Figure 1).

The total breath hydrogen (TBH₂) during the lactose challenge (sum of the increase in breath hydrogen over baseline at each 30 min interval from 30 min to 270 min) is plotted against the daily dairy food intake for lactase persistent (LP) subjects (solid circles) and lactase nonpersisitent (LNP) subjects (open circles). Regression lines are not plotted (R²=0.01; P>0.6 for both LP and LNP subjects). Note that some points overlap and, therefore, not all points are clearly visible. ppm Parts per million