Sodium, potassium, calcium, phosphorus, and magnesium in foods from the United States total diet study

JOURNAL

OF FOOD

COMPOSITION

AND ANALYSIS

3, 145- 165 (1990)

Sodium, Potassium, Calcium, Phosphorus, and Magnesium in Foods from the United States Total Diet Study J.A.T.PENNINGTON*" Food

and Drug Administration, *Division and tKansas City District Q&e, Received

March

AND B.

YOUNG?

qf Nutrition, Wushington, D.C. 20204. Kansas City, Missouri 64106, U.S.A.

6, 1990, and in revised

form

August

U.S.A.;

10, 1990

Data on the concentrations of sodium, potassium, calcium, phosphorus, and magnesium in the 234 foods of the United States Total Diet Study from 1982 to 1989 are summarized per 100 g and per typical serving portion. Per serving, mixed dishes and soups were higher in sodium; mixed dishes, root/tuber vegetables, and dairy products were higher in potassium; dairy products were higher in calcium; dairy products, mixed dishes, and animal flesh were higher in phosphorus; and nuts, mixed dishes, and legumes were higher in magnesium. Of the top 20 foods highest in each element per serving, the coefficients of variation averaged 20% (range IO-48%) for sodium, 15% (range 2-47%) for potassium, 21% (range 12-24%) for calcium, 14% (range 7-22%) for phosphorus, and 17% (range 7-24%) for magnesium. Nutrient variation reflects genetic, environmental, processing, and analytic factors. Sodium variability most likely reflects the variable amount of salt added to foods and recipe ingredients by industry. o 1990 Academic press, hc.

INTRODUCTION

The United States Total Diet Study is a yearly program which monitors the levels of contaminants and nutrients in the food supply and diets of selected age-sex groups (Pennington and Gunderson, 1987). The food list and diets are periodically revised when new information from national food consumption surveys becomes available. The current program (based on the 1982 revision) includes the collection and analyses of 234 core foods four times per year (Pennington, 1982, 1983). The nutritional evaluation of these foods includes analyses for 11 mineral elements: the macroelements sodium, potassium, calcium, phosphorus, and magnesium; and the microelements iron, zinc, copper, manganese, selenium, and iodine. Previous papers have presented the intakes of these elements for eight age-sex groups from 1982 to 1984 (Pennington et al., 1986), from 1982 to 1986 (Pennington et al., 1989), and from 1982 to 1989 (Pennington and Young, 1990). This paper presents the concentrations of the macroelements in the Total Diet Study foods and food groups from 1982 to 1989; the following paper presents results for the microelements. METHODS

AND

MATERIALS

The Total Diet Study foods are collected approximately four times per year, once from each of the four geographic regions of the United States (east, central, west, and south). The collection within a geographical area consists of the purchase of 246 foods and ingredients from each of three cities. The foods are purchased from supermarkets ’ To whom

correspondence

should

be addressed.

145

0889-1575/90

$3.00

Copyright 0 1990 by Academic Press, Inc. All rights of reproduction in any form reserved.

146

PENNINGTON

AND TABLE

TOTAL

DIET

STUDY

YOUNG

I

COLLECTION

LOCATIONS

Location

Date

April

1982

July

Buffalo,

1982

November February

June

CT;

CA; Phoenix,

Green

1983

Norfolk,

VA; Atlanta,

Boston,

MA; New York,

1983 1983

December

1983-

January

1984

March-April

Bay,

Honolulu, Topeka,

WI;

AZ;

1982

September

June-July

1984

September-

Chicago,

Newark,

Salt

NJ

Lake

IL;

City,

Detroit,

UT

MI

GA; Jacksonville,

FL

NY; Montgomwyville,

HI;

San Diego,

KS; St.

Louis,

1984 Beaumont/Port Juan,

October

NY; Hartford,

Fresno,

CA; Portland, MO; Dayton,

Arthur/Orange,

TX;

PA OR

OH

Nashville,

TN;

San

PR

Lancaster,

PA;

Tacoma,

Nassau-Suffolk,

WA; Bakersfield,

NY; Rochester,

CA; Salt

Lake

NY

City,

UT

1984

January-February

St.

Cloud,

MN; Rockford,

IL;

Flint,

MI

1985 April July

1985 1985

October-November 1985 January April

Dallas/Ft.

Worth,

Portland,

ME; Long

Los

Angeles/Long

Falls, 1986 1986

Macon,

GA; Charleston,

BeachlAsbury

Beach,

Park,

CA; Sacramento,

NJ;

WV New York,

NY

CA; Sioux

SD

Chattanooga, Cleveland, Wichita,

TX;

TN;

Ft.

Smith,

OH; Davenport,

AR; IA/Reek

Miami,

FL

Island-Moline,

IL;

KS

and fast-food chains within each city. The cities selected for inclusion in the program represent standard metropolitan statistical areas and are within commuting distance of a Food and Drug Administration (FDA) field office. Table 1 indicates the locations of the collections for the Total Diet Study program from 1982 to 1989. The same foods were purchased from the three cities over a 4week period. The foods from each weekly purchase were sent by air freight (packed in dry ice where necessary) to the Total Diet Laboratory in the FDA Kansas City District Office. Upon arrival in Kansas City the foods were logged in and checked to be sure the appropriate items were collected in requested quantities. If discrepancies were noted or if foods were damaged, the field office responsible for the delivery was asked to repeat the collection of the needed foods.

MACROELEMENTS

IN

TOTAL

July

STUDY

147

FOODS

l-Continued

TABLE

Date

DIET

Location

1986

Spokane,

WA; Albuquerque,

October

1986

Providence,

Januarg

1987

Memphis,

April-May

1987

RI; TN;

NM; Denver,

Albany,

Omaha,

NE; Fargo,

Brownsville/Harlingen/San Baton

July-Auqust

Rouge,

Portland,

CO

NY; Pittsburgh,

PA

ND

Benito,

TX;

Birmingham,

AL;

LA

OR; Fresno,

CA; Phoeniz,

AZ

1987 October

1987

Peoria,

January

1988

Baltimore,

March-April

El

IL;

Paso,

Indianapolis,

IN;

MD; Charleston, TX;

Pueblo,

Milwaukee,

SC; Tallahassee,

CO; Reno,

WI FL

NV

1988

June-July August November January

1988

Syracuse,

1988 1988

NY; New York

Ponce,

PR; Jackson,

Akron,

OH; Battle

Nassau/Suffolk,

1989

Passaic,

(Berqen

Co.,

MS; Columbus, Creek,

MI;

NJ);

Lincoln,

NY; Washington,

Manchester,

NH

GA

DC;

NE Patterson/Clifton/

NJ

Foods that required preparation or that were ingredients for mixed dishes were sent to a contract kitchen in close proximity to the Kansas City Laboratory. At the contract kitchen the foods were rinsed, cooked, and/or otherwise prepared for TABLE

2

LIMITSOFQUANTITATION (L,)FoR SODIUM,POTASSIUM,CALCIUM, PHOSPHORUS,AND MAGNESIUM FORTOTALDIETSTUDY FOODS

Element

Lq (mg/lOO

Na

0.20

K

0.50

Ca

0.20

P

0.050

Mg

0.10

gl

148

PENNINGTON

AND TABLE

QUALITY

CONTROL

EVALUATION

YOUNG

3 OF TOTAL

DIET

Spiked Percent

a NIST Standard

STUDY

DATA

SRMa

recovery

+ SD (n)

Percent

recovery

+ SD (n)

100.4

c

7.0

(456)

89.3

+ 6.3

(222)

100.8

t

7.8

(456)

91.7

+ 7.6

(226)

96.8

+ 11.7

(435)

96.4

+ 8.6

(216)

98.0

+

7.8

(437)

83.7

+ 5.6

(216)

97.8

-+

8.0

(456)

97.7

+ 6.6

(223)

Reference

Material

oyster

tissue.

consumption. The water used for rinsing and cooking procedures was deionized. Noniodized salt was added to mixed dishes as specified by recipe and to several other foods as indicated by package instructions, but other foods (e.g., meats and vegetables) were not salted. The prepared foods were then returned to the laboratory. The similar foods from the three cities were cornposited. Each of the 234 foods for a single collection represented an equal weight composite from the three cities of the geographical area. Aliquots of each of the 234 composite foods were then analyzed for nutritional elements. The five macroelements were determined by inductively coupled plasma atomic emission spectrometry (Marts and Meloan, 1982). Twenty-eight test portions of each food were analyzed for sodium, potassium, and magnesium. For calcium and phosphorus, which were not determined in the first collection, there were 27 analyses. In total, there were 32,393 analyses. The foods were analyzed in series with 15-30 test portions per series. For each element being determined, the series analysis included two reagent blanks, duplicate analysis of at least one test portion, at least one spiked recovery analysis, and at least one standard reference material (SRM) from the National Institute of Standards and Technology (NET). The limits of quantitation for the analytical methodology (Table 2) were based on repetitive analyses of blank solutions (Keith et al., 1983). Values below the limits of quantitation were reported as zeros. Values for sodium, potassium, calcium, and phosphorus were rounded to the nearest whole number; values for magnesium were carried to one decimal point. The data were evaluated for outliers by means of the Grubbs extreme deviation test (Grubbs, 1969). Median and mean (plus or minus standard deviation) concentrations of the five elements in the 234 foods were determined per 100 g and per typical serving portion. The concentrations of the elements by food

MACROELEMENTS

IN

TOTAL TABLE

DIET

STUDY

149

FOODS

4

SODIUM,POTASSIUM,CALCIUM,PHOSPHORUS,ANDMAGNESIUMCONTENTOFTOTAL FOODSIN~~PER IOOg" rood YBlW" scdim PotaIll"m CDlCIL.m PhoM!or"r

DIETSTUDY q all”EIIM

150

PENNINGTON TABLE

AND

YOUNG

4-Continued

MACROELEMENTS

IN TABLE

TOTAL

DIET

STUDY

FOODS

151

&-Continued

groups per serving portion were determined. Coefficients of variation (CVs) were calculated for foods highest in each element per serving to assessthe variability of the elements.

152

PENNINGTON TABLE

laod

Yale?”

Pcdlrn

POIBEII”m

AND

YOUNG

4-Continued CalclM

RESULTS

Results of the quality control measures are shown in Table 3. There were 12-20 spiked recoveries per collection. Average spiked recoveries ranged from 96.8 to 100.8%, and recoveries for SRMs ranged from 83.7 to 97.7%.

154

PENNINGTON TABLE

AND 4-Continued

YOUNG

MACROELEMENTS

IN

TOTAL

DIET

STUDY

FOODS

155

An evaluation for outliers resulted in the omission of two sets of results (one of pancake syrup and one of chocolate powder for milk) and the omission of 10 values for sodium and two values for potassium. Thus, of 32,393 analyses, results for 22 (0.07%) were identified as outliers. The medians and means with standard deviations for the macroelements in the 234 Total Diet Study foods are presented in Table 4 per 100 g and in Table 5 per typical serving portions of table-ready, edible food. Table 6 presents the average levels of the elements per serving by food group. By food groups, the major sources of the macroelements are mixed dishes and soups for sodium; mixed dishes, root/tuber vegetables, and dairy products for potassium; dairy products for calcium; dairy products, mixed dishes, and animal flesh for phosphorus; and nuts, mixed dishes, and legumes for magnesium. Of the seven strained/ junior food groups, dessert and dinners were highest in sodium, vegetables were highest in potassium, dessert and vegetables were highest in calcium, meat/poultry were highest in phosphorus, and vegetables were highest in magnesium. The 20 foods (excluding strained/junior foods) highest in sodium (575-1730 mg/ serving) included 11 mixed dishes, cured ham, four soups, cottage cheese, sauerkraut, tomato sauce, and dill pickles. These were all products to which salt had been added by industry or by homemade recipe. Some of the recipe ingredients also contained salt added by industry (e.g., tomato paste in the homemade lasagna). The CVs for the sodium content of these products averaged 20% and ranged from 10 to 48%; the higher CVs were for vegetable beef soup (CV = 35%) and homemade beef and vegetable stew (CV = 48%). The variability of sodium in these products is most likely due to the variable amounts of salt added by industry. The 20 foods highest in potassium (393-790 mg/serving) included five mixed dishes, chocolate milkshake, seven vegetables, three fruits, three dairy items, and tomato soup. CVs for these products averaged 15% and ranged from 2% for avocados to 47% for cantaloupe. The 20 foods highest in calcium (127-350 mg/serving) included 11 dairy products, three dairy desserts, three mixed dishes, collards, pancakes, and tomato soup. CVs averaged 21% and ranged from 11 to 38% with the higher CVs for vanilla ice milk (CV = 34%) chicken noodle casserole (CV = 36%) and tomato soup (CV = 38%). The variability of calcium in some products may reflect recipe formulations (i.e., the amounts of milk, cheese, or cream in these products).

156

PENNINGTON

AND TABLE

YOUNG

5

SODIUM,POTASSIUM,CALCIUM,PHOSPHORUS,ANDMAGNESIUM CONTENTOFTOTALDIETSTUDY FOODSIN~~PERSERVING'

MACROELEMENTS

IN

TOTAL

TABLE Food r.rvimb

Yeighrof *cd,uI rervins (‘I, Hfdian*earpAm

P.tasIIm *f-San lean*sdw

DIET

STUDY

FOODS

157

S-Continued ca,cim *cd,an*eMt-sdm

Phorphcmn edin *earerdm

-iul “edianlleac-rdm

PENNINGTON TABLE

Pm.SSI”n

AND

YOUNG

5-Continued Calclm

The 20 foods highest in phosphorus (209-4 15 mg/serving) included six mixed dishes, three animal flesh items, seven dairy products, two dairy desserts, pancakes, and raisin bran cereal. CVs averaged 14% and ranged from 7% for evaporated canned milk to 22% for frozen, fried chicken dinner. The 20 foods highest in magnesium (37.5-83. I mg/serving) included two ready-to-

eat cereals, six mixed dishes, eight vegetables (spinach and legumes), two nuts, chocolate milkshake, and fried shrimp. CVs averaged 17% and ranged from 6% for peanuts to 39% for fresh/frozen, boiled spinach. DISCUSSION

Those who regularly use food composition data to plan and evaluate diets usually need to know the average concentrations of nutrients in foods. However, it is useful

MACROELEMENTS

IN TABLE

kcd Wlngb

“eight of Icdlun sewi LO *edtan*ear@m

TOTAL

DIET

STUDY

FOODS

161

S-Continued

Petaraiun *edianIleaw.wn>

Calcium Media*ear+.%“,

PhOlpO.xYS l&dim “ean+_sdm,

Mmc,IM “edianlear@m,

162

PENNINGTON

AND

YOUNG

to consider the variability of nutrients in foods, and to be aware that foods consumed by patients or subjects may not contain precisely the same nutrient levels as specified in food composition tables. Nutrient variation may result from genetic, environmental, processing, and analytic variables. High variation (i.e., high CVs) does not mean that the data are unreliable, but high variability may limit the use of the data in certain situations. The data may serve to assessdiets, especially if multiple records are used, but variable data should be used with caution for 1-day diet records, metabolic studies, or diets of patients who must be closely monitored. Nutrient variability should be considered when recommending specific foods as sources of nutrients either for nutrition education or for patient counseling. The variation of a nutrient in a food, expressed by the CV, is more important, in a practical sense, for those foods indicated to be a source of a nutrient (e.g., calcium in milk, rather than calcium in root vegetables, or magnesium in dark green leafy vegetables, rather than magnesium in cakes and pies). In other words, one would hope for less variability of nutrients in those foods which are routinely suggested as sources for particular nutrients. The data obtained here indicate that average CVs of 14-20% for major sources of the nutrient elements reflect “usual” variability. (This is, of course, assuming appropriate sampling and analytical methodology.) CVs greater than this might reflect more specific reasons for variability and may need to be used with caution. An evaluation of the data by source categories is shown in Table 7. Source categories have been defined by FDA for nutrients with USRDAs (U.S. Recommended Daily Allowances) (Pennington et al., 1990). (Calcium, phosphorus, and magnesium have USRDAs, but sodium and potassium do not.) An excellent source provides 40% or more of the USRDA per serving, a good source provides 25% or more of the USRDA, and a fair source provides 10% or more of the USRDA. The excellent, good, and fair source criteria are, respectively, 400, 250, and 100 mg/serving for calcium and phosphorus where the USRDA is 1000 mg/day; and 160, 100, and 40 mg/serving for magnesium where the USRDA is 400 mg/day. The eight good sources of calcium had an average CV of 15% (range 12-23%); the 18 fair sources had an average CV of 26% (range 16-38%). Foods with higher CVs included fast food hamburger (CV = 32%) vanilla ice milk (CV = 34%) fried shrimp

MACROELEMENTS

IN

TOTAL TABLE

DIET

STUDY

FOODS

6

AVERAGELEVELSOFTHEELEMENTSPERSERVINGBYFOODGROUP

Food

oroup

(n)

Sodium

Potassium,

Calcium (mg

per

Phosphorus

Magnesium

21.9

servlngl

Vegetables Leafy

(7)

Sten/flnvrr

(4)

Beans/peas

(9)

Pact/tuber

(131

Other

117)

Fruits

, juices

Grqin

products

Cookrd RTE

163

70

24

24

157

25

35

9.6

a0

278

33

98

35.3

106

317

28

50

18.6

179

192

18

30

14.4

4

215

16

20

13.1

(25)

grjins

(5)

cereals

Bread,

207

(71

70

41

9

46

14.7

187

171

21

92

33.0

ieo

50

31

68

11.1

118

175

16

95

45.6

rolls,

pasta,

etc.

Nuts

(3)

Eggs

(31

Dairy

(13)

products

Animal

(11)

10:

71

34

102

6.7

232

312

243

215

24.7

flesh

Fish

(4)

Poultry Meat

196

40

154

78.6

260

18

179

23.0

'7F

273

22

197

21.0

318

62

6

4R

5.1

829

420

110

213

41.4

832

178

42

61

13.7

262 (3)

e6

(11)

Breakfast/luncheon

meats

(51

Mixed

dishes

Soups

(4)

(12)

Desserts Dairy-based

(5)

201

309

161

188

28.5

Grain-based

(71

216

73

30

77

12.1

172

98

40

50

10.6

39

34

3

7

4.3

56

12

4

6

0.5

14

46

8

15

5.7

37

339

76

77

37.3

226

15

1R

13.1

5

92

34

65

18.3

7

26

17

12

2.1

45

208

28

122

14.9

40

178

43

75

16.2

46

166

95

91

13.3

Other

(51

Sweeteners Fats

and

(6) sa"ces

Severaoes

(9)

(131

Strained/junior

foods

Veqetables

17)

Fruits,

juirrs

Cereals

(7)

Formulas

(9)

(2)

Meat/poultry

(3)

Dinners

(9)

Dessert

Ill

8

163

164

PENNINGTON

AND YOUNG

TABLE 7 SOURCE

CATEGORIES

FOR CALCIUM,

PHOSPHORUS,

AND MAGNESIUM

C.3

No.

of

P

CV mean

No.

(range)

foods

foods

of

Good

sourcea

CV mean

No.

(range)

foods

source

a The excellent

of

1

(%I

22

0

-

8

15 (12-23)

7

16 (8-21)

0

-

26 (16-38)

53

14 (6-31)

14

15 (6-29)

phosphorus

was the

frozen,

fried

chicken

lowfat

plain

yogurt;

fast

milk;

lowfat

strawberry

milk.

The good

of

FEUDS

(range)

18

source

STUDY

CV mean

(%I

0

sourceb

(Fair)

DIET

Mg

(%)

Excellent

IN TOTAL

dinner. b The good

sources

chocolate lowfat

of

calcium

milkshake; milk,

phosphorus

buttermilk;

skim

milk,

and evaporated

chocolate included

pudding;

fast

noodle

casserole;

food

included

fried

beef/calf

chocolate and

liver;

milkshake;

cottage lowfat

plain

cheese; yogurt;

food yogurt;

sources

of

chocolate chicken

lasagna.

(CV = 34%) chicken noodle casserole (CV = 36%), and tomato soup (CV = 38%). The one excellent source of phosphorus had a CV of 22%; the seven good sources had an average CV of 16% (range 8-2 1%); the 53 fair sources had an average CV of 14% (range 6% for peanuts to 3 1% for tomato soup). There were no excellent or good sources of magnesium. The 14 fair sources had an average CV of 15% (range 7% for peanut butter to 29% for granola). ACKNOWLEDGMENTS The authors acknowledge the laboratory analyses performed by the chemists and technicians of the FDA Total Diet Laboratory in Kansas City, Missouri; and the computer assistance provided by David Graham of the Total Diet Laboratory, Dennis Wilson of the Division of Mathematics, and Sharon Schoen of the Division of Information Resources Management in the FDA Center for Food Safety and Applied Nutrition, Washington, D.C.

REFERENCES GEBHARDT,

S. E., CUTRUFELLI,

Juices: Raw,

Processed,

R., AND MATTHEWS,

Prepared.

Nutrition Information Service.

R. H. (1982).

Composition

ofFoods.

Fruits

and Fruit

Agriculture Handbook No. 8-9. U.S. Department of Agriculture, Human

MACROELEMENTS

IN

TOTAL

DIET

STUDY

FOODS

165

GRUBBS, F. E. (1969). Procedures for detecting outlying observations in samples. Technometrics ll( I), l21. KEITH, L. H., CRUMMETT, W., DEEGAN, J., JR., LIBBY, R. A., TAYLOR, J. K., AND WENTLER, G. (1983). Principles of environmental analysis. Anal. Chem. 53, 22 lo-22 18. MARTS, R. W., AND MELOAN, C. E. (1982). Rapid digestion/determination of food composites by ICP, SARAP Report, Vol. 6, No. 105-79. Department of Health and Human Services. PENNINGTON,J. A. T. (1982). Documentation for the Revised Total Diet Study: Food List and Diets. National Technical Information Service, PB82 I92 154, Springfield, VA. PENNINGTON, J. A. T. (1983). Revision of the Total Diet Study food list and diets. .I Amer. Diet. Assoc. 82, 166-173. PENNINGTON,J. A. T., AND GUNDERSON, E. L. (1987). A history of the Food and Drug Administration’s Total Diet Study, 1961 to 1987. J. Assoc. Ofl Anal. Chem. 70, 772-782. PENNINGTON,J. A. T., AND YOUNG, B. E. (in press) Total Diet Study nutritional elements, 1982-1989. J. Amer. Diet. Assoc. PENNINGTON, J. A. T., AND YOUNG, B. E. (1990). Iron, zinc, copper, manganese, selenium and iodine in foods from the United States Total Diet Study. J. Food Compos. Anal. 3, I66- 184. PENNINGTON, J. A. T., WILKENING, V. L., AND VANDERVEEN, J. E. (1990). Viewpoint: Descriptive terms for food labeling. J. Nutr. Ed. 22, 5 l-54. PENNINGTON,J. A. T., YOUNG, B. E., AND WILSON, D. B. (1989). Nutritional elements in U.S. diets: Results from the Total Diet Study, 1982- 1986. J. Amer. Diet. Assoc. 89, 659-664. PENNINGTON,J. A. T., YOUNG, B. E., WILSON, D. B., JOHNSON,R. D., AND VANDERVEEN, J. E. (1986). Mineral content of food and total diets: The Selected Minerals in Foods Survey, 1982-1984. J. Amer. Diet. Assoc. 86, 876-89 1.