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Relationship Between Nutritional Knowledge and the Amount of Sugar-Sweetened Beverages Consumed in Los Angeles County Lauren N. Gase, Brenda Robles, Noel C. Barragan and Tony Kuo Health Educ Behav 2014 41: 431 originally published online 9 April 2014 DOI: 10.1177/1090198114529128 The online version of this article can be found at: http://heb.sagepub.com/content/41/4/431

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HEBXXX10.1177/1090198114529128Health Education & BehaviorGase et al.

Article

Relationship Between Nutritional Knowledge and the Amount of Sugar-Sweetened Beverages Consumed in Los Angeles County

Health Education & Behavior 2014, Vol. 41(4) 431­–439 © 2014 Society for Public Health Education Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1090198114529128 heb.sagepub.com

Lauren N. Gase, MPH1, Brenda Robles, MPH1, Noel C. Barragan, MPH1, and Tony Kuo, MD, MSHS1,2

Abstract Although consumption of sugar-sweetened beverages (SSBs) is associated with many negative health outcomes, including obesity, diabetes, and cardiovascular disease, the relationship between consumer nutritional knowledge and the amount consumed is poorly understood. The objective of this study was to examine the relationship between knowledge of daily calorie recommendations and the amount of SSBs consumed in a large, economically and racially diverse sample of adults recruited at selected Metro subway and bus shelters in Los Angeles County. In June 2012, the Los Angeles County Department of Public Health conducted street intercept surveys to assess food attitudes and consumption behaviors and public opinions related to a recent 8-week health marketing campaign targeting SSB consumption. Descriptive and comparative analyses were conducted, including a negative binomial regression model, to examine the relationship between knowledge of the daily calorie recommendations and the amount of SSBs consumed. Among survey respondents (n = 1,041), less than one third correctly identified the daily calorie recommendations for a typical adult. After controlling for sociodemographics and weight status, respondents who correctly identified recommended calorie needs reported, on average, drinking nine fewer SSBs per month than respondents who did not. Results suggest that efforts to reduce SSB consumption might benefit from the inclusion of educational interventions that empower consumers to make healthy choices. Keywords Dietary Guidelines for Americans, health promotion, nutrition, obesity, sugar-sweetened beverages The consumption of sugar-sweetened beverages (SSBs) has increased dramatically over the past decades (Duffey & Popkin, 2007; Nielsen & Popkin, 2004). On a typical day, 80% of U.S. youth and 63% of adults consume at least one SSB (Bleich, Wang, & Gortmaker, 2009). SSBs are defined as liquids that are sweetened with various forms of sugars that add calories, including (but not limited to) soda, fruit drinks, sports drinks, and energy drinks (United States Department of Agriculture, 2010). On average, these sugary drinks contribute an estimated 203 kilocalories per day to the diet of a typical adult in the United States; this is equivalent to about 9% of a person’s total daily caloric intake (Bleich, Herring, Flagg, & Gary-Webb, 2012). Prior research has established that SSB consumption is higher among younger adults, in African Americans and Mexican Americans (as compared with European Americans), and in persons with lower income and/or with less than a high school education (Bleich et al., 2009). The 2010 Dietary Guidelines for Americans recommends that all persons, regardless of age, reduce their daily intake of SSBs, as these sugary

drinks provide excess calories and few essential nutrients to the diet (U.S. Department of Agriculture, 2010). In several studies, SSBs have been found to be potential contributors to overweight/obesity (Chen et al., 2009; Rivard, Smith, McCann, & Hyland, 2012) and to other chronic conditions such as diabetes, elevated triglycerides, cardiovascular disease, and dental caries (Centers for Disease Control and Prevention, 2010; Vartanian, Schwartz, & Brownell, 2007). Among adults, a number of environmental, social, and individual factors have been found to influence consumption 1

Los Angeles County Department of Public Health, Los Angeles, CA, USA David Geffen School of Medicine at the University of California, Los Angeles, CA, USA 2

Corresponding Author: Lauren N. Gase, Division of Chronic Disease and Injury Prevention, Los Angeles County Department of Public Health, 3530 Wilshire Blvd, 8th Floor, Los Angeles, CA 90010, USA. Email: [email protected]

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Socio-economic and other environmental determinants Price relative to other substitutes

Environmental Influences

Availability

Advertising and promotion

Consumption of sugar -sweetened beverages among adults

Social Influences

Individual Influences Attitudes

Behavioral control

Taste

Social norms

Beliefs Knowledge/awareness Health literacy

Demographic, cultural and other individual differences

Information

Figure 1.  Conceptual model of predictors of sugar-sweetened beverage consumption among adults. Note. Developed based on the Integrative Model of Behavioral Prediction (Yzer, 2011; Zoellner, 2012).

of SSBs (Figure 1). Numerous aspects of the physical environment, including availability, advertising, product promotion, and price, have been shown to be related to the consumption of obesogenic foods, including SSBs (French, 2005; Story, Kaphingst, Robinson-O’Brien, & Glanz, 2008). Because SSBs are often readily available in convenience stores, restaurants, homes, and workplaces, they are easy to access and consume (Centers for Disease Control and Prevention, 2010). Exposures to environments in which SSBs are heavily marketed can influence preference, purchases, and consumption amount, with the link most clearly demonstrated for young children (Hattersley, Irwin, King, & Allman-Farinelli, 2009; Institute of Medicine, 2005). SSBs are relatively inexpensive, allowing persons with few resources to purchase them. A recent comprehensive review of the literature concluded that a 10% increase in the price of these sugary drinks could reduce their consumption by nearly 8% (Andreyava, Long, & Brownell, 2010). SSB consumption has been linked to several social and individual factors described in the Integrative Model of Behavioral Prediction, including social norms, behavioral control, and attitudes (Yzer, 2011; Zoellner, Estabrooks, Davy, Chen, & You, 2012). Social norms, including perceptions of peers’ feelings about SSB drinking, have been demonstrated to be associated with consumption in adults (Hattersley et al., 2009; Perkins, Perkins, & Craig, 2010). Likewise, the level of behavioral control, such as how much willpower and confidence to self-regulate, has been shown to influence consumption (Ezendam, Evans, Stigler, Brug, &

Oenema, 2010; Zoellner et al., 2012). Attitudes toward sugary drinks have been described as an important predictor of behavioral intention to consume SSBs (Hattersley et al., 2009; Jordan, Piotrowski, Bleakley, & Mallya, 2012; Zoellner et al., 2012). Sufficient knowledge about the content and consequences of food and beverage choices is often seen as a prerequisite to making healthy decisions and is foundational in developing many public health interventions to modify eating behavior, including SSB consumption (Ball et al., 2011; Klohe-Lehman et al., 2006). Limited literature suggests that knowledge about the potential negative health consequences of SSB consumption is associated with lower levels of sugary drink consumption (Hattersley et al., 2009; Huffman & West, 2007). Furthermore, providing information about the number of excess calories that SSBs contain (e.g., through media campaigns or point-of-purchase signage) has been shown to lead to changes in attitudes (Jordan et al., 2012; New York City Department of Health and Mental Hygiene, 2010) and purchasing rates (Bergen & Yeh, 2006; Bleich et al., 2012). New York City, Philadelphia, Boston, San Francisco, and Los Angeles have all implemented media campaigns designed to raise awareness about the sugar content of SSBs and their potential negative health effects. Focus group testing of these campaigns and evaluation findings suggest promising interventional impacts, including participants who reported learning new information from the campaigns and increased behavioral intention to reduce consumption after exposure to the counteradvertisements (Jordan et al., 2012; Health Resources in

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Gase et al. Action, 2011; New York City Department of Health and Mental Hygiene, 2010; Samuels and Associates, 2010). In spite of this emerging evidence on SSB consumption, the relative importance of nutritional knowledge among U.S. adults in making decisions about whether to consume sugary drinks or how much to consume is poorly understood. Presently, the majority of the research has been performed outside the United States, with children or adolescents, or on very specific population groups (e.g., college students, armed forces). This study sought to assess whether accurate knowledge of daily calorie recommendations was associated with the amount of SSBs consumed. The hypothesis was that adults who correctly identified the daily calorie needs (i.e., had greater knowledge about appropriate nutrient intake) would consume fewer SSBs. The study adds to the literature by assessing the relationship between knowledge and consumption using data from a public opinion street intercept survey of a large, economically and racially diverse sample of adults in Los Angeles County.

Method Street Intercept Survey The present study used a cross-sectional observational design. Data collection took place during 7 days in June 2012, carried out by 17 trained interviewers from the Los Angeles County Department of Public Health (DPH). The verbally administered 15-item street-intercept survey took respondents approximately 5 to 10 minutes to complete. The survey assessed respondents’ sociodemographics, use of public transportation, self-reported SSB consumption behaviors, knowledge of daily nutrient recommendations (calories, sodium, etc.), and awareness and message recall of the “Sugar Pack” health marketing campaign. The campaign, which provided information about the number of sugar packs in SSBs, ran from February to May 2012 on Los Angeles Metro subways and buses (Barragan et al., 2014). Respondents were recruited from three public transportation bus and/or rail (Metro) stops in public places, using a protocol that systematically accounted for duration of the recruitment period and volume of foot traffic. Site locations were selected based on target audience demographics and the estimated reach of the campaign. To be eligible for the survey, respondents had to be a Los Angeles County resident, at least 18 years of age, speak English or Spanish, and be willing and able to complete the administered survey at the time of recruitment. All study protocols and materials were reviewed and approved by the Los Angeles County DPH Institutional Review Board prior to fieldwork.

Variable Construction The number (amount) of SSBs consumed was derived by adding together self-reported frequencies of drinking “non-diet

soda” and “sport drinks or energy drinks.” Open-ended responses were converted to the total number of SSBs consumed per month. Because of the large number of “never” responses, the number of SSBs consumed is also reported as a categorical variable: frequent (≥1 SSB per day), sometimes (1-6 SSBs per week), rarely (1-3 SSBs per month), or never drinkers. Respondents were not asked about their consumption of diet drinks. Knowledge of daily calorie recommendations was derived from respondents’ answer to the open-ended question, “How many calories is a healthy adult supposed to consume each day?” Respondents who reported a value in the range of 1,600 to 3,000 kilocalories (the range a typical adult is supposed to consume based on gender and activity level, as per the 2010 Dietary Guidelines for Americans) were coded as “right” (i.e., correctly identified). Respondents who reported a value less than 1,600 kilocalories, more than 3,000 kilocalories, or stated that they “did not know” were coded as “wrong” (i.e., incorrectly identified). Covariates were selfreported (age, race/ethnicity, and education level) or observed by the interviewer (gender and weight status). Questions about recall and impact of the “Sugar Pack” health marketing campaign were asked at the end of the survey; these evaluation results are reported elsewhere (Barragan et al., 2014).

Statistical Analyses Descriptive statistics (frequencies for categorical variables, means for continuous variables) were initially generated for all variables and reviewed for inclusion in subsequent modeling analyses. Because of the large number of respondents who reported no SSB consumption, means, medians, and frequencies were generated for soda, sport/energy drinks, and total SSB consumption. Cross-tabulations of the knowledge of daily calorie recommendations variable by gender, weight status, education level, and race/ethnicity were carried out to examine bivariate relationships. Because the outcome of interest was a count variable with a large number of zeroes and a highly skewed distribution, a negative binomial regression model was constructed to allow for overdispersion. Variable selection for inclusion in the model was guided by the conceptual model (Figure 1). The primary predictor of interest was accurate knowledge of daily calorie recommendations (a dichotomous variable). Other covariates, including age (as a continuous variable) and gender, weight status, education level, and race/ethnicity (as categorical variables), were included as proxy measures of other predictors of SSB consumption. Incident rate ratios, contrasts for groups of dummy variables (education level and race/ethnicity), and pair-wise comparison of the estimated marginal means of the number of SSBs consumed for knowledge categories, education levels, and gender were conducted. Parameter estimates were judged to be significant if the two-tailed p value was less than .05. All calculations

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Table 1.  Respondent Characteristics, Street Intercept Survey, 2012 (N = 1,041). Respondent Characteristics

Frequency, n (%)

Gendera  Men  Women Weight statusa  Underweight/normal  Overweight/obese Racea  White/non-Hispanic   African American/Black  Hispanic/Latino   Asian/Pacific Islander  Other Educationa   Less than high school   High school graduate/GED   Some college   College or professional graduate

  527 (50.6%) 476 (45.7%)   648 (62.3%) 351 (33.7%)   148 (14.2%) 279 (26.8%) 414 (39.8%) 114 (11.0%) 70 (6.7%)   99 (9.5%) 275 (26.4%) 289 (27.8%) 302 (29.0%)



Mean (SD)

Age (years)

39.6 (15.2)

a

Percentages may not add to 100% because of missing data and rounding.

were performed in late 2012 and early 2013 using Stata version 12.1 (StataCorp LP, College Station, TX).

Results The survey response rate was 56%. Respondent characteristics (n = 1,041) are shown in Table 1. Compared to the general population in Los Angeles County (based on the 2010 U.S. Census), the study sample included more African Americans (26.8% vs. 9.3%), fewer non-Hispanic Whites (14.2% vs. 27.6%), and more high school graduates (83.2% vs. 75.9%). Approximately one third of the respondents (33.7%) were observed to be overweight or obese. This estimate is somewhat lower than the self-reported overweight/obesity rates (37.1% overweight, 23.6% obese) in the general adult population in Los Angeles County, as measured by the 2011 Los Angeles County Health Survey (Los Angeles County Department of Public Health [LACDPH], 2012). Overall, about a quarter of the respondents reported consuming a SSB at least once a day, roughly 36% consumed a SSB on a weekly basis, and 13% consumed a SSB rarely (i.e., on a monthly basis; see Table 2). Consumption of sports and energy drinks was reported less frequently than soda consumption. Analyses suggest that respondents who drank sports/energy drinks were somewhat unique from respondents who drank soda; roughly a third of respondents who reported drinking sports/energy drinks reported never drinking soda.

These estimates of SSB consumption are comparable to estimates obtained by the 2011 Los Angeles County Health Survey and the 2009 California Health Interview Survey, which reported frequent SSB consumption (at least once a day) as 35.5% and 24.3%, respectively (Babey, Jones, Yu, & Goldstein, 2009; LACDPH, 2011). About one third of the respondents accurately reported daily calorie recommendations for a typical adult, 40% reported an incorrect value (the vast majority of which underestimated calorie recommendations), and about 20% reported that they “did not know.” Among subgroups, disparities in knowledge of daily calorie recommendations was greatest among respondents with lower education levels, with only 8% of respondents with less than a high school education correctly reporting daily calorie recommendations, as compared with almost one half of those with a college or professional degree (Table 3).

Relationship Between Knowledge and Amount of SSBs Consumed Observations that contained missing data for the dependent variable or for any of the predictor variables were excluded from the negative binomial regression analysis (case-wide deletion), yielding a total sample size of 863 for use in the model. Negative binomial regression modeling detected that knowledge of daily calorie recommendations was significantly associated with the amount of SSBs consumed (Table 4). Predictive margins, after controlling for covariates (age, gender, race/ethnicity, education level, and weight status), revealed that respondents who correctly identified the number of calories a typical adult is supposed to consume each day drank, on average, 9.21 fewer SSBs per month than respondents who did not (p = .001). SSB consumption was significantly higher among high school graduates and those with some college (as compared to those with a college or professional degree). When average frequency of SSB consumption among respondents with lower education levels (less than high school, high school graduate, and some college) was compared to respondents with a college or professional degree, a significant difference between groups was found (χ2 = 12.23, p = .0005), with those from lower education levels reporting drinking 10.39 more SSBs per month. Gender was also significantly associated with the number of SSBs consumed, with men reporting drinking 7 more SSBs per month than women, after controlling for other factors. Among race/ethnicities, Latino ethnicity was significantly associated with drinking fewer SSBs than Whites, while age and weight status were not significant predictors.

Sensitivity Analyses To test the robustness of the multivariate model, sensitivity analysis was performed by manipulating both the independent

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Gase et al. Table 2.  Self-Reported Consumption of Sugar-Sweetened Beverages Among Adults in Los Angeles County, 2012. Amount of SSBs Consumed Mean number of SSBs consumed per month (SD) Median number of SSBs consumed per month Frequency, n (%)a  Frequent (≥1 SSB/day)   Sometimes (1-6 SSBs/week)  Rarely (1-3 SSBs/month)  Never

Soda

Sports Drinks/Energy Drinks

Total SSBs

16.3 (40.9) 4.3

6.3 (15.4) 0

22.7 (45.8) 8.6

203 (19.5%) 320 (30.7%) 120 (11.5%) 386 (37.1%)

93 (8.9%) 202 (19.4%) 113 (10.9%) 612 (58.8%)

259 (24.9%) 374 (35.9%) 136 (13.1%) 248 (23.8%)

Note. N = 1,041. SSB = sugar-sweetened beverage. a Percentages within each column may not add to 100% because of missing data and rounding.

Table 3.  Knowledge of Daily Calorie Recommendations Among Adults in Los Angeles County, 2012. Respondent Characteristicsa

Correctly Identified Caloric Needsb Frequency, n (%)

Incorrectly Identified Caloric Needsc Frequency, n (%)

337 (32.4%)

633 (60.8%)   293 (61.6%) 313 (59.4%)   390 (60.2%) 214 (61.0%)   66 (44.6%) 177 (63.4%) 272 (65.7%) 70 (61.4%) 39 (55.7%)   87 (87.9%) 189 (68.7%) 177 (61.3%) 154 (50.1%)

Full sample Gender  Men  Women Weight status  Underweight/normal  Overweight/obese Race  White/non-Hispanic   African American/Black  Hispanic/Latino   Asian/Pacific Islander  Other Education   Less than high school   High school graduate/GED   Some college   College or professional graduate

181 (34.4%) 148 (31.1%) 220 (34.0%) 107 (30.5%) 69 (46.6%) 82 (29.4%) 114 (27.5%) 39 (34.2%) 28 (40.0%) 8 (8.1%) 75 (27.3%) 105 (36.3%) 141 (46.7%)

Note. N = 1,041. a Percentages within each row may not add to 100% because of missing data and rounding. bReported 1,600 to 3,000 kcal. cReported 3,000 kcal, or “Did Not Know.”

Table 4.  Negative Binomial Regression Analysis of Consumption of Sugar-Sweetened Beverages Among Adults in Los Angeles County, 2012. Covariate

Parameter Estimate

Knowledge of daily calorie recommendations Age Women (Ref: men) Underweight/normal (Ref: overweight/obese) Race/ethnicity (Ref: White/non-Hispanic)   African American/Black  Hispanic/Latino   Asian/Pacific Islander  Other Education (Ref: college graduate or professional degree)   Less than high school   High school graduate/GED   Some college

95% CI

Incident Rate Ratio (95% CI)

−0.424** −0.006 0.324** 0.244

(−0.671, −0.177) (−0.014, 0.002) (0.088, 0.561) (−0.007, 0.495)

0.33 −0.473** −0.187 0.085

(−0.341, 0.407) (−0.829, −0.117) (−0.646, 0.273) (−0.435, 0.605)

0.654 (0.511, 0.837) 0.994 (0.986, 1.002) 1.383 (1.091, 1.753) 1.276 (0.993, 1.640)   1.033 (0.711, 1.502) 0.623 (0.436, 0.890) 0.830 (0.524, 1.314) 1.089 (0.647, 1.831)   1.287 (0.831, 1.991) 2.405 (1.779, 3.250) 1.390 (1.029, 1.877)

0.252 0.9878** 0.329*

(−0.185, 0.689) (0.576, 1.179) (0.028, 0.630)

Note. Multivariable analysis conducted on the subsample of respondents with no missing data for any of the covariates of interest, N = 863. CI = confidence interval. *p < .05. **p < .01. Downloaded from heb.sagepub.com at FLORIDA ATLANTIC UNIV on November 20, 2014

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and dependent variables. First, we examined the difference in SSB intake using two scenarios: (a) examining the difference between respondents who over and underestimated daily calorie recommendations and (b) coding only respondents who specified “2,000” calories as the daily calorie limit as “right,” since this figure has been widely disseminated. In the first scenario, both respondents who underestimated calorie recommendations and who reported that they “did not know” drank significantly more SSBs than respondents who correctly identified the daily calorie needs (p = .002, .007, respectively). Respondents who overestimated daily calorie recommendations were not significantly different than the reference group (p = .782); however, this estimate is likely not reliable due to the small cell size of the group (

Relationship Between Nutritional Knowledge and the Amount of Sugar-Sweetened Beverages Consumed in Los Angeles County.

Although consumption of sugar-sweetened beverages (SSBs) is associated with many negative health outcomes, including obesity, diabetes, and cardiovasc...
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