Chocolate is almost synonymous with Valentine’s Day, but it's doubtful that saint valentine even tasted it. During the martyr's lifetime in third-century Rome, chocolate was still limited to native South America.

Today chocolate is enjoyed by people the world over, with some 2.3 billion pounds of chocolate consumed in America each year. That amounts to 10.8 pounds per person.

The gift of chocolate

Legend has it that chocolate was a gift of the gods.

Legend has it that chocolate was a gift of the gods. The cacao tree was supposedly brought to mankind by Quetzalcoatl, the Aztec god who taught mortals how to make a drink from it.

Giving someone chocolates still carries a wealth of meaning. The custom even has royal approval, ever since 1900 when Queen Victoria sent special tins of chocolate to soldiers in the bore war to wish them a happy new year.

And of course chocolate often sends a message of love, whether it's a gift-wrapped box for mother's day or a valentine's present of heart-shaped truffles.

Chocolate, love and sex

French doctors prescribed chocolate to women patients for a broken heart.

Chocolate has long been associated with love. At one time, nuns were forbidden to eat it because of its sexual reputation. Casanova is believed to have thought of hot chocolate as the "elixir of love". And in the 18th century, French doctors prescribed chocolate to women patients for a broken heart.

Science may hold a clue - chocolate contains a substance called phenyl ethylamine, a naturally occurring chemical in the brain which promotes feelings of euphoria associated with being in love. It also contains a variety of other substances which may help create a feeling of well-being. Do you know?

That same 100 grams of chocolate also contains 5 milligrams of methylxanthine and 160 milligrams of Theo bromine, both caffeine-like stimulants. When taken in large quantities, these stimulants can induce nausea and vomiting-a good reason to limit your valentine's day nibbling to a few chocolates.

Meanwhile, chocolate is poisonous to dogs and other pets, and can even be lethal. Don’t give it to your dog. Theo bromine is toxic to dogs, and one ounce of chocolate could kill a 10-pound canine.