approaches and study designs. Methodologic problems in assessing sodium intake make this particularly challenging.
The committee identified a number of data and methods gaps in studies on sodium intake and risk of adverse health outcomes among population groups. Further research in the areas highlighted below would strengthen the evidence base on the association between lower (1,500 to 2,300 mg) levels of sodium and health outcomes in the general population and population subgroups:
1. standardized methodological approaches to measure sodium intake in population groups. Specific examples include standardizing the use of multiple 24-hour urine collections and validating sodium intake estimates with data on urine volume, urine creatinine, and body weight;
2. approaches using dietary sodium intake levels corresponding to levels in current guidelines (i.e., 1,500 to 2,300 mg per day) when examining associations between sodium intake and health outcomes;
3. analyses examining the effects on health outcomes of dietary sodium in combination with other electrolytes, particularly potassium;
4. methods that account for potential confounding factors in dietary studies, including the influence of reported total daily caloric intake on observational associations between sodium and health outcomes, and methods that clarify attributes of individuals with apparently low sodium intake or excretion; and
5. analyses of interactions with antihypertensive medication and blood pressure in studies examining associations between sodium intake and health outcomes.
In addition, the committee identified a need for RCT research, and observational and mechanistic studies, particularly in population subgroups. Examples of such clinical trials include those to examine
1. effects of a range of sodium levels on risk of cardiovascular events, stroke, and mortality among
a. patients in controlled environments, where randomized trials may be more feasible, such as the elderly in chronic care facilities and other institutionalized individuals; and