Systematic review and meta-analysis on the impacts of food taxes

Overview

Are you interested in joining this Marsden funded research evaluating the impact of food on sales, purchasing, consumption and other outcomes?

We are looking to support a Masters student (thesis or dissertation) to join our team, and lead a piece of research synthesising international studies on the impact of food taxes. Food taxes are only emerging as useful policy instruments, but there are some concerns e.g. about substitution to other foods, and equity. Pacific countries are leading in this area with five already introducing excise taxes on unhealthy foods. Elsewhere there are examples of failed and overturned legislation.

Objective

Systematically identify studies that have evaluated food taxes internationally, and synthesize their findings by meta-analysis, to assess tax impacts on sales/purchasing and consumption of taxed and untaxed foods (substitution), and any equity differences by socioeconomic position.

Funded. Start date 2025. Would suit a dissertation and could be developed into thesis. Would suit a PH Registrar.

Would suit someone with excellent grades in these papers (or equivalents):

• PUBH 711 Principles of Epidemiology*
• PUBH 721 Methods for Epidemiological Research*

Excellent grades in these papers would also be beneficial:

• PUBH 725 Applied Biostatistics 1 – Fundamentals
• PUBH 726 Applied Biostatistics 2 – Regression methods

Fiscal policies are recommended by the WHO for addressing NCDs, and although many countries have introduced excise taxes on sugary drinks, only a few countries have introduced food taxes.

Dr Teng will supervise a post-graduate student to do a systematic review of real-world food tax evaluations that use natural experiment methods, and meta-analysis of the international evidence.

The review will report on purchasing and dietary outcomes associated with increased taxes on unhealthy food. Findings will be synthesised by meta-analysis, including by food type. Meta-analyses have been done previously for sugary drinks by the supervising team, but the literature on food taxes has been sparse and there are no known available meta-analyses. We will report on all equity effects where these are available (such as heterogeneity in effects by household income). The methods used will adjust for different tax levels between jurisdictions (e.g. using tax elasticities), and a two-stage meta-analysis approach will be applied, first combining studies from the same jurisdiction, and then combining these summarised jurisdiction results.

Opportunity

1. Develop your knowledge about the impacts of WHO recommended policies
2. Join a policy evaluation team looking at impact of taxes in Tonga, PHP Andrea Teng, Dr Alice Kim, Dr Viliami Puloka, Prof Nick Wilson.
3. Skills development
   1. systematic review and meta-analysis methods
   2. develop policy understanding around strategies to address the food environment and obesity epidemic
   3. experience working with developing countries. Pacific is already a leader on food taxes
4. High impact publication in an international journal

Useful information

• Graduate research at the University of Otago
• Scholarships at the University of Otago