Sodium Intake recommendations in Adults

Application of Lower Sodium Intake Recommendations to Adults -- United States,
1999-2006

Reported by: C Ayala, PhD, EV Kuklina, MD, PhD, J Peralez, MPH, NL Keenan, PhD, DR Labarthe, MD, PhD, Div for Heart Disease and Stroke Prevention, National Center for Chronic Disease Prevention and Health Promotion, CDC.

In 2005--2006, an estimated 29% of U.S. adults had hypertension (i.e., high blood pressure), and another 28% had prehypertension.[1]
Hypertension increases the risk for heart disease and stroke,[2] the first and third leading causes of death in the United States.[3]
Greater consumption of sodium can increase the risk for hypertension.[4]
The main source of sodium in food is salt (sodium chloride [NaCl]); uniodized salt is 40% sodium .
In 2005--2006, the estimated average intake of sodium among persons in the United States aged ≥2 years was 3,436 mg/day.[5]
In 2005, the U.S. Department of Health and Human Services and U.S. Department of Agriculture recommended that adults in the United States should consume no more than 2,300 mg/day of sodium (by equal to approximately 1 tsp of saltweight), but those in specific groups (i.e., all persons with hypertension, all middle-aged and older adults, and all blacks) should consume no more than 1,500 mg/day of sodium.[6]
To estimate the proportion of the adult population for whom the lower sodium recommendation is applicable, CDC analyzed data from the National Health and Nutrition Examination Survey (NHANES) for the period 1999--2006. The results indicated that, in 2005--2006, the lower sodium recommendation was applicable to 69.2% of U.S. adults. Consumers and health-care providers should be aware of the lower sodium recommendation, and health-care providers should inform their patients of the evidence linking greater sodium intake to higher blood pressure.

NHANES is an ongoing series of cross-sectional surveys on health and nutrition designed to be nationally representative of the noninstitutionalized, U.S. civilian population by using a complex, multistage probability design. All NHANES surveys include a household interview followed by a detailed physical examination, including blood pressure tests.* Data from four NHANES survey periods (1999--2000, 2001--2002, 2003--2004, and 2005--2006) were used to estimate the percentages of U.S. adults in the three risk groups for whom lower sodium intake of ≤1,500 mg/per day was recommended in 2005.† To represent the three risk groups, three nonoverlapping populations were defined for the analysis: all adults aged ≥20 years with hypertension, all adults aged ≥40 years without hypertension, and blacks aged 20--39 years without hypertension.[6] Participants first were categorized as having hypertension or not having hypertension, using an average of two or more blood pressure measurements (87% of the sample had three or more measurements). Hypertension was defined as having systolic blood pressure of ≥140 mm Hg, or diastolic blood pressure of ≥90 mm Hg, or taking antihypertension medication; prehypertension was defined as systolic blood pressure of 120--139 mm Hg or diastolic blood pressure of 80--89 mm Hg, and not taking antihypertension medication. Overall for the four survey periods, 22% of participants with hypertension had normal blood pressure readings but were categorized with hypertension because they self-reported taking antihypertension medication. Percentage estimates and 95% confidence intervals (CIs) were calculated using statistical software to account for nonresponse and complex sampling design. The significance of linear trend across survey periods was determined by using orthogonal polynomial coefficients calculated recursively.

Overall in 2005--2006, 69.2% of U.S. adults aged ≥20 years (approximately 145.5 million persons) met the criteria for the risk groups recommended for lower sodium consumption of ≤1,500 mg/day. Among adults aged ≥20 years, 30.6% were found to have hypertension; 34.4% did not have hypertension but were aged ≥40 years, and 4.2% did not have hypertension but were black and aged 20--39 years (Table). The overall percentage of persons in these risk groups increased significantly over the four NHANES study periods: 64.4% in 1999--2000, 67.4% in 2001--2002, 69.0% in 2003--2004, and 69.2% in 2005--2006 (p for linear trend = 0.05) (Table).


* Additional information available at http://www.cdc.gov/nchs/data/nhanes/databriefs/calories.pdf.