The Role of Prices in Diet and Health of Older Adults

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PROJECT SUMMARY Price-based policy interventions, such as sugar-sweetened beverages (SSBs) or high-calorie food taxes, have the potential to improve people’s diets and reduce obesity rates. But “sin taxes” in the US or elsewhere have been politically difficult to implement, and the possible health benefits are hard to predict. This project investigates two issues that are of high significance for understanding the effectiveness of such health policies. The first is to understand to what extent such price interventions change consumer food prices. The second is to understand how overall food and beverage consumption responds to price changes, and whether such changes translate into improved health. We study them in separate aims in the context of Mexico, which imposed both a tax on sugar-sweetened beverages (approximately 9 percent) and energy-dense “junk” foods (8 percent on non-basic foods that contain ≥275 calories per 100 grams), effective January 2014. Our specific aims are to: (1) Aim 1: Study how the law changed prices for sugar-sweetened beverages (SSBs) and junk food relative to other foods using detailed barcoded price data. (2) Aim 2: Study how changes in food prices over time relate to changes in food purchases and health. a) Estimate own and cross-price elasticities of the household demand for food, calories and nutrients (fats, proteins, and carbohydrates, including sugar and fiber). We consider the full consumer basket and estimate substitution patterns between all food and nutrient purchases, using Household Expenditure Survey data (ENIGH) and barcoded price data. b) Analyze how changes in food prices before and after the tax policy was implemented affected self-reported and objectively-measured health outcomes for older adults (born prior 1962), such as body mass index, hip-to-waist ratio, diagnosed diabetes or hypertension, blood pressure measures, and glucose and cholesterol levels. ►We also look at the short- term changes in their medical therapy and expenses for type 2 diabetes and hypertension.◄ These analyses rely on the Mexican Health and Aging Study (MHAS) and barcoded price data. c) ►Explore how relationships in Aim (2b) vary by individual’s 2012 health condition, socio-economic status, their sex and age; and by the dietary intake of foods, such as SSBs and high-calorie foods averaged at the locality level by SES, sex and age. We do this using the MHAS, 2012 Mexican Nutritional and Health Survey, and price data.◄ (3) Aim 3: Simulate alternative tax policies, such as higher SSBs or junk food tax, or calorie and nutrient tax using key parameters: tax elasticities of prices (from Aim 1), price elasticities of food purchases and health (from Aim 2).