Best N-Acetyl Cysteine Supplements: Top 10 NAC Brands Reviewed

N-Acetyl Cysteine (NAC) has a similar structure to the amino acid L-cysteine, as it is its acetylated form. N-acetyl cysteine shares a similar structure with the enzyme glutathione, being its direct precursor.

NAC has an easy digestibility and high bioactivity in the human body. It has been found that upon administration of 200-400 mg NAC, the peak plasma levels can be reached within 1-2 hours.

Because of the fact that it is a potent precursor of glutathione, the administration of NAC shows a strong antioxidant effect that has a positive action against radicals, such as hypochlorous acid and hydroxyl, but not against hydrogen peroxide and superoxide.

Top 5 Best Selling NAC Supplements


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NOW Supplements, NAC (N-Acetyl Cysteine)600 mg with Selenium & Molybdenum, 100 Veg Capsules


#1

Now Foods NAC
Doctor's Best NAC Detox Regulators with Seleno Excell, Non-GMO, Vegetarian, Gluten Free, Soy Free, 60 Veggie Caps

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Doctor's Best NAC
Jarrow Formulas N-A-C Sustain, Supports Liver and Lung Function, 600 mg, 100 Sustain tabs

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Thorne Research NAC
Thorne Research - NAC (Formerly Cysteplus) - N-Acetylcysteine for Liver Support, Detoxification, and Immune Function - 90 Capsules

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Throne NAC
Country Life NAC 750mg N-Acetyl Cysteine High Potency Antioxidant Free-Radical Protection & Immune System, Liver & Lung Health Support - Non-GMO, Gluten-Free, Vegan Supplement - 60 Vegan Caps

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Country Life NAC

What Is N-Acetyl Cysteine (NAC)

NAC has a similar structure to the amino acid L-cysteine, as it is its acetylated form. N-acetyl cysteine shares a similar structure with the enzyme glutathione, being its direct precursor.

Although L-cysteine and glutathione have been studied with independent usage, it has been found that their properties do not meet those of N-acetyl cysteine, as the use of NAC increases the glutathione levels far more effectively, compared to the use of isolated glutathione.

The reason lies in the fact that glutathione is rapidly degraded in the small intestine and the oral intake does not lead to a significant increase in the serum levels. NAC has an easy digestibility and high bioactivity in the human body. 

It has been found that upon administration of 200-400 mg NAC, the peak plasma levels can be reached within 1-2 hours.

N-acetyl cysteine is discharged easily from the body, showing toxicity in normal doses. A large part of this disposal is through urine in the form of urinary sulfate (sulfur).

How Does N-Acetyl Cysteine Work

The primary function of NAC in the human body is to be the source of the powerful antioxidant glutathione. 

After passing through several antioxidant cycles, glutathione breaks down to glutamate and amino acids in their free form - L-cysteine and glycine. Eventually, the same amino acids can be used for the formation of new glutathione. 

The problem in this step is the poor bioavailability of L-cysteine, as NAC provides the needed cysteine required for this process.

Because of the fact that it is a potent precursor of glutathione, the administration of NAC shows a strong antioxidant effect that has a positive action against radicals, such as hypochlorous acid and hydroxyl, but not against hydrogen peroxide and superoxide.

Besides the connection with the antioxidant activity, N-acetyl cysteine gives evidence of strong chelating properties with some minerals. 

Studies on humans and animals suggest that NAC successfully bonds with the lead in the blood and facilitates its excretion from the body. NAC successfully prevents the occurrence of lead intoxication.

Proven and Potential Benefits:

1) Antioxidant and immune-stimulating effect

  • Increases the glutathione levels at accelerated rates, including the ones in the brain, but does not counteract all free radicals;
  • NAC in a dose of 800 mg daily successfully suppresses the protein ECP, which is associated with the degranulation of the white blood cells eosinophils. The high levels of this protein are associated with increased inflammation and asthma;
  • Increases the number and activity of erythrocytes in the blood, while at the same time inhibits the activity of the enzyme GST in the leukocytes, as this enzyme is associated with cell damage. While the effect on erythrocytes is significant, the impact on GST is insignificant;
  • Powerful antibacterial effect against the bacteria Helicobacter pylori, which grows in the stomach. In this case, NAC drastically enhances the effect of standard therapy and is not used as a standalone agent.
  • N-acetyl cysteine is associated with the lead in the blood and helps for its disposal from the body. The efficiency is extremely high;
  • In addition to helping with lead intoxication, NAC exhibits a protective effect on the kidney tissue;
  • Contributes to the detoxification of the liver in cases of high doses of paracetamol. 7 grams of paracetamol every 216 minutes for a total of 17 doses have been used in a controlled laboratory environment;
  • Intake of N-acetyl cysteine prior to the use of big amounts of alcohol helps protect the liver tissue from damage. However, if NAC is taken after alcohol, the amino acid enhances the action of the alcohol and the damage to liver tissue. The reason for the double effect is not clear.

2) Nervous system

  • It crosses the blood-brain barrier and increases the glutathione levels in the nerve tissues;
  • Reduces the amount of glutamate in the brain only a few hours after oral intake. A loading dose of 2400 mg is used;
  • It affects dopamine differently, depending on its levels. At low dopamine activity NAC can stimulate the dopamine receptor, while with higher levels of dopamine it rather inhibits the further release of the neurotransmitter;
  • Potential benefits that counteract the symptoms of acute stress and anxiety. Experiments on humans have shown that NAC improves depressive conditions, resulting in chewing of nails and picking the skin off;
  • Inhibits the irritability in autism, but is used in the therapy together with other drugs. It is believed that it can help against the development of autism because of the relationship between autism and lipid peroxidation and the levels of glutamate in the brain;
  • Observations on humans and animals have shown promising benefits in the countering of the obsessive-compulsive disorder (OCD). One of the possible mechanisms is associated with increased antioxidant activity, while people suffering from the syndrome have a deficit of vitamin E and increased lipid peroxidation in the brain. Another possible mechanism is the inhibition of glutamate in the brain. Last but not least, it is considered that NAC can improve the effect of medication type SRI (serotonin reuptake inhibitors), which are used for the treatment of the syndrome;
  • NAC is used as an effective agent to combat addictions. Studies have shown that N-acetyl cysteine reduces the urge for marijuana only after 4 weeks of use, although the effect is moderate. Far more powerful, however, is the effect of suppressing the desire for cocaine in the clearance period of the drug addiction.
  • The benefits of NAC for the treatment of nicotine dependence are promising. The use of 2400 mg for 4 weeks results in a significant reduction in the number of cigarettes smoked per day, without stopping smoking completely, i.e. that is completely voluntary.

3) Cardiovascular and physical strength

  • The intake of 800 mg of NAC for 12 weeks results in an increase of the glutathione in the red blood cells;
  • Potential benefits for the increase of the aerobic endurance and regulation of muscle fatigue, but high doses are needed. 

What Is the Recommended Dosage of NAC

The recommended daily dose varies between 200 and 2400 mg per day, depending on the objective.

The standard daily use includes the intake of 600 mg, 2 times daily, as the use is not bound with more fluids or food.

Contraindications and Side Effects

  • It is considered that N-acetyl cysteine is a safe nutritional supplement; a dose of 2400 mg per day is completely safe;
  • There are rare side effects such as nausea, vomiting, diarrhea or constipation;
  • Do not take NAC after alcohol because it can worsen the liver damage;
  • The use of N-acetyl cysteine might lead to an unpleasant sweat smell;
  • There have been rare cases of allergy to the amino acid, so take it with caution;
  • N-acetyl cysteine slows the blood clotting, therefore it is not recommended to be used after surgery or problems with bleeding;
  • The intake of NAC is not recommended to pregnant and breastfeeding women due to the lack of sufficient data on the side effects. The use of NAC by pregnant women is permitted only under medical supervision and in certain situations, involving mostly drug intoxication.

How to Combine N-Acetyl Cysteine

  • Besides alcohol, the negative interaction of n-acetylcysteine with other substances is unknown;
  • The intake of NAC while taking activated charcoal is not recommended, because the amino acid inhibits the action of active charcoal;
  • If your objective is an immune-stimulating effect, n-acetylcysteine gets combined successfully with supplements, such as zinc, vitamin C, cat's claw and garlic;
  • For the detoxication of the liver, we recommend the combination of milk thistle extract (Silymarin), curcumin, berberine, Schisandra, and L-methionine;
  • For the maintenance of eye health, NAC gets combines wonderfully with lutein and vitamin A.

Where Can We Find N-Acetyl Cysteine

NAC can be found as a separate nutritional supplement, especially in the form of capsules with a concentration of up to 600 mg or in the form of powder sachets with a concentration of 200 mg.

The amino acid is available as a dietary supplement but can be found in pharmacies. One of the most popular options is NOW Foods N-Acetyl Cysteine 600 mg.

Sometimes N-acetyl cysteine is used in combination with other products, most common of which are formulas for detoxification by NOW Foods Liver Detoxifier & Regenerator or eye formulas as NOW Foods Ocu Support.

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