Food myths dating back thousands of years seemed to have been disproved by one brief experiment when the BBC 2 television programme TheTruth About Food investigated their power. According to the programme makers, a bit of old-fashioned flirting is far more effective than food, although feeding your love a juicy strawberry (or two) can prove a seductive scene-setter.

To test the power of oysters, chocolate and strawberries, which are all attributed with aphrodisiac powers, the researchers matched two men and two women with attractive members of the opposite sex and served them these foods. They then tested the participants for physiological responses - but found none. Blushes detected by thermal imaging when the couples first meet were not intensified by the so-called aphrodisiacs. The foods left them unmoved, leaving us to assume that Casanova hardly needed his daily diet of 50 oysters to boost his libido. Actually, oysters have recently been found to contain the chemicals D-aspartic acid and NMDA which encourage the release of the sex hormones oestrogen and testosterone - so perhaps he did get it right? Possibly those taking part in the experiment were not given enough?

Using food to enhance a seduction scene is nothing new. Mankind has sought out special foods to arouse the libido and enrich sexual potency since the beginning of time. Foods named after Aphrodite, the Greek Goddess of love, are embedded in our folklore. But, until now, they have seldom been tested scientifically or taken that seriously.

The foods that the BBC tests are just a small sample of all the so-called aphrodisiacs available. Documented aphrodisiacs range from fish, to herbs, spices, fruits, vegetables and chocolate. Many fall into this category because of their exotic nature, or because of the ancient Doctrine of Signatures, which declares that the hidden nature of the plant is revealed through its external appearances.

This doctrine is the product of medieval alchemists and herbalists, though similar beliefs were held by both the native Americans and Oriental cultures. It was thought that God marked everything with a sign (signature) which indicated the purpose of its creation. Take walnuts - by the 17th century, the bumpy nut kernels inside the shell were so similar to the shape of the brain that they were eaten to strengthen it. The walnut's woody shell was likened to the skull. Given that theory it's easy to see why vegetables such as celery, asparagus, chillies, truffles and avocados were listed as aphrodisiacs and why oysters were the most popular aphrodisiac of them all.

Prunes were highly prized as aphrodisiacs, too, particularly during Elizabethan times when they were served free in brothels. The Arabs ate sea slugs because these creatures swell and enlarge when touched. Chocolate seems to have been a favourite throughout time, yet even that had very little effect on those taking part in BBC2's experiment. This is strange as it contains two substances that serve to lift our mood, Phenylethylamin and Seratonin. Both occur naturally in the human brain and are released into the nervous system when we are happy or experiencing feelings of passion. Chocolate is known to induce feelings of well-being bordering on euphoria.

Chocolate's use as an aphrodisiac goes far further back than the Doctrine of Signatures. The early Mayan and Aztec cultures believed it invigorated men and made women less inhibited. The Aztec emperor Montezuma drank 50 goblets of chocolate a day to enhance his sex life.

So why didn't the experiment work, either for chocolate or any of the other foods eaten by the participants? I ask this question because we are approaching St Valentine's Day, and if I am to keep this page topical I should highlight dishes that are particularly suitable for lovers.

It seems that despite all the folklore associated with aphrodisiacs, those feelings we associate with love and desire are far too complex to be turned on and off by a few mouthfuls of food.

Those who watched and enjoyed the seduction scene in the 1963 screen version of Tom Jones, with Albert Finney and Joyce Redman lusting after each other as they wordlessly consume a spicy banquet, will realise this erotic sequence gained its momentum from the flirtatious manner in which they eyed each other while eating. The food was merely a prop. If there were aphrodisiacs on that table, it wouldn't have made much difference to the sensuous way they ate.

Yes - it's fun to add a dish of oysters to the St Valentine's Day dinner. They act as a symbol, a suggestion that seduction is also on the menu. It is also great fun to share a dish of asparagus dripping with melted butter, except that the English asparagus season is several months away. Any asparagus on the supermarket shelves during February will have been imported and taste nothing like those firm green shoots that emerge here in May.

I think it's worth noting that the dish of aphrodisiacs tested on the programme are not eaten during a romantic candlelit dinner. Perhaps they would have been effective if served in different circumstances. Circumstances which would allow them to be sensuously enjoyed in candlelight rather than nibbled in the back of a car.

Jill Fullerton-Smith has written a splendid book supporting The Truth About Food (Bloomsbury, £15.99).