Figure 2From: Causal assessment of dietary acid load and bone disease: a systematic review & meta-analysis applying Hill's epidemiologic criteria for causality The relationship between change in NAE and change in urinary calcium, limited to randomized studies that followed the Institute of Medicines' guidelines for calcium metabolism studies (R2 = 0.406; p < 0.0001). This material is reproduced with permission of John Wiley & Sons, Inc. from Fenton et al. J Bone Miner Res 2009;24:1835-1840.Back to article page