Published: 30 October 2007
After at least 530 million years of clamming up, the oyster has revealed its secret curative properties to mankind. And they are not only aphrodisiac.
French biologists who have been studying the way oysters produce nacre, also known as mother-of-pearl, believe the process could be replicated to provide cures and preventative treatments for osteoporosis, arthritis and certain skin complaints.
"The key is biomineralisation," said Christian Milet at the Muséum National d'Histoire Naturelle in Paris. "Humans and oysters share the capacity for self repair. A human bone heals, as does a cracked oyster's shell. We now believe nacre can be used to stimulate bone growth."
Biomineralisation is as old as bivalve molluscs, which gives it quite a few million years on the human species. More than 4,000 years ago, the Maya people of central America realised that nacre was not only beautiful but extremely hard and durable. They used it to make false teeth. In other cultures, including ancient Chinese and Egyptian, paste made from crushed nacre was recommended as a beauty cream.
The aphrodisiac quality of oysters has been recognised for many years but never scientifically proven. However, the mollusc's high content of zinc, which in humans is required for the production of testosterone, could be one explanation. Other research has shown that the shellfish are rich in certain amino acids that trigger increased levels of sex hormones.
For the biomineralisation process to work there does not need to be an "R" in the month. But scientists already know that some oysters are better at it than others. Those we eat, and which do not produce pearls, are the least scientifically interesting.
The oysters that produce the largest quantities of nacre are those, such as the Pinctada oyster, which also produce pearls. This is because natural pearls are formed when an oyster, while taking a gulp of water containing plankton, inadvertently swallows a piece of grit. To avoid the discomfort of sharing its shell with a nasty, jagged foreign object, the mollusc envelops it with smooth nacre: the pearl.
News of the French biologists' progress in understanding nacre-making emerged with the opening of an exhibition, Perles, une histoire naturelle, at the natural history museum in Paris. Apart from showing some of the biggest pearls ever found – including a 171-gram seawater pearl – the exhibition provides a rare opportunity to view a globe made by the jeweller Mikimoto on which the oceans are represented by 12,000 cultured pearls, the continents are made of gold and the equator is drawn with 377 rubies.
But Mr Milet's discovery is not going appear in the world's hospitals immediately. "We have already carried out in vivo bone graft tests in which we have obtained a perfect bond between the nacre and the bone. The medical uses of the biomineralisation will be seen some years into the future," he said. "We have already asserted that not only can nacre be grafted on to bone and be accepted by the human body, it also releases active molecules which induce bone regeneration."