Glucosamine: what is it & what does it do?

Glucosamine sulfate, or glucosamine for short, is a chemical that naturally exists in our bodies. Put simply, it’s the fluid and the tissue that’s found around, and provides some cushioning, for our joints.¹

As we get older, we produce less glucosamine, which can cause certain age-related health conditions to develop (more on these below).²

Glucosamine is also a widely used supplement, but the type of glucosamine that’s present in supplements isn’t always the natural form of it, but a synthetic version that’s made in labs.

You can get glucosamine sulfate, which we’ve just mentioned, as well as glucosamine hydrochloride, and N-acetyl glucosamine. While all of these different versions may offer similar qualities, they don’t deliver the same results when used for supplements.

As for glucosamine supplements, they don’t tend to contain just glucosamine. They’re often combined with other ingredients, such as chondroitin sulfate, methylsulfonylmethane (MSM), and even, shark cartilage.

Some people believe these combination supplements are more effective than just taking a supplement that contains nothing but glucosamine sulfate. However, at the time of writing this article, there was no evidence to suggest a combination formula was any more effective than just taking glucosamine on its own…³

How does glucosamine work?

It’s naturally used by the body to create numerous different chemicals that are responsible for building tendons, ligaments and cartilage, as well as the thick fluid around our joints.⁴

This fluid acts as a cushion. But this isn’t always the case, not for people who have osteoarthritis. This is because their fluid and cartilage breaks down and becomes thinner. This causes friction all around the joints, as well as pain and stiffness.

It’s believed glucosamine supplements have the ability to increase the cartilage and fluid that surrounds the joints or help prevent breakdown of these substances, or potentially, a combination of the two.

Meanwhile, according to some research, the sulfate element of glucosamine is considered to have more of a key role, as it’s integral to the formation of cartilage. As a result, some researchers believe glucosamine sulfate may be more effective than other forms, such as glucosamine hydrochloride or N-acetyl glucosamine, that don’t contain the sulfate element.

For more insight on osteoarthritis read, ‘What is osteoarthritis?’

What foods are high in glucosamine?

Food sources of glucosamine are few and far between. The only natural food sources are shellfish shells from shrimp, lobster and crabs.⁵

It’s these shells that are harvested and used to make the synthetic version of glucosamine that goes into the supplements that are made in labs.

What are the benefits of taking glucosamine?

Glucosamine is often taken to help ease and prevent joint-related issues, the main one being osteoarthritis. You can take it orally as glucosamine tablets/supplements or you can apply it topically as a cream or as a glucosamine gel.               

Glucosamine benefits

1. It may reduce inflammation

It’s not 100% clear how glucosamine eases inflammation, especially as most of the research carried out so far has involved using glucosamine chondroitin, which is similar to glucosamine. Like glucosamine, chondroitin is linked to the production of healthy cartilage within the body.⁶

2. It boosts healthy joints

One of glucosamine’s main ‘jobs’ is to support the development of the tissues that are present between our joints. And it does this by helping create several chemicals that are involved in the production of articular cartilage and synovial fluid.⁷

Some research has also found glucosamine supplemental glucosamine may protect joint tissue by preventing cartilage from breaking down and becoming thinner.

3. It may treat bone and joint disorders

Glucosamine is widely used to treat bone and joint conditions, such as osteoarthritis, rheumatoid arthritis and osteoporosis. However, more research to understand why and how it works is still required.⁸

How much glucosamine should I take?

The Arthritis Foundation’s recommended guidance for taking glucosamine is 1,500 milligrams a day, and this can be in capsule, tablet, liquid or powder/drink form.⁹

This guidance is the same as the typical dosage guidelines that are out there, which also say you can take the 1,500mg in one go or break it down into multiple doses that are taken throughout the day.

If used topically, then creams containing 30 mg/gram of glucosamine sulfate, 50 mg/gram of chondroitin sulfate, 140 mg/gram of chondroitin sulfate, 32 mg/gram of camphor, and 9 mg/gram of peppermint oil can be applied to skin for up to eight weeks at a time.¹⁰

Glucosamine can also be injected into your muscles too, with the typical dose being 400mg, twice a week for six weeks.

The vast majority of glucosamine supplements are available as:

1. Glucosamine sulfate 
2. Glucosamine hydrochloride 
3. Glucosamine with chondroitin sulfate (this combination tends to be more rare)

According to all of the research carried out to date, glucosamine sulfate or glucosamine and chondroitin produce the best results.

What are the side effects of taking glucosamine?

On the whole, glucosamine supplements can be taken without people experiencing any adverse side effects. However, it is still possible for some people to experience^11,12:

• Nausea and vomiting
• Heartburn
• Abdominal pain
• Diarrhoea
• Constipation

More uncommon side effects include: skin reactions, headaches and drowsiness.

You should avoid taking glucosamine supplements if you¹³:

1. Are pregnant or breastfeeding

There isn't currently enough evidence to show the impact of glucosamine on pregnant or breastfeeding women. Check with your GP before taking glucosamine supplements.

2. Have asthma

One piece of research has linked an asthma attack with taking glucosamine however, more research is required to understand glucosamine’s effects on asthma. In the meantime, the safest option is to avoid taking it if you have asthma.

3. Diabetes

Some initial studies have found that glucosamine sulfate may potentially increase blood sugar in people with diabetes. However, more research is required to evidence this, especially as it’s believed to not impact people with Type 2 diabetes.

4. Glaucoma

Glucosamine sulfate may possibly increase pressure inside the eye and potentially make glaucoma worse. If you have glaucoma, talk to your GP before taking glucosamine.

5. High cholesterol

Research on animals has revealed that glucosamine may increase cholesterol levels. However, this is not the case for humans, but research has found that it may increase insulin levels, which may cause cholesterol levels to rise.

6. Are allergic to shellfish

It’s believed that glucosamine supplements may trigger an allergic reaction in people who are sensitive to shellfish, despite the fact reactions in people with a shellfish allergy are caused by the meat of shellfish, not the shell.

However, some people have developed an allergic reaction after using glucosamine supplements. This could be due to the fact that the shells used to create the supplements may have become contaminated with shellfish meat.

7. Are having surgery

Glucosamine sulfate may affect blood sugar levels and interfere with blood sugar control during and after surgery. It’s therefore recommended that people should stop taking glucosamine sulfate at least two weeks before they are due to have surgery.

Interactions

Glucosamine supplements should not be taken with the blood-thinning drug, Coumadin, as it may increase its effects and cause bruising and serious bleeding as a result of this.

There is some evidence to suggest glucosamine may interfere with certain cancer drugs, known as topoisomerase II inhibitors. They include Adriamycin (doxorubicin), VePesid (etoposide), VM26 (teniposide), mitoxantrone, and daunorubicin. It’s believed glucosamine may prevent these medications from being fully effective.

As you now know now from reading this article, glucosamine is often used to help with joint care. For practical guidance on joint care read, ‘4 top tips to help stiff joints'.

Last updated: 19 April 2021