day and projections from effects on blood pressure that dietary sodium intake up to 2,300 mg daily2 is not likely to cause any harm.
The relationship between other electrolytes and changes in blood pressure remains unresolved. Yet, as noted in the Report of the Dietary Guidelines Advisory Committee (DGAC) (USDA and HHS, 2010b), the effects of lowering sodium intake on blood pressure cannot always be disentangled from the effects of total dietary modification. For example, the committee’s review revealed that in a number of studies the effects of dietary sodium on CVD outcomes sometimes persisted even after controlling for blood pressure, suggesting that associations between dietary sodium and risk of CVD may be mediated through other dietary factors (e.g., the effects of other electrolytes), or through pathways in addition to blood pressure. Further, older data indicate that some people in the population may be salt sensitive, while others are not, and that blood pressure response to sodium varies widely (see Chapter 3). In this context, new data have raised questions about the health effects of lowering sodium intake on health outcomes.
Thus, in response to its charge, the committee focused its examination of evidence on the associations between dietary sodium intake and direct health outcomes, not on blood pressure as an indirect or intermediate marker of CVD outcomes (see Appendix D). In deriving its findings and conclusions about the evidence for associations between dietary sodium intake and health outcomes, the committee examined the quality as well as the quantity of the evidence. The conclusions and recommendations drawn from the committee’s findings are described below.
The committee’s assessment of the evidence reviewed was guided by a number of factors. These included the study design, the quantitative measures of dietary sodium intake and confounder adjustment, and the number and consistency of relevant studies available.
From the evidence reviewed on health outcomes, the committee found that a number of the populations evaluated were outside the United States and included groups that consumed mean levels of sodium much higher than 3,400 mg per day, the average amount consumed by adults in the United States (USDA and HHS, 2010b). Thus, the applicability of some of the results to the U.S. population was of concern. For example, in the studies reviewed, “high” sodium intake levels ranged from about 2,700 to more than 10,000 mg per day.
Overall, the committee found both the quantity and quality of relevant studies to be less than optimal. Further, almost all of the evidence on
2 Applies to adults aged 19-50 years.