جایگزینی نوشیدنی های سالم برای نوشیدنی های ناسالم در میان دانشجویان.دغدغه های بهداشتی و چشم انداز اقتصاد رفتاری

Excessive intake of sugar-sweetened beverages by undergraduates is closely related to the increasing prevalence of obesity, making investigations of the substitution of healthy for unhealthy beverages imperative. According to the concept of price elasticity in behavioral economics, the choice of healthy over unhealthy behaviors is facilitated by increasing the cost of less-healthy alternatives or reducing the cost of healthier alternatives. Furthermore, evoking health concerns by using health claims may induce substitution of healthy for unhealthy beverages. A total of 108 18–22-year-old undergraduates participated in a laboratory experiment and were given a certain amount of money and allowed to purchase a healthy beverage and a less-healthy beverage with or without receiving health claims. Increasing the price of a type of beverage was shown to reduce purchases of that beverage type and lead to substitution with the alternative type. Moreover, the effect of price elasticity on healthy beverage substitution was more pronounced when participants’ health concerns were evoked. The results suggest that lowering the cost of alternative commodities and evoking health concerns by health-related claims would foster the substitution of healthier for unhealthy beverages among college students.

Overweight and obesity have increased dramatically worldwide and in the United States over the past 30 years among both adults and children (Adderley-Kelly, 2007, Hedley et al., 2004, Huang et al., 2003 and Mokdad et al., 2001), and concern is growing that sugar-sweetened beverage (SSB) consumption may contribute to increasing obesity rates (Huffman & West, 2007). Frary, Johnson, & Wang (2004) reported that patterns of beverage consumption are associated with adolescent obesity and overweight and those unhealthy beverages (e.g., sugar-sweetened or soft drinks) have a negative impact on adolescent diet quality. Furthermore, a randomized controlled study reported that SSB consumption might promote obesity and that reducing consumption would benefit body weight (Ebbeling et al., 2006). A self-report survey about sugared beverages indicated that SSB consumption among undergraduates is substantial and probably contributes considerable non-nutritive calories, which may contribute to weight gain (West et al., 2006). Hence, interventions targeting excess SSB intake may have an important role in obesity-prevention efforts for college-aged populations (Huffman & West, 2007). Given that healthy or unhealthy beverage consumption is a crucial factor in college student obesity and overweight, research on how to decrease unhealthy beverage purchases is important. Most studies of obesity or unhealthy food and beverage consumption have focused on demographic (DeBate et al., 2001, Huffman and West, 2007 and West et al., 2006), biological (Lee et al., 2007 and Talpade, 2006), psychological (Newell et al., 1990 and Stevenson et al., 2007), behavioral (Kremers et al., 2007 and Rao, 2006), and socio-cultural (Klaczynski et al., 2004 and Wichrama et al., 2006) correlates. Few studies have examined effects of the interplay of price and purchase on unhealthy beverage consumption. Obesity is due, in part, to excess intake of energy-dense, nutrient-poor foods and a sedentary lifestyle (Epstein, Roemmich, & Raynor, 2001). Interventions to treat or prevent obesity must shift food choices from energy-dense foods to healthier low-fat, nutrient-dense alternatives. One way to encourage such shifts is to limit access to unhealthy foods (Goldfield and Epstein, 2002 and Smith and Epstein, 1991). According to behavioral-economic findings, one approach is to vary the cost of alternative commodities (Dufwenberg, 2007, Harrison, 2005 and Rachlin, 1989). For example, consumption of less-healthy foods can be reduced by taxing high-fat, low-nutrient snack foods (Jacobson & Brownell, 2000), whereas consumption of healthy alternatives can be increased by reducing the price of healthier, low-fat snack foods in vending machines (French et al., 1997) and the prices of fruits, vegetables, and low-fat foods in cafeterias (Cinciripini, 1984 and Jeffery et al., 1994). Based on a behavioral-economics perspective, increasing the price of a commodity should reduce its consumption, a phenomenon termed “same-price elasticity” (Bickel, Madden, & Petry, 1998). However, increasing the price of one commodity may also increase consumption of a substitute commodity, a phenomenon called “cross-price elasticity.” The present study tested the relationship between changes in price and purchases of beverages in a laboratory setting. Previous research suggests that college students will be less likely to choose unhealthy (or healthy) beverages as their price increases. Moreover, college students will be more likely choose healthier beverages when the price of less-healthy beverages increases, despite a preference for unhealthy beverages. Previous studies have suggested that consumer health concerns are closely related to dietary consumption (e.g., Ares et al., 2009, Kähkönen et al., 1999 and Sun, 2008). Recent years have seen a significant increase in concerns about health and wellness and a corresponding growth in consumer demand for healthy food products (Glazer, 2008). For example, consumers in the United States are turning to food and beverages to help address specific health concerns (Landi, 2007). Moreover, consumer health concerns are influenced by health claims (e.g., Silvergrade, 1991 and Wansink et al., 2004). Therefore, we predicted that health concerns evoked by health claims would induce substitution of healthy for unhealthy beverages. Health claims regarding beverage consumption may facilitate the effect of cross-price elasticity on purchases of healthy beverages. Following this logic, it was also predicted that health claims may weaken the effects of increasing prices for healthy beverages (i.e., the same-price-elasticity effect).

In principle, obesity-prevention efforts targeting unhealthy beverages may represent a promising avenue to explore with undergraduate populations. Behavioral economics provides an approach to understanding factors that affect the choice of healthy and unhealthy foods and activities. The strong same-price-elasticity relationship between purchases and prices across the full range of prices suggests that any increase in the price of unhealthy beverages may result in a reduction in purchases of unhealthy beverages, and reductions in the price of healthy beverages may result in increased purchases of these healthier alternatives. The cross-price-elasticity finding indicated that any increase in price of unhealthy beverages may result in increased purchases of healthier alternatives. Additionally, health claims may strengthen the cross-price-elasticity effect and undermine the same-price-elasticity effect. The results suggest that beverage-price policies and beverage-label regulation should be implemented in the hope that price-manipulation techniques and health concerns might be effective to reduce or even reverse the trend toward increasing body weight and obesity worldwide.