In 2004 UK TV chef Jamie Oliver ran an exper­i­ment at a school in Green­wich, Lon­don for an upcom­ing show of his, Jamie’s School Din­ners. By var­i­ous means Oliver attempted to improve the eat­ing habits of the school’s stu­dents and, by-and-large, succeeded. Tracking his progress–and that of the children–were two Oxford econ­o­mists, Michele Belot and Jonathan James.

The two noted how Oliver’s cam­paign had inad­ver­tently cre­ated “a near-perfect exper­i­ment” and so began fol­low­ing the aca­d­e­mic achieve­ments of the chil­dren with much supe­rior eat­ing habits than their peers and the school as a whole.

Five years later the exper­i­ment started to show results: specif­i­cally, that the eat­ing habits of school chil­dren has a pro­found pos­i­tive effect on their edu­ca­tion.

Their answer – a pro­vi­sional one, since they are still refin­ing the research – is that feed­ing pri­mary school kids less fat, sugar and salt, and more fruit and veg­eta­bles, has a sur­pris­ingly large effect. Autho­rised absences, the best avail­able proxy for ill­ness, fell by 15 per cent in Green­wich, rel­a­tive to schools in sim­i­lar Lon­don bor­oughs. And rel­a­tive to other bor­oughs, the pro­por­tion of chil­dren reach­ing Level Four* in Eng­lish rose by four and a half per­cent­age points (more than six per cent), while the pro­por­tion of chil­dren achiev­ing Level Five* in Sci­ence rose by six points, or almost 20 per cent.

* I freely admit my igno­rance: I’ve no idea what these lev­els refer to. (And I’m not a fan of Jamie Oliver, if you were wondering.)