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Urea is a metabolic byproduct of amino acid metabolism that is excreted by the kidneys.

Research analysis led by Kamal Patel.
All content reviewed by the Examine.com Team. Published: Jul 5, 2013
Last Updated:

Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what supplements affect urea
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-c Minor - See study
An increase in urea is seen with citrulline supplementation (possibly due to increased serum ornithine sequestering ammonia)
grade-c Minor - See study
An increase in urea has been noted with glutamine supplementation
grade-c Minor Moderate See 2 studies
Mixed effects, but it appears that when ammonia is decreased that urea is also increased but if ammonia is unchanged whatever reason for this also means that urea is unchanged.
grade-c - - See study
Although it is theoretically plausible that arginine can increase urea concentrations (secondary to the actions of ornithine), it does not appear to reliably occur
grade-c - - See study
grade-c - - See study
The lone study assessing urea failed to find a significant interaction between it and supplementation of chromium.
grade-c - - See study
No significant alterations in serum urea, suggesting no renal toxicity with the low doses (300mg) of this supplement
grade-c - - See study
Urea is not altered in the blood when compared to control.
grade-c - - See all 4 studies
grade-c - Very High See all 5 studies
No apparent effect in studies.
grade-d Minor - See study
A slight increase in urea has been noted, requires replication
grade-d - - See study
No apparent effect in one study in healthy, active participants taking 500 mg of a potent extract.
grade-d - - See study
No significant influence on urea
grade-d - - See study
It's simply not clear from one study and a small, non-significant reduction.