565388 research-article2015
RSH0010.1177/1757913914565388Energy drink consumption is associated with unhealthy dietary behaviours among college youthEnergy drink consumption is associated with unhealthy dietary behaviours among college youth
Peer Review Energy drink consumption is associated with unhealthy dietary behaviours among college youth
Energy drink consumption is associated with unhealthy dietary behaviours among college youth Authors Natalie S Poulos Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA Keryn E Pasch Department of Kinesiology and Health Education, The University of Texas at Austin, 1 University Station, D3700, Austin, TX 78712, USA Email: kpasch@austin. utexas.edu
Corresponding author: Keryn E Pasch, as above
Keywords energy drinks; college students; dietary behaviours; caffeine
Abstract Aim: Energy drink consumption has been associated with a variety of health risk behaviours, yet little research has explored the relationship between energy drinks and dietary behaviours of emerging adults. Therefore, the purpose of this study was to explore the relationship between energy drink consumption and dietary behaviours among energy drink users and non-users within a sample of college youth. Methods: College freshmen (n = 585, m age = 18.7 years; 47% non-Hispanic White, 20.9% Hispanic, 25.5% Asian, 2.7% non-Hispanic Black and 4.4% other; 56% female), at a large, southwest university self-reported their energy drink consumption in the past week and a variety of dietary behaviours, including past week soda, diet soda, pre-packaged salty snacks, pre-packaged sweet snacks, fast food, restaurant food, frozen food, fruits, vegetables, milk and breakfast consumption. Linear regression analyses were run to determine associations between energy drink consumption and dietary behaviour among users and non-users of energy drinks. Analyses controlled for gender, race/ethnicity and body mass index (BMI). Results: Overall, 17.5% of students had consumed energy drinks in the past week. Energy drink users were more likely to be male, White and have a greater BMI. Students also reported low past week intake of fruits, vegetables, milk and breakfast. Past week energy drink consumption was associated with increased soda and frozen meal consumption. Conclusion: Given a rapidly expanding energy drink market, future dietary interventions among college youth may want to consider the implications of energy drinks, as results of this study suggest consumption of these beverages is associated with unhealthy dietary behaviours and a greater BMI. Introduction College youth face many changes as they transition from adolescence to adulthood. Of the many changes that occur, previous research suggests that this period of transition from high school to college is associated with weight gain.1,2 Research suggests college youth do not meet national dietary recommendations and often have poor-quality diets3 because of lower consumption of fruits, vegetables, whole grains and milk and a higher consumption of sweetened beverages, salty snacks, and fast food.4–6 For example, only 6%–29% of college youth report consuming five or more servings of fruits and vegetables per day,2,7 even though current recommendations state that students should consume two to three cups of vegetables and two cups of fruits per day.8 One growing, yet
Copyright © Royal Society for Public Health 2015 SAGE Publications ISSN 1757-9139 DOI: 10.1177/1757913914565388
understudied dietary behaviour that has been associated with other unhealthy behaviours, such as alcohol use, is the consumption of energy drinks. An energy drink is a beverage that contains caffeine in combination with other ingredients such as sugar, amino acids, herbal extracts and B vitamins.9,10 While energy drinks are a relatively new product, the energy drink market has grown exponentially. For example, the energy drink market increased 240% between 2004 and 2008,11 yielding profits of US$26.9billion worldwide and US$7.9billion in the United States.9 This trend is expected to continue, as research has suggested that energy drink profits will continue to increase9 as the energy drink market growth rate is expected to be 13.4% annually between 2013 and 2018.12
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Peer Review Energy drink consumption is associated with unhealthy dietary behaviours among college youth
The initial target consumer of energy drinks was the athlete, but has expanded to additional markets, including college youth.13 These consumers have been targeted due to the generation’s fast paced lifestyle and susceptibility to marketing.13 Because of this, it is not surprising that previous research suggests between 34% and 51% of college students have consumed energy drinks in the past month.14–16 While previous research has shown positive effects of small doses of caffeine on attention, endurance and performance during cognitively demanding tasks,17 the increasing rates of consumption are concerning for a variety of reasons. First, these drinks contain large doses of caffeine that can range between 50 and 505 mg of caffeine per serving, and potentially provided more caffeine per drinking occasion as compared to sodas (35–50 mg caffeine/serving) and coffee (77–150 mg of caffeine/serving).10 Additionally, problematic side effects associated with greater energy drink consumption include caffeine intoxication/ dependence, tachycardia, hypertension and heart failure.10 Furthermore, associations with energy drinks include high-risk behaviours such as marijuana use, sexual risk-taking, fighting, alcohol consumption and intention to drive under the influence of alcohol.14,18 Finally, the sugar content of these beverages should be considered as it is often a primary ingredient,9 classifying it as a sugarsweetened beverage (SSB) similar to beverages such as soda. While energy drinks are less studied in their relationship with weight gain and risk of metabolic syndrome or diabetes, consumption of other SSBs, such as soda, have been linked with each of these problematic outcomes.19,20 Little research has documented the relationship between energy drinks and dietary behaviour, yet it is possible that energy drink consumption may be related to other dietary behaviours. For example, one of the most commonly reported side effects of energy drinks are episodes of ‘jolt and crash’, or increases in energy state followed by a rapid decrease in energy state.15 Given these dramatic shifts in energy state, students may turn to
calorically dense foods to maintain or return to the previously high energy state after experiencing one of these episodes. This may be problematic as relying on calorically dense foods has been associated with weight gain and obesity21 and may exacerbate already poor diet quality.
Purpose The purpose of this study was to examine the associations between energy drink consumption and dietary behaviours among college youth. As energy drink consumption is a relatively new dietary behaviour, we were specifically interested in the behaviours of energy drink users as compared to non-users. It was hypothesised that energy drink consumption would be positively associated with unhealthy dietary behaviours and inversely associated with healthy dietary behaviours.
Material and Methods Participants All incoming freshmen at a large, southwestern university in fall 2009 (n = 6,198 students), who agreed to participate in research (86% of freshmen), were eligible to participate in an online survey, which took place in April–June 2010. Of eligible students, 2,971 students were randomly selected to participate. Students were able to log on to a secure website from a location of their choice and complete the survey in as many sittings as necessary. Informed consent was collected from students on the first page of the survey and student responses were anonymous. A total of 603 participants (20% response rate) agreed to participate. Participants who were under 18 years of age (n = 4), upperclassman (n = 13) or identified themselves as transgender (n = 1) were excluded from the analysis due to small samples. This resulted in a final sample of 585 participants. The study was approved by the Institutional Review Board.
Measures and covariates Students completed a survey on a range of variables which included measures of dietary behaviours and energy drink
consumption. Individual dietary behaviours, including soda (e.g. Coke, Pepsi, Sprite; do not include diet soda/ pop), diet soda (e.g. Diet Coke, Diet Pepsi, Diet Sprite), milk, sweet snacks (e.g. cookies, candy), salty snacks (e.g. crackers, chips, beef jerky) and frozen food consumption (e.g. TV dinners, pizza, taquitos) were measured for the past week (range = 0 times per day to 4 or more times per day). These measures were adapted from previous research in similar populations,22 by maintaining question phrasing, but also including measures that were hypothesised to be relevant to energy drink consumption (e.g. salty snacks). Fruit consumption was measured by a single question, ‘How many servings of fruit do you usually consume per day?’ (range = 0 servings per day to 5 or more servings per day).7 Vegetable consumption (excluding potatoes, French fries and potato chips) was measured by asking a similar question (range = 0 servings per day to 5 or more servings per day).7 Students were not provided with examples of what constitutes a serving of fruit or vegetable. Breakfast consumption was measured through the single item, ‘In the past 7 days, on how many days did you eat breakfast?’ (range = 0 days per week to 7 days per week).22 Fast food consumption was measured by asking a single question, ‘Please indicate how often you did the following in the past 12 months: Eat fast food’ (range = 0 times in the last 12 months to several times a day).22 Restaurant food consumption (excluding fast food establishments) was also measured according to past year (range = 0 times in the last 12 months to several times a day). Both measures of fast food consumption and restaurant consumption have been used in previous research among this population.22 As the majority of dietary behaviours were asked about past week consumption, all variables were recoded to reflect past week consumption. Energy drink consumption was measured by a single question measuring past week consumption: ‘During the past 7 days, how many times did you drink an energy drink (e.g. Red Bull, Monster, Full Throttle)?’ (range = 0 times per day to 4 or more times per day). This measure was adapted from previous research to be
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Peer Review Energy drink consumption is associated with unhealthy dietary behaviours among college youth
similar to other food/beverage items used with college students.22 For analyses, past week energy drink use was dichotomised to represent users and non-users. Users were those who reported consumption of at least one energy drink within the past week. Gender was self-reported and included as a covariate (male or female) as gender has been previously associated with energy drink consumption.18 Body mass index (BMI), a common measure of body fat based on height and weight,23 was calculated based on self-reported height in inches and weight in pounds and used as a continuous covariate. BMI was included as a covariate in all analyses as it was significantly associated with energy drink consumption (β = .06, standard error (SE) = .03, p = .04) in this sample. Race/ethnicity was self-reported by students as Non-Hispanic White, Hispanic, Non-Hispanic Black, Asian American/Pacific Islander and Other. For analyses, race/ethnicity was coded as White or non-White. Race/ethnicity was included as a covariate as it has been found to be associated with energy drink consumption previously.14,24
Statistical analysis T-tests and chi-square analyses were used to determine differences in gender, race/ethnicity, BMI and dietary behaviours between users and nonusers of energy drinks in the past week. Linear regression was used to determine whether past week ever use energy drink consumption was associated with each individual dietary behaviour while accounting for covariates. Covariates included race/ethnicity, gender and BMI. Prior to analysis, skewed variables (soda, diet soda, salty snack, sweet snack and frozen food) were square-root transformed to normalise data. Once transformed, all skewness and kurtosis values fell within normal limits. Models were run with both the transformed and non-transformed data. Results did not differ; therefore, to assist with interpretability, non-transformed data are presented. All results are presented with two-sided p-values with an alpha = .05. All analyses were conducted using Statistical Package for the Social
Sciences 19 (SPSS 19, IBM Corporation, Armonk, New York, 2011).
Results The sample consisted of freshmen (m age = 19 years), a majority of whom were female (56%), 46% were White, 21% Hispanic, 26% Asian, 3% non-Hispanic Black and 4% other. The average BMI fell within the normal range (m = 22.9). Demographic characteristics of the sample were similar to the overall freshman class from which it was drawn (53% female, 51% White, 21% Hispanic, 20% Asian, 5% Black and 8% other race/ethnicity). In all, 17.5% of students consumed at least one energy drink within the past week. Of the students who consumed energy drinks in the past week, 77.3% consumed energy drinks 1–3 times per week, 13.6% consumed energy drinks 4–6 times per week, 5.7% consumed energy drinks 1 time per day and 3.4% consumed energy drinks 2 or more times per day. Overall, the consumption of each food or beverage varied from 1.3 times per week (restaurant food) to 11.3 times per week (vegetables) (Table 1). Almost all students (99.4%) reported eating food purchased at a restaurant at least once in the past week, while just over one quarter (26.6%) reported consuming diet soda (Table 1). Almost all students (94.6%) consumed at least one fruit or vegetable per week; however, only 23.4% of students consumed five or more fruits and vegetables per day. When comparing energy drink users and non-users, a greater percentage of energy drink users were males and White. Additionally, energy drink users had a significantly greater BMI and consumed more soda and frozen meals than non-users (Table 1).
Past week energy drink consumption and dietary behaviours Past week energy drink consumption was significantly associated with consumption of regular soda and frozen food, after controlling for BMI, gender and race/ethnicity according to both non-transformed and log-transformed p-values (Table 2). Results suggest that for every additional energy drink consumed, emerging adults consume 1.47 more regular sodas and 0.75 more
frozen meals per week (Table 2). Past week energy drink consumption was not associated with past week consumption of diet soda, salty snacks, sweet snacks, fast food, restaurant food, fruits, vegetables, milk, breakfast or a combined measure of fruit and vegetable consumption (Table 2). Of note, relationships between energy drink consumption and vegetable and diet soda approached significance (Table 2). Data on the relationship between energy drink and alcohol consumption were collected as part of this study, yet have been published elsewhere.18
Discussion This study found that 17.5% of students consumed energy drinks weekly and that energy drink consumers are more likely to be White males.24 As previous research has focused on past month energy drink consumption, a direct comparison to the present study is not possible as it was focused on weekly consumption. However, in previous work with this sample, we found that 38% of students consumed energy drinks in the past month.25 This is similar to work with other samples which found monthly prevalence rates to be 34%–51%.14–16 A significant relationship was found between past week energy drink consumption and some dietary behaviours. As hypothesised, past week energy drink consumption was positively associated with soda and frozen food consumption, yet energy drink consumption was not associated with other negative dietary behaviours (salty snack, sweet snack, fast food or restaurant food) or any of the healthy dietary behaviours (fruit, vegetable, milk and breakfast consumption), although relationships with vegetables and diet soda approached significance. These results suggest that those individuals who consume energy drinks also engage in some specific unhealthy dietary behaviours. Given significant associations with soda and frozen food, it is possible that past week energy drink consumption is associated with convenience foods that are dorm friendly. For example, students report consuming energy drinks to study
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Peer Review Energy drink consumption is associated with unhealthy dietary behaviours among college youth
Table 1 Demographic characteristics and mean weekly dietary behaviours among a sample of college youth overall and by energy drink user status (n = 585) Descriptive variable
Overall (SE)
Users (SE)
Non-users (SE)
% consumed at least once in past week –
Gendera Male
44%
71.6%
38.0%
Female
56%
28.4%***
62.0%
–
Ethnicitya White
46%
55.7%*
44.1%
Non-White
54%
44.3%
55.9%
BMIb
22.94 (4.25)
23.91 (4.74)*
22.76 (4.14)
–
Sodab
2.92 (4.38)
4.41 (5.63)**
2.56 (3.96)
61.4
Diet sodab
1.35 (3.66)
2.03 (4.05)
1.22 (3.57)
22.6
Pre-packaged salty snacksb
3.44 (3.93)
3.85 (3.84)
3.36 (3.95)
76.4
Pre-packaged sweet snacksb
4.10 (4.70)
3.91 (3.63)
4.15 (4.90)
77.9
Frozen mealsb
1.40 (2.34)
2.13 (3.08)*
1.24 (2.12)
41.9
Fast food mealsb
1.37 (1.59)
1.58 (1.51)
1.32 (1.60)
97.4
Restaurant mealsb
1.34 (1.57)
1.49 (1.75)
1.32 (1.53)
99.4
Breakfastb
3.63 (2.05)
3.64 (2.46)
4.12 (2.46)
91.8
Milkb
4.96 (6.09)
4.94 (5.70)
4.97 (6.18)
74.6
Fruitb
9.78 (7.57)
10.74 (6.69)
11.34 (7.53)
84.5
Vegetableb
11.28 (8.27)
11.41 (7.12)
13.01 (7.95)
89.7
Fruit and vegetableb
23.96 (12.59)
22.15 (11.46)
24.36 (12.83)
94.6
SE: standard error; BMI: body mass index. aChi-square. bT-tests. *p
RSH0010.1177/1757913914565388Energy drink consumption is associated with unhealthy dietary behaviours among college youthEnergy drink consumption is associated with unhealthy dietary behaviours among college youth
Peer Review Energy drink consumption is associated with unhealthy dietary behaviours among college youth
Energy drink consumption is associated with unhealthy dietary behaviours among college youth Authors Natalie S Poulos Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA Keryn E Pasch Department of Kinesiology and Health Education, The University of Texas at Austin, 1 University Station, D3700, Austin, TX 78712, USA Email: kpasch@austin. utexas.edu
Corresponding author: Keryn E Pasch, as above
Keywords energy drinks; college students; dietary behaviours; caffeine
Abstract Aim: Energy drink consumption has been associated with a variety of health risk behaviours, yet little research has explored the relationship between energy drinks and dietary behaviours of emerging adults. Therefore, the purpose of this study was to explore the relationship between energy drink consumption and dietary behaviours among energy drink users and non-users within a sample of college youth. Methods: College freshmen (n = 585, m age = 18.7 years; 47% non-Hispanic White, 20.9% Hispanic, 25.5% Asian, 2.7% non-Hispanic Black and 4.4% other; 56% female), at a large, southwest university self-reported their energy drink consumption in the past week and a variety of dietary behaviours, including past week soda, diet soda, pre-packaged salty snacks, pre-packaged sweet snacks, fast food, restaurant food, frozen food, fruits, vegetables, milk and breakfast consumption. Linear regression analyses were run to determine associations between energy drink consumption and dietary behaviour among users and non-users of energy drinks. Analyses controlled for gender, race/ethnicity and body mass index (BMI). Results: Overall, 17.5% of students had consumed energy drinks in the past week. Energy drink users were more likely to be male, White and have a greater BMI. Students also reported low past week intake of fruits, vegetables, milk and breakfast. Past week energy drink consumption was associated with increased soda and frozen meal consumption. Conclusion: Given a rapidly expanding energy drink market, future dietary interventions among college youth may want to consider the implications of energy drinks, as results of this study suggest consumption of these beverages is associated with unhealthy dietary behaviours and a greater BMI. Introduction College youth face many changes as they transition from adolescence to adulthood. Of the many changes that occur, previous research suggests that this period of transition from high school to college is associated with weight gain.1,2 Research suggests college youth do not meet national dietary recommendations and often have poor-quality diets3 because of lower consumption of fruits, vegetables, whole grains and milk and a higher consumption of sweetened beverages, salty snacks, and fast food.4–6 For example, only 6%–29% of college youth report consuming five or more servings of fruits and vegetables per day,2,7 even though current recommendations state that students should consume two to three cups of vegetables and two cups of fruits per day.8 One growing, yet
Copyright © Royal Society for Public Health 2015 SAGE Publications ISSN 1757-9139 DOI: 10.1177/1757913914565388
understudied dietary behaviour that has been associated with other unhealthy behaviours, such as alcohol use, is the consumption of energy drinks. An energy drink is a beverage that contains caffeine in combination with other ingredients such as sugar, amino acids, herbal extracts and B vitamins.9,10 While energy drinks are a relatively new product, the energy drink market has grown exponentially. For example, the energy drink market increased 240% between 2004 and 2008,11 yielding profits of US$26.9billion worldwide and US$7.9billion in the United States.9 This trend is expected to continue, as research has suggested that energy drink profits will continue to increase9 as the energy drink market growth rate is expected to be 13.4% annually between 2013 and 2018.12
Month 201X Vol XX No X l Perspectives in Public Health 1
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Peer Review Energy drink consumption is associated with unhealthy dietary behaviours among college youth
The initial target consumer of energy drinks was the athlete, but has expanded to additional markets, including college youth.13 These consumers have been targeted due to the generation’s fast paced lifestyle and susceptibility to marketing.13 Because of this, it is not surprising that previous research suggests between 34% and 51% of college students have consumed energy drinks in the past month.14–16 While previous research has shown positive effects of small doses of caffeine on attention, endurance and performance during cognitively demanding tasks,17 the increasing rates of consumption are concerning for a variety of reasons. First, these drinks contain large doses of caffeine that can range between 50 and 505 mg of caffeine per serving, and potentially provided more caffeine per drinking occasion as compared to sodas (35–50 mg caffeine/serving) and coffee (77–150 mg of caffeine/serving).10 Additionally, problematic side effects associated with greater energy drink consumption include caffeine intoxication/ dependence, tachycardia, hypertension and heart failure.10 Furthermore, associations with energy drinks include high-risk behaviours such as marijuana use, sexual risk-taking, fighting, alcohol consumption and intention to drive under the influence of alcohol.14,18 Finally, the sugar content of these beverages should be considered as it is often a primary ingredient,9 classifying it as a sugarsweetened beverage (SSB) similar to beverages such as soda. While energy drinks are less studied in their relationship with weight gain and risk of metabolic syndrome or diabetes, consumption of other SSBs, such as soda, have been linked with each of these problematic outcomes.19,20 Little research has documented the relationship between energy drinks and dietary behaviour, yet it is possible that energy drink consumption may be related to other dietary behaviours. For example, one of the most commonly reported side effects of energy drinks are episodes of ‘jolt and crash’, or increases in energy state followed by a rapid decrease in energy state.15 Given these dramatic shifts in energy state, students may turn to
calorically dense foods to maintain or return to the previously high energy state after experiencing one of these episodes. This may be problematic as relying on calorically dense foods has been associated with weight gain and obesity21 and may exacerbate already poor diet quality.
Purpose The purpose of this study was to examine the associations between energy drink consumption and dietary behaviours among college youth. As energy drink consumption is a relatively new dietary behaviour, we were specifically interested in the behaviours of energy drink users as compared to non-users. It was hypothesised that energy drink consumption would be positively associated with unhealthy dietary behaviours and inversely associated with healthy dietary behaviours.
Material and Methods Participants All incoming freshmen at a large, southwestern university in fall 2009 (n = 6,198 students), who agreed to participate in research (86% of freshmen), were eligible to participate in an online survey, which took place in April–June 2010. Of eligible students, 2,971 students were randomly selected to participate. Students were able to log on to a secure website from a location of their choice and complete the survey in as many sittings as necessary. Informed consent was collected from students on the first page of the survey and student responses were anonymous. A total of 603 participants (20% response rate) agreed to participate. Participants who were under 18 years of age (n = 4), upperclassman (n = 13) or identified themselves as transgender (n = 1) were excluded from the analysis due to small samples. This resulted in a final sample of 585 participants. The study was approved by the Institutional Review Board.
Measures and covariates Students completed a survey on a range of variables which included measures of dietary behaviours and energy drink
consumption. Individual dietary behaviours, including soda (e.g. Coke, Pepsi, Sprite; do not include diet soda/ pop), diet soda (e.g. Diet Coke, Diet Pepsi, Diet Sprite), milk, sweet snacks (e.g. cookies, candy), salty snacks (e.g. crackers, chips, beef jerky) and frozen food consumption (e.g. TV dinners, pizza, taquitos) were measured for the past week (range = 0 times per day to 4 or more times per day). These measures were adapted from previous research in similar populations,22 by maintaining question phrasing, but also including measures that were hypothesised to be relevant to energy drink consumption (e.g. salty snacks). Fruit consumption was measured by a single question, ‘How many servings of fruit do you usually consume per day?’ (range = 0 servings per day to 5 or more servings per day).7 Vegetable consumption (excluding potatoes, French fries and potato chips) was measured by asking a similar question (range = 0 servings per day to 5 or more servings per day).7 Students were not provided with examples of what constitutes a serving of fruit or vegetable. Breakfast consumption was measured through the single item, ‘In the past 7 days, on how many days did you eat breakfast?’ (range = 0 days per week to 7 days per week).22 Fast food consumption was measured by asking a single question, ‘Please indicate how often you did the following in the past 12 months: Eat fast food’ (range = 0 times in the last 12 months to several times a day).22 Restaurant food consumption (excluding fast food establishments) was also measured according to past year (range = 0 times in the last 12 months to several times a day). Both measures of fast food consumption and restaurant consumption have been used in previous research among this population.22 As the majority of dietary behaviours were asked about past week consumption, all variables were recoded to reflect past week consumption. Energy drink consumption was measured by a single question measuring past week consumption: ‘During the past 7 days, how many times did you drink an energy drink (e.g. Red Bull, Monster, Full Throttle)?’ (range = 0 times per day to 4 or more times per day). This measure was adapted from previous research to be
2 Perspectives in Public Health l Month 201X Vol XX No X
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Peer Review Energy drink consumption is associated with unhealthy dietary behaviours among college youth
similar to other food/beverage items used with college students.22 For analyses, past week energy drink use was dichotomised to represent users and non-users. Users were those who reported consumption of at least one energy drink within the past week. Gender was self-reported and included as a covariate (male or female) as gender has been previously associated with energy drink consumption.18 Body mass index (BMI), a common measure of body fat based on height and weight,23 was calculated based on self-reported height in inches and weight in pounds and used as a continuous covariate. BMI was included as a covariate in all analyses as it was significantly associated with energy drink consumption (β = .06, standard error (SE) = .03, p = .04) in this sample. Race/ethnicity was self-reported by students as Non-Hispanic White, Hispanic, Non-Hispanic Black, Asian American/Pacific Islander and Other. For analyses, race/ethnicity was coded as White or non-White. Race/ethnicity was included as a covariate as it has been found to be associated with energy drink consumption previously.14,24
Statistical analysis T-tests and chi-square analyses were used to determine differences in gender, race/ethnicity, BMI and dietary behaviours between users and nonusers of energy drinks in the past week. Linear regression was used to determine whether past week ever use energy drink consumption was associated with each individual dietary behaviour while accounting for covariates. Covariates included race/ethnicity, gender and BMI. Prior to analysis, skewed variables (soda, diet soda, salty snack, sweet snack and frozen food) were square-root transformed to normalise data. Once transformed, all skewness and kurtosis values fell within normal limits. Models were run with both the transformed and non-transformed data. Results did not differ; therefore, to assist with interpretability, non-transformed data are presented. All results are presented with two-sided p-values with an alpha = .05. All analyses were conducted using Statistical Package for the Social
Sciences 19 (SPSS 19, IBM Corporation, Armonk, New York, 2011).
Results The sample consisted of freshmen (m age = 19 years), a majority of whom were female (56%), 46% were White, 21% Hispanic, 26% Asian, 3% non-Hispanic Black and 4% other. The average BMI fell within the normal range (m = 22.9). Demographic characteristics of the sample were similar to the overall freshman class from which it was drawn (53% female, 51% White, 21% Hispanic, 20% Asian, 5% Black and 8% other race/ethnicity). In all, 17.5% of students consumed at least one energy drink within the past week. Of the students who consumed energy drinks in the past week, 77.3% consumed energy drinks 1–3 times per week, 13.6% consumed energy drinks 4–6 times per week, 5.7% consumed energy drinks 1 time per day and 3.4% consumed energy drinks 2 or more times per day. Overall, the consumption of each food or beverage varied from 1.3 times per week (restaurant food) to 11.3 times per week (vegetables) (Table 1). Almost all students (99.4%) reported eating food purchased at a restaurant at least once in the past week, while just over one quarter (26.6%) reported consuming diet soda (Table 1). Almost all students (94.6%) consumed at least one fruit or vegetable per week; however, only 23.4% of students consumed five or more fruits and vegetables per day. When comparing energy drink users and non-users, a greater percentage of energy drink users were males and White. Additionally, energy drink users had a significantly greater BMI and consumed more soda and frozen meals than non-users (Table 1).
Past week energy drink consumption and dietary behaviours Past week energy drink consumption was significantly associated with consumption of regular soda and frozen food, after controlling for BMI, gender and race/ethnicity according to both non-transformed and log-transformed p-values (Table 2). Results suggest that for every additional energy drink consumed, emerging adults consume 1.47 more regular sodas and 0.75 more
frozen meals per week (Table 2). Past week energy drink consumption was not associated with past week consumption of diet soda, salty snacks, sweet snacks, fast food, restaurant food, fruits, vegetables, milk, breakfast or a combined measure of fruit and vegetable consumption (Table 2). Of note, relationships between energy drink consumption and vegetable and diet soda approached significance (Table 2). Data on the relationship between energy drink and alcohol consumption were collected as part of this study, yet have been published elsewhere.18
Discussion This study found that 17.5% of students consumed energy drinks weekly and that energy drink consumers are more likely to be White males.24 As previous research has focused on past month energy drink consumption, a direct comparison to the present study is not possible as it was focused on weekly consumption. However, in previous work with this sample, we found that 38% of students consumed energy drinks in the past month.25 This is similar to work with other samples which found monthly prevalence rates to be 34%–51%.14–16 A significant relationship was found between past week energy drink consumption and some dietary behaviours. As hypothesised, past week energy drink consumption was positively associated with soda and frozen food consumption, yet energy drink consumption was not associated with other negative dietary behaviours (salty snack, sweet snack, fast food or restaurant food) or any of the healthy dietary behaviours (fruit, vegetable, milk and breakfast consumption), although relationships with vegetables and diet soda approached significance. These results suggest that those individuals who consume energy drinks also engage in some specific unhealthy dietary behaviours. Given significant associations with soda and frozen food, it is possible that past week energy drink consumption is associated with convenience foods that are dorm friendly. For example, students report consuming energy drinks to study
Month 201X Vol XX No X l Perspectives in Public Health 3
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Peer Review Energy drink consumption is associated with unhealthy dietary behaviours among college youth
Table 1 Demographic characteristics and mean weekly dietary behaviours among a sample of college youth overall and by energy drink user status (n = 585) Descriptive variable
Overall (SE)
Users (SE)
Non-users (SE)
% consumed at least once in past week –
Gendera Male
44%
71.6%
38.0%
Female
56%
28.4%***
62.0%
–
Ethnicitya White
46%
55.7%*
44.1%
Non-White
54%
44.3%
55.9%
BMIb
22.94 (4.25)
23.91 (4.74)*
22.76 (4.14)
–
Sodab
2.92 (4.38)
4.41 (5.63)**
2.56 (3.96)
61.4
Diet sodab
1.35 (3.66)
2.03 (4.05)
1.22 (3.57)
22.6
Pre-packaged salty snacksb
3.44 (3.93)
3.85 (3.84)
3.36 (3.95)
76.4
Pre-packaged sweet snacksb
4.10 (4.70)
3.91 (3.63)
4.15 (4.90)
77.9
Frozen mealsb
1.40 (2.34)
2.13 (3.08)*
1.24 (2.12)
41.9
Fast food mealsb
1.37 (1.59)
1.58 (1.51)
1.32 (1.60)
97.4
Restaurant mealsb
1.34 (1.57)
1.49 (1.75)
1.32 (1.53)
99.4
Breakfastb
3.63 (2.05)
3.64 (2.46)
4.12 (2.46)
91.8
Milkb
4.96 (6.09)
4.94 (5.70)
4.97 (6.18)
74.6
Fruitb
9.78 (7.57)
10.74 (6.69)
11.34 (7.53)
84.5
Vegetableb
11.28 (8.27)
11.41 (7.12)
13.01 (7.95)
89.7
Fruit and vegetableb
23.96 (12.59)
22.15 (11.46)
24.36 (12.83)
94.6
SE: standard error; BMI: body mass index. aChi-square. bT-tests. *p
