Glucosamine supplements: a critical evaluation. By Vic Goyaram

A critical evaluation of Glucosamine-based Joint supplements

Researched and composed by Vic Goyaram

Introduction

Glucosamine is a very popular ingredient in supplements meant for patients of osteoarthritis as well as people engaged in sports and physical exercise for the maintenance of healthy joints and joint regeneration.  Most joint supplements are based on Glucosamine which is purported to help to support the structure and function of joints because it is a substrate for the biosynthesis of glycosaminoglycan (GAG), the building blocks of joints (Fallon, 2001). Glucosamine exists under several forms in supplements, namely Glucosamine hydrochloride, N-Acetylglucosamine and the most popular chemical form Glucosamine sulphate. The latter form is the most studied scientifically. Glucosamine by itself accounted for USD 720 million in terms of sales in 2005. This article attempts to review key aspects of glucosamine supplementation, including a discussion of the evidence for and against its effectiveness in joint healing.

Glucosamine product formulations and dosages

Most joint products contain glucosamine either as Glucosamine sulphate by itself or with added Chondroitin and MSM (Figure 1).  However, although these different forms of glucosamine may be chemically related the effects may not be the same when taken as supplements for the purported benefits.  Sulphate is the form which has been used in most scientific studies on Glucosamine. Additionally, some joint product formulations will also include other ingredients like MSM, Bromelain and Collagen (Figure 2) which may be involved in joint support. These products may come in the form of tablets, capsules or powder although tablets remain the most common formulation, from personal observation.

Figure 1: The most common glucosamine-based joint support
product formulation containing MSM and Chondroitin

Figure 2: Example of more advanced formulations containing 
glucosamine and other ingredients. The effectiveness of such formulas
 will be subject of another article.

The dosages vary from product to product but most contain about 1500-2000mg Glucosamine per recommended serving.

Dosage and precautions

Glucosamine is not recommended for children as it is mainly used to treat OA (a condition that affects adults) and its safety for children has not been studied. The recommended dosage for adults is 500 mg, 3 times daily, for 30 - 90 days. Once daily dosing as 1.5 g (1,500 mg) may also be used. Most studies show that glucosamine needs to be taken for 2 - 4 months before it is effective, although you may experience some improvement sooner. Glucosamine and chondroitin can be used along with nonsteroidal anti-inflammatory drugs (NSAIDs) to treat OA. Glucosamine must not be administered haphazardly because it can have interaction with or counteract the effect of some medications like Warfarin (Glucosamine may increase the blood thinning effect of warfarin), Nonsteroidal anti-inflammatory drugs (NSAIDs) (Glucosamine may reduce the need for NSAIDs), blood sugar lowering medications or insulin (Glucosamine may change the dose needed for blood sugar lowering medications and insulin).  Therefore it is always best to obtain medical clearance before commencing glucosamine treatment in the presence of existing medical conditions that necessitate the use of the above drugs.

Evaluating the evidence for the effectiveness of Glucosamine

The use of glucosamine is common among athletes at all ages and levels (Buckwalter 2003) but here is little if any evidence currently available about the claimed anti-inflammatory, analgesic, or protective effects of glucosamine in the athletic environment.  One study by Ostojica et al. (2007) studied the effect of 4 weeks of glucosamine administration (1500 mg per day) on the functional ability and the degree of pain intensity in competitive male athletes who had acute knee injury.  No significant difference was seen in pain intensity and knee swelling between the glucosamine and placebo group.  However, improvements in knee flexion and extension were noted thereby indicating that glucosamine may have an effect on joint mobility in injured states.

Glucosamine has been studied in cases of osteoarthritis (OA). Osteoarthritis is a type of arthritis that occurs when cartilage breaks down and is lost, either due to injury or to normal wear and tear. It commonly occurs with age. In some studies, glucosamine supplements have:

(a) decreased the joint pain of OA, 

(b) improved function in people with hip or knee OA, 

(c) reduced joint swelling and stiffness and 

(d) provided relief from OA symptoms for up to 3 months after stopping treatment

Not all studies are positive, however, and several more recent ones have not found any positive effect from taking glucosamine For example, in the large clinical trial by Sawitzke et al. (2008), called the 2006 Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), conflicting and somewhat confusing results. The study of about 1,600 people with OA of the knee found that glucosamine alone, or in combination with chondroitin did not reduce pain in the overall group, although it did appear to lessen pain among those with moderate to severe OA of the knee. This study has provided the impetus for further research. Studies are currently being conducted to see whether the glucosamine-chondroitin combination may in fact help those with more severe OA in an attempt to see whether any benefit is seen in more severe cases.  The study also tested whether glucosamine or chondroitin (together or alone) slowed the loss of cartilage in their knees. They showed no difference in cartilage loss compared with people who took placebo. In light of these conflicting findings, more research is warranted on Glucosamine before it can conclusively be said to be effective.

References

Buckwalter, JA. 2003. Sports, joint injury, and posttraumatic osteoarthritis. Journal of Orthopaedic and Sports Physical Therapy, 33: 578–588.

Fallon K. Glucosamine in the management of osteoarthritis. Int SportsMed J. 2001; 2(4).

Ostojica S.M, M. Arsicb, S. Prodanovicc, J. Vukovica & M. Zlatanovicd. Glucosamine Administration in Athletes: Effects on Recovery of Acute Knee Injury. Research in Sports Medicine: An International Journal. Volume 15, Issue 2, 2007. pages 113-124

Sawitzke et al. The Effect of Glucosamine and/or Chondroitin Sulfate on the Progression of Knee Osteoarthritis: A GAIT Report. Arthritis Rheum. 2008 October; 58(10): 3183–3191

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My Bio: I am a Mauritian originally from Roche Bois, Port Louis and now based in Cape Town, South Africa where I am busy with my postgraduate studies in molecular biology of exercise. My research, supervised by Prof. Edward Ojuka, looks at the influence of nutrition and exercise in gene expression in muscle, research which is relevant and applicable to exercising individuals, sports persons and diabetic individuals. The knowledge that I share with you stems from my 18 years of experience in bodybuilding and 8 years (and counting) of university education in the field. I have also published work in the American Journal of Physiology: Endocrinology and Metabolism (2013), International Journal of Sport Nutrition and Exercise Metabolism (2013) and co-authored two book chapters on exercise and diabetes. I also presented my research work at the 2012 International Sports and Exercise Nutrition Conference (UK). I am grateful to each and everyone at the UCT Research Unit for Exercise Science and Sports Medicine. "Knowledge without sharing is worth nothing"

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