The pleasure-inducing chemical dopamine contains tyrosine and phenylalanine, a pair of amino acids that can be found in protein-packed foods like fish, meat and beans.

To cater for the aversion to red meat, and a new-found need for omega-3 fatty acids, fish dishes are on every menu, even in steak houses.

Ironically, these compounds are formed by the reaction of iron with the unsaturated fatty acids that make seafood healthier to eat than red meat.