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. 2010 Jun 23;92(2):436–443. doi: 10.3945/ajcn.2010.29672

FIGURE 3.

FIGURE 3

Box plots of urinary proline betaine excretion of volunteers recording no citrus fruit consumption (no citrus), citrus fruit consumption (citrus), and citrus fruit consumption only on day 1 (only D 1). A: Proline betaine in the Belfast (UK) sample (no citrus: n = 96; citrus: n = 96; only D 1: n = 28). B: Proline betaine in the West Bromwich (UK) sample (no citrus: n = 181; citrus: n = 71; only D 1: n = 27). C: Receiver operating characteristic curves to assess the predictive ability of excretion of proline betaine for discrimination of citrus fruit intake and no citrus fruit intake as reported in the dietary recall data for the training set [International Collaborative Study of Macronutrients, Micronutrients, and Blood Pressure (INTERMAP) UK Belfast sample] and test set (INTERMAP UK West Bromwich sample). The optimal operating point (▪) for the training set was a peak integral value of 39.4 for proline betaine. This represented a specificity and sensitivity of 90.6% and 86.3%, respectively, for the training set and 92.3% and 80.6%, respectively, for the validation set.