Consumer Report
What’s Wrong with Glucosamine?
by Cy Willson
Nowadays, I’m real cautious about sounding like a know-it-all. Even though I’m a young whippersnapper, I’ve learned that things you take as Gospel today, are often found to be completely wrong tomorrow.
Consider that HMB and androstenedione were once thought to be enormously beneficial toward our muscle-building efforts. Conversely, there are things that we once thought to be worthless, but then suddenly got an 11th-hour reprieve. Remember "whey rules, casein sucks," or soy is the bomb?
Anyhow, my point is that we should continually watch and research the various supplements that are currently available and assess whether they’re beneficial or harmful, and to what degree. Along these lines, I’m going to take a look at one supplement that has become VERY popular with both the bodybuilder and even Joe Average.
Beef takes it for that knee injury he got while trying to rip a fire hydrant out of the ground and Stevie takes it for the sore digits he got while opening letters. Hell, even the old lady down the street uses it.
So what is it? Glucosamine. Now, before I get to why you might want to reconsider your use of this supplement, I’ll do the obligatory rundown on the supplement itself and why it’s so popular.
What is it?
Glucosamine, chemically known as (2-amino-2-deoxy beta-D-glucopyranose) is an aminomonosaccharide found in the body that’s synthesized from glucose and utilized for biosynthesis of glycoproteins and glycosaminoglycans.
Considering that glucosamine serves as a substrate for, and enhances the production of, proteoglycans (proteoglycans are vital components of articular cartilage that attract water molecules in order to stay healthy), it makes sense that it might inhibit deterioration of cartilage.(1)
It’s also demonstrated somewhat of an anti-inflammatory effect as well as relieving related pain. No wonder it’s been prescribed as a possible treatment for osteoarthritis. To top it off, it was also shown to be just as effective as ibuprofen at treating osteoarthritis, with the exception of a slower onset of action. All the while, glucosamine is much safer than NSAIDS in terms of potentially toxic side effects. This is why glucosamine is so versatile. Its use applies to everyone.
Whether you’re a body builder, fighter, football player, or an old lady, this substance can really help alleviate the pain and help aid recovery of injuries. So, if it’s so good, why am I even writing this-here article? Good question.
What’s the Problem?
The problem as some of you may or may not know is that numerous studies have shown glucosamine to cause insulin resistance: in rats, humans, in vitro, and in vivo.
It induced insulin resistance in human skeletal muscle cultures from both non-diabetic and Type-2 diabetics.(2) Another study, this time using rats, showed that it induced insulin resistance in both skeletal muscle and throughout the rest of the body, thereby preventing the insulin-induced increase in muscle glycogen.(3) Another study had similar findings.(4) Glucosamine also induced insulin resistance in adipocytes.(5,6,7,8)
Insulin resistance in fat cells isn’t necessarily a bad thing, as it may help you to drop body fat. Still, if the compound is also causing insulin resistance in muscle tissue, you’re on the fast track to trouble.
To see if this would happen to humans, researchers took 10 healthy subjects and gave them glucosamine. What they found was that it would indeed affect insulin action and the subjects displayed some of the characteristics associated with diabetes.(9)
Additionally, glucosamine has been shown to impair exercise induced glucose uptake. This may be because of its ability to affect GLUT 4 translocation in skeletal muscle. This puts a big damper on the whole idea of glucose entering cells without insulin after a workout.(10,11) Not only that, but it impairs the action of insulin itself. This can be very detrimental and can actually affect the use of certain supplements.
For instance, this could affect how quickly you can recover from your workouts as well as to what extent. New and powerful supplements like Biotest Surge could be negatively affected as well. For those of you who have been reading about Biotest Surge, its main mechanism of action is to elicit a large release of insulin. However, if muscle tissue is resistant, how in the hell are you going to get any benefit from this mode of action?
Well, you obviously won’t. So what’s a T-man to do? Keep reading and I’ll give you an alternative, one that’s also well known and often used in conjunction with glucosamine.
Chondroitin
This substance is classified as a mucopolysaccharide that’s found in cartilage. It provides the same benefits to cartilage as glucosamine, but appears to work through a different mechanism. While glucosamine serves as a substrate for glycosaminoglycan synthesis, it appears that chondroitin works instead by being incorporated into cartilagenous tissue itself.(12)
It’s basically just as effective as glucosamine in terms of treatment of osteoarthritis, pain, and inflammation.(13,14,15) Numerous studies have also shown it to be as effective as ibuprofen and allowed people to lower the dosage of NSAIDs.(16,17,18,14) As an interesting side note, chondroitin was also found to improve joint function and pain for up to 3 months after cessation of use.
Let’s not forget that chondroitin is devoid of dangerous effects on the stomach, platelets, and kidneys.(14) The same can’t be said for NSAIDS.
The obvious benefit to using chondroitin over glucosamine is the fact that chondroitin hasn’t been shown to affect insulin action/sensitivity in a negative manner, while glucosamine has. As far as dosages go, 800-2400 mg per day is the usual dosage used to treat osteoarthritis. For the typical body builder however, a minimum dosage of around 1600-2400 mg may be necessary for treatment. For prophylactic use, a dose of 400 mg would be sufficient.
Closing Statement
Now I don’t want you guys freaking out on me here. I’m not saying that glucosamine will break into your house, rob you, and add insult to injury by messing up your Star Wars diorama. All I’m saying is that there’s quite a bit of evidence pointing to the idea that it can affect you in a negative manner. And when I say "in a negative manner," I mean that glucosamine might slow down your muscle gains. Similarly, glucosamine may make it easier to put on fat, which probably isn’t something you want to do.
Anyhow, if you’re currently using glucosamine, I’d recommend either monitoring yourself in terms of gains (muscle and/or fat) and possibly the way you feel, or you can go ahead and actually have your insulin sensitivity checked. Personally, I’d rather play it safe and avoid glucosamine — including the glucosamine/chondroitin blends —and just stick with plain chondroitin. Either way, take this as a friendly warning.
References Cited
1. Runkel DR, Cupp MJ. "Glucosamine sulfate use in osteoarthritis." Am J Health Syst Pharm 1999; 56(3):267-269
2. Ciaraldi TP, et al. "Glucosamine regulation of glucose metabolism in cultured human skeletal muscle cells: divergent effects on glucose transport/phosphorylation and glycogen synthase in non-diabetic and type 2 diabetic subjects." Endocrinology 1999 Sep;140(9):3971-80
3. Patti ME, et al. "Activation of the hexosamine pathway by glucosamine in vivo induces insulin resistance of early postreceptor insulin signaling events in skeletal muscle." Diabetes 1999 Aug;48(8):1562-71
4. Virkamaki A, et al. "Activation of the hexosamine pathway by glucosamine in vivo induces insulin resistance in multiple insulin sensitive tissues." Endocrinology 1997 Jun; 138(6):2501-7
5. Kresko RC, et al. "Glucosamine-induced insulin resistance in 3T3-L1 adipocytes is caused by depletion of intracellular ATP." J Biol Chem 1998 Aug 7;273(32):20658-68
6. Ross SA, et al. "Development and comparison of two 3T3-L1 adipocyte models of insulin resistance: increased glucose flux vs glucosamine treatment." Biochem Biophys Res Commun 2000 Jul 14;273(3):1033-41
7. Nelson BA, et al. "High glucose and glucosamine induce insulin resistance via different mechanisms in 3T3-L1 adipocytes." Diabetes 2000 Jun;49(6):981-91
8. Hawkins M, et al. "Role of the glucosamine pathway in fat-induced insulin resistance." J Clin Invest 1997 May 1;99(9):2173-82
9. Monauni T, et al. "Effects of glucosamine infusion on insulin secretion and insulin action in humans." Diabetes 2000 Jun;49(6):926-35
10. Miles PD, et al. "Exercise-stimulated glucose turnover in the rat is impaired by glucosamine infusion." Diabetes 2001 Jan;50(1):139-42
11. Baron AD, et al. "Glucosamine induces insulin resistance in vivo by affecting GLUT 4 translocation in skeletal muscle. Implications for glucose toxicity." J Clin Invest 1995 Dec;96(6):2792-801
12. Menzel EJ. "Polymeric chondroitin sulfate vs. monomeric glucosamine treatment of osteoarthritis." Wien Med Wochenschr 2000;150(5):87-90
13. Uebelhart D, et al. "Effects of oral chondroitin sulfate on the progression of the knee osteoarthritis:a pilot study." Osteoarthritis Cartilage 1998 May;6 Suppl A:39-46
14. Ronca F, et al. "Anti-inflammatory activity of chondroitin sulfate." Osteoarthritis Cartilage 1998 May;6 Suppl A:14-21
15. Alekseeva LI, et al. "Structum (chondroitin sulfate) — a new agent for the treatment of osteoarthrosis." Ter Arkh 1999;71(5):51-3
16. Fioravanti A, et al. "Clinical efficacy and tolerance of galactosaminoglucoronoglycan sulfate in the treatment of osteoarthritis." Drugs Exp Clin Res 1991; 17:41-44
17. Leeb BF, et al. "A metaanalysis of chondroitin sulfate in the treatment of osteoarthritis." J Rheumatol 2000; 27:205-211
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