Homeopathic medicine, colon cleanses, juice fasts: Of all the unproven health remedies, one of the weirdest may be taking colloidal silver. People drink the silver solution in an attempt to keep infections at bay, but those who drink too much turn a disturbing shade of blue-gray, a condition known as argyria.

Now, researchers have figured out why too much of the shiny drink can leave someone looking like the Tin Man. The same chemical process that develops black-and-white photographs also pigments the skin, according to an October 9 study in ACS Nano.

"It’s the first conceptual model giving the whole picture of how one develops this condition," said study co-author Robert Hurt, a researcher at Brown University, in a press release.

Enthusiasts of colloidal silver believe the metal's antibacterial properties will keep them from getting sick. There's no proof it works, but there is proof that taking too much can leave people permanently blue.

To find out how that happens, Hurt's team added silver to chemical mixtures to mimic the conditions in the human stomach and intestines, and also created a mock-up of human skin tissue.

The team found that stomach acid strips silver atoms of one electron (electrons have a negative charge), making a positively charged silver ion, or salt. The silver ion then seeps into the bloodstream through channels normally only used by other salts. From the bloodstream, the salts wind up in the skin.

When light hits the skin, electrons from the surrounding area immediately bond to the silver ions, turning them back into silver atoms. The chemical conversion results in darker particles, and the skin turns blue. The same chemical reaction is used to develop black-and-white prints.

So far, there's no known way to reverse the trend. To avoid looking like a Smurf, it's probably best to avoid the health tonic altogether.

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