Food Purchasing Intention, Nutrition
Conditions
Keywords
Food taxation, Food subsidies
Brief summary
Scientific context The increase in the consumption of unhealthy food coupled with a suboptimal consumption of healthier options have increased the risk of non-communicable diseases (NCD) worldwide. Among other public policies to address the rise in NCD -such as front of pack labelling, regulation of food and beverages in schools, marketing regulations targeted to children- taxation has been recognized as a cost-effective strategy to reduce consumption of taxed products. Although subsidies have been used to reduce food insecurity, with the rise in NCD associated with unhealthy diets, studies have explored the feasibility of combining subsidies to incentivize the consumption healthy food with taxes on unhealthy options. The impact of prices on dietary behaviour of consumers has been demonstrated in experimental designs as well as in economic analysis of observational data on purchases. Although some experimental studies have been used to study the impact of taxation and subsidies among specific populations in France, none has evaluated the impact in the general population. Objective The aim of the study is to evaluate the impact of implementing taxes on unhealthy food and beverages and subsidies to healthy food, separately and combined, on the nutritional quality of purchases, overall and by income level, in an experimental online supermarket. Intervention description: The intervention includes taxation of lower nutritional quality products (identified using the front-of-pack nutrition label Nutri-Score - classes D and E) and/or subsidies for products of higher nutritional quality (identified as raw products or Nutri-Score A and B). Design The intervention will be a parallel arm randomized trial stratified by income against a control situation with no changes in prices and the presence of the Nutri-Score on-pack for all pre-packed products in all interventions (control, taxes and subsidies). Expected public health impact: This study will allow to investigate the potential synergistic effect on the nutritional quality of food choices of combining taxation and income-based subsidies in a context of social inequalities in rising non-communicable disease associated with poor diets. Following a proportional universalism perspective, income-based subsidies can mitigate the regressivity of taxation according to income. As no countries have implemented this combination of fiscal policies to improve diets, the results of this study will contribute to the scientific knowledge on the topic and will provide preliminary results to decision makers.
Interventions
Sponsors
University of Paris 13
Paris School of Economics
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
DOUBLE (Investigator, Outcomes Assessor)
Intervention model description
Parallel arm randomized trial stratified by income : * Low-income participants (\<poverty line) : three-arm parallel arms - control, taxation and taxation+subsidies * high-income participants (\>= poverty line) : two-arm parallel arms - control, taxation
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Adult subjects (\>18 years old) included in the NutriNet-Santé cohort study from all income levels. * For the subsidies + taxation arm: inclusion only of low income-participants (below the poverty threshold 1,288€ - 60% of the median standard of living of the population)
Exclusion criteria
⁃ Subjects never engaging in grocery shopping. Participants will be excluded for this based on self-reported grocery shopping frequency using a short questionnaire at the inception of the study.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| NS-2023 NPM score | Peri-procedure (end of shopping session) | Nutri-Score-2023 Nutrient Profile Model (NS-2023 NPM score) The NS-2023 NPM Score provides a global assessment of the nutritional quality of foods and beverages. The NS-2023 NPM score for foods and beverages is computed considering nutrient content for 100g/100ml . It allocates positive points for content in energy (KJ;0-10 points), total sugar (g ;0-15 points), saturated fatty acids (g;0-10 points) and salt (g;0-20 points). Negative points are allocated to content in fruits, vegetables, and legumes (%;0-5 points), fibers (g;0-5 points) and proteins (g;0-7 points). Final NS-2023 NPM scores are based on a discrete continuous scale ranging theoretically from -17 (most healthy) to +55 (less healthy). Overall NS-2023 NPM score of the shopping cart will be assessed using a weighted average (by Kcal) NS-2023 NPM score of the items in the shopping cart, for 100g. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Energy | Peri-procedure (end of shopping session) | weighted average of Energy content of the shopping cart (Kcal/100g) |
| Saturated fatty acids | Peri-procedure (end of shopping session) | weighted average of saturated fatty acids content of the shopping cart (g/100g) |
| Sugars | Peri-procedure (end of shopping session) | weighted average of sugars content of the shopping cart (g/100g) |
| Salt | Peri-procedure (end of shopping session) | weighted average of salt content of the shopping cart (g/100g) |
| Fibers | Peri-procedure (end of shopping session) | weighted average of Fibers content of the shopping cart (g/100g) |
| Proteins | Peri-procedure (end of shopping session) | weighted average of protein content of the shopping cart (g/100g) |
| Fruit and vegetables | Peri-procedure (end of shopping session) | weighted average of content of the shopping cart in fruit and vegetables (%) |
| Food categories | Peri-procedure (end of shopping session) | Variation of different categories of untaxed products when prices of taxed products increase Decomposition of the total effect on the primary outcome based on the variation of volumes from the different categories of products in the basket. |
| Purchase cost | Peri-procedure (end of shopping session) | Total price of products in the shopping cart (€) for each participant |
| Lespeyres price index | Peri-procedural (end of shopping session) | Price index evaluating the fiscal impact of the intervention. ((∑〖p\_1 q\_0 〗)/(∑p\_0 q\_0 ))x100, where p\_1 is the price of food i in the interventions arm, p0 is the price of food i in the control arm. q\_0 is the quantity purchased of food i. |
| Passche price index | Peri-procedure (end of shopping session) | Passche price index: changes in prices paid relative to new patterns of consumption. Paasche price index formula: ((∑〖p\_(i,1) q\_(i,1) 〗)/(∑p\_(i,0) q\_(i,1) ))x100, where p\_(i,1)is the price of food item i in the intervention arm, q\_(i,1) is the quantity purchased of food item i in the intervention arm and p\_(i,0) is the price of food i in the control arm. |
Countries
France
Contacts
CONTACTChantal Julia, MD, PhD
Outcome results
None listed