The sugar industry has manipulated scientific research on fluoride since the 1930s — exaggerating its benefits, suppressing concerns about serious side effects and shifting attention away from sugar’s role in tooth decay, according to a study published Monday in the journal Environmental Health. Internal sugar industry and dental organization documents, analyzed by the study’s author Christopher Neurath, detail how the sugar industry helped shape the public health policies that, for decades, touted fluoride as a “magic bullet” against tooth decay.