Heneghan C, Howick J, O'Neill B, et al. The evidence underpinning sports performance products: a systematic assessment. BMJ Open 2012;2:e001702. There is a typographical error in the abstract (it is correct in the main body of the text). The last line of the results section of the abstract should read “Only three of the 74 (4.1%) studies were judged to be of high quality and at low risk of bias.”