(milligrams per 24 hours) ranged from 2,232 among African American men in Goodman, Mississippi, to 4,012 among African American men in Jackson, Mississippi. Measures from men in the other centers—Chicago and Hawaii—were between 3,550 and 3,650. Urinary sodium levels for women among the four centers ranged from 2,538 among African Americans in Goodman to 3,035 among Hawaiians (Loria et al., 2001). These 1985–1987 urinary estimates are consistent with the observed pattern increase in mean daily dietary sodium intake between NHANES II (1976–1980) and NHANES III (1988–1994).

INTERMAP is an international cooperative study that aimed to clarify the role of multiple dietary factors in blood pressure among middle-aged and older individuals in East Asian and Western countries (Zhou et al., 2003). The investigators recognized advances in knowledge of the relationships between nutrient intake and blood pressure—furthered by INTERSALT and the Dietary Approaches to Stop Hypertension (DASH) feeding trials, for example—and used those advances as a reference point and rationale for INTERMAP’s design and methods. The cross-sectional study of nearly 4,700 men and women ages 40–59 years was conducted by INTERMAP staff in China, Japan, the United States, and the United Kingdom. Research support came from NHLBI; the Chicago Health Research Foundation; and national agencies in China, Japan, and the United Kingdom. Mean daily sodium intake was determined from two timed 24-hour urine collections. INTERMAP participants were recruited from 1997 to 1999.

Urinary sodium levels (milligrams per 24 hours) were 4,202 among U.S. men and 3,272 among U.S. women (Zhou et al., 2003). These are consistent with the dietary data obtained from NHANES showing that intake is well above recommended levels and suggest somewhat greater underreporting of dietary intake among women. The available 24-hour urinary sodium measures support the NHANES time trend of increasing sodium intake between the early 1970s and the 1990s (Briefel and Johnson, 2004).

The Coronary Artery Risk Development in Young Adults (CARDIA) study, conducted in the United States, included a trio of consecutive 24-hour urinary sodium collections for a subsample of the cohort in 1990–1991 (Loria et al., 2001). Complete data were obtained for 920 participants, ages 25–37 years, half of whom were Caucasian, the other half African American. However, energy intake was not estimated. Urinary sodium levels (milligrams per 24 hours) were 4,430 for African American men, 4,550