There's more to urine than just piss and vinegar
Urine is a nitrogen-rich liquid byproduct created by the kidneys—it's the body's primary means of expelling water-soluble chemicals generated through the metabolic process. Urine is actually a secondary waste disposal mechanism. Blood first passes through the liver where where toxins, dead cells, and various waste is removed and eliminated. then pumped through the kidneys where excess fluids and water-soluble molecules—nitrogen, vitamins, minerals, proteins, antibodies, and other metabolites—are extracted and transferred to the bladder to await expulsion.
There's a misconception that urine is sterile when it exits your body. It's not. That myth began in the 1950s. Edward Kass, an epidemiologist at Harvard Medical, began screening pre-op surgery patients for urinary tract infections and the samples that passed were marked "negative." The notion that urine is sterile likely grew from those sample markings.
It's close—your pee is roughly 95 percent water, 5 percent metabolites. But recent studies have shown that like the surface of your skin, the inside of your skull, and the depths of your bowels, your urinary tract is host to bacterial colonies.
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