Several more obscure chocolate ingredients seem to act by affecting the brain's own neurotransmitter network.
Neurotransmitters are the chemical messengers of the brain. They work by transporting electrical signals between nerve cells. These signals cause changes in the sensations and emotions that we experience.
Love drug?
Chocolate contains a natural 'love drug'. Tryptophan is a chemical that the brain uses to make a neurotransmitter called serotonin. High levels of serotonin can produce feelings of elation, even ecstasy - hence the name of the designer drug that also works by increasing serotonin levels.
Lust drug?
While tryptophan could be considered 'chocolate's ecstasy', another chemical called phenylethylamine has earned the nickname 'chocolate amphetamine.' High levels of this neurotransmitter help promote feelings of attraction, excitement, giddiness and apprehension. Phenylethylamine works by stimulating the brain's pleasure centres and reaches peak levels during orgasm.
But many scientists are sceptical that chocolate could produce mood-altering effects in this way. Chemicals like tryptophan and phenylethylamine, which are also found in many other foodstuffs, are present in chocolate only in very small quantities.
Chocolate pot?
The same is true of anandamide, the current favourite candidate for a psychoactive chocolate ingredient. Anandamide is a neurotransmitter that targets the same brain structures as THC, the active ingredient in cannabis. But to make a substantial impact on the brain's own natural anandamide levels, experts estimate you would need to eat several kilos of chocolate!
Neuroscientist Daniele Piomelli suggests that chocolate works more indirectly to produce its 'high'. As well as anandamide itself, chocolate contains two chemicals known to slow the breakdown of anandamide. Chocolate might therefore work by prolonging the action of this natural stimulant in the brain. The animation below shows how this could work.
Is Chocolate Good For You?
Should chocolate be an essential component of a balanced diet? Back in the 17th and 18th centuries, many treatises were written extolling the medicinal virtues of chocolate and today it's a regular feature in army food rations.
During the Gulf War, critical equipment flown out to US forces included a specially formulated heat-stable chocolate bar. But the jury is still out on whether or not it's good for us.