Much of the data available in 1988 had been derived from small numbers in cross-sectional studies, chiefly clinical, only a few population-based. Large samples were needed to provide adequate power to detect relationships among LCT and demographic, dietary, and other factors. Prospective data were needed to assess whether LCT was an independent risk factor for future development of high blood pressure in people normotensive at baseline, whether LCT could be modified, and whether this change was associated with changes in blood pressure.