is no method for determining which individuals fall within the 20 percent of the population that will not become hypertensive. Furthermore, because excess sodium intake can gradually increase blood pressure throughout life, before individuals develop clinically defined hypertension, and taste preferences for salty foods may be established early in life, long before individuals are aware of their risk for hypertension, a focus on at-risk subgroups could potentially fail to reach individuals who would benefit from a reduced sodium intake.
Although the extension of recommendations from high-risk groups to the general population has engendered controversy (Alderman, 2010; Cohen et al., 2006; Loria et al., 2001; McCarron, 2000, 2008; McCarron et al., 2009), numerous expert advisory panels (see Appendix B), including the most recent Dietary Guidelines Advisory Committee (DGAC, 2005), have consistently and repeatedly concluded, after careful evaluation of stakeholder concerns and the available scientific evidence, that the evidence and public health concerns warrant extending recommendations for sodium intake reduction to members of the general population across the lifespan. Recent data, including results of a clinical trial that documented the long-term benefits of sodium reduction in terms of cardiovascular events (Cook et al., 2007), have only strengthened the scientific rationale for population-wide sodium reduction (Bibbons-Domingo et al., 2010).
While the clinical problem of hypertension most commonly affects middle-aged and older adults in developed countries such as the United States, the genesis of elevated blood pressure is a lifelong process in which blood pressure rises gradually with age. There is a progressive dose-response relationship, without an apparent threshold, between salt intake and increased blood pressure across a range of salt intakes (DGAC, 2005). Published findings indicate that the genesis of hypertension begins in childhood and that blood pressure-related vascular disease is already evident at early ages (Cutler and Roccella, 2006). Specifically, in autopsy studies of children and young adults, elevated blood pressure in children is directly associated with fatty streaks and fibrous plaques in the aorta and coronary arteries (Berenson et al., 1998). In young adults, there is a direct relationship between blood pressure and coronary artery calcium scores (Loria et al., 2007; Mahoney et al., 1996).
As in adults, sodium reduction during childhood lowers blood pressure. Therefore, decreases in sodium intake during childhood and early adulthood are thought to help blunt the well-documented increases in blood pressure that occur with age among the U.S. population and thereby prevent the development, or delay the onset, of clinical hypertension (Cutler and Roccella, 2006; Ellison et al., 1989; He and MacGregor, 2006).
In addition to the progressive nature of increasing blood pressure levels and associated cardiovascular disease risks throughout life as noted above,