The Importance of NAC (N-acetylcysteine), According to Experts

The rising popularity of NAC supplements coincides with a growing body of evidence supporting NAC supplement benefits. Here are five benefits, in particular, that you may experience.

1. Glutathione Production

While NAC is an efficient antioxidant in its own right, its ability to increase levels of a more powerful antioxidant—glutathione—plays a much greater role in its health-promoting effects (2).

Commonly dubbed the body’s ‘master antioxidant,’ glutathione exists in every human cell, acting as the primary shield against oxidative stress caused by free radicals (the highly reactive and unstable molecules that can damage cells and cause aging and disease).

Without the protection of glutathione, vital cell components like DNA and the mitochondria, which generate energy, can suffer damage. This could eventually lead to cell death and the development of disease.

Native Note: Our glutathione levels tend to decrease with age, so it’s crucial to maintain their levels with a quality NAC supplement (4). How does NAC produce the antioxidant glutathione? Once NAC enters the body, it is first converted to the amino acid cysteine which is then used by the liver as a “building block” to construct glutathione.

2. Liver Function

Among its many functions, the liver acts as a filter to break down and remove harmful substances from your body.

Take prescription medication, for example: As the liver processes these medications, it may produce free radicals, which could potentially induce oxidative harm to the organ itself. Fortunately, NAC, which functions as an antioxidant, safeguards the liver by neutralizing these damaging free radicals that emerge from drug metabolism (5).

That being said, NAC's ability to stimulate glutathione production is particularly crucial for liver health. For instance, the commonly used painkiller acetaminophen (Tylenol) can inflict substantial liver damage, even leading to liver failure when consumed excessively or over a prolonged period.

This happens because the liver's glutathione reserves are exhausted in the process of detoxifying Tylenol. In the absence of the antioxidant protection offered by glutathione, the surge in free radical formation results in damage to liver cells. Thankfully, NAC supplementation can effectively replenish the liver's glutathione stock, making it the only clinically approved treatment for acetaminophen overdose (6).

Furthermore, studies have demonstrated that NAC supplements can nearly double (1.77x) survival rates in instances of acute liver failure that are not related to acetaminophen overdose (7, 8).

Beyond its antioxidant capabilities and role in generating glutathione, NAC can also boost blood flow and oxygen supply to the liver by escalating levels of nitric oxide (9). Nitric oxide is a powerful vasodilator, meaning it expands blood vessels to facilitate improved blood circulation.

3. Natural Detoxification

Once again, NAC’s role in increasing glutathione takes center stage …

Glutathione generated from an NAC supplement is a key player in detoxifying foreign chemicals and toxic compounds produced within your body. For example, glutathione can neutralize cancer-promoting carcinogens such as aflatoxins produced by certain molds and acrolein—a toxic chemical formed when oils are overheated (10).

4. Cellular Health

Ultimately, good health begins at the level of the individual cell. Cells that are unhealthy and not performing as they should eventually transition into a state known as "senescence," a biological stage where cells stop multiplying and their typical function diminishes.

So, instead of dying, some of these old and dysfunctional "zombie cells” continue to churn out inflammatory compounds that damage tissues and organs. The accumulation of senescent cells is a hallmark of aging and a major driver of age-related diseases such as cancer and Alzheimer’s disease (11).

Luckily, NAC has been identified as a senolytic—a compound that can remove harmful senescent cells from tissues and thus restore healthful and youthful cell functioning (12). In a cell culture study, cells from mutant mice unable to make glutathione were demonstrated to undergo premature senescence. Supplementation with NAC was subsequently shown to increase glutathione levels and prevent premature senescence in these mutant cells (13).

Moreover, in a randomized clinical trial conducted in 2023, 40 obese adults were split into two groups. The intervention group was given 600 mg of NAC daily for four weeks, while the control group was given 600 mg of placebo.

The results were impressive: Those taking NAC significantly reduced the marker of cellular senescence in adipose (fat) tissue (14). This could reduce one’s risk of age-related diseases like heart disease, Alzheimer’s, glaucoma, osteoarthritis, and more.

5. Immune Support

The COVID-19 pandemic of 2020 increased awareness of the critical importance of a strong immune defense. NAC can enhance immune responses by recalibrating an overly active immune system or rejuvenating a weak and inefficient one (15). In fact, a review of studies (though limited) suggests that an NAC supplement could potentially reduce complications and death in patients with COVID-19 infection (16). This effect of NAC is likely due to its ability to block the replication of viruses and suppress inflammation and oxidative stress—key contributors to COVID-19 disease severity.

NAC’s role as a potent immune booster is mostly due to its ability to restore glutathione levels in immune cells, thus protecting against infections (17). As an essential component of the immune system, glutathione shields immune cells from oxidative damage. Low levels of glutathione are associated with impaired functioning of various immune cells, inflammation, oxidative stress, and susceptibility to infections (18).

Another important function of glutathione is its unique ability to recycle and thus replenish the antioxidant forms of the vitamins C, E, and A once they are used in the body (19). Each of these essential vitamins has important immune-boosting functions (20).

Glutathione is a molecule composed of three amino acids: cysteine, glycine, and glutamate. While NAC provides the cysteine component, it doesn't provide glycine.

So, even if there's plenty of NAC, without sufficient glycine, the production of glutathione could be limited. In simpler terms, for NAC to help make glutathione effectively, there also needs to be enough glycine present (21).

That said, combining glycine and NAC in a supplement could be expected to have a synergistic effect on driving greater glutathione production. Human clinical trials have reported higher levels of glutathione, resulting from a combination of NAC and glycine supplements versus each supplement alone (22). In a study in old mice, supplementation with a blend of NAC and glycine for seven weeks improved cardiac function and inflammation, whereas an NAC supplement alone did not (23).

As a bonus, glycine provides multiple health benefits of its own: improved sleep quality, collagen synthesis, anti-inflammatory activity, cell protection, antioxidant activity, neurotransmission, improved muscle health, better blood sugar control, immune support, and tissue restoration (24, 25).

As a safe and natural nutritional product with a myriad of health benefits, anyone can take NAC for general health maintenance and disease prevention.

Nevertheless, NAC may be especially useful in providing antioxidant, anti-inflammatory, and overall immune support for people with the following conditions (14):

• Diabetes
• Cancer
• Neurological disease (Alzheimer’s and Parkinson’s)
• Cardiovascular disease
• Inflammatory bowel disease
• Autoimmune diseases
• High blood pressure
• Respiratory diseases
• Infections

In addition, people taking multiple medications, particularly acetaminophen (Tylenol), can benefit from the increased glutathione production from Native NAC to protect the liver and enhance drug detoxification.

Lastly, NAC may be used to improve brain health and athletic performance (27, 28).

Can I Take NAC Every Day?

Yes. NAC is a safe dietary supplement composed of amino acids—the same amino acids found in high-quality protein foods such as meats, eggs, and dairy.

Are There Any Side Effects From Taking NAC?

The side effects of NAC supplementation are usually mild and may include:

• Gas
• Bloating
• Constipation
• Diarrhea
• Nausea
• Vomiting

Who Should Not Take NAC?

If you have a medical condition or are taking any medication, consult with a healthcare professional before using it. This also applies to women who are pregnant or breastfeeding.

Which is More Effective For Increasing Glutathione Levels: an NAC Supplement or Glutathione Itself?

Oral supplementation with glutathione remains controversial. Glutathione supplements are poorly absorbed and are broken down via digestion. However, innovations like liposomal and sublingual forms of glutathione have been designed to prevent it from being broken down in the stomach, leading to improved glutathione levels. Nevertheless, it's worth noting that these supplements can be quite expensive.

In addition to driving glutathione production, there are other important benefits of an NAC supplement (e.g., its ability to break down mucus). Making glutathione from its precursor molecules is more in keeping with how the body naturally produces it from dietary protein (amino acids). In other words, NAC provides the body with the “raw materials” needed to produce the finished product for optimal functioning.

All things considered, an NAC supplement has more to offer and is a more natural approach to increasing glutathione levels.