American’s nutritional and health status appear to be trending toward healthier diets, as measured by a reduction in cholesterol intake and an increase in calcium intake. The levels of food energy and total fats, however, increased substantially.Changes in American diet, nutrient economic responses, Health Economics and Policy, Poster 3601001,

Huang, Kuo S.

Huang, Sophia Wu

English

Research Papers in Economics

 
 
 
 
 
Do Americans Change Toward Healthy Diets? 
 
 
 
 
 
Kuo S. Huang and Sophia Wu Huang 
 
Economic Research Service 
U.S. Department of Agriculture 
Washington, DC 20036-5831 
 
 
 
Poster prepared for the Agricultural & Applied Economics Association’s 
 2010 AAEA, CAES & WAEA Joint Annual Meeting,  
Denver, Colorado  
July 25-27, 2010 
 
 
The views expressed here are those of the author and cannot be attributed to the 
Economic Research Service or the U.S. Department of Agriculture. 
 
 
 
  
Introduction 
 
The American Diet   
• As obesity and overweight in the United States impose a greater physical and economic toll 
on the Nation, the public has become more aware of the relationship between diet and weight.   
 
• For several decades, Federal nutrition education efforts have focused on providing 
consumers with information to help them make healthy food choices. The Government has 
taken steps through various food programs to reduce obesity among Americans.   
 
• As the Government’s efforts intensify, whether there has been a change toward a healthy 
diet is a timely research issue of interest to researchers and food policy decisionmakers.   
 
• To understand the American diet, we compared the changes in nutrients contributed by 
major food groups over years with the economic factors that affect changes in nutrient 
availability.    
 
Data for This Study   
• Per capita food consumption data for 131 food items during 1953-2006 came from the 
USDA/Economic Research Service’s Food Availability Data.  These individual foods 
were then aggregated into 14 food groups: beef, pork, poultry, fish, eggs, dairy, fats, 
fruits, vegetables, processed fruits/vegetables, flour, starch, sugar, and beverages.      
 
• The values of 28 nutrients for each food item were compiled from the USDA/Agri-
cultural Research Service’s The Online Version of Agriculture Handbook No. 8.    
 
• All food group price indexes were obtained from the U.S. Department of Labor’s Consumer 
Price Index, and per capita total expenditure was obtained from the U.S. Department of 
Commerce’s Personal Consumption Expenditures.  
 
Methodology 
Step 1: Measure food demand elasticities  
An aggregate differential-form food demand system consisting of 14 food groups for 1953-
2006 was estimated by incorporating the parametric constraints of homogeneity, symmetry, 
and Engel aggregation:   
   
     dqi / qi =  j eij (dpj / pj) + ηi (dm / m) ,         
 
 
where  pi  is price, qi is quantity, eij = ( qi/ pj)(pj/qi) is price elasticity, and  
ηi = ( qi/ m)(m/qi) is income elasticity.  
 
 
  
Step 2: Measure food nutrient values   
The availability of a nutrient, φk , was measured using per capita food consumption data 
and associated unit nutrient values:   
  
     φk =  i aki qi  ,    
 
where aki is kth nutrient from a unit of the ith food. 
 
Step 3: Measure food nutrient demand elasticities 
By incorporating the demand system into a nutrient availability equation, we obtained a 
nutrient demand system:  
 
     dφk / φk =  j πkj (dpj / pj ) + ρk (dm / m ) ,                      
 
where πkj =  i eij aki qi / φk is nutrient price elasticity, and ρk =  i ηi aki qi / φk is nutrient 
income elasticity. 
 
 
 
Results 
• Among 28 nutrients in this study, results show that 4 nutrients are currently public health 
concerns—excessive intake levels for food energy, total fat, cholesterol, and intake level 
shortfalls for calcium. The results provide a comparison of U.S. average nutrient values per 
capita per day for these four nutrients between 1953-79 and 1980-2006.  The responses of 
these four nutrients to changes in income and the price of 14 food groups are also included.  
 
• Food energy: Between the two periods, food energy intake increased substantially, 
from 2,999 to 3,468 kilocalories (kcal) per day. This 16-percent increase reflects higher 
intake levels of some energy-yielding food groups—fats, poultry, flour, and sugar. Fats 
contributed the most to this increase, increasing from 546 to 736 kcal per day. The 
estimated nutrient responses indicate that a price increase of 10 percent for pork, poultry, 
dairy, and flour would reduce energy intake within a range of 15 and 21 kcal per day.  
 
• Total fats: The consumption of total fat increased from 137 to 162 grams per day 
between the two periods. The increase came mostly from fats, increasing from 61 to 83 
grams per day. Other major sources of total fats, such as red meats and dairy products, 
showed a slight decrease. The effect of a 10-percent price increase for fats would reduce 
total fats intake by only 0.3 gram per day, while the same price increases for dairy and 
flour would reduce total fats intake for each group by about 3 grams.  
 
• Cholesterol: The level of cholesterol in the American diet declined from 430 to 402 
milligrams per day between the two periods. The decrease reflects reduced consumption 
from egg, where nutrient values decreased from 182 to 143 milligrams. The effects of a 
10-percent increase in the price of eggs would reduce cholesterol consumption by only  
1.54 milligrams per day.  The same price increase in beef, pork, poultry, and fish would 
reduce cholesterol intake to within a range of 1.6 and 3.8 milligrams. 
  
• Calcium: Calcium levels in the U.S. food supply is quite stable, with a slight increase 
from 865 to 890 milligrams per day between the two periods. Dairy consumption, as a 
major source (about 77 percent) of calcium, decreased slightly from 676 to 671 
milligrams per day. A 10-percent increase in dairy price would reduce calcium intake by 
3.66 milligrams per day, while the same price increase for fish and fats would reduce 
calcium intake for each group by about 9 milligrams.  
 
 • The nutritional effects from higher consumer income are mixed.  A 1-percent income 
increase would improve calcium intake (currently insufficient) by 2.49 milligrams per day, 
but it would also increase intake of nutrients that are already excessive, such as energy by 
7.31 kcal, total fats by 0.59 grams, and cholesterol by 1.13 milligrams.   
 
 
Conclusion 
• American’s nutritional and health status appear to be trending toward healthier diets, as 
measured by a reduction in cholesterol intake and an increase in calcium intake.  The levels of 
food energy and total fats, however, increased substantially.   
 
• The estimated nutrient responses show that changes in the availability of all nutrients 
vary depending on how food prices and income changes manifest themselves through the 
food demand relationships. Nutrient response estimates can be used to study food 
program effects on the overall availability of nutrients.  
  
                                 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
  
   
Nutrient values and their economic responses by food groups  
         
                                  Nutrient  
changes  Period  Beef  Pork  Poultry  Fish  Eggs  Dairy  Fats  Fruits  Vegetables 
Processed 
Fruits/vegetables  Flour  Starch  Sugar  Beverages  Total 
     
     
Changes in nutrient values between 1953-1979 and 1980-2006 
   
     
Energy (Kcal)  1953-79  248  203  74  13  63  376  546  44  19  173  531  168  533  9  2999 
   1980-06  223  187  161  16  50  359  736  53  25  204  607  246  591  12  3468 
Total fat 
(gram)  1953-79  20.3  18.9  4.9  0.4  4.3  19.9  61.2  0.3  0.1  4.1  1.4  0.7  0.0  0.6  137.1 
   1980-06  18.4  17.4  10.8  0.5  3.4  19.6  82.6  0.5  0.2  4.9  1.6  1.0  0.0  0.7  161.5 
Cholesterol 
(milligram)  1953-79  64.8  40.3  27.3  4.5  181.7  76.4  34.5  0.0  0.0  0.0  0.0  0.0  0.0  0.0  429.7 
   1980-06  57.1  36.9  59.6  5.5  142.7  69.5  30.2  0.0  0.0  0.0  0.0  0.0  0.0  0.0  401.5 
Calcium 
(milligram)  1953-79  7.3  10.2  4.3  4.9  22.8  676.4  4.1  11.1  19.4  56.0  22.0  15.8  5.8  4.9  864.8 
   1980-06  6.3  9.4  9.3  4.0  17.9  671.3  3.3  10.7  24.6  64.7  25.1  16.1  20.5  6.5  889.6 
                                               
  Nutrient 
responses     Beef  Pork  Poultry  Fish  Eggs  Dairy  Fats  Fruits  Vegetables 
Processed 
Fruits/vegetables  Flour  Starch  Sugar  Beverages  Income 
     
 
   Nutrient responses of a 10-percent price increase or a 1-perent income increase       
Energy (Kcal)     1.04  -15.22  -15.22  -5.35  -1.31  -17.15  -8.03  -4.75  3.39  13.04  -20.45  -4.07  -0.98  1.09  7.26 
Total fat 
(gram) 
 
-0.53  -1.06  -0.23  -0.21  -0.08  -3.16  -0.27  -1.74  -0.10  4.29  -2.71  -0.23  0.13  0.05  0.58 
Cholesterol 
(milligram) 
 
-2.06  -1.60  -1.70  -3.80  -1.54  -1.94  -0.96  -1.29  -0.37  3.78  -1.21  -0.40  0.16  0.31  1.13 
Calcium 
(milligram)     0.44  -0.89  -0.51  -9.39  -0.29  -3.66  -8.55  -0.21  -0.12  2.63  -0.63  -0.19  4.58  2.61  2.48 
Kcal=kilocalories; and Beverages=Nonalcoholic beverages. 
Notes: Nutrient values are based on 131 selected food items. Total fat refers to saturated and unsaturated fatty acids. Fats refers to butter, margarine, and cooking oils.   
 
       
                                 
                   
                                 
                                 
                                 
                                  
  
   
    

Do Americans Change Toward Healthy Diets?

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