Urine Sodium Excretion Increased Slightly among U.S. Adults between 1988 and 2010

Abstract

Little information is available on temporal trends in sodium intake in the U.S. population using urine sodium excretion as a biomarker. Our aim was to assess 1988–2010 trends in estimated 24-h urine sodium (24hUNa) excretion among U.S. adults (20–59 y) participating in the cross-sectional National Health and Nutrition Examination Survey (NHANES). We used subsamples from a 1988–1994 convenience sample, a 2003–2006 1/3 random sample, and a 2010 1/3 random sample to comply with resource constraints. We estimated 24hUNa excretion from measured sodium concentrations in spot urine samples by use of calibration equations (for men and women) derived from the INTERSALT study. Estimated 24hUNa excretion increased over the 20-y period (1988–1994, 2003–2006, and 2010) [mean ± SEM (n)]: 3160 ± 38.4 mg/d (1249), 3290 ± 29.4 mg/d (1235), and 3290 ± 44.4 mg/d (525), respectively (Ptrend = 0.022). We observed significantly higher mean estimated 24hUNa excretion in each survey period (P <0.001) for men compared to women (31–33%) and for persons with higher body mass index (BMI) (32–35% for obese vs. normal weight) or blood pressure (–26% for hypertensive vs. normal blood pressure). After adjusting for age, sex, and race-ethnicity, temporal trends in mean estimated 24hUNa excretion remained statistically significant (Ptrend = 0.004). We observed no temporal trends in mean estimated 24hUNa excretion among BMI subgroups, nor after adjusting for BMI. While several limitations apply to this analysis (the use of a convenience sample in 1988–1994 and using estimated 24hUNa excretion as a biomarker of sodium intake), these first NHANES data suggest that mean estimated 24hUNa excretion increased slightly in U.S. adults over the last 2 decades and this increase may be explained by a shift in the distribution of BMI.

Asian American Dietary Sources of Sodium and Salt Behaviors Compared with Other Racial/Ethnic Groups, NHANES, 2011-2012

“…In the United States, Changes in sodium intake over time have also been reported using repository-based analyses of spot urine samples and application of recalibration equations to estimate 24-hour excretion in NHANES. 30 Between 1988 and 2010, estimated 24-hour urinary sodium excretion increased by 130mg/day; however, increasing BMI over the same time period likely contributed to these increases. 30 Current efforts for reducing population sodium intake are geared toward reformulation and increasing consumer awareness of sodium in packaged and restaurant foods.…”

“…30 Between 1988 and 2010, estimated 24-hour urinary sodium excretion increased by 130mg/day; however, increasing BMI over the same time period likely contributed to these increases. 30 Current efforts for reducing population sodium intake are geared toward reformulation and increasing consumer awareness of sodium in packaged and restaurant foods. However, the reach to Asian Americans, who have high sodium intakes, 12 may be limited for two reasons.…”

Dietary Sodium and Blood Pressure: How Low Should We Go?

“…ACCEPTED MANUSCRIPT 12 The 2015 DGAC report based its final recommendations on reviews from three primary sources. Regarding the question: "What is the relationship between dietary sodium intake and BP in adults?"…”

“…10,11 This complex methodology is often identified as the rate limiting step in conducting well-designed studies and randomized clinical trials to better and more definitively address lingering questions regarding dietary sodium and its impact on BP. 12 Cost, quality control, and participant burden represent major deterrents from incorporating these methods and efforts to abbreviate, simplify and otherwise minimize these limitations have perpetuated without satisfactory alternatives. 12 Overnight, spot and first morning urine collections have been suggested as viable alternatives, but none of these are considered as reliable as the mean of multiple 24 hour urine collections for individuals, although recent studies have offered encouraging results for estimating average sodium intake among Western (North American and European) adults aged 20-59.…”

“…12 Cost, quality control, and participant burden represent major deterrents from incorporating these methods and efforts to abbreviate, simplify and otherwise minimize these limitations have perpetuated without satisfactory alternatives. 12 Overnight, spot and first morning urine collections have been suggested as viable alternatives, but none of these are considered as reliable as the mean of multiple 24 hour urine collections for individuals, although recent studies have offered encouraging results for estimating average sodium intake among Western (North American and European) adults aged 20-59. 13 On the basis of 2009-2010 National Health and Nutrition Examination Survey (NHANES) data, the average sodium intake for all persons age 2 years and older was 3,463 mg/day.…”