PAbstract
Background: The health belief model (HBM) has been used in numerous nutritional studies, but the effectiveness of the constructs has not yet been specified in Iranian adolescents. The purpose of this study is to assess the association between health belief model constructs and diet quality in Iranian adolescents.
Method: 1055 adolescents aged 13 – 15 years old completed this cross-sectional study. Participants were selected from private and public secondary schools in Shiraz, Iran, using cluster random sampling. A modified version of revised children’s diet quality index (M-RCDQI), was calculated for each adolescents and its association with the model construct was assessed using linear regression. Body mass index (BMI), district of education, knowledge and sex were entered into the regression analysis as covariates. P value <0.05 was considered statistically significant. Dietary intake was analyzed via the modified Nutritionist IV software for Persian food.
Result: Mean M-RCDQI score was 58.91± 8.58 out of the total of 90 points. Among the M-RCDQI components, the worse scores were obtained by dairy intake, dietary fiber and vegetables in which less than 20% of the students reached maximum score. Among HBM constructs, cue to action (B=0.194, p=0.003) and self-efficacy (B=0.04, p=0.007) had positive, significant association with adolescents’ diet quality. Also there was a positive, significant association between cue to action and fruits consumption (B= 0.026, P=0.026), and a negative significant association was seen between cue to action and total fat intake (B= -0.629, p=0.021) as well as intake of linoleic acid (p=0.016). Furthermore, self-efficacy had a direct significant association with dairy intake.
Conclusion: M-RCDQI could be a suitable tool for assessment of diet quality index in Iranian adolescents and it is recommended for use in further studies. Cue to action and self-efficacy would both be effective mediators in improvement of nutritional behavior among adolescents.
Introduction
Healthy eating patterns during adolescence, as well as any other healthy behavior, can play a significant role in growth and development of a teenager. Research shows that many of these patterns can result in very serious outcomes during adulthood (1). Improper eating behavior and irregular food intake can make an individual susceptible to reduced learning ability and academic underachievement (2), in addition to serious systemic diseases such as hyperlipidemia, arthrosclerosis, diabetes mellitus, certain types of cancer and osteoporosis in adulthood (1). Adolescence is a crucial time in life; it is in this period that an individual starts becoming self-sufficient and making independent choices regarding eating habits (3). However, many adolescents follow diets inconsistent with the recommendations for healthy eating behavior (4), which could cause serious problems as these habits will in most probability make their way well into adulthood (5). A study in Tehran, Iran’s capital, on 7669 adolescents revealed that regardless of good nutritional awareness among 82% of girls and 75% of boys, only 25 % of the boys and 15 % of the girls had proper dietary behavior (6).
Diet quality indices are used to evaluate an individual’s overall diet quality and level of adherence to dietary guidelines (7). The revised children’s diet quality index (RCDQI) was designed to estimate diet quality among children, preschoolers in the first place, and groups of 2- to 18-year-olds in the next (8). Behavioral theories and their constructs are proposed as strategies to determine and understand the impacts of dietary behavior (9). There is consensus among the research community that using behavioral change models and theories in design and implementation of dietary interventions can add to their effectiveness (10, 11). The health belief model (HBM) was initially designed to provide us with models of disease prevention, as opposed to treatment (12). The model indicates that health behavior changes can be predicted through perceived susceptibility, perceived severity, perceived benefits and perceived barriers, as well as cues to action and self-efficacy. Perceived susceptibility is one’s belief regarding one’s predisposition to diseases and conditions. Perceived severity is one’s belief regarding the gravity of that condition. Perceived benefits is one’s belief that certain measures can reduce the risks and perceived barriers is one’s speculations about the cost of those measures. Cue to action is as an incentive for preparedness and self-efficacy is defined as an individual’s faith in his/her capability for successful action (13).
HBM was previously used in many nutritional studies, but the effectiveness of its constructs has not yet been specified among Iranian teenagers. The present study aims to assess the effectiveness of HBM constructs in improving adolescents’ diet quality; we believe our results would help health planners use the most effective construct to design cost-effective interventions, aimed at improvement of diet quality in a vast population of adolescents in Iran.
Method and material
Study design and participants
This cross-sectional study was done among 1124 adolescents. Participants were 13-to-15 year-old adolescents selected through cluster random sampling from private and public secondary schools in Shiraz, the largest city in southern Iran. Thirty eight urban schools of 4 educational districts, and one class (average 30 students) in each school was selected randomly. Students with chronic diseases or special diet and non-Iranian students were excluded from the study. All study procedures and aims were explained to participants and their parents before the start of the study.
Measurements
Demographic characteristics and Anthropometric assessment: A questionnaire on demographic characteristics including gender, age, parents’ education and occupation was filled by face to face interview. Height was measured without shoes to the nearest 0.1 cm using a non-stretchable tape. Weight was measured in light clothing, to the nearest 0.1 kg using a digital scale (Seca, Germany). The measurements were taken twice and average values were recorded. BMI was calculated as body weight (kg) divided by height square (m2). Underweight was defined as a BMI less than the 5th percentile, overweight as a BMI at or above the 85th percentile and below the 95th percentile, and obesity as a BMI at or above the 95th percentile for adolescents of the same age and sex.
Nutritional assessment: Information relating the participants’ dietary intakes were collected over the previous month using a validated FFQ (14) and it was assessed using modified NUTRITIONIST 4 for Persian food.
A modified version of revised children diet quality index (M-RCDQI) was calculated based on the studies by kranz (8, 15). The 13 components of the index were as follow: six key food groups, iron , protective fatty acids, two components associated with consumption of excess calories, and another item attempting to characterize the energy balance (8, 16). In terms of scoring, children consuming within the recommended levels received full points (varying from 2.5 to 10 points, depending on the component) with reductions made proportionally to the suboptimal intake or overconsumption based on the recommended level (8). As some components of the index are not common in the dietary pattern of Iranians, we made certain alterations; for instance, whole grain breads, are not easily accessible, but beans and legumes are used in many Iranian dishes and their minerals and fiber can be substituted for whole grains;, now, since dietary fiber is an important item in public health, we replaced whole grains with it, with maximum of 5 points in the scoring system. Also daily consumption of natural juices is not a routine dietary habit among Iranians and none of our participants had more than 360 ml (12 Oz) of juices per day to be scored as “excess juice” in the index (8). Thus, juice intake was added to “fruits” category and each 4-ounce was considered equivalent to one serving (16). Excess juice is a negative factor in assessment of diet quality and given that extra juice is not an issue in our children’s diet, the authors therefore decided to replace an unhealthy eating habit among Iranian adolescent. Studies have shown that there is a high consumption of salty snacks among Iranian adolescents (17). Therefore, salty snacks were substituted for “excess fruit juice” as a component of diet quality index. As there is no cut point for the consumption of salty snacks, a tertile classification was used and 10, 5 and 0 points were assigned to first, second and third tertile respectively.
Total physical activity using the modified version of Adolescent Physical Activity and Recall Questionnaire-)APARQ( (18) was used to assess calorie intake and energy balance in adolescents. After classification of physical activity to sedentary, moderate and vigorous, each individual energy intake was compared to appropriate EER±10%, based on age, sex and 3 level of physical activity.
Our scoring system was based on over-consumption for fat, added sugar, EPA & DHA, and linoleic, linolenic acid, dairy, and energy balance, and under-consumption for fruit and vegetable, dairy and fiber intake, total grain and linolenic acid, linoleic acid, EPA & DHA and energy balance. Total M-RCDQI score was 90. For validity assessment of M-RCDQI, a principal component analysis was performed using Eigen value>1, factor loading>0.4 and a varimax rotation. All components had factor loading more than 0.4, except for total grains, which was not excluded since it was the component of main index. Overall, 61.6% of the variance could be explained by the modified index. A moderate positive correlation existed between the modified components and M-RCDQI (dietary fiber score: r=0.412, p<0.0001 and salty snack score: r=0.501, p<0.0001)
Knowledge: To assess participants’ nutritional knowledge, we used the general nutrition knowledge questionnaire (GNKQ) (19) with four subcategories: 1) Dietary advice (4 items), 2) nutrient content of different food items (21 items), 3) best food choices (10 items), 4) health and diet-related diseases (10 item), was used. Each correct answer was rewarded 1 point and each incorrect answer and “I don’t know” received a score of zero. Reliability of the questionnaire was acceptable (Cronbach’s α= 0.76).
Perceived benefits and barriers: The questionnaire which assessed perceived benefit and barrier of healthy eating, (20) involved practical obstacles (6 items), as well as internal obstacles (5 items) and 5 items referring to the benefits of healthy eating. A Likert scale was used for scoring ranging from “not important at all”=1 to “very important” = 5. In this study, Cronbach’s alpha for barriers and benefits were 0.71 and 0.75 respectively.
Self-efficacy: Self-efficacy (SE) for healthy eating was assessed in different situations such as being alone, being with friends and family, and in certain places like restaurants and malls (20). Scoring was based on a Likert scale ranging from 1 = “not confident at all” to 5=“very confident”. Using Cronbach’s α, reliability of the questionnaire was determined as 0.78.
Perceived severity: The questionnaire to assess perceived severity contained items about individual assessment of health problem severity and its potential risk factors. The reliability of the 7- item questionnaire (21) was assessed 0.81 in theis study. A 5-point Likert scale was used to score the responses, ranging from “strongly disagree”=1 to “strongly agree” = 5.
Perceived susceptibility: Self-evaluation of the risk of health problems was assessed through one question: “In your opinion, if you do not make healthy food choices, will you get severely ill in the future?” (21). Reliability of this tool was determined as 0.85 in the study. A 5-point Likert scale ranging from “strongly disagree”=1 to “strongly agree” = 5, was used for scoring.
Cues to action: The health belief model posits that a cue is necessary for prompting engagement in health-promoting behaviors. Internal and external Cues to action were assessed by 6 items in our study (13) and the reliability was 0.79 Using alpha Cronbach’s α. Responses were scored via a 5-point Likert scale, ranging from completely disagree=1 to completely agree=5.
Ethics: Our research proposal was approved by the ethics committee of Shiraz University of Medical Sciences (IR.SUMS.REC.1394.13). Parents and school headmaster, gave their permission by signing a written informed consent.
Statistical analyses
Descriptive analysis was done to assess demographic and anthropometric characteristics, as well as mean intake, mean score and maximum percentage achieving maximum score in each item. Using single variable analysis, all covariates with p value < 0.2 were entered into the regression analysis. Linear regression was done to assess the association of the M-RCDQI score and its components with the health belief model constructs. P value <0.05 was considered statistically significant. Data were analyzed via SPSS (ver.19) and modified Nutritionist IV software for Persian food was used to assess dietary intakes.
Results
1055 out of 1124 (rate of participation: 93.8%) (53.3% boys) secondary school students completed the study. Mean age and BMI of participants was 13.88 ± 0.91 year and 20.27 ± 4.14 respectively. About one fourth of the participants were overweight or at risk for becoming overweight (table 1). Mean modified-RCDQI score was 58.91± 8.58 ranging from 24.41 to 82.37 points of the total maximum of 90 points. Of the M-RCDQI components, grain was in the best situation; In this regard, more than 80% of adolescents reach the maximum score. Furthermore, the worse scores were obtained for dairy intake, dietary fiber, vegetable and EPA+DHA in which less than 20% of students reached maximum score. Only 6.4% of adolescents had 3 or more servings of dairy products per day, and sugar intake formed more than 10% of total calorie intake in 73.2% of students. Mean intake of salty snack seems to be high among students. (Table 2).
Among HBM constructs, cue to action (B=0.194, p=0.003) and self-efficacy (B=0.04, p=0.007) had positive significant association with adolescents’ diet quality (table 3). For every unit increase in cue to action score, a 0.19 unit increase in M-RCDQI predicted, holding all other variables constant. Evaluating the relationships between cue to action and M-RCDQI components, we found a positive, significant association between cue to action and fruit consumption (B= 0.026, P=0.026), and also a negative significant association was observed between cue to action and total fat intake (B= -0.629, p=0.021) and linoleic acid (p=0.016). For every unit increase in cue to action score, a 0.62 unit decrease in fat intake is predicted, holding all other variables constant. Furthermore, self-efficacy had a direct significant association with dairy intake (table 4).
Discussion
Our study results revealed the mean modified-RCDQI score of participants as 60.36 ± 8.56, ranging from 25.61 to 84.01. There haven’t been any reports relating mean scores in other studies on adolescents, but studies on younger children have produced fairly similar RCDQI scores. Average total score was 59 (ranging from 21-86) in Kranz et al.’s study (15) and 61.8 (SD=9.8) (ranging from 36.1 to 86.2) in a study by Quandt et al. (22).
There is a lack of adherence to Dietary Guideline recommendations among children and adolescents, which may put them at an increased risk of chronic disease for the rest of their lives (23). Previous studies on adolescents in Iran have shown the dire need for improvements in their diet quality (24, 25) and it’s been suggested that dietary habits should be corrected among 74 percent of the adolescents (26).
Components of Modified version of RCDQI: Dietary guidelines recommended consumption of less than 10 percent of calories per day from added sugars, but our participants mean intake of added sugar was about 13% of total calorie and just 26.8% of them adhered to the recommended amount. Other studies in Iran also reported high intakes of total added sugar and sugar contain drinks among adolescents. (17, 27)
We included cube sugar, honey, jam, fruit/sport drinks, cola and soda, candy, chocolate in our study but not cakes and cookies in added sugar group. Including cake and cookies would present the higher sugar intake of adolescents, given that these snacks are used more than one third of snack in high school students (28). In the present study sugar and cube sugar and sugar sweetened beverages accounted for the greatest amount of added sugar and since numerous studies suggest that high added sugar consumption may contributes to development of non-communicable disease such as diabetes, cardiovascular disease and metabolic syndrome in adolescents (29) certain attempts should be considered using the appropriate behavior change models or theories, to reduce its consumption according to dietary guidelines and prevent possible related public health problems in teenagers.
Acceptable Macronutrient Distribution Range (AMDR) and Dietary Guidelines recommend 25-35% of fat consumption. In our study mean intake of total fat covered more than 32 percent of total calories, and 69.5% of the adolescents met the recommended amount in this relation. EPA & DHA was very low and only 5.6% of adolescents reached the maximum score for that.
Previous Iranian studies in the same age group reported various findings regarding fat intake, some showing a fat intake lower than 30% of total calories (27, 30) and some higher than 30% (17, 31, 32) with the highest mean of about 37% observed in a study by Hejazi (33). It seems that the intake of fat has increased over time among Iranian adolescents, which is in direct relationship with the recent increases in consumption of fast-foods and processed foods in the community, especially among adolescents and the youth (34, 35).
Polyunsaturated fatty acids, especially linoleic acid, are the main fatty acid components of most edible oils in Iran, namely cooking oil and frying oil (36). The National Health and Nutrition Examination Survey (2005-2006) has identified Potato/corn/other-type chips, pizza, processed food, fried potatoes and salad dressing to be among the first 15 sources of linoleic acid intake (PFA 18:2) (37), all of which are widely used in the adolescents’ dietary patterns (38, 39) in addition to vegetable oil, which is a main source of linoleic acid. As a main animal source of omega 3, fish is neither a common menu nor that affordable for the bigger part of the Iranian Population and still there is a significant gap between fish consumption and the amounts for a healthy diet in Iran (40).
Refined wheat and rice are the main staple in our country which form the main part of the population carbohydrate intake (about 67% of total calorie, based on Food and Agriculture Organization (FAO) (41). In the present study, grains intake was calculated based on age and sex (42, 43). Mean intake of grains was about 12 Oz and 87.8% met the recommended amount. Consumption of whole grain products is not common in our community due to lack of access. Whole grain products are not acceptable in the eyes of the public because of their dark color; these products are usually sold in special markets for certain individuals, such as patients with diabetes or people who have both the knowledge and means, and they are not available in all bakeries. On the other hand, it is expected that dietary fiber consumption has been decreased with increasing western dietary pattern (44) in recent years. In light of all this, we decided to replace whole grains with dietary fibers. Mean Dietary fiber was 22.96 ± 6.78 considering age and sex appropriate amount and only 13% of the participants reach the maximum score for this food item.
Our results were consistent with the findings of previous studies in the same age group in Iran (33, 45) as well as other countries. In a survey in 2011–12, over 74 % of children reported meeting the daily recommendation for total grain intake (at least 6 oz eq/d), but less than 0.5% of the children, aged 6–18, had met the whole grain recommendations (46).
In our study no one met the recommended amount for whole grain (at least half of total grain intake) which is thought to be due to lack of access to whole grain products. Although our study have shown that dietary fiber have increased compare to previous studies in this age group, it does not meet the recommended amount yet.
According to research, daily consumption of fruits and vegetables in adequate amounts can reduce risks of non-communicable disease (47). Despite of the numerous benefits of fruits and vegetables consumption, large proportions of adolescents do not eat fruits and vegetables on a daily basis. In our study, 70.4% of the adolescents reach the maximum score for fruits intake but only 17.4% met the recommended amount for vegetables. Several studies assessed fruits and vegetables intake as a preventive factor of chronic diseases. In Shokrvash study in Iran, only 30% and 34.6 % of adolescents received optimal intake of daily fruits and vegetables (48) and also Montazerifard reported that only 16.2% of adolescents have daily intake of fruits and vegetables (17). In a Global School-based Student Health Survey conducted in the Eastern Mediterranean Region (EMR) between 2005 and 2009, only 19•4% of adolescents reported consuming F&V ≥5 times/d (49).
The probable reason for higher report of fruits intake in our study, is the season of data gathering, in which fruits (especially citrus) are more affordable in autumn and winter for most of the families compare to fruits in spring and summer.
Dairy intake have always been a problem among different age group in our country. In 2014, per capita consumption of milk and dairy products was about 60 kg which is unfortunately very low, almost half the world average (50). In the present study mean daily intake for dairy was 1.62 ±0.90 cups and only 6.4% reach the maximum score of 3 serving a day. Daily dairy intake was 1.6 – 1.7 serving in a systematic review on Iranian adolescents (51). Montazerifard have shown that only 16.3% of adolescents have daily intake of dairy products regardless of the amount (17). Although the Iranian ministry of health has a program for free milk distribution in schools, the program was covered only 30-40% of students, it hasn’t been consistent during recent years and it was frequently interrupted due to lack of governmental funding.(52). There has been an increase in dairy prices over the past years; therefore, many families simply cannot afford an intake of 3 servings of dairy products a day. Lack of awareness in society relating the importance of meeting these daily amounts of dairy products has made matters even worse (53).
In the present study, Iron intake amounted to 14.75±5.04. The mean Iron intake may be above the recommended amount in this study (8-11 mg for boys and 8-15 mg for girls adolescents) (42) however, about 60% of the participants weren’t receiving the adequate amount. Iron deficiency is a serious problem leading to academic underachievement and learning difficulties, as well as amplified behavioral disorders, among adolescents (54). Previous research shows that 70% of 14-18-year-old female adolescents have less regular intake of iron than the adequate amount recommended by the DRI (17). It is thought that because of the large amount of grain intake in Iranian dietary pattern, the main Iron intake would be non-heme which has lower absorption rate compare to hem iron and can be affected by factors such as the consumption of tea (55) which is a common drink in Iran.
Regarding unhealthy food behaviors in adolescents, sodium intake, especially salty snack consumption, is an issue to be considered. Mean intake in the third tetile of salty snacks was more than 60 grams (about 0.5-1 gr salt in different products) in a day in our participants. Although 89% of adolescents were aware of disadvantages of crisps and corn balls, almost half of them used such snacks during their break time in school (6). Of salty snacks, potato chips/crisps had the highest rate of consumption among adolescents (6).
A recent study on the relationship between physical activity and screen-time viewing among elementary school children in the United States (2009-2010) didn’t find a firm association between low levels of screen-time viewing and higher levels of physical activity (56) and a review of literature revealed no evidence of a causal relationship between sedentary behavior and obesity among the youth; only a low level of association was deduced between screen-time and obesity from cross-sectional evidence (57). According to these results, in the present study scoring the energy balance was based on EER, with consideration to sex, age and physical activity (sedentary, moderate and vigorous) and not just the screen time. Only 29.5% of participants met the appropriate energy intake for their sex, age and physical activity in our study.
Health belief model constructs: Health behavior models are common tools for modification and improvement of nutrition behaviors (58) and they would be quite useful in prevention programs, as it was their original purpose (12). Although cue to action and self-efficacy have significant association with adolescents’ diet quality in our study, the effect was not strong and it seems that there are many other factors that may affect more.
There are few cross-sectional studies used this model in same age group, So some comparisons have been conducted with intervention studies and other age groups such as college and under graduate students. A systematic review, as our study, identified self-efficacy as one of the mechanisms most consistently associated with dietary behavior changes (58). Hosseini et al. (59) study was almost congruent with our study and perceived self-efficacy had statistically significant relationships with daily milk consumption while no statistically significant relationship was seen between the daily consumption of milk and perceived susceptibility, and perceived severity in students grade 7 to 9. However, there were differences regarding perceived benefits and barriers with our results. In Naghashpour (60) study, HBM was used for increasing the impact of nutrition education. All HBM constructs and dairy intake were significantly improved after the intervention but the association between the construct and the dairy intake behavior was not reported. Other intervention using HBM increased knowledge, model constructs and nutrition behavior, but the direct or indirect effect of each construct on the behavior was not mentioned (61, 62). One study on college students have shown that among all HBM constructs, perceived barrier and self-efficacy have significant association with eating healthy diet (21) which is similar to our results in terms of self-efficacy. In O’Connell study (63) perceived susceptibility and severity of obesity, cues to dieting and benefits of dieting, were the predictors of dieting behavior in obese and non-obese adolescents. In that study, susceptibility to the causes of obesity could best explain the dieting behaviors of non-obese adolescents, which is not in agreement with our study results, and cues to action was the most important predicting factor for the exercising behavior but not dieting behavior of obese adolescents. Since the participants in our study were all healthy adolescents, their perceived severity and perceived susceptibility of unhealthy diet might not affect their eating behavior, however, this does not negate the importance of these two constructs and it would happened due to unawareness of adolescents about the risks of unhealthy eating habits, which should be addressed in educational programs.
The strengths of this study is to modify a suitable index for teenagers, according to Iranian dietary pattern and nutrition problems of this age group based on recent researches, which seems well assessed their diet quality. Other studies are suggested to confirm the suitability of this index in Iranian children.
Dietary fiber, as a component of our modified diet quality index, was lower than the recommendations and policy maker should make the whole grain products available and affordable for all social-economy groups to reach the dietary guidelines as a preventive action to reduce the increasing chronic diseases.
Furthermore, it seems that eating salty snack is relatively high among adolescents. Some strong and widespread regulations on school shops that do not permit sales unhealthy snack at school, decrease salt in formulation of these snacks and band TV advertisement of salty snacks are some of the suggested strategy to decrease these harmful snack in order to increase diet quality among adolescents and prevent some salt related non-communicable disease such as high blood pressure, cardiovascular disease, stroke and kidney failure in adulthood.
Although HBM-based interventions have been successful in improving eating behaviors in many studies, it is not specified which constructs were more effective in improvement of eating behaviors, and there are very few researches in this age group to make a comparison. However, given the fact that selecting effective constructs would be helpful in saving time and money in big educational projects, we suggest cues to action and self-efficacy as useful constructs for changing nutritional behaviors in similar populations.
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