L-Cysteine is a conditionally essential amino acid. It can be made in the body. However, it becomes deficient under stress or when dietary intake of methionine and serine is inadequate.
L-Cysteine is a key amino acid in the production of Glutathione (more about this later). The N-Acetyl form of L-Cysteine has greater absorption and allows it to pass through the blood brain barrier.
L-Cysteine is such a powerful liver detoxifier that in the US Cysteine is prescribed by doctors for the treatment of acetaminophen (Paracetamol) poisoning.
Glutathione is our bodies most powerful endogenous antioxidant. It helps reduce oxidative stress, inflammation and toxicity in the body that can lead to poor health outcomes and rapid ageing. It is critical for a healthy immune response.
L-Cysteine is said to be the limiting amino acid in the production of glutathione. It combines with L-Glutamine and L-Glycine to make this super molecule.
NAC plays a critical role in detoxification. It has been shown to prevent the side effects of certain drugs, environmental toxins, pollutants, and heavy metals1.
As mentioned earlier, it’s not uncommon for doctors to use NAC acutely to support liver and kidney health after toxicity occurs with overdose of acetaminophen2.
NAC may also have further application for NAFLD (Non-Alcohol Fatty Liver Disease) and other hepatic disorders due to its powerful detoxifying and anti-inflammatory benefits3.
Immunity & Respiratory Illness:
A big reason NAC is back in the news and has become popular again is because of its immune supporting and upper respiratory tract health benefits.
NAC has been shown to work as an expectorant and loosen mucous that forms during upper respiratory illness. Its powerful anti-inflammatory benefits have been shown to reduce symptoms of COPD (Chronic Obstructive Pulmonary Disease)4.
In fact, a 1-year study of patients with COPD showed significant improvement in lung function after supplementation daily of 600mg of NAC5.
NAC may also reduce symptoms of bronchitis6. Bronchitis occurs when membranes in your lungs become so inflamed, they swell and shut off the airways causing wheezing, coughing and respiratory attacks.
Both NAC and Glutathione have been shown to support immune health. A lot of the studies have been in immune compromised individuals that have HIV.
In fact, supplementation with NAC completely restores natural killer cell function in these individuals7. In another study of patients with the flu, NAC was able to reduce the virus’s ability to replicate and reduced viral load which may reduce symptoms and length of the illness8.
Approximately 15% of couples trying to conceive are burdened by infertility. One of the causes can be a condition called varicocele (where the veins of the scrotum become inflamed due to oxidative stress).
Patients with varicocele treated with surgery and NAC (600mg daily) had 22% higher pregnancy rates than the control group who didn’t receive NAC9.
Women with PCOS have a reduced fertility rate due to disrupted ovulation cycles. This may be due to inflammation and insulin resistance. NAC, as part of a treatment protocol has been shown to induce ovulation which may increase pregnancy rates10.
Inflammation & Insulin Sensitivity:
We've talked much about NAC’s powerful anti-inflammatory benefits. This also extends to fat cells. Obesity and high blood pressure cause oxidative stress and inflammation that may lead to insulin resistance11.
Animal studies show NAC supplementation may stabilise blood sugar and improve insulin sensitivity by lowering inflammation in fat cells12.
In addition, NAC supplementation may improve heart health by reducing oxidative stress and improving NO2 (Nitric Oxide) production13.
Brain Health & Memory:
NAC can replenish glutathione and regulate glutamate levels in the brain. This balance between glutamate and glutathione may help support brain health, learning and memory14.
Much of our age-related brain decline is due to oxidative stress over time. NAC’s may slow this decline by reducing the oxidative damage to cells responsible for the production and registering of neurotransmitters15.
NAC is a potent antioxidant, anti-inflammatory and immune supporting amino acid. It is a precursor to Glutathione and may benefit health and performance through many varied mechanisms16.
Dosing may be best at night and is between 600 – 1200mg daily. The addition of vitamin C may help boost bioavailability.
Side effects are rare if dosed appropriately but may include nausea, vomiting or diarrhoea. People with blood clotting disorders, on blood thinning medication or having surgery should not consume NAC as it may slow clotting.
NAC powder has a slightly sour bitter astringent taste that is best mixed in a fruity flavoured drink to consume.
Disclaimer: The above article is merely a guide to inform about a particular ingredient. It is based on referenced research. However, it is in no way a recommendation or a treatment for any health conditions or diseases. You should always consult with your qualified health care provider before changing your supplement, training, or nutritional strategy. If you are using any prescribed medication, please check with your prescribing physician to see if NAC is right for you.