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Procedia Science 4 ( 2015 ) 138 – 147

38th National Nutrient Databank Conference Nationwide Variation of Sodium Levels and Portion Sizes of Menu Items

Robin G. Thomasa*, Jaspreet K.C. Ahujaa, Marlon G. Danielb

aNutrient Data Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, USA bUniversity of Maryland, College Park, MD 20742 , USA

Abstract

Sodium levels are typically high in Chinese dishes due to the use of ingredients such as soy . Chinese restaurants are popular among many Americans, outnumbering in total number the combined top three major establishments. The Nutrient Data Laboratory expanded the number of Chinese in its USDA National Nutrient Database for Standard Reference with new analytical data. This study aimed to examine the variability of sodium and order size in Chinese entrées. Eleven popular entrées were sampled from independent restaurants in up to 12 nationwide locations and sent for nutrient analysis according to National Food and Nutrient Analysis Program protocol. Mean sodium levels ranged from 252 to 553 mg/100 g among the 11 entrées; differences in variability were indicated by CV’s ranging from 13% (general Tso’s chicken) to 56% (lemon chicken). The weight of an order varied among the different restaurants for each dish, creating an even greater impact on the sodium level per order. Sodium levels per order showed significant differences across four U.S. regions (p<0.0001). The high variability of sodium levels in prepared Chinese foods impacts the amount of sodium consumed from these foods.

Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license © 2015 The Authors. Published by Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the National Nutrient Databank Steering Committee. Peer-review under responsibility of the National Nutrient Databank Steering Committee

Keywords: sodium variability; Chinese restaurants; portion size

* Corresponding author. Tel.: +1-301-504-0630; fax: +1-301-504-0632. E-mail address: [email protected]

2211-601X Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the National Nutrient Databank Steering Committee doi: 10.1016/j.profoo.2015.06.019 Robin G. Thomas et al. / Procedia Food Science 4 ( 2015 ) 138 – 147 139

1. Introduction

Americans have been advised to reduce their daily sodium intake to no more than 2,300 mg, or 1,500 mg for high risk populations1. Over 90% of the American population consumes more than 2,300 mg sodium per day which is the Institute of Medicine (IOM) Tolerable Upper Intake Level (UL) for adults2. In 2011-2012, the mean daily sodium intake was 3,478 mg for the U.S. population aged 2 years and older3. Men aged 40-49 years had the greatest mean daily intake (4,646 mg), more than twice the UL. This excessive sodium intake is of public health concern as it has been determined to be a major risk factor for hypertension, which is a key contributor to cardio- and cerebrovascular diseases4, 5. Cardiovascular disease (CVD) is the leading cause of death in the U.S., accounting for 1 of every 3 deaths in 20106. To help reduce this widespread incidence of CVD, several government and private institutions have set recommendations and guidelines for reduction of sodium intake1, 7, 8.

As part of its strategies to reduce sodium consumption, the IOM recommends, “USDA should enhance the quality and comprehensiveness of sodium content information in its tables of food composition” and “monitor the sodium content of the total food supply”9.The Agricultural Research Service’s Nutrient Data Laboratory (NDL), in collaboration with other Federal agencies, is monitoring levels of sodium in commercially processed and restaurant foods which are the primary sources of sodium in the U.S. diet10, 11. These efforts involve use of laboratory analyses or Nutrition Facts Panel information to update foods in the USDA National Nutrient Database for Standard Reference (SR), which is the foundation for most food composition tables, used by consumers, public health professionals, food manufacturers, restaurants and research scientists12, 13.

Restaurant foods contribute substantial amounts of sodium to the U.S. diet14. Restaurants account for 25% of the sodium consumed by the overall U.S. population, and 50% for those reporting consumption of any restaurant foods, as reported in the 2007-08 What We Eat in America, National Health and Nutrition Examination Survey (WWEIA, NHANES)14, 15. Chinese restaurants are ubiquitous in the United States16, found in cities and small towns across the country17. Numbering near 47,00018, Chinese restaurants exceed the number of top three major fast food establishments (McDonald’s, Burger King and Wendy’s) combined17. Salt is used liberally in traditional Chinese , providing about 75% of the sodium consumed in China19. Other sources of sodium intake in include , preserved , tenderizers, and monosodium glutamate19.

Independent restaurants are more numerous than major chain outlets serving Chinese food in the U.S.20, 21 -- in 2013 there were only 2,000 restaurant chains with Chinese menu items22. Independent restaurants may have less consistent recipes and preparation methods than restaurant chains, which introduces a greater chance of variability in food composition. Upon examining variability of mineral levels in foods, Pennington23 suggested that variations in mineral levels in a Chinese dish were due to different ratios of to other ingredients across various restaurant locations. Regional differences may exist in from different parts of China. Anderson et al.19 found the use of discretionary salt is twice as high in Northern as in Southern provinces, contributing about 3,600 and about 1,800 mg/day, respectively. These regional differences likely impact the cooking styles of Chinese chefs in U.S. restaurants, reflecting the varying sodium levels of their cuisine.

The objective of this study was to explore the possible impact of individual restaurant, region of sample pick-up, and order size on the variability of sodium levels in commonly consumed dishes from Chinese restaurants in the U.S.

2. Methods

Popular Chinese menu items were sampled nationwide and analyzed to contribute to the sodium monitoring effort and to expand the Chinese restaurant category of foods in SR. NDL selected the following 11 Chinese restaurant entrées (excluding ) for analysis based on WWEIA, NHANES 2005-0624 and 2007-0825 consumption data: beef and vegetables, chicken and vegetables, chicken , general Tso’s chicken, , lemon chicken, , shrimp and vegetables, sweet and sour , chow mein and vegetable . The 140 Robin G. Thomas et al. / Procedia Food Science 4 ( 2015 ) 138 – 147

WWEIA, NHANES 2005-06 and 2007-08 data sets each include two non-consecutive days of 24-hour recall dietary intake data for a nationally representative sampling of approximately 8,000-9,000 American children and adults24,25.

2.1. Sample protocol

The menu items were sampled and analyzed according to the standard USDA National Food and Nutrient Analysis Program (NFNAP) protocol26, 27. Contract agents purchased samples of each specified menu item from retail outlets in up to twelve counties/cities across the United States. NDL staff in collaboration with USDA National Agricultural Statistics Service statisticians selected these counties, cities and primary retail outlets using a multi-stage probability- proportional-to-size method based on 2000 U.S. census data. Potential pick-up locations and their respective regions are shown in Figure 1. Three locations were randomly chosen from the options in each of the four regions – West, Midwest, Northeast, and South – for a total of twelve sites. NDL instructed the trained pick-up agents to shop at a Chinese restaurant near the designated primary retail outlet in each of the twelve selected locations. Chinese restaurants in the U.S. are primarily independent20-22, so NDL chose to collect samples from these non-chain establishments.

Figure 1. NFNAP regions and county sample (2000 design)

For each menu item, the laboratories required a minimum of 2.2 pounds (1,000 grams) product for comprehensive nutrient analyses, necessitating the purchase of 2-4 orders per item. The pick-up agents stored each order in a separate plastic bag, froze íƒ&) the food in the bag shortly after purchase and shipped it on dry ice by overnight delivery to the Food Analysis Laboratory Control Center (FALCC) at the Virginia Polytechnic Institute and State University. FALCC photographed and weighed each menu order. NDL used the photographs to verify the contents of each menu item and determine the need for any adjustments in the compositing. For example, one of the chow mein orders included noodles stored in a separate bag, whereas the others did not include any noodles. NDL directed FALCC to discard the noodles. NDL also requested FALCC to discard the whole dried peppers and lemon slices noted in the photos of some of the dishes as these ingredients are meant to impart flavor and not typically consumed. FALCC measured the gram weight of each order received from each location for all 11 entrées after making the above adjustments. Thus, there were 2-4 weights for each location for each dish. All weights were measured and reported to a tenth of a gram. FALCC homogenized all of the 2-4 orders received from each location for a total of up to 12 Robin G. Thomas et al. / Procedia Food Science 4 ( 2015 ) 138 – 147 141 composites for each menu item. Some entrées had fewer than 12 composites due to unavailability of those dishes at each location. Two additional samples of lemon chicken were picked up during a later sampling for a total of 14 composites. FALCC shipped the composited samples to a commercial, pre-qualified analytical laboratory along with standard reference materials for quality control. The lab conducted analysis of sodium (and other minerals) using a modified AOAC Inductively Coupled Plasma (ICP) method28.

2.2. Statistical analyses

Descriptive statistics (mean, median, standard deviation, range and coefficients of variation) were calculated for both dependent variables (sodium content and item weight) by food type and region. Due to the large differences observed in order size, NDL examined sodium per order in addition to sodium per 100 g. Frequencies and proportions were described by independent variables of interest (menu item and region). To compare differences in the dependent variable by food type and region individually, One-way Analysis of Variance (ANOVA) was utilized. Post hoc analysis (Tukey’s HSD (Honest Significant Difference) test) was used to test pair-wise difference within the factors. $OODQDO\VHVZHUHFRPSOHWHGXVLQJ6$6YHUVLRQ &DU\1& ZLWKDQĮ 

3. Results and discussion

3.1. Variability of sodium levels per 100 g

Results of the analysis of sodium in the 11 dishes are shown in Table 1. Mean sodium levels ranged from 252 mg per 100 g of lemon chicken to 553 mg per 100 g of orange chicken. With a mean ± SD of 435 ± 55 mg/100 g, general tso’s chicken had the lowest variability in sodium levels (CV 13%) while at 252 ± 141 mg/100 g, lemon chicken had the greatest (CV 56%). Thus, although the average total amount of sodium was relatively low in the lemon chicken (252 mg per 100 g), it ranged from as low as 97 mg per 100 g to as high as 490 mg per 100 g.Different restaurants may have used greatly varying types and amounts of sodium-containing ingredients such as breading, and seasonings. For example, products such as soy sauce from various foodservice suppliers used by the chefs may have different levels of sodium. In a study of variability of minerals in foods, Pennington23 found foods with the highest sodium levels had the least variability.

Table 1. Amount of sodium in Chinese restaurant entrées, sorted by variability (%CV)

Sodium, mg/100 g

Standard Food Item n Mean Deviation Median Minimum Maximum CV, %

General Tso's Chicken 12 435 55 448 298 501 13

Vegetables Lo Mein 12 430 63 401 371 578 15

Kung Pao Chicken 12 402 89 395 284 535 22

Chicken and Vegetables 11 431 113 411 273 711 26 Shrimp and Vegetables 12 375 98 381 149 514 26

Vegetable Chow Mein 10 344 92 344 227 528 27

Beef and Vegetables 12 393 120 377 118 584 31 Orange Chicken 9 553 183 506 381 950 33 Sweet and Sour Pork 12 304 118 293 144 578 39 Chicken Chow Mein 12 311 127 328 75 505 41 142 Robin G. Thomas et al. / Procedia Food Science 4 ( 2015 ) 138 – 147

Sodium, mg/100 g

Standard Food Item n Mean Deviation Median Minimum Maximum CV, %

Lemon Chicken 14 252 141 201 97 490 56

3.2. Variability of order size

The weight in grams for each order (i.e. the amount served to the pick-up agent when ordering the menu item) is shown in Table 2. The entrées ranged from 535 ± 156 g/order of general tso’s chicken to 777 ± 214 g/order of vegetable chow mein. The average weight per order for all 11 entrées – 637 g – is over 3 times the U.S. Food and Drug Administration’s (FDA) Reference Amount Customarily Consumed Per Eating Occasion of 195 g for mixed dishes with sauce29. The entrée weight variability ranged from 18% CV for shrimp and vegetables (601 ± 106 g) to 41% for orange chicken (1 order = 648 ± 268 g). Variability in order sizes could be attributed to differences in amounts and proportions of ingredients used by the various restaurants19,23 or different sizes on the menu at the time of purchase.

Table 2. Order size of Chinese restaurant entrées, sorted by variability (%CV)

Weight, g Standard Menu item n Mean Deviation CV, % Shrimp and Vegetables 36 601 106 18 Beef and Vegetables 36 574 107 19 Chicken Chow Mein 37 604 123 20 Sweet and Sour Pork 36 609 132 22 Chicken and Vegetables 11 693 165 24 Vegetable Lo Mein 12 741 201 27 Vegetable Chow Mein 10 777 214 28 General Tso's Chicken 38 535 156 29 Kung Pao Chicken 37 604 190 31 Lemon Chicken 37 623 199 32 Orange Chicken 9 648 268 41

3.3. Variability of sodium levels per order

Mean ± SD sodium levels in an order of the sampled Chinese restaurant entrées ranged from 1,525 ± 1,025 mg in lemon chicken to 3,378 ± 1140 mg in orange chicken (Table 3). Six of the eleven entrées exceed the UL of 2,300 mg/day for sodium30. The average of all 11 entrées, 2,432 mg, is two-thirds greater than the daily Adequate Intake guideline of 1,500 mg sodium30 for most children and adults. According to FDA guidelines, or main dishes containing over 600 mg per serving exceed the sodium limit, making them ineligible for the ‘healthy’ claim31. The high sodium levels in these entrées may especially concern the many Chinese restaurant patrons who consume an entire entrée at mealtime. When sodium levels per gram weight of an order were examined instead of per 100 g of food, the variability was even greater (Figure 2 and Table 3). The CV increased from 13 to 31% for general Tso’s chicken (mean ± SD = 2,374 ± 729 mg/serving) and increased from 56 to 69% for lemon chicken (1,525 ± 1,052 mg/serving). With a mean ± SD of 3,150 ± 778 mg/serving, vegetable lo mein had the lowest variability in sodium based on an order (CV 25%). Robin G. Thomas et al. / Procedia Food Science 4 ( 2015 ) 138 – 147 143

Table 3. Amount of sodium in an order of Chinese restaurant food, sorted by variability (%CV)

Sodium, mg/serving Standard Menu Item n Mean Deviation Median Minimum Maximum CV, %

Vegetable Lo Mein 12 3150 778 3177 1983 4150 25 Vegetable Chow Mein 10 2611 777 2758 1690 4110 30 General Tso's Chicken 12 2374 729 2322 1434 4323 31 Chicken and Vegetables 11 2964 926 2713 1654 4670 31 Shrimp and Vegetables 12 2279 746 2189 698 3634 33 Orange Chicken 9 3378 1140 3396 1941 5638 34 Kung Pao Chicken 12 2468 939 2299 1200 4453 38 Beef and Vegetables 12 2297 899 2047 544 3791 39 Chicken Chow Mein 12 1868 788 1852 396 3384 42 Sweet and Sour Pork 12 1840 833 1639 859 3765 45 Lemon Chicken 14 1525 1052 1106 469 4196 69

6000

5000

4000

3000

2000 Sodium, mg per 1 order

1000

0

Orange Chicken Lemon Chicken Kung Pao Chicken Vegetable Lo Mein Beef and VegetablesChicken ChowSweet Mein and Sour Pork Vegetable GeneralChow Mein Tso's Chicken Chicken andShrimp Vegetables and Vegetables

Figure 2. Variability of sodium per order of Chinese restaurant entrées, sorted by variability (%CV) 144 Robin G. Thomas et al. / Procedia Food Science 4 ( 2015 ) 138 – 147

3.4. Regional variation

Mean sodium levels (mg per 100 g) of each entrée obtained from the four regions (West, 396; Midwest 399; Northeast, 362; South, 356) were not significantly different from each other (p=0.43), but the comparison of mean sodium levels per order (West, 2,255; Midwest 3,239; Northeast, 2,069; South, 2,160) did show regional variation (p<0.0001). Post hoc analysis found sodium levels per order were significantly different between Chinese restaurants in the Midwest and Northeast (p<0.05), Midwest and West (p<0.05) and between the Midwest and South (p<0.0001) (Figure 3). The Midwest – represented by pickup locations in Madison County, Indiana, St Clair County, Michigan, and Cass County, Missouri – had the highest sodium levels for an order of Chinese food, on average. Sodium levels in the Midwest were greatest for an order of chicken and vegetables, 4,115 mg; vegetable lo mein, 4,113 mg; orange chicken, 4,033 mg; and kung pao chicken, 3,681 mg.

4500

4000

3500

3000

2500

2000 MW

1500 NE S 1000 W 500

0

Figure 3. Sodium (mg) per order of Chinese restaurant entrées by region of U.S., in alphabetical order

3.5. Strengths and limitations

The selection of foods and the sampling design are the major strengths of the current study. Selection of menu items to examine was based on nationally representative food consumption survey data from 2005-200824, 25. The NFNAP protocol provides a strong probability-based sampling design26, 27, resulting in a statistically representative sample using locations that are nationally representative of the U.S. food retail arena. Furthermore, independent restaurants, from which food samples were obtained, represent the vast majority of Chinese restaurants20-22.

The present study also has some limitations. NDL relied on older WWEIA, NHANES food consumption data24, 25 which were the most recently available at the time of food item selection. NDL will continue to review more current survey data which may reveal different dishes that are more highly consumed. Those foods will then be considered for future sampling and analysis. NDL did not instruct pick-up agents to purchase a - or dinner-size or other Robin G. Thomas et al. / Procedia Food Science 4 ( 2015 ) 138 – 147 145 specified size entrée. Thus, if there were different entrée size options on the menu, the agents may have purchased the largest size in order to meet the sample size requirement for analysis, which may have skewed the results. The selected restaurants may not represent the Chinese restaurant industry in the U.S. The study’s results were for specific entrées and the variability in sodium, order size, and regional differences may not be applicable to other dishes from Chinese restaurants.

4. Conclusion

Sodium levels in independent Chinese restaurant foods are highly variable, which may impact the amount of sodium consumed from these foods. The order weight has an even greater impact on the variability of sodium level due to the variability in order size among restaurants for each menu item. The wide variability in sodium levels of similarly named Chinese dishes makes assessment of sodium intakes and monitoring changes in sodium levels especially challenging. The addition of these food items using analytical data from NFNAP enhances the restaurant foods category in SR. It is best to examine not only the mean sodium values, but also the standard error, minimum and maximum values, in order to gain a comprehensive evaluation of the sodium content of foods derived from Chinese restaurants. This is especially true for the more highly variable dishes such as lemon chicken. Ideally, when conducting similar research, other investigators should sample from as many different restaurants as resources allow, to account for large variability in the sample. Additional nationwide sampling and analysis may capture even more of the variability and provide more meaningful estimates of sodium from these foods. Further research is recommended for foods from other types of independent ethnic restaurants such as Latin American, Middle Eastern, and Indian, where wide variability in nutrient levels may be similarly observed.

The high variability in these dishes shows that there is potential for sodium reduction. Independent Chinese and other restaurant owners and chefs are found to be willing to reduce the sodium content of their dishes with sufficient training and support, based on efforts in , Pennsylvania, Shasta County, and Schenectady County, New York32-34. Programs to educate, train and assist restaurant owners and chefs have resulted in some positive changes toward reducing sodium levels in their food32-35. These changes need to be monitored via future sampling and analysis. Consumers trying to limit their sodium intake should be aware of differences in sodium levels of various entrées, select dishes with lower sodium levels, and be cognizant of portion sizes. Menu labeling with sodium levels, as proposed for larger restaurants [36], would greatly assist in consumers’ efforts to educate themselves to limit their sodium intake from Chinese restaurant dishes.

Acknowledgements

The authors thank the NFNAP team: David Haytowitz, Denise Trainer, Kris Patterson and Pamela Pehrsson of NDL and Katherine Phillips of Virginia Tech’s FALCC. CDC:USDA Interagency Agreement 8040-52000-064-19 contributed funding for this study.

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