jueves, 24 de junio de 2010

Sodium Intake Among Adults --- United States, 2005−2006


Excessive dietary sodium consumption increases blood pressure, which increases the risk for stroke, coronary heart disease, heart failure, and renal disease (1). Based on predictive modeling of the health benefits of reduced salt intake on blood pressure, a population-wide reduction in sodium of 1,200 mg/day would reduce the annual number of new cases of coronary heart disease by 60,000---120,000 cases and stroke by 32,000---66,000 cases (2). Dietary Guidelines for Americans 2005 recommends that specific groups, including persons with hypertension, all middle-aged and older adults, and all blacks should limit intake to 1,500 mg/day of sodium (3). These specific groups include nearly 70% of the U.S. adult population (4). For all other adults, the recommended limit is <2,300 mg/day of sodium. To estimate the proportion of adults whose sodium consumption was within recommended limits, CDC analyzed data from the National Health and Nutrition Examination Survey (NHANES) for 2005−2006, the most recent data available. Estimated average sodium intake and sources of sodium and calories by food category also were analyzed. This report summarizes the results of that analysis, which determined that only 5.5% of adults in the ≤1,500 mg/day group, and only 18.8% of all other adults consumed <2,300 mg/day. Overall, 9.6% of all adults met their applicable recommended limit. To help reduce sodium intake to below the recommended limits, food manufacturers and retailers can reduce sodium content in processed and restaurant foods, public health professionals and health-care providers can implement sodium reduction strategies and educate consumers about sodium, and consumers can modify their eating habits.

Data from the 2005−2006 NHANES,* a continuous survey of the health and nutritional status of the U.S. civilian, noninstitutionalized population, were used to estimate the daily sodium intake of adults aged ≥20 years. Approximately 71% of the adults (4,773 of 6,719) completed a physical examination component in NHANES mobile examination centers. Blood pressure measurements and one 24-hour dietary recall were obtained during examination. Another 24-hour dietary recall was obtained by telephone 3--10 days later. The final analytical sample consisted of 3,922 persons, after 253 participants were excluded because their record lacked a blood pressure measurement and 598 other participants were excluded because they had fewer than 2 days of dietary recall measurements. Mean blood pressure was calculated as an average of the available blood pressure measurements, with 95% of participants having two or three measurements. Participants were identified as hypertensive if they were on antihypertensive medication or if they had a mean systolic blood pressure of ≥140 mmHg or a mean diastolic blood pressure of ≥90 mmHg. The weighting of the 2-day dietary subsample took into account the complex multistage probability design, survey nonresponse, and poststratification in representing the U.S. civilian, noninstitutionalized population. Mean values for daily sodium and caloric intakes were calculated as averages of two dietary recalls. Daily sodium intake was calculated for two groups. The first group consisted of non-blacks aged 20--39 years, without hypertension, whose sodium consumption was recommended to be <2,300 mg/day. The second group consisted of all adults aged ≥20 years with hypertension, all adults aged ≥40 years without hypertension, and blacks aged 20--39 years without hypertension, whose sodium consumption was recommended to be ≤1,500 mg/day (Box).

To identify the major food sources of sodium, CDC categorized all foods reported as consumed by each participant into nine major groups, in accordance with the U.S. Department of Agriculture food coding scheme: 1) milk and milk products; 2) meat, poultry, fish, and mixtures; 3) eggs; 4) legumes, nuts, and seeds; 5) grain products (including foods in which grains are the primary ingredient, such as pizza); 6) fruits; 7) vegetables; 8) fats, oils, and salad dressings; and 9) sugars, sweets, and beverages.† Subgroups of the four food groups that contributed more than 5% of sodium intake (grains; meat, poultry, fish, and mixtures; vegetables; and milk and milk-based products) also were categorized. Sodium density, a measure that allows for comparison of sodium intake without confounding the related associations between total intakes of calories and sodium, was defined as milligrams of sodium per 1,000 kcal. Percentages and mean value estimates with standard errors were calculated using statistical software to account for the complex sampling design. Percentages of daily sodium intake for each food group were calculated by dividing the sodium intake in milligrams from each food group by the total sodium intake from all food consumed (in milligrams) and multiplying by 100. Percentages of daily energy intake were calculated using the same procedure. Differences in means were tested for statistical significance using the unpaired Student t test. Statistically significant differences in proportions were determined using the chi-square test. Results were considered statistically significant at p<0.05.

During 2005−2006, only 9.6% of all participants met the applicable 2005 recommended dietary limit for sodium (5.5% among the ≤1,500 mg/day group; 18.8% among the <2,300 mg/day group) (Table 1). U.S. adults consumed an average of 3,466 mg/day of sodium (Table 2). Most of the daily sodium consumed came from grains (1,288 mg; 36.9%) and meats, poultry, fish, and mixtures (994 mg; 27.9%), followed by vegetables (431 mg; 12.4%). Average daily sodium and calories consumed was 3,691 mg and 2,272 kcal for the <2,300 mg/day group and 3,366 mg and 2,068 kcal for the ≤1,500 mg/day group (Table 2). Although the ≤1,500 mg/day group consumed statistically significantly less sodium (p<0.001) and calories (p<0.001) than the <2,300 mg/day group, no difference was observed in overall sodium density or in eight of the nine main categories. Small but statistically significant differences in density were observed for two of the grain subcategories, one of the meats subcategories, and one of the vegetables subcategories. The ≤1,500 mg/day group consumed less sodium and calories from grains (1,205 mg versus 1,474 mg of sodium and 704 kcal versus 839 kcal) and sugars, sweets, and beverages (118 mg versus 138 mg of sodium and 286 kcal versus 361 kcal). However, that group consumed more sodium and calories from certain types of vegetables (109 mg versus 74 mg of sodium and 42 kcal versus 29 kcal).

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

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