical trials of cysteine supplementation have shown benefits for skin disorders, hair loss, asthma, bronchitis, allergies, cystic fibrosis, chronic obstructive pulmonary disease, heavy metal toxicity, iron deficiency, diabetes & diabetic nephropathy, seizure disorders, reducing cytoxic treatment side effects, HIV infection, and alcoholism. Cysteine deficiency and oxidative stress have been linked to Huntington’s disease, Alzheimer’s disease, arthritis, cardiovascular disease, AIDS and cancer.
Health Problems Associated to Cysteine Deficiency:
- Autism – Commonly deficient in autistic patients. Lack of cysteine impairs detoxification and methylation processes. Low levels linked to neurological symptoms in autism which is often considered an oxidative stress disorder.
- Depression – Oxidative stress in the brain alters neurotransmitter function. Antioxidants protect our brain which is very sensitive to oxidation. Several antioxidants – vitamins A, C and E, alpha lipoic acid, CoQ10, glutathione and cysteine – play a key role in prevention and treatment of depression.
- Diabetes – Glutathione-containing enzymes protect B-cells which are particularly sensitive to oxidative stress. Type 2 diabetics have abnormal antioxidant status. Supplementation with the glutathione precursor cysteine restores antioxidant status.
- Estrogen – Prevents oxidation of estrogen into a dangerous form that causes breast cancer.
- Fatigue – Several studies confirm that oxidative stress exacerbates clinical symptoms of fatigue. Mitochondrial dysfunction (inefficient energy metabolism) can be treated therapeutically with antioxidants such as selenium, cysteine, alpha lipoic acid and glutathione of which unusually low levels are seen in chronic fatigue patients.
- Inflammation – Protects organs such as blood vessels, brain and liver from inflammatory damage. Precursor to glutathione production. Supplementation with N-Acteyl Cysteine (NAC) raises glutathione.
- Pain – Reduces pain caused by systemic inflammation due to its potent antioxidant properties.
- Sleep Apnea – Oral supplementation with cysteine, the precursor to glutathione, has therapeutic potential for sleep apnea. Snore time and duration were significantly reduced for patients treated with N-Acetyl Cysteine (NAC) compared to untreated sleep apnea patients.
- Sports Nutrition – Reduces time to fatigue in endurance sports such as cycling. Precursor to glutathione. Supplementation raises glutathione levels.
- Telomeres – Stem cell treatment with N-Acetyl Cysteine (NAC) corrects DNA damage in telomeres.
- Weight Management – Supplementation with this antioxidant reduced body fat in obese patients.
How to Acquire Cysteine
- N-Acetyl Cysteine (NAC) * * Regardless of dietary protein intake, cysteine supplementation with N-Acetyl Cysteine (NAC) has been found to be safe at doses up to 2000 mg daily.
- Undenatured (bioactive) whey protein such as Immunocal™ which is listed in the Physician’s Desk Reference
