-
Food choices and diet costs: Food choices and diet costs:
An economic analysisAn economic analysis
Adam Drewnowski, PhDAdam Drewnowski, PhD
Director, Center for Public Health NutritionDirector, Center for
Public Health Nutrition
Director, NIH Roadmap Center for Obesity ResearchDirector, NIH
Roadmap Center for Obesity Research
Professor of Epidemiology and MedicineProfessor of Epidemiology
and Medicine
School of Public Health and Community MedicineSchool of Public
Health and Community Medicine
University of WashingtonUniversity of Washington
Poverty and Obesity: Disparities in Diet and HealthPoverty and
Obesity: Disparities in Diet and Health..ECOR Interdisciplinary
Forum, Seattle, WA, March 2, 2007ECOR Interdisciplinary Forum,
Seattle, WA, March 2, 2007
-
Disparities in diet and health:Disparities in diet and health:A
new focus on money and timeA new focus on money and time
Some basic points: Some basic points: •• EnergyEnergy--dense
foods cost lessdense foods cost less
•• NutrientNutrient--rich foods cost morerich foods cost
more
•• Healthier diets cost more per MJHealthier diets cost more per
MJ
•• There are inequities in food accessThere are inequities in
food access
•• Consumer food choices are driven byConsumer food choices are
driven by
•• Taste, cost, convenience, Taste, cost, convenience,
health, varietyhealth, variety
-
Consumers care about food costsConsumers care about food
costs
-
Some health professionals do not
-
Are healthy diets available to all?Are healthy diets available
to all?
Is this the perfect diet…………or is it economic elitism?
The Harvard SPH Food Pyramid
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Taste, cost, convenience = sugar + fat
Food choices
Energy density
Health
Taste
Cost
Variety
Time/Con-venience
Obesity
Grains,Sugar/fat
Sugar/fatGrains,
Sugar/fat
Grains,Sugar/fat
Obesity
-
First questionFirst question
Do energyDo energy--dense foods cost less?dense foods cost
less?
•• Energy density defined as MJ/kgEnergy density defined as
MJ/kg
•• Energy cost defined as $/MJ (Energy cost defined as $/MJ
(€€/MJ)/MJ)
•• Energy and nutrients from databasesEnergy and nutrients from
databases
•• Mean national food prices in France Mean national food prices
in France
-
0
10
20
30
40
0 10 20 30 40 50 60 70 80 90 100
water content (g/100g)
En
erg
y d
en
sit
y (
MJ
/kg
)
Fats Sw eets Grains Vegetables Fruit Meat Dairy
grains
butter
oil
vegetablesfruitPotato chips
meats
Energy density (MJ/kg) depends on thewater content of foods
-
0
200
400
600
800
1000
0.01 0.1 1 10 100 1000
Energy cost (Euros/1000kcal)
En
erg
y d
en
sit
y (
kc
al/
10
0g
)
oil
butter
Energy density (kcal/100g) and energy cost (Euros/1000kcal) –
INCA study
spreads
Log scale!
-
0
200
400
600
800
1000
0.01 0.1 1 10 100 1000
Energy cost (Euros/1000kcal)
En
erg
y d
en
sit
y (
kc
al/
10
0g
)
oil
butter
sugar
desserts
soft drinks
Energy density (kcal/100g) and energy cost (Euros/1000kcal) –
INCA study
-
0
200
400
600
800
1000
0.01 0.1 1 10 100 1000
Energy cost (Euros/1000kcal)
En
erg
y d
en
sit
y (
kc
al/
10
0g
)
oil
butter
sugar
desserts
soft drinks
grains
bread
pasta
Energy density (kcal/100g) and energy cost (Euros/1000kcal) –
INCA study
-
0
200
400
600
800
1000
0.01 0.1 1 10 100 1000
Energy cost (Euros/1000kcal)
En
erg
y d
en
sit
y (
kcal/
100g
)
oil
butter
sugar
desserts
milk
grainscheese
yogurtpasta
Energy density (kcal/100g) and energy cost (Euros/1000kcal) –
INCA study
-
0
200
400
600
800
1000
0.01 0.1 1 10 100 1000
Energy cost (Euros/1000kcal)
En
erg
y d
en
sit
y (
kc
al/
10
0g
)
oil
butter
sugar
desserts
milk
grainscheese
meat
pasta
Energy density (kcal/100g) and energy cost (Euros/1000kcal) –
INCA study
-
0
200
400
600
800
1000
0.01 0.1 1 10 100 1000
Energy cost (Euros/1000kcal)
En
erg
y d
en
sit
y (
kc
al/
10
0g
)
oil
butter
sugar
desserts
milk
grainscheese
fish/shellfish
foie gras
pasta
meat
Energy density (kcal/100g) and energy cost (Euros/1000kcal) –
INCA study
-
0
200
400
600
800
1000
0.01 0.1 1 10 100 1000
Energy cost (Euros/1000kcal)
En
erg
y d
en
sit
y (
kc
al/
10
0g
)
oil
butter
sugar
desserts
milk
grainscheese
fish/shellfishpasta
meat
vegetables
Energy density (kcal/100g) and energy cost (Euros/1000kcal) –
INCA study
-
0
200
400
600
800
1000
0.01 0.1 1 10 100 1000
Energy cost (Euros/1000kcal)
En
erg
y d
en
sit
y (
kc
al/
10
0g
)
oil
butter
sugar
desserts
milk
grainscheese
fruit
fish/shellfish
vegetables
nuts
pasta
Energy density (kcal/100g) and energy cost (Euros/1000kcal) –
INCA study
-
0
200
400
600
800
1000
0.01 0.1 1 10 100 1000
Energy cost (Euros/1000kcal)
En
erg
y d
en
sit
y (
kc
al/
10
0g
)
oil
butter
sugar
desserts
milk
grainscheese
fruit
fish/shellfish
vegetables
nuts
pasta
Wine/alcohol
Energy density (kcal/100g) and energy cost (Euros/1000kcal) –
INCA study
-
0
200
400
600
800
1000
0.01 0.1 1 10 100 1000
Energy cost (Euros/1000kcal)
En
erg
y d
en
sit
y (
kc
al/
10
0g
)
oil
butter
Disparity in food costs:Are “junk” foods simply cheaper?
sugar
desserts
soda
grains
fruit
fish
vegetables
High glycemic IndexHigh glycemic loadHydrogenated fatsTrans
fatty acidsAdded sugarsAdded fatsEnergy dense foodsEmpty
caloriesMinimal nutritional value
Low energy densityHigh satiating power
AntioxidantsPhytochemicalsFiberCLAVitaminsMinerals
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Second questionSecond question
Are energyAre energy--rich foods nutrientrich foods
nutrient--poor?poor?
•• EnergyEnergy--dense foods cost lessdense foods cost less
•• Grains, fats, oils are more affordableGrains, fats, oils are
more affordable
•• EnergyEnergy--dense foods taste better dense foods taste
better
•• Palatability = energy densityPalatability = energy
density
•• Are lowAre low--cost, energycost, energy--dense foods low in
dense foods low in
key nutrients?key nutrients?
-
We need to create a nutrient density score for foods:
• Nutrient Density Score is the ratio between the amount of
nutrients in a food and the energy that the food provides
NDS = (NAS/ED) * 100
• Nutrient Adequacy Score is based on percent DVsfor N key
nutrients as provided by 100 g of food
NAS = (ΣΣΣΣ (Nutrienti/DVi) * 100)/N• Nutrient-to-price ratio
NPR = NAS/price per 100g
Work by Work by DarmonDarmon, Drewnowski, Monsivais, Drewnowski,
Monsivais
-
0
100
200
300
400
500
600
700
800
900
0.1 10 1000
Nutrient Density Score/100 kcal
En
erg
y D
en
sit
y (
kc
al/
10
0g
)
Yes – energy dense foods have lower Nutrient Density Scores
(NDS/100kcal)
Fats/oils
Darmon, Darmon, Maillot, Drewnowski JADA 2005
F+V
sugar
-
0.1
1
10
100
1000
0.01 0.1 1 10
Price (Euros/100g)
Nu
trie
nt
Ad
eq
ua
cy
Sc
ore
/10
0g
All foods F+V
Higher nutrient-density (per 100g) usually means higher cost
(also per 100g)
Darmon, Darmon, Maillot, Drewnowski JADA 2005
-
0
10
20
30
40
10 100 1000
Nutrient Density Score (NNR version)
En
erg
y d
en
sit
y (
MJ
/kg
)
vegetables fruit
NNR scores for vegetables and fruit
applesaucegrape juice
raisins
fried potatoes
potato chips
canned pears
cantaloupemango
tangerinesstrawberries
grapefruitkiwi
spinachromaine
broccolitomato
avocadoblueberries
potatoes
OJ
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Third questionThird question::
Do energyDo energy--dense dense dietsdiets cost less?cost
less?
•• French INCA study conducted by AFSSAFrench INCA study
conducted by AFSSA
•• Sample of 1,985 adults; 7Sample of 1,985 adults; 7--day food
diariesday food diaries
•• National prices for 650 foodsNational prices for 650
foods
•• Diet costs measured in Diet costs measured in €€/d/d
•• Energy cost measured in Energy cost measured in
€€//10MJ10MJ
-
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10
Energy density (KJ/g)
Die
t c
os
t (E
uro
s/w
ee
k)
EI1
At each intake quintile, At each intake quintile,
higher energy density = lower cost higher energy density = lower
cost ((€€/wk)/wk)
INCA dataINCA data
-
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10
Energy density (KJ/g)
Die
t c
os
t (E
uro
s/w
ee
k)
EI1
EI2
At each intake quintile, At each intake quintile,
higher energy density = lower cost higher energy density = lower
cost ((€€/wk)/wk)
INCA dataINCA data
-
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10
Energy density (KJ/g)
Die
t c
os
t (E
uro
s/w
ee
k)
EI1
EI2
At each intake quintile, At each intake quintile,
higher energy density = lower cost higher energy density = lower
cost ((€€/wk)/wk)
EI3
INCA dataINCA data
-
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10
Energy density (KJ/g)
Die
t c
os
t (E
uro
s/w
ee
k)
EI1
EI2
At each intake quintile, At each intake quintile,
higher energy density = lower cost higher energy density = lower
cost ((€€/wk)/wk)
EI3
EI4
INCA dataINCA data
-
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10
Energy density (KJ/g)
Die
t c
os
t (E
uro
s/w
ee
k)
EI1
EI2
At each intake quintile, At each intake quintile,
higher energy density = lower cost higher energy density = lower
cost ((€€/wk)/wk)
EI3
EI4
EI5
INCA dataINCA data
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Spend less = Eat moreSpend less = Eat moreAre obesity and
poverty linked by the low cost of energyAre obesity and poverty
linked by the low cost of energy--
dense foods that are both palatable and convenient? dense foods
that are both palatable and convenient?
Drewnowski & Specter, Am J Drewnowski & Specter, Am J
ClinClin NutrNutr 2004;79:62004;79:6--1616
-
The Energy Density curve
Drewnowski and Specter AJCN 2004:79:6-16
0
2 5
Food costs (log)
Sugar
fat
Energydensity
Food energyrequirement
Food energy
Low quality High quality
The paradox – it is possible to spend less and get moreBut the
calories will be refined grains, added sugar and fat
-
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100 120 140 160
Energy intake (MJ/week)
En
erg
y d
en
sit
y (
KJ
/g)
As dietary ED increases As dietary ED increases ––
so do total energy intakesso do total energy intakes
INCA dataINCA data
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Last question:Last question:
What happens when you stratify What happens when you
stratify
diets by energy diets by energy costcost??
Food expenditures can be a proxy for SESFood expenditures can be
a proxy for SES
-
An epidemiological dogma fallsAn epidemiological dogma falls
The unshakeable relationship The unshakeable relationship
between nutrients and calories between nutrients and
calories
disappearsdisappears
-
A principle of nutritional epidemiology
• “Intakes of virtually all nutrients are positively correlated
with total caloric intake”
• “People who consume more total food have higher nutrient
intakes”
• “Nutrient intakes are biologically important in relation to
caloric intakes”
• Hence the need to correct for energy in epidemiologic
studies
•Willett and Stampfer in Nutritional Epidemiology, 2nd Ed, OUP
1998
-
The INCA (1998) data set
• INCA is a nationally representative study of 1,985 French
adults
• Dietary intakes based on 7-day diet records.
• More than 850 foods in the nutrient database
• Mean national food prices supplied by the French government
(INSEE); by market research agencies (SECODIP), as well as Paris
websites
• Diet costs estimated by multiplying unit price for each item
by portion size and summing over all foods consumed by that
person
• That is the estimated cost of the diet – assuming that all
foods are purchased and prepared at home
-
LowLow--cost diets: cost diets: Spend less Spend less –– but eat
morebut eat more
0.0001290277255237Folates (µµµµg/day)
0.00012969290828242287ß-Carotene (mg/day)
0.00018.07.57.26.9Vitamin E (mg/day)
0.00012.92.82.42.2Vitamin D (µµµµg/day)
0.000196857965Vitamin C (mg/day)
0.00018.28.79.09.4Energy Intake (MJ/d)
0.00015.76.06.16.4Energy Density (MJ/kg)
0.0001Q4 (9.0) Q3 (6.9)Q2 (5.9)Q1 (4.9)
P AnovaQuartiles of energy cost (€/10MJ)
AndrieuAndrieu, , DarmonDarmon, Drewnowski, EJCN, 2006,
Drewnowski, EJCN, 2006
-
80
100
120
140
Q1 Q2 Q3 Q4
% o
f Q
1
Energy Intake
Vitamin C
Vitamin Dß CaroteneFolates
4.9 €/10MJ 5.9 €/10MJ 6.9 €/10MJ 9.0 €/10MJ4.5 €/d 5.3 €/d 6.0
€/d 7.4 €/d
Energy Density
Vit E
Low cost diets: more energy, fewer nutrients
Referent diet
-
0
10
20
30
40
50
% diet cost % dietary energy
ValVal--dede--Marne: Contribution of Marne: Contribution of
foodfood groups to groups to dietdiet energyenergy andand to to
dietdiet costcost (Drewnowski & Darmon, AJCN, 2005)
� The energy/price hierarchy is such that the lowest-cost food
groups contribute the most to energy intakes
Meat/Fish F+V Dairy Grains Sugar Fats/oils
-
Final question:Final question:
What about food prices in Seattle?What about food prices in
Seattle?
•• We collected food prices in 2004 and 2006We collected food
prices in 2004 and 2006
•• Same supermarkets, same foods, same Same supermarkets, same
foods, same
package sizespackage sizes
•• The foods were divided by energy densityThe foods were
divided by energy density
•• Low ED = vegetables and fruitLow ED = vegetables and
fruit
•• High ED = grains, sugars and fatsHigh ED = grains, sugars and
fats
•• Manuscript (Monsivais et al.) submitted to Manuscript
(Monsivais et al.) submitted to
JADAJADA
-
0
2
4
6
8
10
0.01 0.1 1 10 100 1000
Energy cost ($/1000kcal)
En
erg
y d
en
sit
y (
kc
al/
10
0g
)
oil
butter
sugar
desserts
milk
grainscheese
fruit
fish/shellfish
vegetables
nuts
pasta
Energy density (kcal/100g) and energy cost ($/1000kcal) –Seattle
2006 Supermarket prices
-
Quintiles of Energy Density
2004-2
00
6 P
rice
In
flati
on
(%
)
*
1 2 3 4 5-10
0
10
20
30
]
]
]
]
]
The rising cost of low-energy-density foods
Fruits and vegetablesFruits and vegetables
Fats and sweetsFats and sweets
Monsivais et al. submittedMonsivais et al. submitted
-
Access to healthy foodsAccess to healthy foods
•• AffordabilityAffordability
•• EnergyEnergy--dense foods are cheaperdense foods are
cheaper
•• AccessibiityAccessibiity
•• EnergyEnergy--dense foods are closerdense foods are
closer
•• ConvenienceConvenience
•• Fast foods take less time to prepareFast foods take less time
to prepare
-
0
10
20
30
40
10 100 1000 10000 100000
Energy cost (log cents/10MJ)
En
erg
y d
en
sit
y (
MJ
/kg
)
oilshortening
margarine
sugar cheese
koolAid
beans
mayonnaise lettuce
potatoes
fresh tomatoescrackers
ground beef
white bread
milk
eggs
zucchini squash
green peppers
What can you get for $100/week for a family of 4. The USDA
Thrifty Food Plan: 1999
-
Is obesity an economic issue?Is obesity an economic issue?
-
A challenge for public health nutritionA challenge for public
health nutrition
Less expensive More expensive
• High-fat energy-dense foods are often the cheapest options for
the consumer •Editorial, The Lancet January 31, 2004
• If a meal of grilled chicken, broccoli and fresh fruit costs
more and is less convenient than a burger and fries, the battle
against obesity will be lost •Editorial, The Lancet January 31,
2004
-
Food choices and diet costs: Food choices and diet costs:
An economic analysisAn economic analysis
Adam Drewnowski, PhDAdam Drewnowski, PhD
Director, Center for Public Health NutritionDirector, Center for
Public Health Nutrition
Director, NIH Roadmap Center for Obesity ResearchDirector, NIH
Roadmap Center for Obesity Research
Professor of Epidemiology and MedicineProfessor of Epidemiology
and Medicine
School of Public Health and Community MedicineSchool of Public
Health and Community Medicine
University of WashingtonUniversity of Washington
Poverty and Obesity: Disparities in Diet and HealthPoverty and
Obesity: Disparities in Diet and Health..ECOR Interdisciplinary
Forum, Seattle, WA, March 2, 2007ECOR Interdisciplinary Forum,
Seattle, WA, March 2, 2007
