Researchers studied over 436,000 people in the UK to see if glucosamine supplements—a popular over-the-counter product many people take for joint health—might also protect the kidneys. They found that people taking glucosamine had lower levels of protein in their urine, which is a sign of kidney damage. However, the study couldn’t prove that glucosamine actually causes this protection. The findings suggest glucosamine might work by protecting blood vessel linings in the kidneys, but more research is needed to confirm whether the supplement is truly responsible for the benefit or if other factors are involved.

The Quick Take

  • What they studied: Whether taking glucosamine supplements is connected to having healthier kidneys, measured by checking for protein in urine
  • Who participated: Over 436,000 adults from the UK Biobank who reported whether they used glucosamine supplements, with researchers measuring protein levels in their urine samples
  • Key finding: People who took glucosamine were about 19% less likely to have protein in their urine (a sign of kidney problems), but the study couldn’t prove glucosamine caused this benefit
  • What it means for you: While glucosamine users showed better kidney markers, this doesn’t mean the supplement definitely protects your kidneys—people who take glucosamine might differ in other healthy habits. Talk to your doctor before starting glucosamine based on these findings alone

The Research Details

This was a cohort study, meaning researchers followed a large group of people and compared those who used glucosamine to those who didn’t. They looked at data from 436,200 UK adults and measured protein in their urine (called albuminuria), which is an early warning sign of kidney problems. The researchers used statistical methods to account for differences between groups like age, sex, and weight. They also performed a special genetic analysis called Mendelian randomization, which tries to determine if associations are truly causal by looking at inherited genetic traits. This genetic approach helps separate real cause-and-effect relationships from coincidences.

Understanding whether glucosamine actually protects kidneys is important because millions of people take this supplement. If it truly helps, it could be a simple way to prevent kidney disease. The genetic analysis was particularly valuable because it helps researchers figure out whether the connection they found is real or just happens by chance. This matters because people who take glucosamine might also exercise more, eat healthier, or have better overall health habits—which could explain the kidney benefits instead of the supplement itself.

This study is fairly reliable because it used a very large sample size (over 436,000 people) and adjusted for major factors like age, weight, and sex that could affect results. The findings held up even when researchers tested them different ways. However, the genetic analysis didn’t find strong evidence that glucosamine causes the kidney benefit, which suggests the connection might be more complicated than it appears. The study relied on people self-reporting whether they took glucosamine, which can be less accurate than measuring actual supplement use.

What the Results Show

The main finding was that glucosamine users had significantly lower levels of protein in their urine compared to non-users. Specifically, people taking glucosamine were about 19% less likely to have detectable protein in their urine (the odds ratio was 0.81, meaning lower odds of kidney problems). This association remained strong even after researchers adjusted for age, sex, and obesity measures. The relationship was consistent across different statistical tests, suggesting it wasn’t just a random finding. Protein in urine is considered an early warning sign that blood vessels in the kidneys aren’t working properly, so lower protein levels suggest better kidney health.

When researchers used genetic analysis to try to prove that glucosamine actually causes better kidney health, they found weak evidence. The genetic approach didn’t show a clear cause-and-effect relationship, which suggests the connection between glucosamine use and kidney health might be more complicated. This could mean that people who take glucosamine differ in other important ways (like overall health consciousness or diet) that actually explain the kidney benefits. The study also found that protein in urine was quite common among UK Biobank participants, affecting a significant portion of the population.

Previous research has suggested glucosamine might have protective effects on various health outcomes, but scientists haven’t understood how it works biologically. This study is the first to show a connection between glucosamine and kidney protein levels, which fits with a theory that glucosamine might protect the delicate blood vessel linings in kidneys. However, the genetic analysis results contradict the observational findings, which is similar to a pattern seen in other supplement research where associations don’t always prove causation.

The biggest limitation is that the study couldn’t prove glucosamine actually causes the kidney benefits—it only showed an association. People who take glucosamine might be healthier in other ways (better diet, more exercise, higher income) that actually explain the kidney protection. The study relied on people self-reporting their supplement use, which can be inaccurate. The genetic analysis had limitations because glucosamine is a supplement rather than a medication, making it harder to find genetic markers that represent actual glucosamine use. The study was conducted in the UK, so results might not apply equally to other populations.

The Bottom Line

Based on this research alone, there is moderate evidence that glucosamine use is associated with better kidney markers, but low evidence that it actually causes this benefit. If you’re considering glucosamine for joint health, this study doesn’t provide strong enough evidence to recommend it specifically for kidney protection. If you already take glucosamine, there’s no reason to stop based on this study. Anyone with kidney disease or concerns should discuss glucosamine use with their doctor before starting.

This research is most relevant to people considering glucosamine supplements, especially those with family history of kidney disease or those already taking it. People with existing kidney problems should definitely talk to their doctor before using glucosamine. Healthy people without kidney concerns don’t need to change their habits based on this single study. Healthcare providers may find this useful for counseling patients about supplement use.

If glucosamine does protect kidneys, benefits would likely develop gradually over months to years, not days or weeks. Kidney damage typically progresses slowly, so any protective effect would also be slow to measure. Most people wouldn’t notice changes in how they feel, since early kidney problems usually have no symptoms.

Want to Apply This Research?

  • Track daily glucosamine supplement use (yes/no) and note any urine changes or symptoms. If you have access to urine test results from your doctor, log the date and any protein findings to monitor trends over time
  • If interested in kidney health, users could set a reminder to take glucosamine consistently if their doctor recommends it, while also tracking other kidney-protective habits like water intake, blood pressure monitoring, and regular exercise
  • Users should request urine protein testing from their doctor annually or as recommended, logging results in the app to track changes over time. This creates a personal health record showing whether any supplement changes correlate with kidney marker improvements

This research shows an association between glucosamine use and kidney markers but does not prove glucosamine causes kidney protection. This summary is for educational purposes only and should not replace medical advice. Anyone considering glucosamine supplements, especially those with kidney disease, diabetes, or taking medications, should consult their healthcare provider before starting. Do not stop or start any supplements based solely on this study. Results from UK populations may not apply equally to all groups. Always discuss supplement use with your doctor as part of your overall health plan.