Research suggests that N-acetyl cysteine (NAC) — the supplement form of the semi-essential amino acid L-cysteine — is an effective, safe and low-cost treatment option for a range of conditions, including those that are both acute and chronic.
What are the benefits of taking NAC? Not only has been it been used for three decades as an effective mucolytic agent (mucous-thinner), but it also has uses including reducing inflammation, protecting the liver, and preventing/treating drug toxicity, insulin resistance, infertility due to PCOS and more.
What Is NAC?
N-acetyl cysteine, the supplement form of cysteine, is an amino acid that helps the body create and use protective antioxidants.
While cysteine is found in many high-protein foods, NAC is only obtained from taking supplements or prescription drugs.
Because the human body can create some NAC from other amino acids, particularly l-methionine and l-serine, it is considered to be a “semi-essential amino acid.” That means there isn’t a daily requirement of NAC that you must get from your diet, but getting higher amounts can benefit some people.
What is NAC used for? See the multiple potential NAC benefits below.
1. Has Antioxidant Effects and Helps Form Glutathione
NAC is involved in the regulation of the glutamatergic system. In other words, as a precursor of L-cysteine, which results in glutathione biosynthesis, NAC (along with glutamine and glycine) is an amino acid that is needed to produce what’s arguably the most important antioxidant in the human body.
The most important N-acetyl cysteine mechanisms of action are its antioxidant and anti-inflammatory effects. These are due to its ability to increase glutathione levels, scavenge free radicals and reduce oxidative stress.
This is why it’s recommended as a potential treatment for different disorders resulting from free oxygen radicals, such as liver disease, Alzheimer’s, Parkinson’s and even cancer.
2. Can Help Support Pregnancy Outcomes
Is N-acetyl cysteine safe during pregnancy? Studies have shown no maternal or fetal harmful effects of NAC treatment.
Certain studies have even found that NAC used in combination with vitamin E, or vitamins A and E, and essential fatty acids can reduce reactive oxygen species (ROS) and lead to pregnancy rate improvements in those struggling to become and stay pregnant, especially women with PCOS.
This is because it increases levels of the antioxidant glutathione, which positively acts on insulin secretion and reduces insulin resistance, which is believed to be associated with PCOS.
According to an article published in Women’s Health Reviews, NAC seems to work as a therapeutic approach to improve the level of circulating insulin, as well as insulin sensitivity, in PCOS patients with hyperinsulinemia.
NAC also has anti-inflammatory effects that can improve pregnant and birth outcomes among women with infections, who are susceptible to experiencing preterm labors. Doses of about 0.6 grams of NAC daily can be taken orally along with progesterone after week 16 of pregnancy in order to protect against preterm birth recurrence.
Additionally, it can help treat acetaminophen overdose during pregnancy, which is the most common drug overdose reported among pregnant women.
3. Helps Treat Respiratory Issues by Breaking Up Mucus
NAC has the ability to reduce mucus secretions and phlegm, as well as to reduce coughing, wheezing and trouble breathing. This makes it helpful in treating conditions including chronic bronchitis (defined as the presence of chronic productive coughs for more than three months in two consecutive years), as well as colds and the flu.
In addition, there’s evidence that it can be an adjunct treatment for chronic obstructive pulmonary disease (the fourth-leading cause of death in the U.S.) and emphysema.
4. Protects the Liver and Kidneys
When it comes to promoting detoxification, what is N-acetyl cysteine good for? In addition to protecting the organs from free radical damage, another use is helping control side effects associated with taking doses of certain medications/drugs, especially acetaminophen.
NAC is an effective way to help treat emergency acetaminophen toxicity and acute liver failure.
NAC injections can be given to reduce harmful effects of overdosing on the liver and kidneys. It seems to counteract toxicity of chemicals in several ways:
- due to its dual role as a nucleophile and as a -SH donor
- by replenishing glutathione
- by reducing N-acetyl-pbenzoquinonimine
- by performing hepatoprotective actions related to its antioxidant properties
It works best for reducing toxicity when taken within eight to 10 hours of an overdose. Patients that ingest NAC within eight hours typically get well and have less than a 10 percent rate of occurrence of hepatotoxicity, and they have a low chance of suffering from any serious liver/kidney damage.
5. Has Mood-Lifting/Stabilizing Effects
An imbalance of glutamate is believed to be one contributing factor to mood and cognitive conditions. Because it has an impact on levels of the neurotransmitter glutamate in the brain, NAC for anxiety, depression and other mental health conditions may be a useful complementary treatment.
It’s particularly been shown to have positive therapeutic impacts on psychiatric syndromes that are either characterized by oxidative stress or impulsivity and compulsivity.
According to a Psychology Today article:
There have been many studies of this compound, including neuroimaging studies, and it has been investigated in innumerable disorders — depression, bipolar disorder, OCD, PTSD, schizophrenia, addiction, eating disorders, Alzheimer’s disease, and addiction.
While there’s still a need for more research showing how NAC works in the brain, there’s evidence that NAC seems to help with ruminations (difficult-to-control extreme negative self-thoughts). It can help make these thought patterns less distressing and less likely to evoke serious worry or fear and to trigger depression.
6. May Help Stop Cancer Development
Although it hasn’t been shown to be a cancer treatment, there’s evidence that NAC can defend against cancer by neutralizing free radicals that cause damage to DNA. In animal studies, animals fed with NAC experience less cellular damage and fewer lung, colon and bladder tumors compared with those fed a normal diet.
Memorial Sloan Kettering Cancer Center states that “NAC interferes with tumor invasion, metastasis, and blood vessel growth in lab experiments, however it’s not known how well these effects carry over to humans.”
Clinical studies show there are several ways in which NAC can help defend against certain types of cancer. These include:
- regulating the expression of genes that are involved in oxidative stress and inflammation pathways
- increasing antioxidant status
- reducing production of inflammatory cytokines and proteins
Additionally, it can be used to help cancer patients overcome the adverse effects associated with certain drugs and treatments.
7. Defends Against Metabolic Disorders
As mentioned above, NAC improves insulin sensitivity and can help those who are susceptible to developing metabolic disorders.
How to Use NAC Supplements
NAC is an over-the-counter supplement that can be purchased at your local health food store in capsule/tablet form. It’s also available by prescription in injection form.
While cysteine (a sulfur-containing amino acid) is found in foods including chicken, turkey, other meats, garlic, yogurt and eggs, NAC is only acquired by taking supplements or drugs.
There isn’t a daily requirement for NAC or an agreed upon “optimal dose” for NAC supplements. Experts recommend taking an adequate dose for several months and carefully keeping track of its effects on key symptoms — this way you know if it’s helping and how much you need.
Below are general NAC dosage recommendations depending on the symptoms/conditions you are treating:
- Between 600–1,800 milligrams of a NAC supplement daily seems to be effective against many conditions; 600-milligram capsules taken two to three times a day is the recommended dosage to start with.
- There’s evidence that 2,000 milligrams is safe for most adults.
- Higher doses may be needed to treat certain chronic and degenerative diseases, including COPD, impaired glucose control and cancer. For example, doses of about 2,800 milligrams per day for up to three months seem to be effective for adults with COPD, according to some studies.
How long does it take for NAC to work?
This depends on the condition it’s being used to treat, the individual and the dosage taken.
It can work within hours to help treat overdoses and toxicity when given intravenously. It may take up to several months to work for other conditions, although it may work within several weeks for some people.
When should you take NAC, morning or night?
It can be taken any time of day that is most convenient. NAC is available in 500-, 600-, 750- and and 1,000-milligram tablets. You will likely need to divide up your dose and take it twice or three times daily to see results, so consider taking it once it in the morning and again at night.
Risks, Side Effects and Interactions
Is NAC dangerous? While it’s safe for most people to take, some drug interactions and negative reactions are possible. Overall, most experts believe that the use of NAC yields potential benefits that outweigh potential risks.
What are the side effects of NAC? Potential NAC side effects can include:
- indigestion/upset stomach
- fatigue and drowsiness
- skin rash
It might not be safe for people with asthma, bleeding problems or anyone taking nitroglycerin, including blood thinners and certain blood pressure medications. If these apply to you, check with your doctor before using NAC supplements to discuss any possible interactions.
Is NAC hard on the kidneys? Can NAC cause liver damage? In very high doses any supplement is capable of contributing to liver or kidney problems — however, as explained above, generally NAC is considered protective of the liver and kidneys, not a harm to them.
- N-acetyl cysteine (NAC), the supplement form of the amino acid cysteine, can help the body create and use protective antioxidants, especially glutathione (the so-called “master antioxidant”).
- N-acetyl cysteine protects the liver and kidneys and improves detoxification pathways, in addition to having anti-inflammatory effects. This is why NAC injections are used to help reverse drug overdoses and toxicity.
- Other benefits include treating respiratory conditions, PCOS, infertility, metabolic syndrome and certain types of cancers.
- N-acetyl cysteine is not available in foods, but cysteine is. NAC is only obtained from taking supplements or prescription drugs.
- A standard dose is between 600–1,800 milligrams per day, although higher doses around 2,000 milligram/day have also been shown to be safe.