indication of a potential association or to support (or not support) results from other studies. The committee used two major criteria to assess the quality of the evidence for all study designs: (1) the method to estimate sodium intake and the quality of its implementation, and (2) confounder adjustment. Other criteria included the approach used to change sodium intake, the instrument used to estimate sodium intake, the length of the intervention or follow-up of participants, interactions with other factors, and generalizability to the general population or population subgroups.
FINDINGS AND CONCLUSIONS
Recognizing the limitations of the available evidence, the committee found no consistent evidence to support an association between sodium intake and either a beneficial or adverse effect on most direct health outcomes other than some CVD outcomes (including stroke and CVD mortality) and all-cause mortality. Some evidence suggested that decreasing sodium intake could possibly reduce the risk of gastric cancer. However, the evidence was too limited to conclude the converse—that higher sodium intake could possibly increase the risk of gastric cancer. Interpreting these findings was particularly challenging because most studies were conducted outside the United States in populations consuming much higher levels of sodium than those consumed in this country. Thus, the committee focused its findings and conclusions on evidence for associations between sodium intake and risk of CVD-related events and mortality.
Findings and Conclusions for Cardiovascular Disease, Stroke, and Mortality
General U.S. Population
Finding 1: The committee found that the results from studies linking dietary sodium intake with direct health outcomes were highly variable in methodological quality, particularly in assessing sodium intake. The range of limitations included over- or underreporting of intakes or incomplete collection of urine samples. In addition, variability in data collection methodologies limited the committee’s ability to compare results across studies.
Conclusion 1: Although the reviewed evidence on associations between sodium intake and direct health outcomes has methodological flaws and limitations, the committee concluded that, when considered collectively, it indicates a positive relationship between higher levels of sodium intake and risk of CVD. This evidence is consistent with existing evidence on blood pressure as a surrogate indicator of CVD risk.