Assessing the U.S. Population’s Sodium Intake

Sodium intake has become a hot topic as public policymakers address regulatory proposals aimed at lowering the amounts in foods. In 2010, the Institute of Medicine issued a report recommending that new national sodium standards be implemented by the federal government. Several major food manufacturers have long been implementing sodium-reduction strategies through self-regulation.

The usefulness of proposed regulatory steps will depend on accurate and practical methods to monitor the U.S. population’s sodium intake. In the late 1990s, researchers at the Agricultural Research Service’s Beltsville Human Nutrition Research Center developed the Automated Multiple Pass Method (AMPM), an innovative surveying tool used to obtain information on the amounts of foods and beverages consumed by a survey volunteer during a 24-hour period.

The researchers also conducted a study to evaluate the accuracy of the method, using each volunteer’s 24-hour urinary excretion to measure biomarkers of nutrient status. That study, involving 524 male and female volunteers aged 30 to 69 years, confirmed the accuracy of this innovation in food-consumption survey methods.

Now, Donna Rhodes, a nutritionist with the Beltsville center, has used this data to assess sodium intakes. The accuracy of sodium intake was calculated as the ratio of reported dietary intake to that estimated from the urinary sodium excretion. Estimates of sodium intake included salt added in cooking but not salt added at the table.

The results showed that the AMPM-derived dietary sodium-intake estimates (based on volunteers’ reported food consumption) were 93 percent accurate among men and 90 percent accurate among women when cross-checked against the urinary sodium-excretion data.

Results from this study are significant because they demonstrate that the AMPM is a valid tool for estimating sodium intake as well as energy intake. The current USDA-ARS national food and nutrient intake survey uses the automated tool for both in-person and telephone interviews.

“The automated tool will continue to accurately estimate the population’s sodium intakes from foods as food-composition databases produced by ARS are routinely updated to reflect changes in the salt content of foods consumed,” says Rhodes.

The study was accepted for publication by the American Journal of Clinical Nutrition.—By Rosalie Marion Bliss, Agricultural Research Service Information Staff.

Donna Rhodes is in the USDA-ARS Food Surveys Research Group, 10300 Baltimore Ave., Bldg. 005, Beltsville, MD 20705-2350; (301) 504-0348.

"Assessing the U.S. Population’s Sodium Intake" was published in the October 2013 issue of Agricultural Research magazine.