SSB taxes and diet quality in US preschoolers: estimated changes in the 2010 Healthy Eating Index

Background: Taxing sugar-sweetened beverages (SSBs) has been proposed as a strategy to combat child obesity. Yet it is unclear how a tax on SSBs might influence the overall quality of diet in preschool children. Thus, we use simulated price increases and the 2010 Healthy Eating Index (HEI-2010) to explore the relationship between SSB taxes and diet quality in preschool children. Methods: Price and purchase data from the 2009–2012 Nielsen Homescan Panel and a two-part marginal effects model were used to estimate relative changes in purchases with a 20% increase in the price of SSBs. Demand elasticities were applied to dietary intake data for children ages 2–5 years from the National Health and Nutrition Examination Survey (2009–2010 and 2011–2012) to estimate the impact of a 20% SSB tax on dietary intake and quality (HEI-2010). Results: A 20% increase in the price of SSBs was associated with lower total caloric intake (−28 kcal d⁻¹, p < 0.01), caloric intake from juice drinks (−20 kcal d⁻¹, p < 0.01), added sugars (−4.1 servings d⁻¹, p = 0.03), refined grains (−0.63 servings d⁻¹, p < 0.01) and total meat (−0.56 servings d⁻¹, p < 0.01). Beneficial decreases in empty calories and refined grains were offset by unfavourable changes in fatty acid profile, total protein, vegetables and fruit, such that total HEI scores (0–100 range) were not meaningfully changed with a 20% increase in SSB price (difference: −0.85, p < 0.01). Conclusions: A 20% tax on SSBs could decrease caloric intake, and intakes of added sugars and SSBs, but may not improve diet quality as an isolated intervention among US preschool children.