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What Are the Effects of Taking Glucosamine on Your Body?

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Woman holding her knee

Story at-a-glance -

  • For knee pain and discomfort, glucosamine supplements are usually prescribed by conventional physicians
  • Learn about the basics of glucosamine, its uses and what you should consider before taking this supplement

According to the Nutrition Business Journal, Americans spent around $753 million dollars in 2012 on glucosamine and chondroitin supplements, in an attempt to address pain and stiffness caused by arthritis and other related diseases.

But are glucosamine supplements, such as glucosamine chondroitin and/or glucosamine-MSM, as beneficial and effective as they are perceived to be?1 Learn about the basics of glucosamine, its uses and what you should consider before taking supplements with this substance.

What Is Glucosamine?

Glucosamine is a compound naturally made in the human body by chondrocytes,2 but can also be found in animal bones, bone marrow, shellfish and fungi.3 Glucosamine is usually recommended to be taken alongside chondroitin, another substance that comes from cartilage.4

Glucosamine and chondroitin supplements, capsules or tablets are common, although other varieties like glucosamine sulfate, glucosamine hydrochloride5 and N-acetyl-glucosamine are available too. Glucosamine is sometimes combined with chondroitin sulfate, MSM, manganese,6 cod liver or shark cartilage in some supplements.7

Other alternatives include glucosamine gel, glucosamine injections (directly inserted into a joint) and powder that's added to water or liquid. Meanwhile, N-acetyl glucosamine is available as an enema.8,9

Sources of Glucosamine

Glucosamine is found in low concentrations in meat, with most amounts found in the skin.10 Homemade bone broth is an outstanding food source of glucosamine, minerals, silicon, chondroitin sulfate and components of collagen and cartilage. Apart from these two examples, there are no major food sources of glucosamine.

Most glucosamine supplements are made from chitin or the hard outer shells of shrimp, lobsters and crabs. However, given that shellfish are common allergens, I recommend avoiding glucosamine supplements if you have a shellfish allergy.11

What Is Glucosamine Used For?

Glucosamine is believed to help with maintenance of the cartilage,  the rubbery tissue cushioning bones at the joints,12 and can assist in joint lubrication, water retention in the cartilage and prevention of cartilage breakdown. Your joint cartilage requires glucosamine because it assists with producing glycosaminoglycans, a major component of the cartilage. Glucosamine also plays a major role in properly incorporating sulfur into the cartilage and helps with both creation and repair.13

For this reason, some people have utilized glucosamine supplements to address rheumatoid arthritis, asthma, allergies, chronic venous insufficiency, sports injuries, temporomandibular joint problems (TMJ) and long-term low back pain. You have to take these purported health benefits of glucosamine and/or chondroitin supplements with a grain of salt, though, as there's not a lot of evidence suggesting glucosamine supplements may be effective for these conditions.14

Furthermore, it's said that only a small amount of the glucosamine you take can actually be used by the body. Research showed that roughly 15 to 20 percent of glucosamine is absorbed from pills and capsules. Glucosamine and chondroitin supplements also tend to be very large and hard-to-swallow, and dosages would often require people to take these multiple times a day. These factors can ultimately lead to non-compliance.

Some of the proposed benefits of glucosamine and chondroitin supplements can also take a while to build up, prompting some patients to give up taking the supplements before seeing if the effects can take place.

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Studies on Glucosamine Supplements Are Inconclusive

Most studies into the health benefits of glucosamine have focused on glucosamine sulfate.15 Such was the case for the three-phased Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT) Study, which tested whether glucosamine hydrochloride (glucosamine and sodium chondroitin) and sulfates (chondroitin sulfate) that are used separately or in combination, celecoxib or Celebrex (a non-steroidal anti-inflammatory drug), and a placebo reduced pain among study participants with knee OA.16,17

Results of the first phase showed that the combination of glucosamine and chondroitin sulfate delivered "significant relief" to a smaller subgroup of study participants who experienced moderate-to-severe knee pain, although there was no effect among patients with mild pain.

In the second phase, the researchers studied if the supplements can prevent joint damage in the knee. It turned out that the glucosamine and chondroitin combination was no more effective in preventing OA-caused joint damage than a placebo.

Differences between groups weren't statistically significant, although participants who lost the least amount of joint space over two years belonged to groups taking either glucosamine alone or chondroitin alone. There's a possibility that taking these supplements combined can limit their absorption into the body, paving the way for a reduced effect of the supplement combination.

In the third phase that spanned four years, glucosamine or chondroitin supplements, whether taken in combination or alone, had no greater benefit for pain relief than celecoxib or a placebo. Results weren't statistically significant, but it showed that celecoxib had the highest odds of delivering at least 20 percent reduction in pain.

Take Note of These Side Effects of Glucosamine

Glucosamine can have potential negative side effects, which often occur if taken in high doses:18,19

  • Upset stomach or indigestion
  • Drowsiness
  • Gas
  • Nausea
  • Worsened asthma

Meanwhile, side effects of the combination of glucosamine and chondroitin include:20

  • Nausea
  • Constipation
  • Bloating
  • Puffy eyelids
  • Hair loss
  • Diarrhea
  • Allergic reactions (hives, breathing difficulties or swelling of the face, lips, tongue or throat)
  • Stomach pain and gas (most probably because chondroitin molecules are large and can be difficult to digest)

Glucosamine and chondroitin supplements may also have severe side effects such as irregular heartbeats or swelling in the legs. Those who are taking these supplements and experience these side effects should contact their physician immediately.21

Glucosamine sulfate, another type of glucosamine supplement, may contain high amounts of sodium or potassium. These amounts may not be suitable for people on a restricted diet or are taking potassium-sparing diuretics. Glucosamine, when taken in a potassium salt form, may also result in an unnecessary salt burden.

Meanwhile, diabetics should avoid taking a glucosamine supplement, because of its tendency to cause insulin to work less effectively. Glucosamine can also increase blood pressure and cholesterol levels. See to it that your blood pressure and cholesterol levels are regularly checked. Glucosamine supplements can interact with the following medicines as well:

Warfarin (Coumadin) — Glucosamine can increase Warfarin's blood-thinning effect and possibly lead to a higher risk of bruising or bleeding.

Non-steroidal anti-inflammatory drugs (NSAIDs)Taking it with NSAIDs can predispose you to health risks such as stomach bleeding.

Blood-sugar lowering medications and insulin — Glucosamine can alter the dose needed for blood-sugar lowering medications and insulin.

Cancer medications such as Doxorubicin, Etoposide and Teniposide — Glucosamine may negatively interact with these drugs and increase cell growth, which is the opposite of what these medications are supposed to do.

Natural Methods to Help Relieve Knee Pain

Instead of taking supplements like glucosamine and chondroitin to alleviate knee pain, I advise you to consider these natural remedies, which are safe and effective:22

Acupuncture — An analysis of the most robust studies available revealed that acupuncture can deliver a clear effect in reducing chronic pain compared to standard pain treatment.23

Massage therapy — A systematic review and meta-analysis published in the journal Pain Medicine concluded that massage therapy helps relieve pain better than getting no form of treatment at all.24

Relaxation techniques — Research has revealed that people who practice long-term relaxation methods tend to have more disease-fighting genes that are "switched on."25

Exercise — Motor control exercises (MCE) that help improve coordination of muscles supporting the spine have been shown to help reduce pain and disability, and improve perceived quality of life of patients, compared with minimal intervention.26,27

Medical marijuana — Some of the strongest research conducted on medical marijuana focused on its potential effects for pain relief. In one study, three puffs of marijuana daily for five days allowed people with chronic pain to experience pain relief and better sleep.28

The turmeric herb also contains anti-inflammatory properties that can help relieve knee or joint pain. These essential oils are known to possess pain-relieving abilities as well:29,30

  • Lavender31
  • Orange
  • Frankincense
  • Turmeric
  • Green apple
  • Peppermint
  • Ginger
  • Myrrh
  • Jasmine
  • Vanilla

If you want to know about other therapeutic remedies for knee pain, check out this article.

A Final Word on Glucosamine Supplements

Joint pain can be very intense and may negatively impact your lifestyle, making it an issue you should try to address quickly. But despite glucosamine's potential ability to help address joint problems, I advise you to consider taking other natural remedies that can assist with relieving joint pain instead.

Studies on glucosamine do not confirm its effectiveness, and the many health risks and complications linked to glucosamine may be devastating in the long run, especially when taken in large doses.

Frequently Asked Questions (FAQs) About Glucosamine

Q: What is glucosamine chondroitin?

A: Glucosamine chondroitin is a combination of supplements that is usually prescribed for people with joint-related problems.32 Glucosamine is naturally made in the human body, and is important in creating molecules for cartilage formation. Meanwhile, chondroitin is another substance that comes from the cartilage that is typically taken alongside glucosamine.33,34

Q: What is glucosamine good for?

A: Glucosamine supplements are prescribed by doctors because it's said to help promote good cartilage health, assist with joint lubrication and water retention and help prevent cartilage breakdown.35,36

It was also highlighted in the GAIT study that taking glucosamine and chondroitin supplements may work in helping provide relief to people who experienced moderate-to-severe knee pain and in possibly preventing osteoarthritis-caused joint damage.

However, be aware that not all glucosamine supplements are effective, and some may deliver adverse side effects.

Q: Is glucosamine safe?

A: Certain groups of people, such as diabetics or those taking medications, should take caution with glucosamine supplements. Side effects have also been noted with these supplements, such as drowsiness, gas, diarrhea, bloating, headaches and nausea, especially when taken in high doses.37,38

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