Prevalence of Excess Sodium Intake in the United States — NHANES, 2009–2012

Sandra L. Jackson, PhD1,2; Sallyann M. Coleman King, MD2; Lixia Zhao, PhD2,3; Mary E. Cogswell, DrPH2

Hypertension, a major risk factor for cardiovascular diseases, occurs among 29% of U.S. adults, and lowering excess sodium intake can reduce blood pressure (1–3). The 2015–2020 Dietary Guidelines for Americans recommend consuming less than 2,300 mg dietary sodium per day for persons aged ≥14 years and less for persons aged 2–13 years.* To examine the current prevalence of excess sodium intake among Americans overall, and among hypertensive adults, CDC analyzed data from 14,728 participants aged ≥2 years in the 2009–2012 National Health and Nutrition Examination Survey (NHANES). Eighty-nine percent of adults and over 90% of children exceeded recommendations for sodium intake. Among hypertensive adults, 86% exceeded 2,300 mg dietary sodium per day. To address the high prevalence of excess sodium consumption in the U.S. population, the Institute of Medicine (IOM) recommended reducing sodium in the food supply, as excess sodium added to foods during commercial processing and preparation represents the main source of sodium intake in U.S. diets (4).

NHANES is a nationally representative, multistage survey of noninstitutionalized persons in the United States. The survey includes an in-person examination with a 24-hour dietary recall, and a second 24-hour dietary recall administered by telephone 3–10 days later. This cross-sectional study used data from NHANES years 2009–2012 (N = 20,293). For children aged 2–5 years, dietary intake was reported by a proxy, and for children aged 6–11 years, by the participant assisted by a proxy. The unweighted response rate of the examined sample was 77.3% in 2009–2010 and 69.5% in 2011–2012. This study included participants aged ≥2 years who completed two 24-hour dietary recalls (n = 14,900), but excluded pregnant women and women whose pregnancy status was unknown (n = 161), as well as respondents with unreliable dietary recalls (n = 11), yielding 14,728 respondents eligible for analysis.

Normal blood pressure was defined as a mean systolic blood pressure <120 mm Hg and mean diastolic blood pressure <80 mm Hg. Hypertension was defined as mean systolic blood pressure ≥140 mm Hg, mean diastolic blood pressure ≥90 mm Hg, or self-reported use of antihypertensive medication. Among persons who did not meet this definition of hypertension, prehypertension was defined as a mean systolic blood pressure of 120–139 mm Hg or a mean diastolic blood pressure of 80–89 mm Hg. An average of up to three brachial systolic and diastolic blood pressure readings was used for determination of blood pressure values. The majority of study participants had at least two complete blood pressure measurements, but for participants with only one, the single measurement was used. Race/ethnicity was categorized as non-Hispanic white (white), non-Hispanic black (black), and Hispanic. In sensitivity analyses, respondents who self-identified as Mexican-Americans were analyzed separately, and little difference was observed between Mexican-Americans and "other Hispanic" groups.

Estimated mean usual daily sodium intake and caloric intake (continuous variables) were calculated, as well as sodium density (mg of sodium per 1,000 kilocalories consumed). The proportion of persons with excess sodium intake was estimated by sex, age group, and racial/ethnic subpopulation, and among adults (aged ≥19 years), by hypertension status. Recommendations for sodium intake among persons aged <14 years are adjusted downward for age-specific calorie intake (Table 1). Statistical software was used to account for day-to-day variation in sodium intake to estimate usual intake from two 24-hour dietary recalls.† All analyses used survey sample weights (Dietary two-day sample) in statistical software for complex surveys.

The majority of persons in the United States in 2009–2012 exceeded recommendations for dietary sodium (Table 1). Among adults aged ≥19 years, 89% consumed excess sodium. A larger proportion of adult men (98%) than women (80%) consumed more than 2,300 mg of dietary sodium per day (p<0.001), as did a larger proportion of adult whites (90%) than blacks (85%) (p = 0.02). Among children aged 2–18 years, 92%–94% consumed excess sodium.

Sodium intake was typically higher among persons consuming more kilocalories (kcal), and estimated sodium consumed was highest among persons aged 19–50 years (Table 2). Sodium density, which captures milligrams of sodium per 1000 kcal consumed, was highest among adults aged 19–50 years (mean = 1,730 mg/1,000 kcal) and lowest among children aged 2–3 years (mean = 1,466 mg/1,000 kcal). Total sodium intake was higher among males than females (p<0.001), but sodium density did not differ significantly between sexes (p = 0.50).

Among adults with hypertension, 86% consumed dietary sodium in excess of 2,300 mg, which is statistically significantly less than the prevalence for adults with prehypertension (91%, p<0.001) and adults without hypertension (90%, p = 0.01) (Figure). Adults with hypertension had the lowest mean sodium intake (Table 2).

Discussion

Most adults and children in the United States exceed the 2015–2020 Dietary Guidelines for Americans recommendation for dietary sodium. Even among groups at higher risk for cardiovascular disease, including adults aged ≥51 years, blacks, and adults with prehypertension and hypertension, at least three out of four consumed more than 2,300 mg daily, increasing their potential risk of stroke and coronary heart disease mortality (2).

The high prevalence of excess sodium intake and the amount of sodium consumed per calorie in this report are generally consistent with previous reports including one that examined trends in sodium consumption during 2003–2010 in relation to the IOM Dietary Reference Intakes (DRIs) (5–7). This suggests that overall sodium consumption and the concentration of sodium in foods consumed have not changed over the past decade. The top sources of sodium in the U.S. diet include breads and rolls, deli meats, pizza, poultry, soups, sandwiches, cheese, pasta dishes, meat mixed dishes, such as meatloaf with tomato sauce, and savory snacks.§

During 2009–2012, despite some differences by age, sex, race/ethnicity, and hypertension status, the vast majority of Americans across all subpopulations exceeded recommendations for sodium intake. Compared with adults without hypertension, adults with hypertension consumed slightly less dietary sodium, which might indicate efforts to reduce sodium consumption among this group. However, 86% of adults with hypertension still consumed too much sodium. Compared with persons without hypertension, persons with hypertension can benefit even more from reduced sodium consumption (2). Physicians and other health care professionals can counsel their patients to lower sodium intake through following a healthy dietary pattern. One example is the Dietary Approaches to Stop Hypertension eating plan,¶ which emphasizes fruits, vegetables, and low-fat dairy products.

The findings in this report are subject to at least three limitations. First, NHANES data are subject to response bias, although the data are weighted for some nonresponse. Second, dietary data are subject to both recall bias and bias because of underreporting of foods or portion sizes. Finally, sodium intake estimates excluded salt added at the table and from dietary supplements and antacids, which account for about 5%–6% of sodium intake (4).

Given that the majority of the population consumes excess dietary sodium and one third of adults have hypertension (8), sodium reduction is an integral part of initiatives to prevent cardiovascular diseases, such as Million Hearts, which aims to prevent a million heart attacks and strokes by 2017,** CDC's Sodium Reduction in Communities Program,†† and the National Sodium Reduction Initiative, coordinated by New York City, in which some corporations have pledged to reduce sodium content to meet targets for specific food categories.§§ Other initiatives to help consumers lower sodium intake include the U.S. Department of Agriculture Nutrition Standards for school meals and competitive foods, and the Department of Health and Human Services Health and Sustainability Guidelines for Federal Concessions and Vending Operations. Reducing sodium added to foods by food manufacturers and restaurants is a fundamental public health strategy for reducing the intake of sodium to levels consistent with the 2015–2020 Dietary Guidelines for Americans (4). Globally, 36 countries have engaged industry to lower sodium intake through the setting of voluntary sodium targets for foods and meals (9). In the United Kingdom, reduction in sodium intake with this approach was associated with substantial reductions in hypertension and cardiovascular disease deaths (10). Cardiovascular diseases remain the number one killer in the United States (8), and a multifaceted strategy, including changes in individual lifestyles and how foods are produced, might contribute to the reduction of sodium consumption by Americans of all ages.

1Epidemic Intelligence Service, CDC; 2Division for Heart Disease and Stroke Prevention, National Center for Chronic Disease Prevention and Health Promotion, CDC; 3IHRC, Inc., Atlanta, Georgia.

Corresponding author: Sandra L Jackson, SLJackson@cdc.gov, 770-488-4221.

References

1. Aburto NJ, Ziolkovska A, Hooper L, Elliott P, Cappuccio FP, Meerpohl JJ. Effect of lower sodium intake on health: systematic review and meta-analyses. BMJ 2013; 346:f1326.
2. Mozaffarian D, Fahimi S, Singh GM, et al. Global sodium consumption and death from cardiovascular causes. N Engl J Med 2014;371:624–34.
3. Nwankwo T, Yoon SS, Burt V, Gu Q. Hypertension among adults in the United States: National Health and Nutrition Examination Survey, 2011–2012. NCHS Data Brief 2013; 133:1–8.
4. Institute of Medicine. Strategies to reduce sodium intake in the United States. Washington, DC: National Academies Press; 2010.
5. CDC. Usual sodium intakes compared with current dietary guidelines—United States, 2005–2008. MMWR Morb Mortal Wkly Rep 2011;60:1413–7.
6. CDC. Trends in the prevalence of excess dietary sodium intake—United States, 2003–2010. MMWR Morb Mortal Wkly Rep 2013;62:1021–5.
7. Institute of Medicine. Dietary reference intakes for water, potassium, sodium, chloride, and sulfate. Washington, DC: The National Academies Press; 2005.
8. Mozaffarian D, Benjamin EJ, Go AS, et al. Heart disease and stroke statistics—2016 update: a report from the American Heart Association. Circulation 2016;133. ePub December 16, 2015. Available at http://circ.ahajournals.org/content/early/2015/12/16/CIR.0000000000000350.full.pdf.
9. Trieu K, Neal B, Hawkes C, et al. Salt reduction initiatives around the world—a systematic review of progress towards the global target. PLoS One 2015;10:e0130247.
10. He FJ, Pombo-Rodrigues S, MacGregor GA. Salt reduction in England from 2003 to 2011: its relationship to blood pressure, stroke and ischaemic heart disease mortality. BMJ Open 2014;4:e004549.