Taxes on saturated fat, salt, and sugar improve the healthiness of grocery purchases, but changes are frustratingly small
Authors: Lindsay M Jaacks
Journal: The Lancet Public Health (2019)

The EAT-Lancet Commission1Willett W Rockström J Loken B et al.Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems.Lancet. 2019; 393: 447-492Summary Full Text Full Text PDF PubMed Scopus (3424) Google Scholar highlighted that major shifts in diet are needed to meet the proposed healthy reference diet, and could result in substantial reductions in premature mortality. But how can we achieve such major shifts in the healthiness of diets? Fiscal policies are likely to be part of the solution. A meta-analysis concluded that a 10% decrease in price (ie, subsidy) increased consumption of healthy foods by 12% (22 studies) and a 10% increase in price (ie, tax) decreased consumption of unhealthy foods and beverages by 6% (15 studies).2Afshin A Peñalvo JL Del Gobbo L et al.The prospective impact of food pricing on improving dietary consumption: a systematic review and meta-analysis.PLoS One. 2017; 12e0172277Crossref PubMed Scopus (166) Google Scholar However, almost all the studies identified at the time of this review2Afshin A Peñalvo JL Del Gobbo L et al.The prospective impact of food pricing on improving dietary consumption: a systematic review and meta-analysis.PLoS One. 2017; 12e0172277Crossref PubMed Scopus (166) Google Scholar (June, 2014) were experiments done in cafeterias, at vending machines, or at farmer's markets, and thus restricted in their generalisability. Subsequently, a handful of real-world fiscal policies have been tested. Perhaps the most well-known is in Mexico, where the first ever national tax on sugary beverages and non-essential energy-dense foods (ie, junk foods) was implemented on Jan 1, 2014. Within a year, purchases of taxed sugary beverages decreased by 12 mL per person per day and junk foods by 25 g (the weight of about 15 potato chips) per person per month. Although this represented a statistically significant reduction relative to predicted pre-tax trends, it is nonetheless frustratingly small.3Colchero MA Popkin BM Rivera JA Ng SW Beverage purchases from stores in Mexico under the excise tax on sugar sweetened beverages: observational study.BMJ. 2016; 352h6704Crossref PubMed Scopus (514) Google Scholar, 4Batis C Rivera JA Popkin BM Taillie LS First-year evaluation of Mexico's tax on nonessential energy-dense foods: an observational study.PLoS Med. 2016; 13e1002057Crossref PubMed Scopus (150) Google Scholar A 2017 study in The Lancet Public Health presented the results of a 20-store experiment in rural Australia, in which a 20% discount on fruit, vegetables, bottled water, and artificially-sweetened soft drinks was offered for 24 weeks.5Brimblecombe J Ferguson M Chatfield MD et al.Effect of a price discount and consumer education strategy on food and beverage purchases in remote Indigenous Australia: a stepped-wedge randomised controlled trial.Lancet Public Health. 2017; 2: e82-e95Summary Full Text Full Text PDF PubMed Scopus (61) Google Scholar Fruit and vegetable purchases increased by about 20 g (the weight of around two carrot sticks).5Brimblecombe J Ferguson M Chatfield MD et al.Effect of a price discount and consumer education strategy on food and beverage purchases in remote Indigenous Australia: a stepped-wedge randomised controlled trial.Lancet Public Health. 2017; 2: e82-e95Summary Full Text Full Text PDF PubMed Scopus (61) Google Scholar Worryingly, there was a concomitant 13% increase in less healthy food purchases, which translated into increases in sodium, saturated fat, and total energy.5Brimblecombe J Ferguson M Chatfield MD et al.Effect of a price discount and consumer education strategy on food and beverage purchases in remote Indigenous Australia: a stepped-wedge randomised controlled trial.Lancet Public Health. 2017; 2: e82-e95Summary Full Text Full Text PDF PubMed Scopus (61) Google Scholar In The Lancet Public Health, Wilma Waterlander and colleagues6Waterlander WE Jiang Y Nghiem N et al.The effect of food price changes on consumer purchases: a randomised experiment.Lancet Public Health. 2019; 4: e394-e405Summary Full Text Full Text PDF PubMed Scopus (28) Google Scholar tested the effect of price changes on total grocery purchases using a three-dimensional computer simulation of a leading national supermarket in New Zealand. Participants were randomly allocated to control (no change in prices), or one or more of the following price changes: 20% fruit and vegetable subsidy, 20% or 40% sugar-sweetened beverage tax, NZ$2 per 100 g or $4 per 100 g saturated fat tax, $0·02 per 100 mg or $0·04 per 100 mg sodium tax, or $0·40 per 100 g or $0·80 per 100 g sugar tax. Simulated taxes on saturated fat, salt, and sugar resulted in statistically significant improvements in the healthiness of purchases (saturated fat tax mean absolute difference 1·77%, 95% CI 1·03 to 2·52, p<0·0001; sugar tax 1·09%, 0·26 to 1·91, p=0·0099; and salt tax 1·31%, 0·50 to 2·13, p=0·0016), but these too were frustratingly small, with less than a 2% absolute increase in purchases of healthy foods above the control condition, in which 68% of food purchases were classified as healthy. Worrying substitution effects were also observed. Although the saturated fat and salt taxes resulted in about a 4% increase in fruit and vegetable purchases as a proportion of weight of all food purchased, they also resulted in a 3–5% increase in the percentage of total energy of all food purchases from sugar. Although this study6Waterlander WE Jiang Y Nghiem N et al.The effect of food price changes on consumer purchases: a randomised experiment.Lancet Public Health. 2019; 4: e394-e405Summary Full Text Full Text PDF PubMed Scopus (28) Google Scholar represents a promising metho-dological direction for generation of rigorous scientific evidence upon which policies to improve the healthiness of diets could be based, many questions remain. First, how would the food industry respond to these price changes? For example, if the food industry responded to a saturated fat tax by substituting sugar for saturated fat, the observed increases in percentage of total energy of all food purchases from sugar could be even greater in the real world than what was observed in this simulated experiment.6Waterlander WE Jiang Y Nghiem N et al.The effect of food price changes on consumer purchases: a randomised experiment.Lancet Public Health. 2019; 4: e394-e405Summary Full Text Full Text PDF PubMed Scopus (28) Google Scholar Rather than a reactive response to industry, it is time for governments to be proactive and set comprehensive maximum acceptable levels (ie, industry quality standards) for harmful nutrients, especially added salt, sugar, and trans-fats. This strategy has proven successful, for example, with respect to salt in the UK7He FJ Brinsden HC MacGregor GA Salt reduction in the United Kingdom: a successful experiment in public health.J Hum Hypertens. 2014; 28: 345-352Crossref PubMed Scopus (280) Google Scholar and trans-fats in the USA.8Brandt EJ Myerson R Perraillon MC Polonsky TS Hospital admissions for myocardial infarction and stroke before and after the trans-fatty acid restrictions in New York.JAMA Cardiol. 2017; 2: 627-634Crossref PubMed Scopus (53) Google Scholar Another important and related question is what other policies should be adopted concurrently with these price changes to maximise population health benefits? The experiences of countries such as Mexico, Chile, and the UK show that a suite of coordinated policies, including taxes and subsidies, as well as improved point-of-purchase labelling (eg, front-of-pack traffic light and warning labels), food marketing standards across all formats (eg, plain packaging), and population-level monitoring for accountability are key.9Mozaffarian D Angell SY Lang T Rivera JA Role of government policy in nutrition-barriers to and opportunities for healthier eating.BMJ. 2018; 361k2426Crossref PubMed Scopus (184) Google Scholar The small but positive effects observed in this virtual supermarket should not discourage us from pursuing taxes and subsidies as part of a multicomponent, integrated governmental strategy to tackle unhealthy diets. Implementation will not only require rigorous scientific evidence, but also public demand for action and responsive governments. Unregulated markets are an important reason we are in our current predicament and they are not going to get us out of it.10Swinburn BA Kraak VI Allender S et al.The global syndemic of obesity, undernutrition, and climate change: The Lancet Commission report.Lancet. 2019; 393: 791-846Summary Full Text Full Text PDF PubMed Scopus (1043) Google Scholar Regulation of the food industry will be required to ensure that reformulation in response to price changes does not produce unintended consequences and to achieve our shared societal goal of maximising population health. I declare no competing interests. The effect of food price changes on consumer purchases: a randomised experimentPrice changes representing saturated fat, sugar, and salt taxes increased total healthy food purchases. As we observed important substitution effects, a combination of different tax and subsidy policies might be the most effective way to improve diets and decrease diet-related chronic diseases. Full-Text PDF Open Access