Should I Take a NAC Supplement?

Should I Take a NAC Supplement?

A brief look into a trendy amino acid

A variety of different pills and supplements are laid out in a grid against a white backdrop.Photo: Image Source/Getty

PPeople take supplements for all sorts of reasons ? omega-3s for heart health, calcium for strong bones, vitamin B12 for more energy. But rarely is there one supplement that claims to heal seemingly every ailment, from asthma to liver disease. Yet NAC, short for N-acetyl cysteine, is that kind of pill. Or so its fans like to claim.

On Reddit, users say NAC helps them combat anxiety, asthma, insomnia, and other conditions, while some bodybuilders claim it helps combat muscle fatigue. Research suggests NAC can help prevent cognitive decline and even potentially curb aging.

What?s the truth? Here?s the lowdown on one of the trendier supplements in the grocery aisle.

What is NAC?

NAC is the supplemental form of cysteine, which is an amino acid. Specifically, cysteine is what?s known as a ?semi-essential? amino acid, meaning the body can produce it on its own, absorb it from diets high in protein (think poultry and beef), or get it through a NAC supplement.

NAC isn?t a vitamin or a mineral, and because the body makes it on its own, there?s no recommended daily allowance. However, a ?therapeutic dosage? of NAC (meaning the amount that?s expected to have benefits) is considered to be no more than 3 grams per day. Though it?s widely available as a pill, NAC can also be taken intravenously, aerosolized, or in liquid form.

What does it do?

Plenty of health products promise to ?detoxify? the body, but NAC actually does it, explains Angela Grassi, a registered dietitian nutritionist. NAC, she says, produces a powerful antioxidant called glutathione, which removes harmful free radicals ? molecules that cause cell, tissue, and DNA damage. When too many free radicals accumulate in the body, something called oxidative stress occurs, which is often a precursor to inflammation and even cancer. In hospitals, NAC is given intravenously to treat people with acetaminophen overdoses. Its ability to rid the body of free radicals and inflammation is likely one of the reasons why it seems to benefit so many different conditions, including symptoms related to aging.

?I?m a big fan of using NAC in the winter months especially, since it can protect against cold and flu.?

Removing free radicals also helps maintain a healthy immune system overall, says Grassi, which is why NAC is sold in Europe as a treatment for the common cold. It?s also believed that NAC can loosen mucus in people with respiratory disorders like bronchitis and chronic obstructive pulmonary disease (COPD). ?I?m a big fan of using NAC in the winter months especially, since it can protect against cold and flu,? she says.

In addition to eliminating free radicals, NAC can also help regulate an important neurotransmitter called glutamate. Experts say too much glutamate may contribute to mental health conditions like bipolar disorder, addiction, schizophrenia, and OCD. It?s not surprising, then, that people who have taken NAC report improvement in symptoms related to these illnesses. A 2016 study published in the Journal of Clinical Psychiatry looked at five double-blind, randomized, placebo-controlled studies of people using NAC for depression and found that the supplement appeared to improve symptoms of depression more than a placebo.

Should I supplement?

NAC seems to benefit a wide variety of conditions, but experts warn that more research is needed. Even though there are some randomized trials, most studies are finding associations. Experts think it works for many conditions due to the way it acts as an antioxidant and tamps down on inflammation. But it?s still unclear what it works best for.

?NAC has been tried for lots of different things, but the evidence is not overwhelming that it works, except for COPD and acetaminophen overdose,? says Dr. Tod Cooperman, founder and president of, an independent lab that tests the quality of health, wellness, and nutrition products. ?Some of the studies done with NAC don?t give information about dosage, or it?s a study that?s sponsored by the manufacturer of a product. What you want to see is a clinical study with a control, and a large enough study so that the results will be statistically significant.?

Cooperman also warns that NAC ? when taken over the therapeutic dosage of 3 grams per day ? can cause side effects like headache, abdominal pain, vomiting, diarrhea, constipation, and more, though an actual overdose is extremely rare. It?s also been known to affect blood clotting and can give falsely low results of cholesterol during blood tests, so people taking blood-thinning medications or undergoing cholesterol tests should probably steer clear.

Otherwise? ?A lower dose, like a couple hundred milligrams, probably wouldn?t be an issue for most people,? Cooperman says. The evidence just isn?t robust enough to determine whether you really need it.


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