The 18th century lover Casanova famously used to breakfast on 50 oysters every morning.  But does that mean that eating oysters can boost your chances of getting pregnant?

Oysters have long been hailed as a natural aphrodisiac, and if you start looking online, you will find a whole heap of newspaper articles from 2005 quoting a study by a team of American and Italian researchers that analysed bivalve molluscs and found that they were rich in rare amino acids that trigger increased levels of sex hormones.

We were intrigued by all these references, but even more intrigued that we couldn’t find the original source, which is unusual.  So we emailed the man quoted as heading the research, Professor George Fisher of Barry University, Florida.  And we’re delighted to be able to put the record straight, right from the horse’s mouth (as it were).

Prof Fisher confirms that the research – undertaken by his colleague Dr. Antimo D’Aniello, of the Zoological Station of Naples, Italy, and one of his own Barry University students – analysed three species of Mediterranean mussels (not oysters) for an uncommon amino acid, D-Aspartic Acid (D-Asp): “Although they did find D-Asp in those mussels, commonly eaten in pasta dishes, there was no proof or any correlation what-so-ever between the presence of D-Asp and libido.  The old-wives’ tale of eating oysters to improve libido really has no sustainable proof.”

The link between oysters and libido may have been further fuelled by another research study Dr Fisher’s colleague, Dr D-Aniello, did on rats, which found that male rats given D-Asp produced more testosterone.  But Dr Fisher stresses that increased testosterone does not imply an increased libido.

However, Dr D’Aniello did go on to publish further research in which he found that men given a dietary supplement of D-Asp for 90 days had both more sperm and improved sperm motility, with an increased number of pregnancies among their partners.

While the studies on D-Asp have focused on mussels, oysters have been found to rich in copper: a significant decrease in plasma copper levels in seminal fluid has been found in patients who produce no sperm (azoospermic patients).  However, copper is also found in sesame seeds, chocolate and nuts, while excessive intake of copper has been shown to damage the reproductive organs of both men and women4.

So what does all this mean?  Basically, the link between oysters and fertility – or even oysters and libido – is tenuous, to say the least.