Analysis of price changes and food purchases in obese and lean mothers

描述（由申请人提供）：我们最近发现，对不太健康（营养素热量高）的食物征税减少了能量摄入和购买的膳食脂肪，增加了蛋白质购买，而补贴更健康的食物（营养素热量低）增加了购买的能量，而购买的宏量营养素的分布没有变化。本申请的目的是研究是否收入，身体质量指数（BMI），相对强化价值的食物（RRV）和冲动缓和的影响，价格对能源和购买的宏量营养素和饮食质量在一个大样本的225个种族和经济上不同的成年人。参与者将完成五个购物环节，与参考价格购物相比，选择的零食是否被征收+12.5%和+25%的税，或者水果和蔬菜以及不加糖的水是否被补贴-12.5%和-25%。具体目标1将评估价格变化对购买的能量和常量营养素的影响，预测税收将减少购买的能量和膳食脂肪并改善饮食质量，而补贴将增加水果和蔬菜以及购买的能量。具体目标2将评估收入作为食品购买的调节因素，预测低收入家庭将对税收更加敏感，并在这些食品征税时比高收入家庭更大程度地减少购买的能量和脂肪，并更大程度地改善饮食质量。我们预测，低收入家庭将更容易接受健康食品补贴。具体目标3将评估BMI作为食品购买的调节剂，预测BMI较高的参与者对税收不太敏感，并且当这些食品征税时，购买的能量和脂肪减少较少，饮食质量改善更大。BMI较低的参与者将更容易接受补贴，购买更多的水果和蔬菜。具体目标4将测试RRV作为食物购买的调节剂，预测对于不太健康的物品具有较大RRV的参与者对税收对减少能量和脂肪购买以及改善饮食质量的影响的反应较小，反之亦然，那些对健康食品有更大RRV的人将减少购买的能量和脂肪，并改善饮食质量，因为水果和蔬菜的补贴，加糖的水增加了。具体目标5将评估冲动性作为食物购买的调节剂，预测更冲动的参与者对税收对减少能量和脂肪购买以及改善饮食质量的影响的反应较低，发现食物强化和冲动的参与者将在零食征税时显示出能量和脂肪购买的最小减少以及饮食质量的改善。相反，当水果和蔬菜以及非甜味水的价格得到补贴时，那些不那么冲动的人更有可能增加购买水果和蔬菜或非甜味水。 公共卫生相关性：拟议的研究将评估收入、体重指数、食物的强化价值和行为冲动是否会缓和价格变化对能量摄入、购买的宏量营养素和饮食质量的影响。研究影响价格干预措施对粮食购买的有效性的个体差异因素的影响，将有助于深入了解可以利用税收或补贴来影响人口健康的公共政策决策。

DESCRIPTION (provided by applicant): We recently found taxing less healthy (high calorie for nutrient) foods reduced energy intake and dietary fat purchased, and increased protein purchased, while subsidizing healthier foods (low calorie for nutrient) increased energy purchased with no change in distribution of macronutrients purchased. The goal of this application is to study whether income, body mass index (BMI), relative reinforcing value of food (RRV) and impulsivity moderate the effects of prices on energy and macronutrients purchased and diet quality in a large sample of 225 ethnically and economically diverse adults. Participants will complete five shopping sessions that vary whether selected snack foods are taxed by +12.5 and +25%, or fruits and vegetables and non- sweetened water are subsidized by -12.5% and -25% in comparison to shopping at reference prices. Specific Aim 1 will evaluate the effect of price changes on energy and macronutrients purchased, with the prediction that taxes will reduce energy and dietary fat purchased and improve diet quality, while subsidies will increase fruits and vegetables and energy purchased. Specific Aim 2 will assess income as a moderator of food purchases, with the prediction that lower income families will be more sensitive to taxes, and show greater reduction in energy and fat purchased and greater improvement in diet quality when these foods are taxed than higher income families. We predict that lower income families will be more responsive to subsidies for healthier foods. Specific Aim 3 will assess BMI as a moderator of food purchases, with the prediction that higher BMI participants will be less sensitive to taxes, and show less reduction in energy and fat purchased and greater improvement in diet quality when these foods are taxed than lower BMI participants. Lower BMI participants will be more responsive to subsidies in purchasing more fruits and vegetables. Specific Aim 4 will test RRV as a moderator of food purchases with the prediction that participants with greater RRV for less healthy items will be less responsive to effects of taxes on reducing energy and fat purchasing and improving diet quality, and conversely, those who have greater RRV for healthier foods will show a reduction in energy and fat purchased and improvement in diet quality as subsidies for fruits and vegetables and non-sweetened water are increased. Specific Aim 5 will assess impulsivity as a moderator of food purchases with the prediction that more impulsive participants will be less responsive to effects of taxes on reducing energy and fat purchasing and improving diet quality, and participants who find food reinforcing and are impulsive will show the smallest reductions in purchases of energy and fat and improvements in diet quality when snack foods are taxed. Conversely, those who are less impulsive will be more likely to show an increase in purchases of fruits and vegetables or non-sweetened water when the prices of fruits and vegetables and non-sweetened water are subsidized. PUBLIC HEALTH RELEVANCE: Project Narrative The proposed research will assess whether income, body mass index, the reinforcing value of food and behavioral impulsivity, moderate the influence of changing prices on energy intake, macronutrients purchased and diet quality. Examining the effects of individual difference factors that influence the effectiveness of price interventions to influence food purchasing will provide insight into public policy decisions that can use taxes or subsidies to influence population health.