for Americans. The charge reflects the conclusions of the widespread and numerous public health initiatives that began in the early 1970s and have continued through the present time, as discussed in Chapter 2. Overall, these initiatives, many of which relied on expert advisory committees for scientific expertise, concluded that there is strong scientific support for a direct and progressive relationship between sodium intake and blood pressure. They also voiced long-standing concerns about unacceptably high incidence of hypertension among U.S. adults and the associated increased risk for cardiovascular disease (e.g., stroke and coronary heart disease) and the persistence of high intake of sodium among the general U.S. population. All recommended reduced sodium intake as a public health strategy.
Although a primary scientific review to document the relationship between sodium intake and disease risk was not within the committee’s mandate, the study required an understanding of the science relative to two key questions if the committee’s strategy decisions were to be adequately informed. The first question relates to the seriousness and nature of the public health problem. The nature of the recommended strategies should be commensurate with the seriousness and extent of that problem. The second question relates to the nature of the target population—specifically, whether the strategies should focus on the general population or be limited to specified subpopulations.
To understand the nature of the scientific consensus among qualified experts on these two questions, it was deemed useful to review the scientific conclusions from the most current major authoritative consensus bodies, including the 2005 Dietary Guidelines Advisory Committee (DGAC, 2005), the IOM (2005), and the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (NHLBI, 2004), and to update these reports, where applicable and necessary, with other relevant evidence.
The prevalence of hypertension is common and increasing among American adults. It is a condition associated with several factors including obesity, genetics, and food- and physical activity-related behaviors, some of which may be related to culture/ethnicity. While the definition of hypertension has changed over time, rates of hypertension have remained high. The age-standardized prevalence rate of hypertension was 24 percent in NHANES III (1988–1994) (Cutler et al., 2008) and increased to 28–30 percent during the continuous NHANES from 1999 to 2006 (Ostchega et al., 2008). More than half of persons 60–69 years of age, and approximately three-fourths of those 70 years and older, have hypertension (NHLBI, 2004). The number of adults with hypertension in 1988–1994 was approxi-