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What is NAC?

What is NAC?

NAC (N-acetylcysteine) is a supplement form of the amino acid, L-cysteine. This cysteine is used to synthesise an antioxidant, glutathione.

NAC is highly touted for its role in glutathione production, which is essential to facilitate an immune system response and fight free radical damage to cells. This makes it crucial to support heart, brain, and liver health.

Here, we will focus on how NAC tackles mass formations and conditions like thyroid nodular growth, by fighting oxidative stress.

We will also discuss how this supplement can be used in conjunction with Chinese herbs for an added health boost!

Benefits of NAC

Additionally, NAC can…

  • Fight thyroid inflammation and prevents thyroid nodular growth
  • Fight endometriosis and boosts fertility
  • Prevent formation of cysts and tumours

Seems like NAC has a “NAC” (knack) for fighting diseases!

First, a Bit on Ageing and Oxidative Stress...

We’ve written about oxidative stress and the action of antioxidants in our other articles.

Oxidative stress = imbalance between the production of reactive oxygen species (ROS) and the body’s ability to neutralise them with antioxidants. ROS, a type of free radical, is usually released as a byproduct during respiration, from the mitochondria.

ROS levels can increase with age due to...

Mitochondrial dysfunction:
As mitochondria age, they may become less efficient and produce more ROS as a byproduct of their energy-generating processes, due to electron leakage.

Accumulated damage:
Over time, cells and tissues accumulate damage from exposure to environmental stressors, metabolic processes, and DNA damage. This increases ROS production and decreases antioxidant defences, contributing to oxidative stress.

Reduced antioxidant defences:
Ageing is associated with a decline in the body’s antioxidant defences, including enzymes like superoxide dismutase, catalase, and glutathione peroxidase. Thus, an imbalance between ROS production and neutralisation is formed, creating oxidative stress.

Chronic inflammation:
Ageing is also associated with a chronic low-grade inflammatory state known as inflammaging. Inflammation can stimulate ROS production as part of the immune response, contributing to oxidative stress.

ROS causes tumours and cysts…

ROS are highly reactive molecules that contain oxygen and can damage cells by oxidising cellular components like DNA, proteins, and lipids. This oxidative damage can lead to mutations in genes that control cell growth and division, potentially contributing to the development of tumours.

Additionally, ROS can activate signalling pathways that promote cell proliferation and survival, which may further contribute to the growth of mass formations!

ROS causes thyroid nodular growths...

A thyroid nodular growth/thyroid nodule, is a lump or mass that develops within the thyroid gland, which is located in the front of the neck just below the Adam’s apple. These nodules can vary in size and may be solid or filled with fluid (cystic). Thyroid nodules are common, and while the majority are benign (noncancerous), a small percentage can be cancerous.

In the thyroid gland, oxidative stress can damage thyroid cells and impair the synthesis and secretion of thyroid hormones, leading to hypothyroidism.

Additionally, oxidative stress can promote inflammation and cell proliferation, which are processes involved in the formation of thyroid nodules. The accumulation of ROS-induced damage over time can contribute to the development of nodules within the thyroid gland.

Oxidative stress caused by ROS can also worsen hypothyroidism and Hashimoto’s.

1. NAC Busts ROS!

Remember how NAC makes glutathione, an antioxidant?

NAC helps the body make a powerful antioxidant called glutathione, by converting itself into cysteine. 

Glutathione is composed of three amino acids: cysteine, glutamine, and glycine. Among these, cysteine is often the rate-limiting factor in glutathione synthesis. 

This is because, cysteine is less abundant in the diet and can be challenging for the body to produce in sufficient quantities. 

Glutathione can scavenge for ROS like hydrogen peroxide and hydroxyl radicals. These two are the culprits responsible for damaging DNA, causing mutations in genes involved in cell division, thus inducing tumorigenesis and cyst formation.

2. NAC for Thyroid Inflammation

NAC suppresses the activity of nuclear factor kappa B, and reduces levels of tumour necrosis factor-alpha (TNF-α) and interleukins (IL-6 and IL-1β). 

TNF-alpha and IL-6 are the main culprits for thyroid inflammation! In Hashimoto’s, thyroid inflammation often causes enlarged nodules.

3. NAC for Endometriosis

Research has shown that the recurrence rate of endometriosis is between 20 and 40% within five years following conservative surgery.

In TCM, 祛痰药 (mucous-expelling medicine) is often prescribed to prevent the endometriomas from growing back on the ovaries after removal.


According to research patients with endometriosis often have a certain degree of constitutional weakness and deficiency in their kidneys (the foundation of innate constitution).

Therefore, in addition to blood stasis, there is also a deficiency of kidney qi.  Studies have shown that drugs that warm the kidneys also have the function of regulating the endocrine function of the kidneys and adrenal glands. Therefore, it is necessary to treat endometriosis patients with kidney-tonifying and phlegm-dispelling therapy

The mechanism through which NAC works is a little different than how Chinese Medicine works. NAC does not eliminate phlegm the TCM way. Rather, its main expertise is as an antioxidant booster.

There is now increasing evidence to show that ROS is linked to the pathophysiology of endometriosis. Hence, we observe that NAC may help scavenge free radicals in the ovaries, preventing the recurrence of endometriosis after surgery.

4. NAC for Uterine Fibroids

One type of fibroid that may require mucus-thinning medicine to treat is the submucosal fibroid. This type of fibroid grows into the inner cavity of the uterus and can cause heavy menstrual bleeding and other symptoms. Mucous-thinning medications, such as hormonal treatments like GnRH agonists or progestins, may be used to help reduce bleeding associated with submucosal fibroids. These medications can help regulate menstrual bleeding and reduce the amount of mucus-like discharge that may be associated with these fibroids.

Since NAC has mucolytic properties, it seems that submucosal fibroids may be a potential target for this supplement.

5. NAC for Fibrocystic Breast Change

Fibrocystic change is the most common benign lesion in breasts of a woman in her reproductive age. It is an outcome of oestrogen excess due to sex hormone imbalance. Fibrocystic breast changes lead to the development of fluid-filled round or oval sacs, called cysts. When a woman has fibrocystic breasts, she may experience pain, tenderness, and swelling in her breasts. She may also notice lumps in one or both breasts.

The study showed that NAC could mitigate cyclical mastalgia – breast pain that is associated with the menstrual cycle due to hormonal variation often associated with breast swelling, tenderness, and lumpiness and generally bilateral in nature.

Supporting liver health for proper detoxification and elimination of excess oestrogen is also important. This study states that NAC, as an enhancer of glutathione biosynthesis, is one of the frequently used antioxidant drugs for treatment of liver disorders.

If the liver is not functioning correctly, it cannot metabolize estrogen effectively, leading to hormone imbalances.

NAC supports liver function by increasing glutathione levels, which helps to protect the liver from damage caused by oxidative stress and aids in detoxification processes. This is important for oestrogen balance because oxidative stress can damage the ovaries and reduce oestrogen production. 

Furthermore, studies have found that NAC can inhibit the activity of an enzyme called aromatase, which converts testosterone to estrogen. This can be particularly beneficial for people with conditions such as polycystic ovary syndrome (PCOS), which is associated with high levels of testosterone and estrogen imbalances.

Hence, by preventing hormone imbalance, NAC can help prevent fibrocystic change caused by excess estrogen.

6. NAC for Breast Lipoma

Breast lipomas are benign (noncancerous) tumours that develop from soft tissue cells known as mesenchymal cells. These cells help form and support vital tissues such as your bones, muscles, nerves, joints and adipose tissue. 

Lipomas in the breast tend to be slow-growing tumours that sit just underneath the skin. They are not made of breast tissue but of mature fat cells encased within thin, fibrous capsules.

There is insufficient research to support the notion that NAC helps with lipomas, as lipomas are made of fat cells. 

However, the general idea is that lipomas form due to an overgrowth of adipocytes within a fibrous capsule.

This overgrowth of adipocytes could be due to uncontrolled cell proliferation. This connects to the topic of ROS, where ROS could cause DNA damage and hence mutations in genes involved in cell division. 

Hence, NAC, through its role in scavenging these ROS, could potentially prevent the overgrowth of these adipocytes.

7. NAC for a Fertility Boost

If cervical mucus is too thick or hostile to sperm (female infertility), the mucolytic action of NAC may enhance sperm motility and their ability to reach the egg.

In women with PCOS, a condition that can affect fertility, NAC may boost ovulation. PCOS is associated with insulin resistance and elevated androgen levels. NAC has been studied for its ability to improve insulin sensitivity and reduce androgen levels, potentially helping regulate menstrual cycles and promote ovulation.

Dosage for NAC

NAC can be administered orally, intravenously, or by inhalation, being commonly safe and well tolerated, even in high doses. Studies have shown that for respiratory diseases, a dosage of up to 3000 mg/day of NAC is safe and well tolerated.

Another study postulated that going beyond 3000 mg/day may be effective for severe cases of OCD.

NAC + DIM? Is It Safe?

It seems there are a number of people who take Diindolylmethane (DIM) together with NAC for greater efficacy, for reducing breast cancer and prostate cancer.

However, it is controversial, as taking DIM is usually not recommended for those wanting to get pregnant. This is because DIM acts like estrogen in some way, causing hormone modulation effects.

Do Not Combine NAC With...

1. Nitroglycerin and isosorbide, which are used to treat chest pain (angina) and heart failure. They belong to a class of drugs called nitrates, which work by dilating blood vessels, increasing blood flow, and reducing the workload on the heart.

Taking nitroglycerin together with NAC can potentially lead to an interaction that affects blood pressure. Both nitroglycerin and NAC can cause blood vessel dilation, and when taken together, they can have an additive effect, leading to a significant drop in blood pressure. This can result in symptoms such as dizziness, lightheadedness, fainting, or even more severe complications.

2. Activated charcoal is sometimes used in emergency settings to treat certain types of poisoning. It can reduce the effectiveness of NAC when taken together, so they should be spaced apart if both are needed.

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