Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
3 StarsReliable and relatively consistent scientific data showing a substantial health benefit.
2 StarsContradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1 StarFor an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
This supplement has been used in connection with the following health conditions:
1,500 mg daily
Glucosamine sulfate (GS), a nutrient derived from seashells, is a building block needed for the synthesis and repair of joint cartilage. GS supplementation has significantly reduced symptoms of osteoarthritis in uncontrolled1, 2 and single-blind trials.3, 4 Many double-blind trials have also reported efficacy.5, 6, 7, 8, 9, 10 One published trial has reported no effect of GS on osteoarthritis symptoms,11 and GS has been found to be ineffective for low back pain related to lumbar spine osteoarthritis.12 While most research trials use 500 mg GS taken three times per day, results of a three-year, double-blind trial indicate that 1,500 mg taken once per day produces significant reduction of symptoms and halts degenerative changes seen by x-ray examination.13 GS does not cure people with osteoarthritis, and they may need to take the supplement for the rest of their lives in order to maintain benefits. Fortunately, GS appears to be virtually free of side effects, even after three or more years of supplementation. Benefits from GS generally become evident after three to eight weeks of treatment.
250 mg with morning and evening meals
Some autistic children suffer from chronic diarrhea. In a study of children with autistic spectrum disorders and persistent diarrhea for many years, supplementing with 500 mg of glucosamine per day (spread over the morning and evening meal) for 30 days eliminated the diarrhea in five of six cases.14 The authors hypothesized that glucosamine worked by blocking the effect of certain dietary components on the intestinal tract.
1,500 mg daily
One doctor has observed that supplementation with glucosamine sulfate (amount not specified) can increase the growth rate and strength of fingernails and toenails;15however, no controlled trials have been done.
250 mg with morning and evening meals
Some autistic children suffer from chronic diarrhea. In a study of children with autistic spectrum disorders and persistent diarrhea for many years, supplementing with 500 mg of glucosamine per day (spread over the morning and evening meal) for 30 days eliminated the diarrhea in five of six cases.16 The authors hypothesized that glucosamine worked by blocking the effect of certain dietary components on the intestinal tract.
Refer to label instructions
[1 star] Learn More
A few trials have evaluated glucosamine hydrochloride (GH), another form of glucosamine sulfate (GS), as a single remedy for osteoarthritis. One trial found only minor benefits from 1,500 mg per day of GH for 8 weeks in people with osteoarthritis of the knee.17 However, these people were also taking up to 4,000 mg per day of acetaminophen for pain relief, and that treatment might have masked a beneficial effect of GH. In another study, supplementing with GH (2,000 mg each morning for 12 weeks) significantly improved symptoms, compared with a placebo, in people with knee pain due to cartilage damage or osteoarthritis.18 In a four-week study from China, GH was as effective as GS in people with osteoarthritis of the knee.19 Another study found that the combination of GH and chondroitin sulfate was more effective than a placebo in people with moderate to severe knee pain from osteoarthritis, but not in those with mild pain.20 Despite the reported beneficial effects of GH, some investigators believe that the sulfate component of GS itself helps relieve osteoarthritis, and that GS would therefore be more effective than GH.
Refer to label instructions
In a preliminary trial, supplementation with glucosamine hydrochloride (1,500 mg per day) for 12 weeks produced a small but statistically significant improvement of pain in people with rheumatoid arthritis. However, other measures of disease activity, such as the number of swollen and painful joints did not improve.21
Sprains and Strains
Refer to label instructions
Glucosamine sulfate and chondroitin sulfate may both play a role in wound healing by providing the raw material needed by the body to manufacture molecules called glycosaminoglycans found in skin, tendons, ligaments, and joints.22 Test tube and animal studies have found that these substances, and others like them, can promote improved tissue healing.23, 24, 25, 26 Injectable forms of chondroitin sulfate have been used in Europe for various types of sports-related injuries to tendons and joints,27, 28, 29, 30 and one preliminary trial reported reduced pain and good healing in young athletes with chondromalacia patella (cartilage softening in the knee) who were given 750–1,500 mg per day of oral glucosamine sulfate.31 However, specific human trials of glucosamine and chondroitin sulfate for healing sprains and strains are lacking.
Refer to label instructions
[1 star] Learn More
Glucosamine sulfate and chondroitin sulfate may both play a role in wound healing by providing the raw material needed by the body to manufacture connective tissue found in skin, tendons, ligaments, and joints.32 Test tube and animal studies have found that these substances, and others like them, can promote improved tissue healing.33, 34, 35, 36, 37 One controlled trial in humans found that wounds healed with greater strength when they were treated topically with a chondroitin sulfate-containing powder.38 However, no research has investigated the value of oral supplements of glucosamine or chondroitin for wound healing in humans.
How It Works
How to Use It
Healthy people do not need to routinely supplement with glucosamine. Most research with people who have osteoarthritis, uses 500 mg three times per day of GS. Appropriate amounts for other conditions are not known.
Where to Find It
Glucosamine is not present in significant amounts in most diets. Supplemental sources are derived from the shells of shrimp, lobster, and crab, or may be synthesized.
A glucosamine deficiency in humans has not been reported.
Best Form to Take
Glucosamine is available in several forms. The glucosamine sulfate (GS) form (stabilized with a mineral salt) is the only form clearly shown in clinical trials to be effective for osteoarthritis. For this reason, it is the preferred form.
GS is stabilized with one of two mineral salts: sodium chloride (NaCl) or potassium chloride (KCl).39, 40 Although they both appear to effectively stabilize GS, the use of KCl as a stabilizer seems preferable since the average Western diet already provides far too much salt (NaCl) and not enough potassium. However, most of the research has been done with the NaCl-stabilized form.
Concerns have been raised about the quality of GS products on the market. In one study, the amount of glucosamine contained in 14 commercially available glucosamine products varied from 41% to 108% of the amount stated on the label.41 Even when the weight of the sulfate molecule was included, 11 of the 14 products contained less than the amount of glucosamine stated on the label. Some manufacturers may include the weight of the stabilizing salts (NaCl or KCl) in the total weight of the product, without stating so on the label.
Glucosamine hydrochloride (GH) has been widely available as a dietary supplement for years, but only one trial has evaluated this form of glucosamine as a single remedy for OA.42 This trial found only minor significant benefits from 1,500 mg per day of GH for eight weeks, in people with osteoarthritis of the knee who were also taking up to 4,000 mg per day of acetaminophen. To more fairly evaluate the effects of GH, future research should involve people not taking pain-relieving medication.
Interactions with Supplements, Foods, & Other Compounds
Some GS is processed with sodium chloride (table salt), which is restricted in some diets (particularly for people with high blood pressure).
The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.
At the amount most frequently taken by adults—500 mg three times per day of GS—adverse effects have been limited to mild reversible gastrointestinal side effects. In one trial, people with peptic ulcers and those taking diuretic drugs were more likely to experience side effects.43
Animal research has raised the possibility that glucosamine could contribute to insulin resistance.44, 45 This effect might theoretically result from the ability of glucosamine to interfere with an enzyme needed to regulate blood sugar levels.46 However, available evidence does not suggest that taking glucosamine supplements will trigger or aggravate insulin resistance or high blood sugar.47, 48 Two large, 3-year controlled trials found that people taking GS had either slightly lower blood glucose levels or no change in blood sugar levels, compared with people taking placebo.49, 50 Until more is known, people taking glucosamine supplements for long periods may wish to have their blood sugar levels checked; people with diabetes should consult with a doctor before taking glucosamine and should have blood sugar levels monitored if they are taking glucosamine.
In 1999 the first case of an allergic reaction to oral GS was reported.51 Allergic reactions to this supplement appear to be rare.
1. Tapadinhas MJ, Rivera IC, Bignamini AA. Oral glucosamine sulphate in the management of arthrosis: report on a multi-centre open investigation in Portugal. Pharmtherapeutica 1982;3:157–68.
2. Giordano N, Nardi P, Senesi M, et al. The efficacy and safety of glucosamine sulfate in the treatment of gonarthritis. Clin Ter 1996;147:99–105.
3. D’Ambrosio E, Casa B, Bompani G, et al. Glucosamine sulphate: a controlled clinical investigation in arthrosis. Pharmatherapeutica 1981;2(8):5048.
4. Crolle G, DiEste E. Glucosamine sulfate for the management of arthrosis. Curr Ther Res 1980;7:104–9.
5. Qiu GX, Gao SN, Giacovelli G, et al. Efficacy and safety of glucosamine sulfate versus ibuprofen in patients with knee osteoarthritis. Arzneimittelforschung 1998;48:469–74.
6. Reichelt A, Förster KK, Fischer M, et al. Efficacy and safety of intramuscular glucosamine sulfate in osteoarthritis of the knee. Arzneimittelforschung 1994;44:75–80.
7. Drovanti A, Bignamini AA, Rovati AL. Therapeutic activity of oral glucosamine sulfate in osteoarthritis: a placebocontrolled doubleblind investigation. Clin Ther 1980;3(4):260–72.
8. Vaz AL. Double-blind clinical evaluation of the relative efficacy of ibuprofen and glucosamine sulphate in the management of osteoarthritis of the knee in outpatients. Curr Med Res Opin 1982;8(3):145–9.
9. Pujalte JM, Llavore EP, Ylescupidez FR. Double-blind clinical evaluation of oral glucosamine sulphate in the basic treatment of osteoarthrosis. Curr Med Res Opin 1980;7(2):110–4.
10. Poolsup N, Suthisisang C, Channark P, Kittikulsuth W. Glucosamine long-term treatment and the progression of knee osteoarthritis: systematic review of randomized controlled trials. Ann Pharmacother 2005;39:1080–7.
11. Rindone RP. Randomized controlled trial of glucosamine for treating osteoarthritis of the knee. West J Med 2000;172:91–4.
12. Wilkens P, Scheel IB, Grundnes O, et al. Effect of glucosamine on pain-related disability in patients with chronic low back pain and degenerative lumbar osteoarthritis: a randomized controlled trial. JAMA 2010;304:45–52.
13. Reginster JY, Deroisy R, Rovati L, et al. Long-term effects of glucosamine sulphate on osteoarthritis progression: a randomised, placebo-controlled clinical trial. Lancet 2001;357:251–6.
14. Danczak E. Glucosamine and plant lectins in autistic spectrum disorders: an initial report on 6 children with uncontrolled diarrhoea. J Nutr Environ Med2004;14:327–330.
15. Swinburne LM. Glucosamine sulphate and osteoarthritis. Lancet2001;357:1617 [Letter].
16. Danczak E. Glucosamine and plant lectins in autistic spectrum disorders: an initial report on 6 children with uncontrolled diarrhoea. J Nutr Environ Med2004;14:327–330.
17. Houpt JB, McMillan R, Wein C, Paget-Dellio SD. Effect of glucosamine hydrochloride in the treatment of pain of osteoarthritis of the knee. J Rheumatol 1999;26:2423–30.
18. Braham R, Dawson B, Goodman C. The effect of glucosamine supplementation on people experiencing regular knee pain. Br J Sports Med 2003;37:45–9.
19. Qiu GX, Weng XS, Zhang K, et al. A multi-central, randomized, controlled clinical trial of glucosamine hydrochloride/sulfate in the treatment of knee osteoarthritis. Zhonghua Yi Xue Za Zhi 2005;85:3067–70 [in Chinese].
20. Clegg DO, Reda DJ, Harris CL, et al. Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis. N Engl J Med 2006;795–808.
21. Nakamura H, Masuko K, Yudoh K, et al. Effects of glucosamine administration on patients with rheumatoid arthritis. Rheumatol Int 2007;27:213–8.
22. Morrison LM, Murata K. Absorption, distribution, metabolism and excretion of acid mucopolysaccharides administered to animals and patients. In: Morrison LM, Schjeide OA, Meyer K. Coronary heart disease and the mucopolysaccharides (glycosaminoglycans). Springfield: Charles C. Thomas, 1974, 109–27.
23. Denuziere A, Ferrier D, Damour O, et al. Chitosan-chondroitin sulfate and chitosan-hyaluronate polyelectrolyte complexes: biological properties. Biomaterials 1998;19:1275–85.
24. McCarty MF. Glucosamine for wound healing. Med Hypotheses 1996;47:273–5 [review].
25. Glade MJ. Polysulfated glycosaminoglycan accelerates net synthesis of collagen and glycosaminoglycans by arthritic equine cartilage tissues and chondrocytes. Am J Vet Res 1990;51:779–85.
26. Prudden JF, Wolarsky ER, Balassa L. The acceleration of healing. Surg Gynecol Obstet 1969;128:1321–6 [review].
27. Bucci L. Nutrition applied to injury rehabilitation and sports medicine. Boca Raton, FL: CRC Press, 1995, 193.
28. Sprengel H, Franke J, Sprengel A. Personal experiences in the conservative therapy of patellar chondropathy. Beitr Orthop Traumatol 1990;37:259–66 [in German].
29. Lysholm J. The relation between pain and torque in an isokinetic strength test of knee extension. Arthroscopy 1987;3:182–4.
30. Ziegler R, Rau R. Conservative or operative treatment for chondropathia patellae? Beitr Orthop Traumatol 1980;27:201–11 [in German].
31. Böhmer D, Ambrus P, Szögy A, et al. Treatment of chondropathia patellae in young athletes with glucosamine sulfate. In: Bachl N, Prokop L, Suckert R, eds. Current topics in sports medicine. Vienna: Urban & Schwarzenberg, 1984, 799.
32. Morrison LM, Murata K. Absorption, distribution, metabolism and excretion of acid mucopolysaccharides administered to animals and patients. In: Morrison LM, Schjeide OA, Meyer K. Coronary heart disease and the mucopolysaccharides (glycosaminoglycans). Springfield: Charles C. Thomas, 1974, 109–27.
33. Denuziere A, Ferrier D, Damour O, et al. Chitosan-chondroitin sulfate and chitosan-hyaluronate polyelectrolyte complexes: biological properties. Biomaterials 1998;19:1275–85.
34. McCarty MF. Glucosamine for wound healing. Med Hypotheses 1996;47:273–5 [review].
35. Glade MJ. Polysulfated glycosaminoglycan accelerates net synthesis of collagen and glycosaminoglycans by arthritic equine cartilage tissues and chondrocytes. Am J Vet Res 1990;51:779–85.
36. Prudden JF, Wolarsky ER, Balassa L. The acceleration of healing. Surg Gynecol Obstet 1969;128:1321–6 [review].
37. Suyama T, Iga Y, Shirakawa H. The acceleration of wound healing with chondroitin sulfate A and its acidic hydrolysates. Jpn J Exp Med 1966;36:449–52.
38. Prudden JF, Allen J. The clinical acceleration of healing with a cartilage preparation; a controlled study. JAMA 1965;192:352–6.
39. Drovanti A, Bignamini AA, Rovati AL. Therapeutic activity of oral glucosamine sulfate in osteoarthritis: a placebocontrolled doubleblind investigation. Clin Ther 1980;3:260–72.
40. Vaz AL. Doubleblind clinical evaluation of the relative efficacy of ibuprofen and glucosamine sulphate in the management of osteoarthritis of the knee in outpatients. Curr Med Res Opin 1982;8:145–9.
41. Russell AS, Aghazadeh-Habashi A, Jamali F. Active ingredient consistency of commercially available glucosamine sulfate products. J Rheumatol 2002;29:2407–9.
42. Houpt JB, McMillan R, Wein C, Paget-Dellio SD. Effect of glucosamine hydrochloride in the treatment of pain of osteoarthritis of the knee. J Rheumatol 1999;26:2423–30.
43. Tapadinhas MJ, Rivera IC, Bignamini AA. Oral glucoseamine sulfate in the management of arthrosis: report on a multi-centre open investigation in Portugal. Pharmatherapeutica 1982;3:157–68.
44. Virkamaki A, Daniels MC, Hamalainen S, et al. Activation of the hexosamine pathway by glucosamine in vivo induces insulin resistance in multiple insulin sensitive tissues. Endocrinology 1997;138:2501–7.
45. Rossetti L, Hawkins M, Chen W, et al. In vivo glucosamine infusion induces insulin resistance in normoglycemic but not in hyperglycemic conscious rats. J Clin Invest 1995;96:132–40.
46. Barzilai N, Hawkins M, Angelov I, et al. Glucosamine-induced inhibition of liver glucokinase impairs the ability of hyperglycemia to suppress endogenous glucose production. Diabetes 1996;45:1329–35.
47. Russell AI, McCarty MF. Glucosamine in osteoarthritis. Lancet 1999;354:1641; discussion 1641–2 [letters].
48. Muniyappa R, Karne RJ, Hall G, et al. Oral glucosamine for 6 weeks at standard doses does not cause or worsen insulin resistance or endothelial dysfunction in lean or obese subjects. Diabetes 2006;55:3142–50.
49. Rovati LC, Annefeld M, Giacovelli G, et al. Glucosamine in osteoarthritis. Lancet 1999;354:1640; discussion 1641–2.
50. Reginster JY, Deroisy R, Rovati L, et al. Long-term effects of glucosamine sulphate on osteoarthritis progression: a randomised, placebo-controlled clinical trial. Lancet 2001;357:251–6.
51. Matheu V, Bracia Bara MT, Pelta R, et al. Immediate-hypersensitivity reaction to glucosamine sulfate. Allergy 1999;54:643–50.
The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2014.
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