In uence of Television Food Advertisements Related Purchasing Behaviours on Dietary Intake and Obesity Among Children in China

Jinli Xian Chongqing Medical University Mao Zeng Chongqing Medical University Zhengjie Cai Chongqing Medical University Changxiao Xie Chongqing Medical University Yuqian Xie Chongqing Medical University Manoj Sharma Chongqing Medical University Yong Zhao (  zhaoyong@cqmu.edu.cn ) Chongqing Medical University, School of Public Health and Management, Yixueyuan Road, Yuzhong District Chongqing, Chongqing https://orcid.org/0000-0003-3182-0522 Zumin Shi Qatar University

decision-making process involved in purchases. [10] This may in uence children's overweight and obesity. Similarly, in China, a study of the relationship between TV watching and snacking behaviour among children and adolescents showed that watching TV, especially TV ads, was signi cantly related to the demand, purchase and consumption of snacks. [9] Studies from developed countries have consistently shown that TV food ads affected children's food purchase requests and obesity. However, little is known how TV food ads related purchasing behaviours affect children's dietary intake and overweight and obesity. Thus, this study used the data from the 2011 China Health and Nutrition Survey (CHNS) to 1) explore the effect of TV food ads related purchasing behaviours on children's dietary intake of energy, protein, fat and carbohydrates; 2) explore the effect of TV food ads related purchasing behaviours on overweight and obesity among children in China. Liaoning, Shandong), Heilongjiang province was enrolled as a ninth province in 1997. [11] In 2011, three megacities (Beijing, Shanghai, Chongqing) agreed to participate in the study, whose results vary substantially in terms of geography, economic development, public resources and health indicators. [12] A multistage, random cluster process was used to draw the sample in each of these provinces. Counties and cities in each province were strati ed by income (low, middle and high), and a weighted sampling scheme was used to randomly select four counties and two cities in each province. Villages and townships within the counties and urban and suburban neighbourhoods within the cities were selected randomly. In each community, 20 households were randomly selected and all household members were interviewed. [11]

Participants
In 2011, data of 15,732 participants were merged. Data were collected from participants during face-to-face interviews with trained interviewers. Exclusion criteria include missing weight or height information (n=629); below 6 years of age and over 17.99 years of age (n=13,531); unknown values on the primary variables of TV food ads related purchasing behaviours, ethnicity and education (n=33); missing values on the primary variables of age, education, urbanisation index, per capita annual family income, ethnicity, TV food ads related purchasing behaviours, dietary intake of energy, fat, protein and carbohydrates (n=122). The nal sample included in the analysis was 1,417 children aged 6-17.99 years.

Measures
2.3.1 Socio-demographic characteristics. Age, education, urbanisation index and per capita annual family income were encoded and converted into count data. Self-reported education was recoded into three categories (illiterate/primary school, junior middle school, high middle school or higher). [13] The urbanisation index and per capita annual family income were recoded into tertiles (low, medium, high). [13] 2.3.2 TV food ads related purchasing behaviours. TV food ads related purchasing behaviours were assessed by the questions "do you ask your parents to purchase the foods seen on TV ads?", "do your parents purchase advertised foods for you?" and "do you purchase the foods seen on TV ads by yourself?". Respondents reported the frequency ("very seldom", "seldom", "sometimes", "often", "very often" and "unknown") of these purchasing behaviours. The options of "very seldom", "seldom", "sometimes", "often" and "very often" were de ned as "<1 time/month", "1-3 times/month", "1-2 times/week", "3-4 times/week", "≥5 times/week", respectively. For each of the above purchasing behaviours, responses of 'very seldom' and 'seldom' were combined as 'no'; and responses of 'sometimes', 'often' and 'very often' were combined as 'yes' for the analysis.

Dietary intake.
Individual dietary data for the same three consecutive days were recorded for all household members, regardless of age or relationship to the household head. [12] This was achieved by asking each individual, except children aged younger than 12, on a daily basis to report all food consumed at home and away from home on a 24-hour recall basis. [12] If the children were not present, their caregivers would be required to contact them to obtain the children's food consumption information. For children younger than 12, the mother or a mother substitute who handled food preparation and feeding in the household was asked to recall the children's food consumption. [12] 2.3.4 Overweight and obesity. Height and weight were measured in the 2011 CHNS survey. Height and weight of children were measured by at least two trained health workers who followed standard protocol and techniques, with one worker taking the measurements while a second health worker recording the readings [14] . Body weight was measured in light indoor clothing to the nearest tenth of a kilogram with a beam balance scale; height was measured without shoes to the nearest tenth of a centimeter, using a portable stadiometer [14] . The International Obesity Task Force cut-off of body mass index was used for de ning overweight/obesity among children. [15]

Data analyses
Descriptive statistics were used for the sample characteristics. The categorical variables were described using frequency and percentile, and the metrological data description used mean and standard deviation. Student's t-test was performed to examine the relationships between TV food ads related purchasing behaviours and dietary intake of energy, fat, protein and carbohydrates. To determine if the relationships between TV food ads related purchasing behaviours and overweight and obesity existed, odds ratio (OR) and 95% con dence intervals (CI) for the outcome variable were calculated by using binary logistic regression. All statistical tests were conducted using STATA software (Version 12, StataCorp, College Station, TX, USA). Statistical signi cance was considered when P < 0.05 (two-sided). Table 1 presents the descriptive statistics for the demographic variables and overweight/obesity. The mean age of the sample was 10.9 (SD 3.3). Among participants, 63.1% lived in rural areas. The prevalence of overweight/obesity was 17.9%. Overall, 18.3% of the children reported they requested advertised foods from their parents, 16.9% purchased advertised foods by themselves and 21.1% reported that their parents purchased advertised foods for them.  Table 2 indicates that children whose parents purchased advertised foods for them had higher dietary intake of energy, protein, fat and carbohydrates than children whose parents did not purchase advertised foods for them.

Sample characteristics of participants
Children who purchased advertised foods had higher dietary intake of energy, protein, fat and carbohydrates than children who did not purchase advertised foods. In addition, children who requested for advertised foods from their parents were positively associated with their dietary intake of energy, protein and fat.

Discussion
Approximately 20% of the children requested advertised foods from their parents, purchased advertised foods, and reported that their parents purchased advertised foods for them. The reason may be that the marketing strategies of repetition and enticement in TV food ads have the potential to in uence purchase intentions of children and parents. [16] Marketing strategies in TV food ads, such as using celebrity endorsers or cartoon characters to promote products, designing snack packages with cartoon images or adding small toys in snacks, may have a promotion effect on the food purchasing behaviours of children and their parents. [17] In the present study, 21.1% of the children reported that their parents purchased advertised foods for them. Some studies have shown that parents usually have negative attitudes towards ads; they believe that unhealthy foods in ads may have harmful in uences on children's dietary habits. [18][19][20] However, other studies found that parents' behaviour of purchasing snacks for their children was greatly in uenced by media ads and lacked rationality, which may be due to parents' lack of knowledge of the nutritional information in children's snacks. [20,21] In addition, a previous study demonstrated that parents' positive discussions with their children about ads can increase children's understanding of ads and offset the negative effects of ads to a certain degree. [22] Hence, strengthening the education on TV food ads for parents and children, restricting children's purchasing behaviours of unhealthy advertised foods and training children to distinguish between healthy and unhealthy food ads would help children develop correct cognition of advertised foods. In addition, parents correctly interpret the content of TV food ads for their children may also be an effective measure. In fact, many developed countries have restricted TV food ads targeted to children. [23] However, it is not the case in China. The 'Advertising Law of the People's Republic of China' stipulates that the content of ads for children under the age of 14 should not 'persuade children to ask their parents to buy advertising goods or services'. [24] The Chinese government should formulate relevant policies to restrict unhealthy food ads to be broadcast on various media platforms, speci cally on children's programmes. Some public service ads or tips related to healthy dietary habits (i.e. consuming less high-sodium, high-sugar or high-fat foods) should be inserted in children's programmes.
This study demonstrated that TV food ads related purchasing behaviours were positively associated with children's dietary intake of energy, protein, fat and carbohydrates. Advertising foods of poor nutritional quality can in uence children's food preferences and make children tend to choose food rich in fat, re ned sugar and sodium. [25] This inclination may result in higher dietary energy and fat intake in children who request or purchase advertised foods than children who do not. Moreover, the amount of time children spend watching TV was associated with the number of their requests for advertised foods, and the likelihood that parents would purchase these foods. [6,8] This nding may be a reason for a previous conclusion that longer TV viewing time was associated with a higher intake of energy and fat among children. [6] Simultaneously, the current study found that children who purchased advertised foods had higher protein intake, which may be due to the ads of milk and dairy products targeted to children. Milk is rich in a variety of nutrients, especially protein, calcium and vitamins, and its protein digestibility rate is high (92%-98%), which can increase children's protein intake and contribute to the development and growth of children. [26] A previous study found that the popularity of dairy product ads in various media had a positive impact on people's understanding of the bene ts of consuming dairy products and facilitated milk purchase decisions. [27] This nding implies that the government should implement policies to promote healthy food ads on various media platforms, thereby increasing the recognition and consumption of healthy foods among children.
However, a recent study found that individual food purchasing was an inaccurate basis for characterising dietary intake of energy and nutrients, which may be in uenced by food wastage, non-consumption of purchased foods and consuming foods that were purchased by others. [28] Even if an individual consumes only self-purchased foods, it is di cult to fully calculate the nutritional content of the individual consumes by using individual food purchases, because each dietary recall represents only a "sample" from all purchased foods, not the nutritional content of the entire purchased set. [28] Therefore, TV food ads related purchasing behaviours could only re ect the dietary intake of children on a limited level.
TV food ads related purchasing behaviours were positively associated with children's overweight and obesity, which may be a reason for the positive association between screen time and obesity. [6,29,30] This nding may have several possible explanations. Firstly, previous studies have shown that children were exposed to a considerable number of TV food ads, predominantly of foods high in fat, sodium and sugar. [4,31] Purchasing and consuming these foods may be a reason for the increased risk of obesity in children. [32] These ndings are consistent with the result of this study that overweight or obese children had a higher proportion of purchasing advertised foods than children who are not overweight or obese. Secondly, the present study showed that the above TV food ads related purchasing behaviours resulted in higher dietary intake of energy, protein and fat. According to previous studies, excessive dietary energy intake is a major factor in the development of obesity in children; [33] and high fat intake appears to be causally related to overeating and obesity, at least in susceptible individuals. [34] Thirdly, in developing countries such as China, older primary caregivers, such as grandparents, appear to be susceptible and receptive to children's food purchasing requests. [35] Thus, these primary caregivers are likely to give in to children's purchasing requests for unhealthy advertised foods, which may in uence children's eating habits and increase the risk of childhood obesity.
Several limitations of this study need to be mentioned. Firstly, the cross-sectional data analysed in the study restricts conclusions about a causal relationship between TV food ads related purchasing behaviours and dietary intake and overweight and obesity among children. Secondly, we cannot analyse what kinds of the advertised foods were responsible for the results. This key question is worth exploring further. Thirdly, the TV food ads related purchasing behaviours were self-reported by children. Hence, responses could be in uenced by acquiescence bias, extreme response bias or dishonesty. Therefore, the result of the study should be approached with caution.

Implications For Research And Practice
This analysis indicated that TV food ads related purchasing behaviours have a positive effect on children's dietary intake of energy, protein and fat. Moreover, TV food ads related purchasing behaviours are positively associated with children's overweight and obesity. The ndings stress the importance of targeting school-aged children and their parents to promote rational dietary intake and reduce the risk of obesity in children via reducing purchasing unhealthy foods seen on TV food ads. Future research would bene t from longitudinal studies with more precise assessments of purchasing and consuming what kinds of foods seen on TV food ads to further understand the in uences that contribute to the development of chidlren's dietary intake and childhood obesity. Finally, future obesity prevention or dietary intake interventions may consider focusing on healthy TV food ads as an innovative way to promote and target healthy eating and food purchasing behaviors. The result of the study would re ect that Chinese government should formulate regulations on TV food ads; health educators could conduct TV food ads related education or interventions to promote healthy food purchasing behaviours and dietary intake and reduce the risk of childhood obesity.

Conclusion
This analysis constitutes the rst large-scale study of the relationship between TV food ads related purchasing behaviour and dietary intake and overweight and obesity among children in China. The results indicated that TV food ads related purchasing behaviours have a positive effect on dietary intake of energy, protein, fat and carbohydrates of children. Moreover, TV food ads related purchasing behaviours are positively associated with children's overweight and obesity. Hence, conducting studies in China that can track more nutritional behaviours related to TV food ads is necessary.

Declarations
Ethics approval and consent to participate The survey was approved by the institutional review committees of the University of North Carolina and the National Institute of Nutrition and Food Safety. All subjects gave their informed consent for inclusion before they participated in the study, and written informed consent was obtained from a parent or guardian for participants under 16 years old.