Researchers reported a concerning case where a person taking high doses of L-glutamine, a popular dietary supplement, developed sudden kidney damage. L-glutamine is an amino acid that our bodies naturally produce and use for many important functions. While this supplement is generally considered safe, this case suggests that taking large amounts (18 grams daily) might be risky, especially for older adults or people whose kidneys aren’t working well. The kidney damage appeared to come from the supplement causing toxic ammonia buildup in the kidneys. This finding raises important questions about whether L-glutamine supplements need better safety guidelines.

The Quick Take

  • What they studied: Whether L-glutamine supplements could cause kidney damage in a real patient
  • Who participated: One patient (specific age and health details not fully provided in abstract) who was taking 18 grams of L-glutamine daily
  • Key finding: The patient developed acute kidney injury (sudden kidney damage) that appeared to be caused by the L-glutamine supplement, likely through toxic ammonia buildup in the kidney cells
  • What it means for you: If you take L-glutamine supplements, especially in high doses, you should be aware of potential kidney risks—particularly if you’re older or already have kidney problems. Talk to your doctor before starting or continuing this supplement.

The Research Details

This is a case report, which means doctors documented what happened to one specific patient. The patient was taking 18 grams of L-glutamine daily as a dietary supplement when they developed acute kidney injury—a condition where the kidneys suddenly stop working properly. The researchers examined what might have caused this damage and proposed that the supplement created too much ammonia inside the kidney cells, which is toxic and damaged the delicate filtering structures.

Case reports are like medical detective stories. Doctors observe something unusual in a patient and investigate what caused it. While this type of study can’t prove that something always causes harm, it can alert doctors and the public to potential dangers that need further investigation.

This research matters because L-glutamine supplements are widely available and many people take them without knowing potential risks. Most supplements are assumed to be safe, but this case shows that even ’natural’ substances can cause serious problems at high doses. The finding is especially important for protecting vulnerable groups like elderly people and those with existing kidney disease.

This is a single case report, which is the lowest level of scientific evidence. It describes what happened to one person, not many people. We cannot conclude that L-glutamine always causes kidney damage, but it does suggest a possible connection worth investigating further. The case was published in a reputable kidney disease journal (Nephron), which adds credibility. However, more research with larger groups of people would be needed to confirm whether this is a common problem or a rare occurrence.

What the Results Show

The patient developed acute kidney injury after taking 18 grams of L-glutamine daily. Acute kidney injury means the kidneys suddenly lost their ability to filter waste from the blood properly. Tests showed that the damage occurred in the tubules—the tiny filtering units inside the kidneys that clean the blood.

The researchers believe the L-glutamine caused this damage by increasing ammonia production inside the kidney cells. Ammonia is a toxic waste product that the body normally processes carefully. When too much ammonia builds up in the kidney cells, it can poison and damage them, leading to kidney failure.

This is significant because L-glutamine is marketed as a safe supplement that supports muscle health and immune function. Most people taking it don’t expect it to harm their kidneys, especially at doses that are commonly recommended.

The case highlights that the kidneys play a special role in handling L-glutamine and ammonia production. This means that people with already-weakened kidneys might be at higher risk of problems. The researchers noted that elderly patients are particularly vulnerable because kidney function naturally declines with age.

While L-glutamine supplements are widely considered safe, there is limited research on what happens at very high doses over long periods. This case report adds to growing awareness that amino acid supplements, despite being ’natural,’ can cause harm in certain situations. It aligns with other research showing that high-dose supplements can sometimes have unexpected side effects.

This is a single case involving one patient, so we cannot say how common this problem is. We don’t know if this would happen to most people taking L-glutamine or only to certain individuals with specific health conditions. The report doesn’t provide complete details about the patient’s age, other health conditions, or medications, which could have contributed to the kidney damage. More research with many more patients would be needed to understand how often this happens and who is at highest risk.

The Bottom Line

If you take L-glutamine supplements: (1) Talk to your doctor first, especially if you’re over 65 or have any kidney problems. (2) Don’t take more than recommended doses without medical supervision. (3) Have your kidney function checked regularly if you take this supplement long-term. (4) Watch for warning signs like changes in urination, swelling, or unusual fatigue. These recommendations are based on one case report, so confidence is moderate—more research is needed.

This finding is most important for: elderly people, anyone with kidney disease or reduced kidney function, people taking high-dose L-glutamine supplements, and athletes or fitness enthusiasts who use amino acid supplements. People with healthy kidneys taking normal doses may have lower risk, but caution is still warranted. Anyone considering L-glutamine should discuss it with their healthcare provider first.

Kidney damage from this supplement appeared to develop while the patient was actively taking high doses. If you stop taking the supplement, kidney function may improve, but recovery time varies. Some kidney damage can be permanent, so prevention through careful use is important.

Want to Apply This Research?

  • If using L-glutamine supplements, track daily dose (in grams), any symptoms like changes in urination frequency or color, energy levels, and swelling in legs or face. Log any lab results showing kidney function (creatinine and BUN levels).
  • Set a reminder to discuss L-glutamine supplementation with your doctor before starting or continuing use. If approved by your doctor, use the app to track your daily dose and set alerts for regular kidney function check-ups.
  • Create a monthly check-in to review kidney health markers if available, track any new symptoms, and schedule regular doctor visits to monitor kidney function through blood tests. Use the app to maintain a history of supplement use and any health changes.

This case report describes one patient’s experience and should not be interpreted as proof that L-glutamine supplements cause kidney damage in everyone. If you are currently taking L-glutamine or considering starting it, especially if you are elderly or have kidney disease, consult with your healthcare provider before making any changes. Do not stop taking prescribed medications or supplements without medical guidance. This information is for educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition.