NAC this amino acid can help expel mucus and is capable of fighting viruses directly. Dosages of 600-1200 mg can help reduce symptoms.
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There are some studies on NAC and the immune system, but current research suggests that it and glutathione may help to improve your immune function. Most of the studies focus on people with human immunodeficiency virus (HIV).
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NAC plays a role in the detoxification of your kidneys and liver. It can help to prevent potential side effects of drugs and environmental factors — such as exposure to heavy metals.

In instances of acetaminophen overdose, doctors often give NAC intravenously to reduce damage to the liver and kidneys.
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Side Note: regulatory bodies tried to restrict access to NAC during the pandemic. It was part of a covid treatment protocol used by some Doctors to treat covid.