Best NAC Supplement: Our Top 5 Picks

There is no fountain of youth or silver bullet that’s going to stop aging and cure all that ails you. That’s the bad news. The good news is that certain supplements support aspects of our health that have ripple effects throughout the body. N-Acetyl Cysteine (NAC) may prove to be one of those supplements, though recent research raises questions about its long-term safety.

Clinical research into NAC has yielded promising results in trials investigating its use for respiratory health1 and its purported antioxidant power.2 Its most commonly touted benefit is its ability to increase your body’s glutathione levels, which is a powerful antioxidant. There are some big caveats here, which we’ll get into later, but there’s no denying that NAC is one of the most popular supplements on the market.

Our guide walks you through everything you need to know about NAC’s potential benefits and risks and gives you recommendations for the best possible product for your needs.

If you’re pressed for time, here are our top recommendations:

At Innerbody Research, we extensively test each health service or product we review, including NAC supplements. Over the course of our research and writing, our team reviewed more than 100 scholarly journal articles pertaining to NAC, antioxidants, aging, and the various ailments NAC has the potential to treat.

We also ordered these products for ourselves. That allows us to speak to the customer experience in detail, relaying information about customer support, shipping logistics, and even capsule size. We also tried these supplements for ourselves to assess their ease of use and, in some cases, their efficacy.

Additionally, like all health-related content on this website, this review was thoroughly vetted by one or more members of our Medical Review Board for accuracy. We’ll continue to monitor the NAC landscape, especially as it relates to the substance’s FDA classification (more on that below).

Over the past two decades, Innerbody Research has helped tens of millions of readers make more informed decisions about staying healthy and living healthier lifestyles.

As we set out to evaluate the various NAC supplements out there, it was necessary that we keep these criteria front of mind at all times. They guided us to our top pick, and you would also be wise to consider them. They include:

• Safety
• Effectiveness
• Cost
• Convenience

Often, effectiveness is the most important of these criteria when we compare one option to another, but in the case of NAC, we found the significant safety concerns pressing enough to elevate safety to that most important position in our consideration. Efficacy is a close second, followed by cost and convenience in their impact on our appraisals.

Safety

Winner: Wholesome Story

In evaluating the safety of the top NAC supplements on the market, we had to look at them from two perspectives. The first scrutinized dosage. In light of recent findings connecting high but not uncommon doses of NAC to the growth and metastasis of certain cancers, we knew we wanted to select supplements that gave you the flexibility to take less than those more dangerous doses, even if that meant taking less than the company’s recommended serving size.3

To be clear, the studies that found cancer risks associated with higher doses of NAC didn’t last very long. Melanoma cells in mice proliferated and spread within just two weeks at a rate faster than the control group.9 That same study fed different groups of mice 50% and 25% of that high dose (which was roughly equivalent to 1.2g/daily). The groups taking lower doses did not see the same increase in cancer proliferation, but that’s not to say they wouldn’t have if the study had lasted a month or a year. So when we point you toward a supplement with a lower dose of NAC, it seems to be a way of reducing a known risk.

It’s also important to remember that the risk appears to be isolated to those who already have specific cancerous cells in the body. Clinical studies in healthy adults have not revealed an increased cancer risk, but NAC has been shown to exacerbate some existing cancers while fighting others.4 So, if you happen to know you’re cancer-free, you might be more confident in taking a larger NAC dose. But everything from unknown exposure to environmental toxins to a dormant HPV case can contribute to cancer risk and put you in a position to have minuscule amounts of cancerous cells proliferate at a greater rate than they otherwise would, thanks to the presence of NAC.

Among our top picks, Wholesome Story’s 600mg dose cuts that seemingly dangerous 1.2g dose in half. Life Extension also offers a 600mg dose, but its other ingredients list isn’t as clean.

According to the FDA’s conversion rates for dosages from mice to humans, that 1.2g human dose applies to 60kg (or 135lb) individuals.5 If you weigh 235lb., you might not share the same risk factor from a 1.2g daily dose. But data for your weight and potentially risky doses isn’t available, so you don’t know for sure that it’s safe.

The other perspective from which we evaluated safety in NAC products was manufacturing. We wanted to see evidence of third-party testing, minimal added ingredients, cGMP compliance, and other markers of safety and quality we expect from our top picks. And Wholesome Story checks all of these boxes.

Effectiveness

Winners: Wholesome Story and Thesis

What makes one NAC supplement more effective than another? At first glance, it might seem that NAC supplements are mostly created equal and that higher doses yield greater efficacy regardless of other factors. But since higher doses can also yield greater risks, we wanted to see a product that offered an effective dose for most uses without going overboard. Many studies have looked at NAC in doses typically ranging from 600mg-1,200mg. In cases of bronchitis and COPD, 600mg appeared sufficient to act as a mucolytic, clearing airways.1

So, at 600mg, Wholesome Story appears to be among the most effective options. And if you feel the need to approach the high end of what typical studies examine without regard for the risks, you can take a second 600mg pill and bring your dose up to 1.2g. We don’t recommend it, but a single bottle of Wholesome Story NAC contains 120 600mg capsules, so you’d still have two months’ worth of doses per order.

If you're looking for a more comprehensive supplement that includes an effective dose of NAC, Thesis Energy makes an interesting choice. The company offers a handful of targeted nootropics, and its Energy formula blends 500mg of NAC with choline, N-acetyl L-tyrosine, and a few other ingredients intended to give you a boost. The addition of caffeine is optional, as well.

Cost

Winner: PureBulk

The price tag on NAC supplements only tells part of the story. We understand that having the capital to invest in larger quantities to access overall savings isn’t in everyone’s budget. But there are certain opportunities among NAC supplements where bulk ordering — especially in powder form — makes a huge difference in cost per dose.

We’ve put a chart below to give you a sense of those savings opportunities. Prices include subscription savings where available, and we’ve left Thesis off the chart because its other active ingredients (1.4g of them) make calculating exclusively for the cost of its NAC unfair to its value. For the record, it still isn’t a better deal than PureBulk and some others unless you’re looking for that combined ingredient effect.

Convenience

Winner: Life Extension

While the experience of purchasing a supplement online and taking it daily is largely the same across the companies in our guide, there are little things that might make some more convenient than others. In evaluating convenience, we considered subscription discounts and flexibility, website navigation, return policy, and capsule size.

Life Extension offers a simple navigation experience with helpful chat support. It has, by far, the most generous money-back guarantee, protecting your purchase for a whole year. And its capsules are among the smallest we’ve come across, considering its 600mg dose of NAC. Even wholesome Story, which contains fewer other ingredients and has the same dose, delivers it in larger capsules.

NAC stands for N-acetyl cysteine. As a pro-drug for cysteine, it’s an effective way to introduce additional cysteine — a non-essential amino acid — to the body through its deacetylation process. A few decades of impressive research have led the medical community at large to regard it as a powerful source of antioxidant protection against reactive oxygen species (ROS). Other studies have illustrated NAC’s potential to revive exhausted T-cells in fights against certain cancers.6 It’s used in clinical practice as an antidote for acute acetaminophen poisoning and to break up thick mucus complicating bronchial disorders.

NAC has been so effective at treating sepsis, inflammation, acetaminophen poisoning, and mucus buildup that the FDA has approved it for certain uses. This is pretty unusual for the FDA, which typically does not scrutinize nutritional supplements beyond verifying a basic level of safety; it’s exceedingly rare for a supplement to be granted FDA approval for any use. In fact, there is some evidence that the FDA may reclassify NAC in the coming years as a drug and exclude it from the definition of a nutritional supplement, which would complicate its inclusion in nutritional supplements significantly.7

While some of NAC’s benefits are undeniable, more recent research has revealed how little we still understand its various mechanisms of action. For example, much of NAC’s antioxidant potential has been associated with a purported ability to increase glutathione (GSH) production, GSH being a powerful antioxidant in its own right. But there are animal studies that show NAC administration clearly provides antioxidant benefits while not having an effect on GSH levels in rats.18 To make matters worse, several studies have explicitly linked commonly used doses of NAC with the growth and metastasis of different cancers, including lung cancer and melanoma.9

For the most part, studies into NAC’s potential benefits have shown it to be perfectly safe. These looked at NAC’s effect on everything from immunity to cognition. These studies came back often touting NAC’s safety, describing only rare and mild side effects typical of nutritional supplements, like:8

• Nausea
• Vomiting
• Headache
• GI distress

But these studies didn’t take a targeted look at NAC’s relationship to cancer, a relationship that is undeniably complicated. As NAC studies turned to its potential as a tool in the treatment of certain cancers, initial results were positive. But later studies saw NAC causing increases in the size and spread of some cancers.

Unfortunately, the more we learn about NAC and some similar supplements, the more we see that two seemingly opposing ideas about a supplement can be true at the same time. One ingredient can simultaneously protect against and contribute to cancer.

In NAC’s case, we don’t fully understand how it does either, but its antioxidant potential may be at the heart of the issue. A typical view of reactive oxygen species through the years has been that they’re bad things that directly cause oxidative damage to important cells. But that point of view regards ROS as a monolith and not the variegated assortment of species they are. It’s true that many ROS are associated with damage to healthy, critical cells. But ROS can also be responsible for damage to cancerous cells. If NAC is somehow reducing ROS activity in the body, an unintentional side effect may be the proliferation of cancer cells.

The most damning of these studies looked into NAC’s relationship to melanoma.9 It found that a 240mg/kg dose of NAC in mice that already had melanoma caused a significant increase in tumor size compared to the control group in just two weeks. That’s roughly the equivalent of a 20mg/kg dose in a 135lb person — a total daily dose of 1,200mg. Daily doses of average NAC supplements range from 600mg-1,200mg, well within potentially dangerous territory.

At this point in our understanding, we haven’t seen NAC cause cancer where it wasn’t already present; we’ve only seen it exacerbate some cancers while appearing to improve the cases of others. If you have no reason to believe you have any cancer in your body or much potential to develop it (e.g., you have no history of cancer in your immediate family), there’s a good chance NAC will be safe for you. But we can’t say that definitively. And if you have a history of cancer in your family or in your own medical record, NAC may be too dangerous a proposition to recommend until we have more evidence to support one path or another.

We’ve tempered our recommendations based on this evidence, and we’ll make specific notes when discussing each product to detail how it might relate to these findings. Talk to your doctor about your health history before starting NAC.

This section might have been called “How NAC supplements work,” but the fact is that the scientific community hasn't quite figured that out yet. There are several theories, including an increase in GSH production or a hydropersulfide byproduct of NAC’s deacetylation to L-cysteine.19 But these only answer some of the questions that arise when we see the ultimate effects of NAC supplementation. And those effects have led to various applications.

Best overall

Wholesome Story is a relatively young company started by a married couple just after the birth of their first child in 2016. Its selection of supplements focuses on potential polycystic ovarian syndrome (PCOS) treatments. Still, many of its supplements — like NAC — offer additional benefits to users. Here’s a quick list of its current offerings:

• NAC
• Myo- and D-chiro-inositol (capsules and powder)
• Myo- and D-chiro-inositol with folate and D3
• Vitex
• Saw palmetto
• Berberine
• Zinc, magnesium, and B6
• DIM (diindolylmethane)
• Spearmint
• IP-6 & inositol

Since most of these supplements benefit men and women alike, you certainly don’t have to have PCOS to use them.

If you are concerned about PCOS, there is no definitive test for the syndrome, only a process of elimination under the guidance of medical professionals. But the syndrome has profound hormonal effects, and symptoms generally include:17

• Irregular or abnormal periods
• Excessive weight gain
• Hair loss or unwanted hair
• Acne
• Depression

Given the sensitivity of its target demographic, Wholesome Story takes pains to ensure the quality of its products. It subjects each supplement to rigorous third-party testing and is one of the few NAC producers to earn a certification from the Clean Label Project. It achieves this partly because it has nothing in its NAC supplement other than free-form NAC housed in a capsule made only of methylcellulose.

With its 600mg dose, Wholesome Story NAC lands in a relatively sweet spot between safety and efficacy. Many of the studies we’ve come across find success at around 600mg, which is half of what was shown to increase the proliferation of cancer cells in one melanoma study on mice.

One bottle of Wholesome Story NAC contains 120 600mg capsules — a 4-month supply — and costs $25.95. You can save 10% by subscribing, which brings your cost down to $23.36 per bottle. Subscriptions can be delivered every 30, 60, 90, or 120 days.

Shipping from Wholesome Story is free on orders over $40, so you’ll need to add another supplement or buy larger quantities to qualify. These costs land Wholesome Story NAC right in the middle of the pack on a cost-per-gram basis. But you also get 90 days to see if the product is right for you, thanks to the company’s straightforward money-back guarantee. Life Extension is the only company in this guide with a longer guarantee. Many companies in the supplement space will sneak different limitations into a warranty like this, covering you for 90 days but maybe only for one bottle or with some other catch. Thankfully, Wholesome Story doesn’t do this, offering 90 days on up to three bottles of its products.

Best budget pick and best money-back guarantee

Life Extension offers a wide array of supplements that cover everything from hormonal health to inflammation management. It’s consistently one of the least expensive options across many market categories, particularly when you utilize its subscription model.

Life Extension NAC is a relatively straightforward version of the supplement, though it contains a couple of extra ingredients to extend its shelf life. For some, these are wholly innocuous, but other people might look to competitors to find an even cleaner product. That said, Life Extension offers certificates of analysis for every one of its products, so you can see that its supplements meet quality and purity guidelines. It also offers measurements for the capsule size, so you can get a sense of whether they’ll be hard to swallow. Having handled these supplements ourselves, we can confidently say that Life Extension's capsules are the smallest offering at 600mg.

Like Wholesome Story, Life Extension utilizes that 600mg dose that should offer most users a reasonable level of safety and efficacy, though data on long-term use at that dose is incomplete, particularly among certain cancer patients.

One bottle of Life Extension NAC contains 60 capsules, which can last up to two months, depending on your preferred dosage. Here’s how the pricing works out:

This is the lowest price for NAC among our top picks, even without the savings from an automatic shipment. Life Extension also has the most variety in its shipping schedule, with deliveries available every 1, 2, 3, 4, 6, 9, or 12 months.

Life Extension offers one of the most extended guarantees of any NAC manufacturer, covering your purchase for an entire year.

Best high-end

Root is a somewhat unusual company in this space. While many supplement manufacturers stick to selling physical products, Root is continuously expanding to deliver targeted medical care and professional advice in a small number of states. It offers meal plans shipped right to your door and consultations with dieticians and other professionals who can help you attain health and wellness goals.

You can purchase any of its supplements independently without being a member or signing up for any special classes. And its supplements can ship anywhere in the US regardless of telemedicine regulations. Its target demographic appears to be women, but nothing stops anyone from making good use of its products.

Root’s NAC supplement is simple. It contains NAC in a 900mg dose and is housed in a vegetable cellulose capsule with stearates for stabilization. Root’s recommended dosage is 1-2 capsules per day. Based on the research we’ve reviewed, 900mg is plenty strong for most people and may even be too strong for anyone under 140lbs., as it’s 50% higher than a commonly successful 600mg dose like you see from Life Extension and Wholesome Story. And we believe twice that dose to be unwise in light of the research we’ve seen, especially for people with a personal or family history of cancer.

One 120-capsule bottle of Root NAC costs $42 and lasts up to four months, but you can save 10% and pay $37.80 when you subscribe. This makes Root our most expensive recommendation among NAC-only supplements, but for those who want a clean formula — and especially those who want to take advantage of Root’s other services — it’s likely to be an effective choice.

Membership with Root provides you with one-on-one sessions with dietitians and doctors, lab testing, a personalized wellness plan, and 20% off supplements. It’s not cheap, though. Month-to-month membership costs $250/month, and an annual membership costs $2,700. Both monthly and annual plans come with a $995 signup fee. Considering the fact that testing companies like Everlywell, myLAB Box, and LetsGetChecked offer similar screenings on an a la carte basis, many of which come with doctor consultations, we’d recommend starting there for lab testing.

Shipping from Root is free on all orders $75 and up, with an $8 flat rate for orders under that. In-stock orders received by noon EST will ship the same day. One frustrating aspect of Root’s subscription system is that it only gives you the option for a new shipment every 90 days, while its bottles contain 120 days’ worth of NAC at the 900mg dose. That means you’ll build up a backlog of NAC every time you receive a new shipment unless you choose to double your dose — which we strongly advise against. Other companies in this space offer more flexible shipping schedules, with the most flexibility coming from Life Extension.

Best powder

Several companies offer supplements in bulk powder form, but few have quantities as large as what Pure Bulk offers. We also appreciate that the company subjects its supplements to third-party testing and offers customers certificates of analysis to show purity and potency.

A big advantage of purchasing NAC in powder form is that no other ingredients are involved. Capsules usually contain cellulose or gelatin, and many include stabilizers like silicon dioxide. With a pure powder, NAC is all you get. And powdered supplements have the potential to absorb more quickly, as they can start making their way into the bloodstream as soon as they hit your mouth.

Powders carry a higher risk of overdosing, though more on a chronic use basis than acutely. And since PureBulk doesn’t provide you with a scoop to measure your NAC, getting the right dosage is a bit harder than with a capsule. You’ll want to use a scale until you’re confident you have a viable measure spoon or can eyeball a safe amount.

You can also purchase NAC from Pure Bulk in capsule form, but between the price and the presence of bovine gelatine, you’d be better off looking elsewhere for capsules.

Pure Bulk sells its NAC powder in the following sizes:

Note: It may look as though the 1g and 1.5kg amounts cost the same per dose, but this is a reality of rounding. The 1g dose’s price was rounded down to $0.07, whereas the 1.5kg dose’s price was rounded up.

You’ll have to get the 500g bag or larger to meet the $50 free shipping threshold. Other sizes will have their shipping fees calculated based on your location. For some, this will be better than the flat fee many companies charge. Compared to Root’s $8 flat fee, the shipping cost for PureBulk NAC to the NY metro area was just over $4.

Best nootropic with NAC

Thesis is one of our favorite nootropic companies. (You can read more about it in our nootropics guide). It offers well-designed blends intended to address specific cognitive or behavioral goals. When you sign up for its program, you’ll get one box shipped to you each month containing four smaller boxes of different nootropic formulas. There are six formulas to choose from, including:

• Energy
• Clarity
• Confidence
• Logic
• Creativity
• Motivation

Your first box will default to a collection of four of those formulas determined by the answers to an intake questionnaire. You can intercept this shipment and make adjustments to your box as you like, and if you want something with NAC in it, you’ll want to make sure there’s at least one box of Energy in there. None of the other Thesis blends contain NAC. That said, they each offer specific benefits to users for different situations. So, you could get a box half-full of Energy (12 portably packaged doses), with six doses of Creativity for more artistic moments and six doses of Motivation for days where you don’t want to get out of bed. You’ll mix and match as you see fit and figure out what works for you, and Thesis’ nootropics experts are available by phone to help guide you to the best combination for your needs.

The NAC dose in each serving of Energy is 500mg. That’s a little below the most commonly effective doses, but with the other ingredients included in the supplement, that might not be a problem. If anything, slightly underdosing the NAC might make this a safer choice than much higher-dose NAC supplements, as long as Energy’s other ingredients are safe for your specific health profile.

Here’s a look at Energy’s full ingredients list:

• Zynamite (a patented mango leaf extract): 300mg
• TeaCrine (similar to caffeine): 100mg
• Sabroxy (Indian trumpet tree bark extract): 100mg
• CDP Citicoline: 200mg
• N-Acetyl L-tyrosine: 300mg
• N-Acetyl cysteine: 500mg
• Caffeine: 100mg
• L-Theanine: 200mg

One interesting thing about Thesis’ nootropic offering is that it lets you choose whether or not to include caffeine in your blends. It turns out that the caffeine in any blend is secluded in its own capsule within each pack, so you can have it shipped to you with caffeine and choose whether to take that capsule with any given dose. The cost with and without caffeine is the same, so we recommend getting it with the added stimulant capsule in case you find that you prefer it.

You can buy a Thesis box as a one-time purchase, but that will cost you $120. When you subscribe, the cost of each box comes down to $79. That’s still expensive, but it’s a savings of $40 compared to the one-off purchase, and canceling is easy on the website’s account portal. Thesis gives our readers 10% off your first order by using code INNERBODY at checkout. Shipping is also free with any order, whether a subscription or one-time purchase. No matter which way you buy, Thesis offers a 30-day money-back guarantee, which is fair, though it’s not as generous as the guarantees Wholesome Story and Life Extension offer.