Modelling impacts of a salt and sugar tax on intra-category food substitutions, BMI and environmental footprints

Abstract

Purpose Taxes on unhealthy foods can help improve population health in the United Kingdom (UK), but the health effects of food substitutions resulting from these taxes are often unclear. We investigated the potential impacts of a salt and sugar tax on hypothetical intra-category food substitutions, cost, body-mass index (BMI), and environmental footprints. Methods Purchase panel data from Kantar (2017) were used to determine the most popular foods high in salt or sugar within eight ‘salt-intensive’/‘sugar-intensive’ food categories. Within food categories, the most popular lower salt (≤1.5g salt/100g product) and lower sugar (≤22.5g sugar/100g product) substitutes were also identified. Hypothetical swaps between high salt/sugar foods and lower salt/sugar substitutes were explored, focusing on changes to cost, caloric intake and BMI, and environmental impacts. Results The suggested intra-category substitutions were largely like-for-like and did not accrue an added overall cost to consumers. The substitutions reduced calorie intake by about 200kcal/day and lowered the prevalence of overweight and obesity in the UK from approximately 60-65% to about 40-45%. The proposed food substitutions led to a total reduction of -2.7Mt of greenhouse gases, ~ -500.000ha of land, -0.5km3 of blue water, -12km3 of scarcity weighted water, ~ -12.000t of phosphorus, and nearly -14.000t of sulphur dioxide over one year for the UK population due to reductions in calorie intake. Conclusion Food substitutions following a tax on salt and sugar could lead to significant benefits for health and the environment, without necessarily resulting in major changes to people’s expenditure on familiar salty and sugary snacks.