What Is N-Acetylglucosamine?

A dietary form of glucosamine that may increase joint lubrication

N-Acetylglucosamine capsules, tablets, and powder

Verywell / Anastasia Tretiak

N-acetylglucosamine (also known as N-acetyl glucosamine) is a simple sugar derived from the outer shell of crustaceans. Chemically similar to glucosamine, a natural substance found in cartilage, N-acetylglucosamine is thought to alleviate joint stiffness and pain, protect the lining of the stomach and intestines, and reduce dark spots on the skin caused by sun exposure and aging.

Available in capsule, tablet, powder, cream, and serum formulations, N-acetylglucosamine is one of three supplemental forms of glucosamine alongside glucosamine sulfate and glucosamine hydrochloride. Despite their similarities, these are not considered interchangeable.

What Is N-Acetylglucosamine Used For?

Glucosamine has long been embraced by consumers as an over-the-counter remedy for osteoarthritis (also known as "wear-and-tear" arthritis). It can be taken alone or used in tandem with chondroitin to restore joint cartilage and reduce joint pain.

Of the three forms of glucosamine on market shelves, N-acetylglucosamine is believed to stimulate the production of hyaluronic acid (a lubricating joint fluid) more effectively than the other two.

N-acetylglucosamine is also believed to benefit other organ systems, preventing or treating such diseases as stroke, inflammatory bowel disease (IBD), multiple sclerosis (MS), and heart disease. In addition, N-acetylglucosamine is purported to have a lightening effect when applied to the skin.

Some of these health claims are better supported by research than others. Here is just some of what the current research says.

Osteoarthritis

Unlike many dietary supplements that lack clinical evaluation, glucosamine's effect on osteoarthritis has been studied extensively by researchers.

One of the largest research efforts, called the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), involved nearly 1,600 people with painful knee osteoarthritis.

After 24 months of daily supplementation, glucosamine was reported to decrease knee pain in people with moderate-to-severe osteoarthritis by 65.7%—more or less the same as a daily dose of Celebrex (celecoxib). By contrast, glucosamine offered no benefit to people with mild knee osteoarthritis.

The effects of glucosamine appeared to increase when combined with chondroitin. In total, 79% of those who received both supplements reported a significant reduction in pain compared to 54% of the control group who received just a placebo.

Although glucosamine performed better than a placebo overall, neither it nor chondroitin (nor the combination of the two) achieved the target 20% reduction in joint pain or 20% improvement in joint function as measured by the Western Ontario and McMaster University Osteoarthritis Index (WOMAC).

Despite nominal benefits in some people, the GAIT researchers concluded that neither glucosamine nor chondroitin achieved a significant reduction in pain or improvement of joint function compared to a placebo.

With respect to N-acetylglucosamine specifically, the supplement has both its benefits and drawbacks. While N-acetylglucosamine stimulates the production of hyaluronic acid, it is poorly absorbed by cartilage cells when compared to glucosamine sulfate (meaning that it has less impact in rebuilding cartilage).

In order to achieve comparable permeability, inordinately high doses of N-acetylglucosamine would be needed. As such, N-acetylglucosamine may be more effective in improving joint function than preventing cartilage loss.

Inflammatory Bowel Disease

N-acetylglucosamine may help reduce the severity and recurrence of IBD, suggests a 2018 study published in the journal PNAS.

For this study, intestinal tissues taken from people with ulcerative colitis (a typically more serious form of IBD) were exposed to N-acetylglucosamine in the test tube. Doing so inhibited T-cell receptors, molecules on the surface of intestinal cells that instigate inflammation.

This suggests that N-acetylglucosamine may aid in the treatment of IBD by tempering the often-unrelenting inflammation that characterizes the disease. Further research is needed.

Multiple Sclerosis

As an autoimmune disease, MS is characterized by the progressive destruction of the outer membrane of nerve cells (myelin sheath). It has been proposed that, by reducing persistent autoimmune inflammation, many of the characteristic symptoms of MS can be delayed.

A 2011 study in the Journal of Biological Chemistry suggested that N-acetylglucosamine can do just that. Mice with chemically-induced MS were treated with oral N-acetylglucosamine. Compared to untreated mice, those provided the supplements had fewer clinical signs of myelin destruction—an indication of suppression of the excessive immune response associated with MS.

The effect was attributed in part to the inhibition of T-cell receptors. Additional research on humans is needed.

Skin Lightening

N-acetylglucosamine has long been touted for its skin-lightening properties by many cosmetic and skincare manufacturers.

According to a 2007 study in the Journal of Cosmetic Dermatology, adults with facial hyperpigmentation were treated with an ointment comprised of 2% N-acetylglucosamine and 4% nicotinamide on one side of the face and a placebo ointment on the other side. After eight weeks, the side treated with the combination was visibly lighter among all participants.

A 2010 study in the British Journal of Dermatology further reported that the same blend of N-acetylglucosamine and nicotinamide exerted a protective benefit against sun damage comparable to a SPF 15 sunscreen.

Despite the positive findings, it is unclear what effect N-acetylglucosamine had compared to nicotinamide. It is also unclear if the cream is able to reduce dark spots (such as solar keratosis) or if it just generally lightens skin.

Possible Side Effects

Although little is known about the long-term safety of N-acetylglucosamine supplements, they are generally regarded as safe (GRAS) by the U.S. Food and Drug Administration (FDA). Side effects tend to be mild and may include:

  • Bloating
  • Constipation
  • Diarrhea
  • Flatulence
  • Heartburn
  • Indigestion
  • Nausea
  • Stomach upset

People allergic to shellfish may also experience an allergic reaction to N-acetylglucosamine, causing itching, sneezing, rash, diarrhea, or shortness of breath. People with a history of anaphylaxis to shellfish should avoid N-acetylglucosamine without exception.

N-acetylglucosamine may also aggravate symptoms of asthma in some people. With that said, the risk is considered low and is mainly evidenced by a solitary case report published in 2002.

As a simple sugar, N-acetylglucosamine may affect blood glucose levels but generally not enough to require intervention. However, you should stop taking N-acetylglucosamine at least two weeks before a scheduled surgery to reduce the risk of high blood sugar and blood clots.

The safety of N-acetylglucosamine during pregnancy is unknown. To be safe, avoid using N-acetylglucosamine while pregnant or breastfeeding.

Interactions

N-acetylglucosamine may slow blood clotting and enhance the effects of anticoagulants (blood thinners) like Coumadin (warfarin) and Plavix (clopidogrel). Taking N-acetylglucosamine with either of these drugs can increase the risk of easy bleeding and bruising.

This is another reason why you should stop taking N-acetylglucosamine two weeks before scheduled surgery.

N-Acetylglucosamine tablets
Verywell / Anastasia Tretiak

Dosage and Preparation

Widely available for purchase online, N-acetylglucosamine supplements are also sold in many natural-foods stores, drugstores, and shops specializing in dietary supplements.

There are no guidelines for the appropriate use of N-acetylglucosamine supplements. Dosages of up to 1,000 milligrams (mg) per day have been used safely in adults for 16 weeks. Similarly, a 2% N-acetylglucosamine ointment has been applied safely to the skin for up to 10 weeks.

Some manufacturers endorse dosages of up to 1,500 mg daily, taken in either a single or split dose. However, there is no clear evidence that higher doses confer to better results in all people. As a rule of thumb, start with the lowest possible dose and increase gradually as tolerated. Never exceed the recommended dose on the product label.

Tablet and capsule formulations are the easiest to use because the dose they provide is consistent. By contrast, N-acetylglucosamine powder (which can be mixed into coffee or tea as a sweetener) requires precise measurement with a proper measuring spoon.

Never switch from one form of glucosamine to another thinking that they are the same. Each has distinctive mechanisms of action and specific dosing instructions.

What to Look For

Unlike prescription drugs, dietary supplements are not strictly regulated in the United States.

To ensure quality and safety, only buy brands that have been voluntarily submitted for testing by an independent certifying body like the U.S. Pharmacopeia (USP), ConsumerLab, or NSF International.

Common Questions

Is N-acetylglucosamine the best form of glucosamine?
Each form has pros and cons worth considering. For example:

  • Glucosamine sulfate has high permeability in cartilage but no tangible effect on hyaluronic acid levels, while the opposite is true for N-acetylglucosamine.
  • You need to take almost twice as much glucosamine chloride to achieve the same blood concentration as glucosamine hydrochloride.
  • The concentration of glucosamine in cartilage and joint fluid is far greater with glucosamine chloride than glucosamine hydrochloride and persists for hours longer.

However, when evaluating which form of glucosamine is "best," most health experts consider glucosamine sulfate superior because it contains sulfate—a mineral that the body needs to produce cartilage. The other two do not.

According to a 2016 review of studies in Seminars in Arthritis and Rheumatism, glucosamine sulfate demonstrated clear superiority over N-acetylglucosamine and glucosamine hydrochloride based on the reduced need for painkillers and nonsteroidal anti-inflammatory drugs (NSAIDs) as well as a reduced incidence of total knee replacement surgery.

How should I store N-acetylglucosamine?
N-acetylglucosamine can be safely stored at room temperature. Avoid excessive heat or moisture exposure, and never use a supplement past its expiration date.

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11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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