If ever a science book was written for kiddies, this is it. The Weisses assure readers that carrots are good for your eyes even though ""lots of gifts and boys probably suspect it's just something parents have invented""--but you can also OD on vitamin A, as a chapter beginning ""When Mr. Smith died he was a bright orange color"" relates. With all the repetitive banality of an easy reader mystery, the authors follow Sir Frederick Gowland Hopkins, a former detective, on the trail of a beriberi cure, and they set Dr. Joseph Goldberger to jouncing over rough Southern roads to the tune of ""Pel-LA-gra. Pel-LA-gra. Pel-LA-gra."" As for ""how vitamins work,"" another chapter heading, the answer, in toto, is that they act like ""tools"" to take food apart. The authors end with a warning against ""junk foods,"" saying the FDA should protect us but doesn't. Here, it's the reviewer's job.