Her beauty was renowned. Although twenty years older than the King of France, Diane de Poitiers was his mistress.

What was her secret? She thought it was gold.

Just like women today, de Poitiers, who was born in 1499, went to great lengths to seek eternal youth. She visited apothecaries for supposed anti-aging elixirs which included spider webs, and various metals, such as gold, to maintain her alabaster skin.

Gold does in fact give you white skin, because of the anemia it causes. But does it also preserve your youth?

De Poitiers believed it.

Her beauty, and possibly her visits to the apothecary, even caused one rival in the French court to spread rumors that her beauty was due to witchcraft. For that, she could have been put to death without trial.

That didn't happen because de Poitiers sought protection from the Prince and became Henri's secret mistress, though he was married and she was twenty years his senior. When Henri became king but was killed in a joust, the queen banished de Poitiers, who then lived out her life at her château until her death in 1566.

Scientists recently had the opportunity to test her hair and found it had five hundred times the normal levels of gold. That means she took it for years, which caused brittle hair, bones and teeth. It can also damage the kidneys, affect the production of white blood cells, inflame the small and large intestines and cause neurological complications.

People still seek out magic cures for aging and there's no shortage of those on the internet. If you're about to try the latest beauty fad, talk to your doctor first.

Remember Ponce De Leon? He spent years in Florida searching for a "fountain of youth," only to die in vain from an arrow wound.