In 1994 they gave sugar to 48 children and nothing happened

1995. The journal JAMA publishes a review of twenty-three controlled studies on sugar and children's behaviour. Conclusion: sugar does not alter children's behaviour or cognitive performance, not even in those their families describe as especially sensitive.

1994. A team led by Mark Wolraich puts 48 children through three three-week diets — 25 preschoolers and 23 schoolchildren flagged at home as sugar-sensitive — without families or researchers knowing which diet was in play. One contained sugar; the other two, sweeteners. Nobody could tell them apart.

1994, a few months earlier. Daniel Hoover and Richard Milich run the experiment that explains everything else: a group of mothers are told their son has just had a drink loaded with sugar. It is a lie; every child was given a sweetener. Those mothers rate their sons as more hyperactive than the rest and, on video, criticise them more, hover closer and talk to them more.

1973. The allergist Benjamin Feingold proposes a diet in California against hyperactivity, cutting out colourings, preservatives and salicylates. Sugar was not on his list. It slipped into the popular version and it is still there.

Sugar's effects on teeth and weight are amply documented. On behaviour, after twenty-three studies and three decades, none has been found.