Evidence: Very High Possible Benefits: Reasonable Safety: High
TABLE OF CONTENTS
What is glucosamine?
Glucosamine is a supplement derived from shellfish or synthesized in the lab commonly used for its pain-reducing effects and for improving knee joint health. This article is about the main benefits of glucosamine, its potential side effects, the best time to take it, and more.
Possible benefits
All of the potential benefits mentioned below are dose-dependent. As with most other supplements, there is a sweet-spot dose that allows you to get most of the benefits without causing meaningful side effects or tolerance buildup in the body. We will discuss the best dosing protocol later in this article.
Major benefits
Slower collagen degradation – Glucosamine can significantly reduce CTX-II, a marker of collagen degradation, in athletes taking 3 grams daily. Whether or not this effect applies to other groups of people or to lower doses isn’t clear yet.
Minor benefits
Reduced joint pain – Glucosamine can reduce joint pain caused by osteoarthritis and possibly other causes. One meta-analysis found that the supplement decreases physical pain by an average of 13 points on a scale from 0-100. The magnitude of this effect is also highly variable as some people experience great reductions in pain while some experience no improvement.
Reduced symptoms of osteoarthritis – The supplement can somewhat reduce the symptoms of osteoarthritis, such as pain. It can also improve the range of motion in people with osteoarthritis. This benefit may only apply to glucosamine sulfate and not glucosamine HCl.
Improved injury rehabilitation – The compound may help rehabilitate joint injuries, especially knee injuries.
Possible side effects
The side effects below are dose-dependent. The risk for them increases (often linearly but sometimes exponentially) as you increase the dose. Some of the side effects only apply to very high doses.
Flatulence – Flatulence means passing gas from the digestive system out of the back passage. This is the most common side effect of glucosamine.
Allergic reaction – An allergy to this supplement is rare but possible.
Nausea – This side effect is most common when people take the supplement on an empty stomach.
Diarrhea – You can usually prevent diarrhea or stomach discomfort by taking this supplement with a meal.
Toxicity – While acute toxicity is extremely rare, taking high amounts of this supplement could lead to chronic toxicity and cause health problems over time. Regularly taking high doses can also cause the body to develop a tolerance to the supplement. To prevent chronic toxicity or the buildup of tolerance, staying below 3 grams in a day is best unless you have a great reason to take more.
Contamination – Contaminated supplements are uncommon in the USA and other well-regulated countries. However, if you wish to buy products from China, India, or other countries without strict regulations, beware that the supplements may be contaminated. Either way, you need to choose the brand you order from wisely. Always read through some reviews for the specific product before you buy it. The FDA (Food and Drug Administration) has the power to regulate dietary supplements but can only do so after they have been on the market for a while. That’s because supplement companies are not obligated to announce to the FDA when releasing a new product. The FDA has to discover the product and test it for potential impurities, which can take a lot of time. During that time, the supplement can be sold on the market even if it’s impure. Also, supplement companies can change their manufacturers without announcing it to the FDA.
Who should not take glucosamine?
You should probably avoid taking glucosamine if you:
don’t experience much knee pain or joint pain in general
are allergic to this supplement
experience a severe adverse reaction after taking the supplement
are pregnant or breastfeeding (while it can be safe to take this supplement during pregnancy or breastfeeding, it can put some unnecessary risk to the child)
Who will benefit the most?
You should consider taking the supplement if you:
have osteoarthritis
experience joint pain, especially knee pain
suffer from the Kashin-Beck disease
do lots of high-impact sports, such as running
How much glucosamine should you take?
The sweet spot dose typically ranges between 900-1500 mg daily for most people. This amount should provide most of the benefits without meaningful side effects.
The higher end of this range usually provides slightly more benefits in the short term. If you plan to take this supplement for a longer time (multiple months or years), the lower end is probably a better way to go since it is safer, and you would develop tolerance faster if you were to take higher doses.
If you are a serious athlete or do lots of high-impact exercise, doses as high as 3 grams daily may be useful for keeping your knee joints and possibly other joints healthy.
The upper safety limit for this supplement is not well-established. To stay on the safe side, don’t take more than the recommended dose unless you have a great reason to do so. Higher amounts may cause problems if you take the supplement for a prolonged period.
Like most other supplements, it is best to cycle glucosamine and take about two days off weekly to reset your tolerance. That will allow you to keep getting the benefits in the long term.
Best time to take glucosamine
Glucosamine is water-soluble, so you don’t have to take it with food to absorb it well.
Whether you take the supplement in the morning or the evening does not make much difference. Both options are fine so feel free to experiment.
Interactions
Chondroitin This combination may be synergistic for improving collagen synthesis and slowing down collagen degradation.
Quercetin Combining glucosamine, chondroitin, and quercetin can lead to greater improvements in joint health than taking these supplements alone.
Boswellia This combination is synergistic for reducing pain and other symptoms of osteoarthritis.
Anticoagulants Glucosamine may have anticoagulant properties. Combining it with other anticoagulants like warfarin can cause too much blood thinning.
Where to buy glucosamine?
In most countries, Amazon is the best option for ordering glucosamine supplements. They offer some very affordable products backed by many positive reviews. Also, you can choose from a wide range of brands without having to search through other markets on the Internet.
Some brands display the dosage per serving instead of per pill or capsule. Therefore, you may accidentally buy something less potent than you intended. Do not fall for this marketing trick.
FAQ
Like most other supplements, it is best to cycle glucosamine and take a break from it for about two days per week to reset your tolerance back to baseline. That will keep your body sensitive to the supplement and allow you to keep getting the benefits in the long term.
All of these options are fine. The two most important things to consider are the price and dosing. Powders are almost always the cheapest form. However, you may need a highly accurate scale to dose them correctly (preferably 0.001g). You can get one for as little as $20 from Amazon. Dosing the powders also takes time which can add up over months or years. The disadvantage of capsules is that they are often made of bovine gelatine, which rarely comes from ethical sources.
Yes. Whether you take the supplement in the morning or the evening does not make much difference. Both options are fine so feel free to experiment.
This supplement should not become harmful once it exceeds the expiration date. However, it can lose potency over time. Keep this supplement in a cold, dark, and dry place so it remains as potent for many months or even years.
While acute toxicity is rare, taking very high amounts of this supplement could lead to various problems over time. High doses can also make you develop tolerance much faster than lower doses.
While you could safely take higher doses, there is usually no point in taking more than 3 grams daily. This amount should give you most of the benefits without meaningful side effects.
The half-life of glucosamine in the body is about 15 hours. This supplement gets metabolized within a few days after you consume it. However, most of the effects of this supplement are cumulative, so they mainly happen in the long term rather than acutely. Therefore, the half-life of this supplement isn’t very relevant in practice.
In the long term, you must take the supplement for about 2-4 weeks to begin noticing most of the benefits.
Unfortunately, most glucosamine supplements on the market are not vegan-friendly. The hydrochloride form is often synthesized from vegan sources but it doesn’t seem as effective as glucosamine sulfate.
No, it does not. The supplement should not interfere with fasting in any significant way. However, you still want to take the supplement with food as it will absorb better.
References
Most of the information in this guide is based on scientific research that can be found and verified in the PubMed medical library. We highly encourage you to use the library to verify anything you read in this article. We excluded from consideration studies that are either confounded or have a high conflict of interest.
