Mednotes

L11 Public Health Interventions

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tagspublichealth, lecture
aliasesL11 Public Health Interventions

13 min read

Overview

This lecture uses a tax on sugar-sweetened beverages (SSBs) as a worked example of population-level food policy. It moves from why population-level prevention matters, through the health rationale for taxing SSBs (dental, cardiometabolic and diet-quality harms of free sugar), the range of tax designs and support/opposition for them, the mechanisms by which such taxes are thought to work, and the evaluation evidence for their effectiveness and cost-effectiveness, finishing with UK and Pacific case studies and a reminder that taxation needs to sit alongside other measures.

Population-level prevention and food policy

  • Prevention strategies operate at two levels:
    • Individual level: requires individual behaviour change.
    • Population level: greater reach and effectiveness, usually policy-level, and focused on the wider determinants of health (modelled as concentric rings from the individual outward through lifestyle, community networks, local economy, built environment, natural environment, to the global ecosystem, each layer shaped by macroeconomic/political/global forces).
  • Food policy is public policy concerning how food is produced, processed, distributed, purchased and consumed. It can be voluntary or mandatory, and operates from the individual/whānau level up to the international level. Key NZ stakeholders: Ministry for Primary Industries, Food Standards Australia New Zealand, Ministry of Health, and local government.
  • ‘Fiscal levers’ available to food policy include taxes, subsidies, income supplements and vouchers (e.g. NZ alcohol excise duty changes, a proposed GST cut on fresh/frozen fruit and vegetables, and WHO advocacy for taxes on sugary drinks).

Background: why sugar and SSBs are a target

  • NZ context: reporting on poor child dental health as an equity issue, with large numbers of children on dental surgery waiting lists (e.g. nearly 2000 children overdue for surgery in Auckland; 1884 surgeries performed against 3307 referrals in the reported year, 1825 still waiting), and children needing serious dental work sometimes unable to sleep or eat properly because of pain, affecting the whole family.
  • WHO definition: free sugars are monosaccharides and disaccharides added to food/drinks by the manufacturer, cook or consumer, plus sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates.
    • WHO strongly recommends reducing free sugar intake throughout the life course, and reducing it to below 10% of total energy intake in both adults and children.
    • WHO conditionally recommends a further reduction to below 5% of total energy intake.
  • SSBs (World Bank definition) are non-alcoholic beverages containing added caloric sweeteners (e.g. sucrose, high-fructose corn syrup). Main categories: carbonated soft drinks, energy drinks, sports drinks, juices that are less than 100% fruit/vegetable, ready-to-drink teas/coffees, sweetened waters, and milk-based drinks.
  • Excess added sugar is linked to: dental caries, heart disease, weight gain (especially abdominal fat) and type 2 diabetes, with downstream associations including raised blood fat, raised blood pressure, fatty liver disease, insulin resistance and gout; fructose specifically may contribute via mechanisms still being explored. Recommended maximum is 12 teaspoons of added sugar/day (for comparison: an energy drink ≈ 12 tsp, a fruit smoothie ≈ 9 tsp, a sports drink or slice of red velvet cake ≈ 8 tsp, a can of fizzy drink ≈ 7 tsp).

Sugar and SSB consumption data (NZ)

  • NZ adults 15+ (2008/09): median free sugar intake overall was 57.3 g/day (11.1% of energy); intake was highest in 15-18 year olds (76.5 g/day, 14.2% TE) and 19-30 year olds (71.7 g/day, 13.4% TE), and lowest in 71+ year olds (43.3 g/day, 10.0% TE), i.e. free sugar intake as % of energy declines with age.
  • NZ Health Survey 2023/24: 12.9% of children aged 2-14 (an estimated 111,000 children) drink fizzy drink at least three times a week.

    • The transcript flags that the described time-series (prevalence rising from ~10% in 2011/12 to a peak of ~13-14% by 2022/23-2023/24, with a slight dip around 2018/19) and the age-band breakdown (2-4y ≈ 6%, 5-9y ≈ 9%, 10-14y ≈ 20.2%) are given on a text-only extracted page whose chart values were reconstructed from a matching rendered slide rather than confirmed directly from that page's text, so treat the exact trend shape and the two younger age-band figures as unverified; the headline prevalence (12.9%, ~111,000 children) and the 10-14y figure (20.2%) are confirmed.

Rationale for and opposition to SSB taxes

  • Organisations recommending taxing SSBs to improve health and reduce obesity: National Heart Foundation of NZ, NZ Dental Association, NZ Medical Association, WHO, World Cancer Research Fund, World Bank Group (SSB taxation described as “an effective policy lever available to governments to correct for market failures and raise societal welfare”).
  • Reasons given for taxing SSBs specifically:
    • Sugar consumption is associated with adverse health effects, including SSB-specific harms (particularly oral health).
    • SSBs are high energy, low nutrient.
    • There are environmental costs to SSB production.
    • An SSB tax is relatively easy to implement compared with other food/nutrition policy options.
    • It generates government revenue.
    • It has public support.
  • Opposition comes largely from industry, using: claims the tax “won’t work”; lobbying of politicians and marketing/“public information” campaigns; contesting the scientific evidence and providing misinformation (including funding research); legal challenges; and warnings of adverse economic effects (on employment, the economy, economic growth, or forcing production overseas).

Types of SSB tax

  • SSB taxes have been introduced across all world regions since the 1940s (earliest: Finland 1940, Norway 1981), with the pace accelerating sharply from the 2010s (e.g. Mexico, France, Chile, UK, and multiple US cities/regions among many others).
  • Tax measures applied to SSBs (World Bank typology):
    • Excise tax: levied on a specific product, typically at manufacture/distribution; can be specific (based on volume or sugar content) or ad valorem (based on % of product value); tiered/sliding-scale designs apply different rates by volume or sugar content.
    • Import tax (tariff/duty): collected on imported products.
    • VAT/GST: a broad-based tax assessed incrementally as a % of price at each stage of production and distribution; a consumption tax ultimately borne by the consumer at purchase (GST is usually a type of VAT).
  • Among currently implemented SSB excise taxes: single-tier volume-based is the most common design (46%, n=22), followed by ad valorem (27%, n=13), tiered volume-based (17%, n=8) and sugar-based (10%, n=5).

How SSB taxes are thought to work

SSB taxes are proposed to reduce consumption and improve population health through four mechanisms:

  1. Increasing retail prices — evaluation evidence clearly shows SSB taxes increase retail prices and reduce sales/purchases of taxed beverages.
  2. Raising public awareness — introducing a tax can strongly signal the health effects of SSB consumption, plausibly even before the tax is passed, though evaluation evidence for this pathway is currently limited.
  3. Incentivising non-price industry responses — well-designed sugar-based and tiered volume-based taxes have been shown to incentivise product reformulation and other industry responses that minimise the tax burden.
  4. Generating government revenue — revenue can be directed to health-improving programmes/services, though the amount is hard to predict precisely, especially where the tax successfully drives reformulation.

Are SSB taxes effective and cost-effective?

  • Evidence base draws on national taxes (Mexico, UK, France, Chile, Denmark, Barbados, Portugal, Finland, Hungary, Saudi Arabia, South Africa) and local/state/regional taxes in the USA.
  • Outcomes evaluated: price, pass-through (of the tax into retail price), sales, substitution in purchasing, substitution in consumption, and health outcomes — with some evidence of a reduction in children’s BMI.
  • Possible adverse effects assessed: cross-border shopping and effects on retailer revenue.
  • Cost-effectiveness: simulation studies model outcomes including BMI, diabetes, cardiovascular disease, cancer and other obesity-related diseases; quality of life and DALYs; over time horizons of >10 years; and costs of implementation against effects on price and revenue generated.

    • The transcript flags this page's extracted text as originally jumbled by pdftotext (a two-column bulleted list plus pull-quote box collapsed into one reading order) and reconstructed into what appears to be the intended grouping without adding content, but the exact original layout is not independently verified; a stray fragment "(R" at the start of the extracted text is also noted as illegible/unclear.

    • Pull-quote from the cited synthesis: of fifteen identified good-quality economic evaluations of sugar tax, all found it cost saving compared with “business as usual” and all showed significant health benefits, making a sugar tax “a promising policy option to reduce the health and economic burden of excessive sugar intake.”

Case study: Pacific Island Countries and Territories

  • Since 2000, one-quarter of Pacific countries have introduced excise taxes targeting unhealthy foods, and three-quarters have introduced taxes on sugary drinks.
  • Several Pacific examples use strong tax designs, including tiered tax levels based on sugar content and effective tax levels, aimed at improving health benefits and pro-equity impacts.

Case study: United Kingdom Soft Drinks Industry Levy (SDIL)

  • UK sugar intake exceeds the recommended maximum of 5% of energy across all age/sex groups (roughly 11-16% depending on age band), with soft drinks a major contributor to sugar intake in both children (4-18y) and adults (19-64y) diet breakdowns.
  • The SDIL was announced in March 2016 and implemented in April 2018. It was designed to incentivise reformulation, is levied on manufacturers/importers (not consumers directly), and uses a tiered structure:
    • Drinks with ≥8 g sugar per 100 mL: higher rate, 24p/litre.
    • Drinks with 5-7 g sugar per 100 mL: standard rate, 18p/litre.
    • Drinks with <5 g sugar per 100 mL: no levy.
  • The levy applies to drinks with sugar added during production or containing sugar (e.g. honey), with at least 5 g sugar per 100 mL ready-to-drink or diluted, that are ready to drink or require dilution/mixing (with water, crushed ice or carbon dioxide, or a combination), that are bottled/canned or otherwise packaged ready to drink, and with an alcohol content of ≤1.2% ABV.
  • Key findings after implementation:
    • Associated with a reduction in purchased sugar from all soft drinks: average reduction of 29.5 g per household per week (around 9%).
    • No evidence of an associated reduction in the total volume of SSBs purchased — the effect was largely driven by reduced sugar concentration (reformulation), not less drink bought.
    • No increase in purchases of confectionery or alcoholic drinks (i.e. no evidence of substitution to these).
    • Children’s and adults’ daily free sugar intake from soft drinks alone fell by approximately 3 g/day and approximately 5 g/day respectively.

Beyond taxation: other measures needed

Taxation alone is not sufficient; the lecture lists complementary measures to reduce SSB consumption and improve health:

  • Regulation of marketing and sponsorship of SSBs, especially to children.
  • Mandatory front-of-pack labelling.
  • Limiting access to SSBs in public settings such as schools, hospitals and sports facilities.
  • Including recommendations about SSBs in dietary guidelines.
  • Ensuring access to potable water in communities and settings.
  • Widening taxation to other beverages (milk- and fruit-based drinks, and artificially sweetened beverages).
  • Setting targets for sugar (and salt) content in foods.
  • Other measures to improve the food environment and promote equity, described as vital.

Self-test

  1. Distinguish individual-level from population-level prevention strategies in public health, and explain why population-level approaches are considered more effective.
  2. Define “free sugars” per the WHO, and state the WHO’s strong and conditional recommended intake thresholds.
  3. Define a sugar-sweetened beverage (SSB) and list its main categories.
  4. List four health effects linked to excessive sugar/SSB consumption.
  5. Give six reasons why SSBs specifically are targeted for taxation.
  6. List four types of opposition tactics used against SSB taxes, and who typically uses them.
  7. Distinguish an excise tax from a VAT/GST as applied to SSBs, and describe the difference between specific and ad valorem excise tax design.
  8. Describe the four mechanisms by which SSB taxes are thought to reduce consumption and improve health.
  9. What outcomes are measured when evaluating whether SSB taxes are effective, and what two adverse effects are also assessed?
  10. Describe the design of the UK Soft Drinks Industry Levy (SDIL), including its tiers and rates.
  11. Summarise the key findings of the SDIL evaluation, including what did and did not change.
  12. A country introduces an SSB tax and sees sugar purchases fall from soft drinks with no fall in the total volume of soft drinks purchased. What mechanism most likely explains this pattern, and what UK evaluation illustrates it?
  13. What proportion of Pacific Island countries have introduced taxes on sugary drinks since 2000, and what tax design feature is highlighted as supporting pro-equity impacts?
  14. List four measures, beyond taxation, recommended to further reduce SSB consumption and improve health.

Answers

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