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Are there any benefits to the osteoarthritis supplements glucosamine and chondroitin? Watch this video and the next video to see what the science says.
Global sales of glucosamine supplements are estimated at $2 billion. Glucosamine is the precursor of two major components of cartilage, but at the marginal blood levels achieved by supplementation, we do not expect it to contribute significantly directly to cartilage formation. There is significant disagreement in the clinical research literature as to whether it works at all. What are the most likely predictors of clinical trial outcomes? Industrial funds. Studies sponsored directly by product manufacturers have shown that patented products are beneficial. but independentlyFunded studies have shown that glucosamine is ineffective. This has raised serious concerns about “publication bias,” the suspicion that the glucosamine industry quietly withheld studies that presented an overly rosy picture in the medical literature rather than publishing them. This is partly why it is strongly recommended in current American College of Rheumatology guidelines. against Use of glucosamine.
The ban on glucosamine includes: part Expert consensus guidelines (excluding other organizations that allow exceptions for medicines, for example, the American Academy of Orthopedic Surgeons and the International Society for the Study of Osteoarthritis (European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Disorders)) are rated Glucosamine. While only the patented, so-called “crystalline” glucosamine sold as a prescription drug in Europe has been conclusively proven to improve osteoarthritic joint pain or function, over-the-counter glucosamine supplements sold in the United States have provided mixed results, including: . Perhaps that's because quality control analyzes by Consumer Reports and others have shown that glucosamine supplements sometimes contain no glucosamine at all. After examining over a dozen glucosamine supplements, we found that only one supplement contained the dosage listed on the label.
Therefore, the discrepancy in study results may reflect the efficacy of using genuine glucosamine rather than a problem of funding bias. If participant-level results were more transparent, we would have more confidence in industry results. The owner of the crystalline glucosamine clinical trial reportedly denied requests to share data, which “raises concerns about the robustness of the study’s findings.”
Nonetheless, the pain relief effect size found in even the best studies of crystalline glucosamine can be considered relatively small. Effect size can be quantified as the “standardized mean difference.” An effect size of 0.2 is considered small, 0.5 is medium, and 0.8 is large. The best study on crystalline glucosamine had an effect size of 0.27, indicating a small effect. Therefore, prescription glucosamine is more effective than Tylenol, but equivalent to a placebo injection, and less effective than NSAID drugs such as ibuprofen. Now, glucosamine is safer than NSAIDs, but the most interesting possibility is that it may provide more than just symptom relief.
Two industry-funded randomized controlled trials found that patients with knee osteoarthritis who were randomized to take prescription glucosamine for three years had less disease progression compared to placebo, as quantified through X-ray measurements. People who took glucosamine had a 62% reduction in osteoarthritis progression, as measured by joint space narrowing, compared to those who were randomly assigned to receive glucosamine instead of placebo. But after two rain-Industry studies have shown no benefit in osteoarthritis disease progression, with no overall benefit from combining all four. But what about the known potential side effects of extending lifespan?
Glucosamine supplementation extends the lifespan of both microscopic worms and aged mice. What about people? In 2012, the Vitamins and Lifestyles cohort first reported on the relationship between glucosamine use and mortality. A study of nearly 75,000 Washington state residents ages 50 to 76 that followed them for about seven years found that those who took glucosamine were 18 percent less likely to die during that period. In 2020, two other cohort studies on this issue were published, including the large UK Biobank study, which followed nearly half a million people over nine years. Glucosamine users were 15% less likely to die, and a 2020 nationwide study found that users had a 27% lower risk of death. Because glucosamine use has been associated with lower CRP blood levels, researchers have suggested that this may be an anti-inflammatory effect. However, when tested in practice, glucosamine appears to have no effect on CRP at all. A more likely explanation may be the so-called “healthy user effect.”
People who choose to take supplements tend to be healthier than those who don't. Studies have shown that supplement users are more likely to be female, have a higher level of education, and make healthier eating and lifestyle choices, including exercising more, smoking less, and experiencing fewer diseases. So maybe, that Why is it that observational studies may show lower mortality rates in people who take vitamins, but when tested in interventional studies, they show no benefit or worse? One of the most dramatic examples of the healthy user effect is that older adults who get the flu vaccine appear to reduce their risk of overall winter death by 50%, although seasonal flu itself rarely causes more than 10% of excess winter deaths. That's why randomized controlled trials are so important to establish cause and effect, and there's no data yet for glucosamine. Cohort studies have attempted to adjust for factors such as age, obesity, exercise, education, and smoking status, but it is not possible to control for unmeasured lifestyle confounders.
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