Ever wonder why urine is yellow? Researchers say they’ve figured it out.

You're in luck if you've always wondered why urine is yellow.

Researchers have identified the enzyme responsible for urine color, solving a mystery that has puzzled scientists for years, according to a study published in the journal Wednesday. Nature Microbiology.

“It's remarkable that an everyday biological phenomenon has been unexplained for so long, and our team is excited to be able to explain it,” said Brantley Hall, an assistant professor in the Department of Cell Biology and Molecular Genetics at the University of Maryland. statement.

What makes urine yellow?

Urine is a combination of water, electrolytes, and waste products that the kidneys filter from the blood. More than 125 years ago, scientists identified urobilin as a yellow pigment in urine, but they did not know what was responsible for the production of urobilin.

According to researchers, the color of urine is related to the red blood cells in the body. When red blood cells break down, a bright orange pigment called bilirubin is produced. The pigment is usually excreted in the intestine, where it can then be excreted or partially absorbed. Once bilirubin enters your gut, microorganisms in your gut can convert the bilirubin into other molecules, research shows.

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Researchers say they have discovered what makes urine yellow.

University of Maryland


“Gut microbes encode the enzyme bilirubin reductase, which converts bilirubin into a colorless byproduct called urobilinogen,” said Hall, lead author of the study. “The urobilinogen is then spontaneously broken down into a molecule called urobilin, which is responsible for the yellow color we all know.”

The study authors said that before their research, scientists thought that multiple enzymes were involved, rather than a single enzyme.

Where do scientists go from here?

The discovery of the bilirubin reductase enzyme could help researchers learn more about gut health, inflammatory bowel disease and jaundice, researchers say.

The research team found that the enzyme is present in almost all healthy adults, but is often lacking in infants and people with inflammatory bowel disease.

“Now that we have identified this enzyme, we can begin to investigate how the bacteria in our gut affect circulating bilirubin levels and related health conditions such as jaundice,” said study co-author and National Institutes of Health researcher Xiaofang Jiang. “This discovery lays the foundation for understanding the gut-liver axis.”

What does it mean if your urine is not yellow?

A healthy, hydrated person's urine should be colorless, which can be a sign that you are drinking. Too much waterAnd the color according to light straw and honey Cleveland Clinic. It turns a darker yellow or amber in those who don't drink enough.

Other colors may come from your diet or medical condition.

According to the Cleveland Clinic, dark brown urine can be a sign of dangerous dehydration. The color can also mean the presence of bile in the urine, which is a sign of liver disease.

Orange urine is also sometimes a sign of dehydration, but it can also mean you have a liver or bile duct condition. The color can also be tied to food coloring or medications.

Certain foods and medications can also cause blue or green urine. According to A Harvard Health PostThe antidepressant amitriptyline and the anti-inflammatory drug indomethacin can turn urine blue.

A pink to reddish color could be a cause for concern or simply mean you are eating beets, blueberries or rhubarb. If these foods have been missing from your diet and your urine is still pink or reddish, it may be cause for concern. The color can be a sign of several conditions, including kidney disease, lead poisoning, and certain types of cancer.