A large dutch study found that the incidence of fatal heart disease was more than 50% lower among men who regularly ate fish than those who ate no fish at all.

There is no shortage of old wives’ tales about the virtues of eating fish: it is “brain food,” according to legend, and cod-liver oil is a cure for all that ails. The wives may have been onto something. Eating a little fish a day may indeed keep the doctor away,…