Johnson CM, Angell SY, Lederer A, Dumanovsky T, Huang C, Bassett MT, Silver LD. Sodium Content of Lunchtime Fast Food Purchases at Major US Chains. Arch Intern Med. 2010;170(8):732-734. doi:10.1001/archinternmed.2010.72
Cardiovascular disease is the leading cause of death in the United States,1 and high blood pressure is a leading risk factor. An extensive body of research describes a direct association between sodium intake and blood pressure.2 Current US recommendations advise adults to limit sodium intake to less than 2300 mg/d,3 and several demographic groups (blacks, middle-aged and older adults, and people with hypertension), which together compose 69% of US adults,4 to limit daily intake to 1500 mg. Despite these suggestions, adults consume an average of approximately 3500 mg of sodium per day.5
Individual efforts to reduce sodium intake have limited effect, likely because more than 75% of dietary sodium comes from packaged and restaurant foods.6 The American Medical Association has called on industry to reduce the sodium content of processed and restaurant foods by 50%. A reduction by this amount would save tens of thousands of lives each year,7,8 and this reduction could save almost $20 billion in health care costs annually.8
There are limited published data on the relationship between restaurant food and sodium intake. Using data from a large cross-sectional survey of patrons exiting fast food chain restaurants in New York City (NYC),9 we assessed the amount of sodium in meal purchases by fast food chain and by chain category.
All NYC fast food chains licensed by the NYC Department of Health and Mental Hygiene that provided nutrition information publicly as of March 1, 2007, were considered for inclusion in the study. When ice cream chains were excluded, 13 chains composed almost 90% of all eligible restaurants. From approximately 1625 eligible locations across the 5 boroughs of NYC, a random sample of 300 chain restaurants was selected. Eleven fast food chains and 2 coffee chains were represented; the 2 coffee chains were excluded from our analysis.
Data were collected from noon to 2:00 PM on weekdays from March 27 to June 8, 2007. Adult patrons (age ≥18 years) exiting the restaurant answered a brief survey and provided their purchase receipt in exchange for a $2 MetroCard.
Nutrition information was ascribed to each menu item using information posted on company Web sites as of March 1, 2007. A meal was defined as any purchase with at least 1 entrée. An entrée was defined as any item that was not a side order (eg, French fries, side salad) or a dessert.
To examine the distribution of sodium content, meals were categorized by sodium level: 600 mg or less, 601 to 1499 mg, 1500 to 2299 mg, and 2300 mg or greater. To assess the relationship between calorie and sodium intake, we calculated sodium density, defined as milligrams of sodium per 1000 calories.
SPSS 15.0 software (SPSS Inc, Chicago, Illinois) was used for statistical analyses. A 2-tailed t test (α level <.05) was used to test for differences in mean sodium levels. For bivariate tables, the χ2 test was used to obtain P values.
The final sample size for the analysis of fast food meals was 6580 receipts from 167 locations, after purchases without entrees were excluded (n = 466). Meals averaged 1751 mg of sodium; 20% had greater than 2300 mg. At fried chicken chains, 55% of meals had more than 2300 mg of sodium, which was higher than the mean percentage at all chains (P < .001). Fried chicken chain meals averaged 66 more calories than burger chain meals (999 calories vs 933 calories; P = .007) but contained almost 900 mg more sodium (2441 mg vs 1548 mg; P < .001). Over half (57%) of all purchases exceeded the 1500-mg recommended daily sodium limit applicable to most Americans, this rose to 84% in fried chicken chains. Mean sodium density for all meals purchased was 2136 mg per 1000 calories (Table).
This study extends analyses of the nutritional content of fast food from calorie to sodium content and shows that fast food is high in sodium as well as calories. Only 1 in 36 purchased meals met the Food and Drug Administration “healthy” sodium level for meals (600 mg), whereas 1 in 5 exceeded the recommended daily limit (2300 mg). Excess sodium intake was not simply the result of large portion size. Average sodium density was 2136 mg sodium per 1000 calories purchased, so even a patron who was mindful of calorie intake would likely exceed standards for healthy sodium intake.
Fast food is an important and growing contributor to dietary intake. Chain restaurant visits, both fast food and casual dining, now represent almost 75% of all restaurant eating occasions.10 However, reducing sodium content in fast food is possible and already under way in some settings. The United Kingdom has worked with fast food chains to obtain commitments to sodium reductions11; in 2004, McDonald's committed to a 30% sodium reduction in its chicken nuggets. The National Salt Reduction Initiative in the United States, coordinated by the NYC Health Department, is now working with the restaurant industry to define sodium targets and to secure industry commitments to reductions.
Important strengths of this study include the use of receipts of meals purchased rather than reliance on patron self-report and the large sample of patrons from randomly selected locations. Limitations include a lack of patron demographic data. In addition, participants were not asked about salt added at the table, potentially underestimating sodium content per meal. A meal as defined in this study may not include purchases that a patron considers a meal, such as a large order of French fries, and may classify as a meal for some purchases that the patron viewed as a snack. Finally, the food establishments studied may not be representative of all fast food restaurants.
Fast food is not only a high-calorie but also a high-sodium food. Its widespread consumption contributes to current high levels of daily sodium intake in the United States, higher blood pressure, and the resulting burden of cardiovascular disease. Consequently, reducing sodium levels in fast food meals is a public health priority. Our findings support the need for the fast food industry to focus on reducing sodium levels across product lines. Government, public health, and industry involvement to accelerate food reformulation will reduce blood pressure and save lives.
Correspondence: Ms Johnson, Cardiovascular Disease Prevention and Control Program, NYC Department of Health and Mental Hygiene, 2 Lafayette St, 14th Floor, CN-46, New York, NY 10007 (firstname.lastname@example.org).
Author Contributions: Ms Johnson had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Johnson, Angell, Dumanovsky, Bassett, and Silver. Acquisition of data: Dumanovsky and Silver. Analysis and interpretation of data: Johnson, Angell, Lederer, Dumanovsky, Huang, Bassett, and Silver. Drafting of the manuscript: Johnson, Angell, and Lederer. Critical revision of the manuscript for important intellectual content: Johnson, Angell, Lederer, Dumanovsky, Huang, Bassett, and Silver. Statistical analysis: Dumanovsky and Huang. Obtained funding: Silver. Administrative, technical, and material support: Lederer, Huang, and Silver. Study supervision: Johnson, Angell, Bassett, and Silver.
Financial Disclosure: Ms Johnson formerly owned 200 shares of Yum! Brands Inc.
Funding/Support: This study was fully funded by NYC tax levy dollars.