It is a non-essential amino acid, which means that humans can synthesize it.
Cysteine is a semi-essential amino acid.
It is considered semi-essential because your body can make it from other amino acids, namely methionine, and serine. It becomes essential only when the dietary intake of methionine and serine is low.
Cysteine is found in most protein-rich foods, such as chicken, turkey, yogurt, cheese, eggs, sunflower seeds, and legumes.
N-acetyl cysteine (NAC) is a supplement form of cysteine.
Adequate consumption of cysteine and NAC is essential for various health reasons, including replenishing your body’s most potent antioxidant, glutathione.
These amino acids also help with chronic respiratory conditions, fertility, and brain health.
Now let’s look at the top 9 health benefits of NAC.
- Essential for making the powerful antioxidant glutathione
NAC is valued primarily for its role in the production of antioxidants.
Along with two other amino acids, glutamine and glycine, NAC is needed to make and replace glutathione.
Glutathione is one of the most important antioxidants in the body, helping to neutralize free radicals that can damage cells and tissues in your body.
It is essential for immune health and to fight cell damage. Some researchers believe that it may even contribute to longevity.
Its antioxidant properties are also crucial in fighting many other diseases caused by oxidative stress, such as:
- Heart disease.
- Some psychiatric conditions.
NAC helps replenish glutathione, possibly the most potent antioxidant in your body. Therefore, it can improve a variety of health conditions.
- It helps with detoxification to prevent or decrease kidney and liver damage.
NAC plays an essential role in your body’s detoxification process.
It can help prevent the side effects of drugs and environmental toxins.
Doctors regularly administer NAC intravenously (IV) to people with an overdose of acetaminophen to prevent or reduce kidney and liver damage.
NAC also has applications for other liver diseases due to its antioxidant and anti-inflammatory benefits.
NAC helps detoxify your body and can treat acetaminophen overdoses.
- Can improve psychiatric disorders and addictive behavior
NAC helps regulate the levels of glutamate, the most crucial neurotransmitter in your brain.
While glutamate is necessary for regular brain action, excess glutamate combined with glutathione depletion can cause brain damage.
This can contribute to mental health conditions, such as bipolar disorder, schizophrenia, obsessive-compulsive disorder (OCD), and addictive behavior.
For people with bipolar illness and depression, NAC can help decrease symptoms and improve their overall ability to function. Additionally, research suggests that it may play a role in treating moderate to severe OCD.
Similarly, an animal study implied that NAC might minimize the adverse effects of schizophrenia, such as social withdrawal, apathy, and reduced attention span.
NAC supplements can also help decrease withdrawal symptoms and prevent relapse in cocaine addicts.
Additionally, preliminary studies show that NAC may decrease marijuana and nicotine use and cravings.
Many of these disorders have limited or currently ineffective treatment options. NAC can be an effective aid for individuals with these conditions.
By regulating glutamate levels in your brain, NAC can alleviate the symptoms of multiple psychiatric disorders and reduce addictive behavior.
- It helps relieve symptoms of respiratory conditions.
NAC can alleviate the symptoms of respiratory conditions by acting as an antioxidant and expectorant, loosening mucus in the air passages.
As an antioxidant, NAC helps replenish glutathione levels in the lungs and reduces inflammation in the bronchial tubes and lung tissue.
People with chronic obstructive pulmonary disease (COPD) experience long-term oxidative damage and inflammation of the lung tissue, causing the airways to constrict, leading to shortness of breath and coughing.
NAC supplements have been used to improve COPD symptoms, exacerbations, and shrinkage of the lungs.
In a one-year study, 600 mg of NAC twice daily significantly improved lung function and symptoms in those with stable COPD.
Those with chronic bronchitis can also benefit from NAC.
Bronchitis occurs when the mucous membranes in the bronchial passages of your lungs become inflamed and swollen and close the airways to your lungs.
By thinning the mucus in your bronchial tubes and increasing glutathione levels, NAC can help decrease wheezing, coughing, and respiratory attacks.
In addition to alleviating COPD and bronchitis, NAC can improve other lung and respiratory tract conditions such as cystic fibrosis, asthma, pulmonary fibrosis, and symptoms of nasal and sinus congestion due to allergies or infections.
NAC’s antioxidant and expectorant capacity can improve lung function by decreasing inflammation and breaking down mucus.
- Improves brain health by regulating glutamate and replenishing glutathione
NAC’s ability to replenish glutathione and regulate glutamate levels in the brain can improve brain health.
The brain’s neurotransmitter glutamate is involved in a wide range of learning, behavior, and memory actions, while the antioxidant glutathione helps reduce oxidative damage to brain cells associated with aging.
Because NAC helps regulate glutamate levels and replenish glutathione, it may benefit people with memory and brain diseases.
The neurological disorder of Alzheimer’s disease decreases a person’s capacity for learning and memory. Animal studies suggest that NAC may slow the loss of cognitive ability in people with Alzheimer’s.
Another brain condition, Parkinson’s disease, is characterized by the deterioration of the cells that generate the neurotransmitter dopamine.
Both oxidative damage to cells and decreased antioxidant capacity contribute to this disease.
NAC supplements appear to improve dopamine function and disease symptoms such as tremors.
While NAC may improve brain health, more research on humans is needed to draw firm conclusions.
By helping to replenish the antioxidant glutathione and regulate glutamate, NAC has the potential to treat diseases such as Alzheimer’s and Parkinson’s.
- It can improve fertility in both men and women.
About 15% of all couples trying to conceive are affected by infertility. In almost half of these cases, male infertility is the main contributing factor.
Many male infertility problems increase when antioxidant levels are insufficient to combat free radical formation in your reproductive system.
Oxidative stress can cause cell death and reduce fertility.
In some cases, NAC has been shown to improve male fertility.
One condition that contributes to male infertility is varicocele: when the veins within the scrotum become enlarged due to free radical damage. Surgery is the primary treatment.
In one study, 35 men with varicocele received 600 mg of NAC per day three months after surgery.
The combination of surgery and NAC supplementation improved semen integrity and couple pregnancy rate by 22% compared to the control group.
Another study in 468 men with infertility found that supplementation with 600 mg of NAC and 200 mcg of selenium for 26 weeks improved semen quality.
The researchers suggested that this combination supplement should be considered a treatment option for male infertility.
Additionally, NAC may improve fertility in women with polycystic ovary syndrome (PCOS) by inducing or increasing the ovulation cycle.
NAC can help improve fertility in men by reducing oxidative stress that damages or kills reproductive cells. It can also help fertility in women with PCOS.
- Can stabilize blood sugar by decreasing inflammation in fat cells
High blood sugar and obesity contribute to inflammation in fat tissue.
This can damage or destroy insulin receptors and increase the risk of type 2 diabetes.
Animal studies show that NAC can stabilize blood sugar by decreasing inflammation in fat cells and improving insulin resistance.
When insulin receptors are intact and healthy, they adequately remove sugar from the blood, keeping levels within normal limits.
However, keep in mind that human research on NAC is necessary to confirm these effects on blood sugar control.
NAC may reduce insulin resistance and improve blood sugar regulation by decreasing inflammation in fat tissue, but there is no human-based research.
- May reduce the risk of heart disease by preventing oxidative damage.
Oxidative damage to heart tissue often leads to heart disease, causing strokes, heart attacks, and other serious illnesses.
NAC can reduce the risk of heart disease by reducing oxidative damage to heart tissues.
It has also been shown to increase nitric oxide production, which helps dilate veins and improves blood flow. This speeds up blood flow to your heart and can lower your risk of heart attacks.
Interestingly, a test-tube study showed that NAC appears to reduce the damage from oxidized “bad” LDL cholesterol when combined with green tea, another factor that contributes to heart disease.
NAC can reduce oxidative damage to your heart, which can lower your risk of heart disease.
- The ability to increase glutathione levels can improve immune function.
NAC and glutathione also boost immune health.
Research on certain NAC and glutathione deficiency diseases suggests that immune function could be improved and potentially recovered by supplementing with NAC.
This factor has been studied more in people with human immunodeficiency virus (HIV).
In two studies, NAC supplementation significantly increased immune function, with almost complete restoration of natural killer cells.
High levels of NAC in your body can also suppress the reproduction of HIV-1.
A test-tube study indicated that in other immunocompromised situations, such as the flu, NAC could hamper the virus’s ability to replicate. This could potentially reduce the symptoms and lifespan of the disease.
Similarly, other test-tube studies have linked NAC to cancer cell death and blocked replication.
Overall, more human studies are needed. So be sure to talk to your doctor before taking NAC during cancer treatment.
NAC’s ability to increase glutathione levels can improve immune function in various diseases.
There is no specific dietary recommendation for cysteine because your body can make small amounts.
For your body to make the amino acid cysteine, it needs adequate amounts of folate, vitamin B6, and vitamin B12.
These nutrients can be found in:
While most protein-rich foods, such as chicken, turkey, yogurt, cheese, eggs, sunflower seeds, and legumes, contain cysteine, some people choose to supplement with NAC to increase their cysteine intake.
NAC has a low bioavailability as an oral supplement, which is not well absorbed. The accepted daily supplement recommendation is 600–1,800 mg of NAC.
NAC can be given as an IV or by mouth, as a spray, or in liquid or powder form.
Eating protein-rich foods can provide your body with the amino acid cysteine, but NAC can also be taken as a supplement to help treat certain conditions.
NAC is likely safe for adults when given as a prescription drug.
However, high amounts can cause:
- Diarrhea .
When inhaled, it can cause:
- Swelling in the mouth
- Runny nose.
- Chest tightness.
People with bleeding disorders or taking anticoagulant medications should not take NAC, as it can slow blood clotting.
NAC has an unpleasant odor that makes it challenging to consume. If you decide to take it, check with your doctor first.
While NAC is considered safe as a prescription drug, it can cause nausea, vomiting, gastrointestinal upset, and oral problems if inhaled.
The bottom line
- NAC plays several critical roles in human health.
- Renowned for its ability to replenish antioxidant glutathione levels, it also regulates the brain’s important neurotransmitter, glutamate. Additionally, NAC helps the body’s detoxification system.
- These functions make NAC supplements a viable treatment option for multiple health problems.
- Check with your doctor to see if NAC can improve your health.