Food price policies improve diet quality
while increasing
socioeconomic inequalities in nutrition
An illustration with experimental economics
Nicole Darmon, Nutrition Research Unit
UMR NORT INRA, INSERM, AMU, Marseille, France
with A. Lacroix, L. Muller, B. Ruffieux, Experimental Economy Laboratory
UMR GAEL INRA, Grenoble, France
Introduction: Social inequalities in diets and health,
and cost constraints, in France
Prevalence of adult obesity, by income, France
25
25,6
(Obepi survey, 2012)
22,8
% prevalence
20
19,4
18,8
16,2
15
16,1
15,3
11,9
10
8,8
7
5
0
<900
900-1200
1200-1500 1500-1900 1900-2300 2300-2700 2700-3000 3000-3800
> 3800-
>5300
Household Income (€/month)
 Strong social gradient in obesity in France
 Link with food budget constraints?
1/20
INTRODUCTION
Budget for food, by income, France
(National budget survey, 2000)
25
22,5
20
17,5
15
12,5
10
7,5
5
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
Household income decile
 Double constraint: low amount of money weights heavily on total budget
 Impact on food choices?
2/20
INTRODUCTION
Food consumption (g/d), by food sufficiency and income, France
g/d
400
387g
351g
(INCA2 survey, 2008)
336g
350
*
Fruit & Vegetables
320g
Means are adjusted on age,
gender, and energy intakes
300
275g
*
250
Starchy food
Dairy products
Mixed dishes, including soups
Sweet products
200
*
Meat/Fish/Poultry
150
F. Insecure FS1
FS2
FS3
FS4
(12%)
Food secure, income quartiles
Bocquier PHN 2015
 Social gradient in diet quality
 Link with diet cost?
3/20
INTRODUCTION
Diet cost (€/d), by quintiles of food group consumption, France
€/d
8
7
6
5
4
Q1
Q2
Q3
Q4
Q5
Fruit and Vegetables
Q1
Q2 Q3 Q4 Q5
Fats and sugar
Drewnowski & Darmon AJPH 2004
 Social gradient in diet quality
Prices important determinants of food choices Link with food prices?
4/20
INTRODUCTION
Energy Cost, €/100 kcal
Cost of 100kcal from different food groups
0.66 €
0.7
0.58 €
0.6
Darmon, Nutr Rev, 2015
0.5
0.4
0.3
0.18 €
0.2
0.06 €
0.1
0.0
Fruit &
Meat
Vegetables & Fish
Prepared dishes Dairy
& Snacks
Sugar/Salt
Cereals
products & Starches
Added
fats
 Healthy food groups are more expensive than unhealthy ones
 Unhealthy food groups are less expensive and more convenient
(easy to transport, stock, prepare)
5/20
INTRODUCTION
100
Nutritional
quality and price of individual food
R² = 0,31
*
SAIN/100g
10
1
0,1
*SAIN : mean adequacy for 15 nutrients
N =687 food items
0,01
log
0,001
0,01
0,1
1
Price (€/100g)
10
100
Darmon, Nutr Rev, 2015
 Healthy foods are more expensive than unhealthy ones
 The structure of food prices doesn’t favor healthy eating,
possibly explaining:
 the socioeconomic gradient in diet quality,
 the higher prevalence of obesity in low-income populations
6/20
Hypothesis and Aim
Hypothesis
Food price policies (subsidies and taxes):
 may orient food choices towards more healthy options
 may help fighting against social inequalities in nutrition
Aim
Use experimental economics
?
To simulate the impact of 2 policies:
- subsidies
- subsidies and taxes
On the food choices of 2 populations:
- medium-income women
- low-income women
7/20
Methods
Two policies
1. ‘Fruits & Vegetables (FV) policy’:
30% price reduction for fruit and vegetables
(i.e. subsidies only)
SAIN
2. ’Nutrient Profile (NP) policy’,
30% price reduction for healthy products
30% price increase for unhealthy products
(i.e. both subsidies and taxes)
F&V +
other
Healthy
Intermediate
Healthy and unhealthy products defined
with the SAIN,LIM nutrient profile system:
(Darmon N, Am J Clin Nutr 2009)
Neutral
Unhealthy
LIM
8/20
Methods
Two populations
1. Low-income group:
95 women below the poverty line,
18.5% were obese
2. Medium-income group:
33 women near the French median income
6.3% were obese.
% prevalence
Prevalence of adult obesity, by income
<900
900-1200 1200-1500 1500-1900 1900-2300 2300-2700 2700-3000 3000-3800 > 3800-
>5300
Household Income (€/month)
9/20
Methods
Experimental economics
1. Subjects were asked to select (on a computer) daily
food baskets that THEY WOULD LIKE TO BUY
2. They were told that THEY WOULD HAVE TO BUY one
of the baskets (randomly selected)
3. At the end of the experiment,
THEY REALLY BOUGHT one of
the baskets they selected
Incentive mechanism used to reveal ‘true’ preferences
Limits the social desirability associated with purely declarative statements
10/20
Methods
Experimental design - Description of one’s session task
Learning
Baseline
F&V policy
NP policy
Task
Yesterday
Yesterday food
basket
Tomorrow
Tomorrow food basket
Tomorrow
Tomorrow food
basket
Tomorrow
Tomorrow food basket
Prices
No posted prices
Market
Market prices
-30%
-30% Fruit & Veg.
-30%
-30% Healthy
Healthy foods
+30%
+30% Unhealthy
Unhealthy foods
Data
collection
Food purchased
Expenditures
Nutritional scores
Food purchased
Expenditures
Expenditures
Nutritional scores
Food purchased
Expenditures
Expenditures
Nutritional scores
Food purchased
Expenditures
Nutritional scores
Incentives
Non-incited
Incited
Incited
Incited
Nutritional scores:
Mean Adequacy Ratio (MAR), % adequacy/basket
Energy Density (ED), in kcal/100g
Free Sugars, % energy
11/20
Results
Daily food baskets selected at baseline by the 2 populations
Expenditure, in €/d
Quantities, in g/d
Medium
Mediumincome
income
1000
Lowincome
income
Low
800
600
400
*
2
1.2
*
*
*
*
0.8
200
0.4
0
0
Fruit & Other Neutral Unhealthy
Veg healthy
*
1.6
Fruit & Other Neutral
Veg healthy
Unhealthy
=> Low income: more unhealthy products, less fruit&veg, less other healthy products,
=> Low income: also lower MAR, higher energy density, higher % energy from free sugars (not shown)
At baseline, low-income women had less healthy diets
12/20
Results
*
Dietary changes (g/d) induced by the 2 prices policies in the 2 populations
1. Fruit & Veg policy
200
*
Mediumincome
income
Medium
150
100
50
Low
income
Low
income
*
2. Nutrient Profile policy
200
150
100
*
50
*
0
0
-50
-50
-100
1
**
*
Fruit & Other Neutral
*
Unhealthy
Veg healthy
=> F&V purchases increased in both
populations, but the magnitude was
lower for the low-income
=> Medium- but not low-income women
also increased other healthy products
-100
*
**
* Unhealthy
Fruit & Other Neutral
Veg healthy
=> F&V purchases increased and
unhealthy products decreased in both
populations
=> Medium- but not low-income women
strongly increased other healthy products
Results
*
Dietary changes (g/d) induced by the 2 prices policies in the 2 populations
1. Fruit & Veg policy
200
*
Mediumincome
income
Medium
150
100
50
Low
income
Low
income
*
2. Nutrient Profile policy
200
150
100
*
50
*
0
0
-50
-50
-100
1
**
*
Fruit & Other Neutral
*
Unhealthy
Veg healthy
-100
*
**
* Unhealthy
Fruit & Other Neutral
Veg healthy
Food policies had a favorable impact on food choices, but the
magnitude of the effect was lower for the low income women
14/20
Results
Nutritional quality at baseline and under the Fruit & Veg policy
1. MAR, %adequacy
14
Medium income
Low income
160
65
3. Free sugars, % kcal
2. Energy Density, kcal/100g
12
140
60
120
10
100
8
80
6
55
50
Baseline
F&V policy
Baseline
F&V policy
Baseline
F&V policy
F&V policy improved nutritional quality in both populations,
BUT the magnitude was lower in the low-income group
Unwanted effects in the low-income group: free sugars increased
Results
Nutritional quality at baseline and under the Nutrient Profile policy
1. MAR, %adequacy
2. Energy Density, kcal/100g
14
Medium income
Low income
160
65
3. Free sugars, % kcal
140
12
120
10
100
8
80
6
60
55
50
Baseline
NP Policy
Baseline
NP Policy
Baseline
NP Policy
The NP policy improved nutritional quality in both populations
BUT the policy did not decrease nutritional inequalities (the low
income group still had a lower nutritional quality than the medium income one)
16/20
Summary of results
Fruit and Vegetables policy
Fruit & Veg increased ------------------------- But lower magnitude for the low-income
Other healthy foods increased------------- But in the medium-income group only
Nutritional quality improved----------------- But unwanted effects for the low income
Nutrient Profile policy
Fruit & Veg increased--------------------------
Other healthy foods strongly increased
Unhealthy products decreased------------
Nutritional quality improved-----------------
Food price policies
improved dietary quality
But lower magnitude for the low-income
But in the medium-income group only
In both populations
But lower magnitude for the low income
BUT low income women benefited
less than medium income women
17/20
Concluding remarks
LIMITATIONS
 Small sample
 Experimental study
 Large (+/- 30%) variations in prices (unrealistic, politically unacceptable
CONCLUSION
Food price policies (subsidies and taxes):
 may orient food choices towards more healthy options
 but they may increase existing social inequalities in nutrition
 it is already known that policies directed at the whole population
benefit more to the high income ones
Study published International Journal of Behavorial Nutrition and Physical Activity, 2014
18/20
Concluding remarks
Importance of
targeting food policies
at low income groups
For instance:
Facilitating the access to
produce markets
Develop urban community gardens
in poor neighborhoods
19/20
Many thanks for you attention
Additional results
Increase of Social Disparities in purchasing power
The purchasing power was improved for both groups by both
policies, but inequalities increased between groups.
The purchasing power of richer women was, relatively to the low
incomes, improved because:
- their initial consumption pattern generated more subsidies and
fewer taxes
-they better adapted the new price structure by opting for wished
substitutions
Suppl