Frequently Asked Questions
N-acetyl-cysteine (NAC) is an anticarcinogenic and antimutagenic agent; it inhibits IL-6 as well as invasion and metastasis of malignant cells. NAC is the acetylated precursor of the amino acids L-cysteine and reduced glutathione. Historically, it is used as a mucolytic agent in respiratory illnesses as well as an antidote for paracetamol hepatotoxicity, but more recently its credits have grown. Animal and human studies have shown it to be a powerful antioxidant and a potential therapeutic agent in the treatment of cancer.
The biological value of NAC is attributed to its sulfhydryl group, while its acetyl-substituted amino group offers protection against oxidative and metabolic processes. In vitro studies showed NAC to be directly antimutagenic and anticarcinogenic; in vivo, NAC inhibited mutagenicity of a number of mutagenic materials.
A) Liver Protectant
Glutathione is required for the detoxification of numerous substances in the liver and is a compound of three amino acids, cysteine, glutamic acid and glycine. Of these, cysteine is most likely to be rate limiting, in other words the availability of cysteine is the biggest factor in how much glutathione can be synthesised. Additional dietary cysteine is thought to be the most effective method of increasing glutathione synthesis, and thus improving glutathione conjugation – the method in which approximately 60% of all toxins are neutralised during phase II of the liver’s detoxification process.
Efficient phase II detoxification ensures that harmful toxic compounds are not able to build up in the liver. NAC has been shown in studies to be the most effective method of increasing glutathione levels. Cysteine also has antioxidant properties, which further enhances its liver protective abilities. NAC often administered in the early stages of paracetamol poisoning.
Research suggests that NAC is one of the most effective methods of elevating glutathione, a compound required for phase II liver detoxification in a process called conjugation. Approximately 60% of all toxins passing through phase II are detoxified via glutathione conjugation, which makes NAC an important factor in liver detoxification. As a sulphur amino acid, cysteine is abundant in ‘smelly’ foods such as eggs and garlic, which are known for their liver supportive properties.
C) Heavy Metal Scavenger
In addition to the indirect detoxification potential of cysteine, through the up- regulation of glutathione conjugation, it is also able to bind to (chelate) heavy metals, thus aiding their removal from the body.
NAC, both alone and as part of glutathione, is a very effective free radical scavenger.
It also forms a part of the potent antioxidant enzyme glutathione peroxidase and is able to quench both reactive oxygen species and peroxide radicals, an action which makes it especially valuable in protecting cell membranes.
N-acetyl cysteine can provide an alternative source of sulfur for glutathione production.
It is a free radical scavenger on its own, effective at reducing oxidative stress, particularly due to heavy metal toxicity.
Because it can directly replenish glutathione stores, NAC is more effective than methionine at preventing liver damage, and is the current treatment for paracetamol. toxicity It is an effective treatment for acute liver failure due to non-paracetamol drug toxicity as well.
E) Cardiovascular Protection
Through its antioxidant effects, NAC can prevent oxidation of LDL cholesterol, a known risk factor in heart disease. NAC also significantly lowers lipoprotein A, which appears to be an even greater risk factor in heart disease than cholesterol.
F) Respiratory Support
NAC breaks up bonds that account for the thick consistency of mucous, thus aiding its removal. A review of scientific studies has found that NAC may help dissolve mucus and improve symptoms associated with chronic bronchitis, asthma, cystic fibrosis and emphysema. Chronic smokers also may benefit from NAC supplementation due to its antioxidant properties (cigarette smoke is a significant source of free radicals).
NAC increases glutathione levels in virally infected cells more efficiently than taking glutathione itself. Raised cellular glutathione inhibits viral spread
One of the best-researched antioxidants for depression is NAC. NAC is a precursor to glutathione, one of the body's most powerful antioxidants. Research has found glutathione depletion and oxidative stress in people with depression. Two recent studies showed NAC is a safe and effective adjunctive treatment that improves depression in patients with depressive disorders.
NAC has both chemopreventive and therapeutic potential in malignancies arising in the lung, skin, breast, liver, head, and neck. NAC is effective in inhibiting tumor cell growth in melanoma, prostate cells, and astrocytoma cell lines (the latter is a primary tumor in the brain). Neovascularization (new blood vessel growth) is crucial for tumor mass expansion and metastasis. NAC inhibited invasion and metastasis of malignant cells by up to 80% by preventing angiogenesis.
A number of cancers express IL-6 and other potentially dangerous cytokines. NAC inhibited (in a dose-dependent manner) the synthesis of IL-6 by alveolar macrophage Peak plasma levels of NAC occur approximately 1 hour after an oral dose; 12 hours after dosing, it is undetectable. Despite a relatively low bioavailability (4-10%), research has shown NAC to be clinically effective. A suggested NAC therapeutic dosage is usually in the range of 600 mg per day.
- Liver protection and liver disorders
- Heavy metal poisoning
- Free radical-related disorders in general
- Cystic fibrosis
- Chronic respiratory congestion
- Viral disorders
500-1200 mg per day (taken on an empty stomach)
Soybeans, spirulina, beef, pork, chicken, turkey, spirulina, lentils, adzuki beans, baked beans, chickpeas, kidney beans, peas.
• Cysteine may produce a false positive in diabetic tests for ketone bodies.
• Best avoided by children, pregnant women and nursing mothers.
• Vitamin C supplementation is often recommended when taking l-cysteine.