Background
A healthy diet has been well established as a key part of chronic disease prevention and mortality reduction [
1‐
3]. Dietary behavior change is the focus of many health promotion interventions seeking to improve health outcomes, which may motivate individuals to alter their diets by taking actions such as increasing fiber and reducing saturated fat intake [
4‐
6].
In designing health promotion interventions for specific groups, understanding the target population’s health belief systems and views on proper dietary habits is critical, as individuals’ ideals about food have been found to be important determinants of food choice [
7]. Studies are needed to examine what diverse populations perceive to constitute a healthy diet [
8], with results informing design of culturally tailored behavior change interventions [
9]. Previous research examining perspectives on healthy eating in diverse groups has revealed distinct ways in which individuals conceptualize a healthy diet. In a review of the literature examining how qualitative research has advanced understanding of the ways in which people interpret healthy eating, Bisogni et al. identified a number of ideals for healthy eating put forth by diverse cultural groups in multiple countries [
10]. Participants in the reviewed studies described healthy eating in terms of specific foods (e.g. fruits and vegetables), food components (e.g. general nutrients, additives), and physical and psychosocial outcomes (e.g. energy, pleasure), among others. Individuals characterize healthy eating in diverse and complex ways, with definitions linking to eating behaviors and spanning various beliefs [
11].
While a number of previous studies have examined views on healthy eating using qualitative methods, a review of the literature reveals that only three such studies have focused exclusively on young adults, a group that warrants particular attention with regards to promotion of healthy eating. In the first, examination of undergraduate Canadian females revealed that participants defined healthy eating in accordance with Canadian dietary guidelines and also mentioned organic food, eating with others, and functional foods [
12]. The second study, which examined how members of a college men’s ice hockey team experienced the multiple factors influencing their food choices, also revealed participants’ notions of a healthy diet [
13]. Most of the players interviewed believed that healthy foods were low-fat foods, and many associated feeling good and having high energy levels with consumption of easy-to-digest foods. Unhealthy foods, in contrast, were described as those such as fries and chips, which may promote feelings of being “bogged down.” Foods such as burgers, pizza, ice cream, cookies and cakes were viewed as tasting good but not healthy [
13]. The third study, in Chinese American young adults, indicated that traditional Chinese cuisine was viewed as healthful, conferring benefits such as normal organ function, enhanced immune system, stronger, bones, and longer lifespan [
14]. Further research is needed to determine which of these factors are specific to particular cultures.
Understanding perspectives on healthy eating in diverse groups of young adults is of importance in promoting health. During the transition period from adolescence to adulthood (18–31 years), not only is the presence of obesity and unhealthy habits associated with increased chronic disease risk, but young adults also gain independence and establish long-term health behavior patterns [
15]. Further, young adults’ current dietary intake is not optimal; a recent study in this population in the U.S. revealed that average daily levels of 6 of the 7 nutrients of concern identified in the
Dietary Guidelines were lower than recommended [
16]. Similarly, in countries undergoing a nutrition transition, such as China, the introduction of a Westernized diet has led to high intake of foods rich in fat and sugar and low in fiber across the lifespan [
17‐
19]. As overweight is a prevalent issue in young adults resulting from such undesirable dietary habits, this population may also engage in dieting practices to achieve weight loss that may potentially have deleterious effects on health [
20,
21].
Young adults completing their undergraduate education, in particular, face nutritional issues that warrant the attention of health professionals. The average college freshman has been shown to gain an average of 1.8 ± 0.7 kg in the first year of university attendance [
22]. Students who are transitioning from home to the college environment may make poor dietary choices and engage in little physical activity, which may contribute to the weight gain observed [
15,
23]. The obesogenic college environment, with availability of all-you-can-eat cafeterias and food high in solid fats and sugars, may play a role in promoting unhealthy choices [
22,
24,
25]. Given the particular challenges undergraduate students face in making healthy choices, they represent an important subgroup of young adults to target in promoting sound dietary habits.
To improve dietary habits of young adults, messages about healthy eating have been delivered both through public health guidelines and interventions. In the U.S., the
Dietary Guidelines for Americans provide evidence-based advice on healthy eating, and outline how people can improve their overall eating patterns [
26]. The United States Department of Agriculture (USDA) has also developed MyPlate, a graphic illustrating the 5 key food groups using the familiar image of a place setting for a meal [
27]. Other countries have developed similar graphics; for example, the Chinese food guide pagoda conveys the essential components of the diet [
28]. As dietary intake of college students has been found to be less than optimal [
16], a number of interventions seeking to promote healthy eating have also been conducted [
29,
30]. A 2016 systematic review of dietary interventions in university students in diverse world areas, however, noted that out of the twenty studies examined, only one intervention was found to be effective in the long term [
30]. In improving upon existing interventions for testing in diverse groups of students, interventions will need to be carefully adapted, evaluated and implemented [
31]. Researchers have noted the importance of addressing cultural, social, environmental and psychological forces that influence health behavior in adapting interventions to foster behavior change [
32]. Understanding health belief systems is particularly important in tailoring interventions to promote optimal dietary practices, as messages must fit within an individual’s frame of reference to be noticed and processed [
33].
As individuals’ eating habits are shaped by the social and cultural contexts of their lives, the ideal diet may be conceptualized differently across diverse populations of young adults. Cross-cultural comparison can reveal valuable findings that may promote cognizance of diverse health belief systems and habits across groups [
34]. A comparison of two groups with historically distinct belief systems related to diet and health may be particularly informative in the design of nutrition education messages. Such differences between Chinese and American populations in general, for example, have been well documented. Studies examining the principles underlying the Chinese diet, such as the Yin-Yang belief system of Traditional Chinese Medicine (TCM), reveal stark differences between such principles and those informing the Western diet [
35‐
37]. In a study of three Asian-American groups, for example, all groups expressed the general belief that specific foods have either hot or cold properties and should be eaten strategically to keep one healthy, a concept absent from the Western system [
35]. However, the “Westernization” of the Chinese diet has also been well documented, reflecting the influence of global trends [
38‐
43]. Chiva notes that the traditional Chinese meal obeys very strict rules and rituals [
44]. However, when economic circumstances allow, people in China eat between meals at any time of day or night, according to supply and demand [
44]. The traditional Chinese diet, characterized by high intake of plant-source foods, has been replaced by a diet high in refined carbohydrate, added sugars, fats and animal-source foods [
42,
43]. Given the powerful effect of global trends and changing social contexts, it is important to examine to what degree beliefs on healthy diets have converged between countries, or remain distinct. No research to date, however, has considered the intersection of cultural variables with undergraduate students’ views on diet. The purpose of the present study was to describe perspectives on healthy eating among Chinese and American young adults completing their undergraduate studies and identify similarities and differences between the two groups.
Discussion
This study is the first to compare views on healthy eating in two distinct groups of undergraduate students. While both groups described healthy eating in terms of principles guiding current nutrition recommendations and specific foods to emphasize, a number of differences were also identified. The diverse views may reflect food-related messages to which participants are exposed both through the media and educational systems in their respective countries; these findings hold important implications for nutrition education initiatives.
For Chinese participants, timing of eating was considered an important aspect of healthy eating and was mentioned much more frequently compared to American participants. The importance of timing of meals is also emphasized in TCM; classic texts note: “Meals should always be taken at the proper time. This makes them easier to digest.
Yang qi increases around noon and is weak at sunset. Thus eat a hearty breakfast, a small lunch, and a frugal meal in the evening and night” [
49]. Digestive organs are thought to be at their weakest after 6 PM; thus, the evening meal should be small so as not to burden the stomach [
50]. Of note, however, recent studies have indicated large shifts in eating patterns in the Chinese population, with the traditional pattern of regularly eating 3 meals per day shifting toward a mixed meals pattern (3 meals plus snacks) [
51,
52]. Further, evening has been shown to be a preferred time for snacking [
52]. Despite the nutrition transition in China leading to changes in timing of food consumption and content of the diet, findings of the current study reveal persistence of traditional beliefs [
18].
Other aspects of Chinese students’ essays also reflected traditional beliefs. For example, physical outcomes were important motivators for consuming a healthy diet, with prevention of digestive problems a common theme. The emphasis on digestive health may also reflect the influence of TCM, which stresses the importance of digestion in maintaining health. In this system, the value of a food is determined both by its nutritional content and the ability of the body to extract that nutrition [
53]. Previous qualitative studies conducted in Chinese populations in diverse world areas have revealed the belief that TCM may serve as a guide for health promotion in terms of adoption of a healthy diet [
54]. Following these principles, a health professional providing medical nutrition therapy to patients holding Chinese worldviews would consider the natural warm state of the body, especially that of digestion, and would give recommendations that would not incorporate too many foods that are cold either in nature or in physical temperature and therefore may affect digestion [
53].
Another possible explanation for the common mention of the importance of a healthy diet for digestive function may relate to the prevalence of functional gastrointestinal disorders in this population. While the degree to which this particular sample had experienced gastrointestinal distress is unknown, a recent study in college students in North China found that functional dyspepsia, irritable bowel syndrome and functional constipation were common [
55]. In designing nutrition education interventions for young adults in China, it may be important to draw the connection between diet and digestive function, emphasizing the ways in which dietary intake may influence health of the gastrointestinal tract and prevent conditions such as constipation. Notably, a study that employed qualitative methods to examine beliefs related to obesity prevention revealed similar findings regarding views on physical outcomes of healthy eating among 40 Chinese American young adults [
14]. Participants identified enhanced health as the most common benefit of healthy eating, including normal organ function, enhanced immunity, and stronger bones [
14]. The Chinese have historically been found to have a strong belief in the relationship between diet and health [
56], and stressing the effect of diet on specific aspects of health may be an important component of an intervention. Findings of the current study further reveal traditional beliefs related to diet, suggesting value in promoting traditional practices in Chinese young adults in efforts to prevent chronic disease as China undergoes a nutrition transition.
In addition to the mention of optimal digestive function as a physical outcome resulting from healthy eating, there was also mention, albeit less frequent, of prevention of weight gain and achievement of an attractive figure through a healthy diet. Previous studies have highlighted the strong desire to lose weight sometimes to ultra-thin and unhealthy levels in Chinese college females, despite their being underweight or normal weight in many cases [
57,
58]. Exposure in the media to Western beauty ideals has been cited as a factor that may contribute to feelings of fatness and worry about loss of control over eating [
59]. Participants’ statements may also in part reflect the public health push in China to reduce rising rates of obesity. Recent economic growth in the country has led to changes in the eating habits of the population and movement toward a more Westernized diet [
17‐
19]. As a result, rates of obesity have increased greatly over the past few decades in most age groups and regions for both men and women [
40]. Elucidating the relationship between diet and obesity in nutrition education efforts in China will be an important component of strategies to reverse the current trends. Of note, revised Chinese dietary guidelines have recently been released and have a focus on chronic disease prevention that may assist young adults to make healthy dietary choices [
60].
In line with previous findings of qualitative studies focused on defining healthy eating in diverse groups, both Chinese and American students emphasized concepts from the dietary guidelines in their countries, such as balance, variety and moderation. A study of undergraduate Canadian females, for example, demonstrated that participants seemed knowledgeable about the Canadian dietary guidelines, including the four food groups, moderation and variety [
12]. Similarly, research in British adults indicated that healthy eating was conceptualized as a balanced and varied diet [
61]. Balance and variety were also key concepts highlighted in a study of perceptions of healthy eating in European adults [
62]. Such principles have also been cited in defining healthy eating in many other studies [
63‐
67].
With regards to specific concepts from dietary guidelines highlighted in the current study, the principle of moderation was common among both Chinese and American participants’ narratives. Despite this commonality, however, each group had unique perspectives on this topic. The Chinese essays included the idea that a sense of hunger should remain at the end of an eating occasion. American students, in contrast, often cited moderation as a justification for consumption of less healthy dietary components, such as foods high in sugar. Participant statements may reflect somewhat differing views with regards to the meaning of moderate eating among the two groups. Notably, previous studies have highlighted the American focus on quantity in eating and the inclination toward excess [
68,
69]. In addition, Chinese immigrants to the United States have been found to have less dietary moderation and higher rates of chronic conditions with acculturation in comparison with less acculturated Chinese counterparts [
70,
71]. While both groups noted the importance of limiting intake of foods high in fat and sugar, as well as total calories, the way in which this knowledge is translated into action may differ, with the concept of moderation taking on different meanings. Discussion of appropriate portion sizes and consumption of food within energy needs comprises an important part of nutrition education efforts, in line with the Academy of Nutrition and Dietetics’ “total diet approach” to healthy eating [
72].
American participants frequently referenced balance, which is a dominant theme for basic nutrition education in the United States [
26]. The current food icon, MyPlate, is based on the concepts of balance, variety and moderation, helping consumers to stay within their daily calorie needs, make smart choices from every food group, and find a balance between food and physical activity [
27]. American students’ essays emphasized both the necessity of consuming a balanced diet and of offsetting consumption with sufficient exercise. The importance placed on physical activity is concurrent with previous research. In a qualitative study of 49 undergraduates at a Midwestern university, for example, LaCaille et al. found that students identified many motivators for physical activity, including being in shape, relaxation, improved mood and energy, and improved self-esteem [
73]. While it is evident that the present group of young adults had knowledge with respect to the importance of exercise and current recommendations, considerable effort is still required to encourage implementation of these guidelines. As indicated in previous studies, many young adults in the U.S. do not adhere to the
Dietary Guidelines and are not meeting the recommendations for physical activity [
16,
74]. As knowledge is only one factor among many that impact behavior, it may be important to focus on other factors in promoting physical activity in young adults in the U.S., such as psychological processes (perceptions, values, attitudes) that may influence health-related choices, and environmental supports that may foster desirable behavior [
29,
73,
75].
In addition, American participants’ views on which foods to restrict also reflect current trends in the nutrition field. In recent years, a number of diet plans involving limiting carbohydrates have gained popularity, including the Atkins Diet [
76], the Paleo Diet [
77], and the South Beach Diet [
78]. In participants’ narratives, a number of carbohydrate-containing foods were identified as targets for restriction. Of note, some participants mentioned restricting carbohydrates generally, without discussion of particular carbohydrate containing foods that would be particularly important to limit, such as sugar-sweetened beverages. In nutrition education initiatives targeting young adults in the U.S., it may important to debunk myths about dietary components such as carbohydrates, emphasizing the science behind current recommendations. Indeed, a previous study seeking to identify the needs of U.S. college students for development of nutrition education programs, identified the concept of “nutrition myths and facts,” both generally as well as on specific topics in the field, among topics of importance [
79].
Several themes not typically addressed in nutrition education interventions also emerged in both groups, such as those relating healthy eating to psychosocial outcomes. Participants mentioned the importance of a sound diet in maintaining mental health, feeling good, and warding off depression. In their review of the literature on interpretations of healthy eating, Bisogni et al. also identified meanings related to psychosocial outcomes, reflecting the complexity of beliefs on healthy eating and connection to various facets of life [
10]. Based on the emergence of these themes, the researchers acknowledged the importance of addressing factors beyond the scope of typical nutrition education initiatives [
10]. To reflect the results of previous studies, mental health has been addressed in a number of nutrition programs implemented in recent years, including the MOVE! weight management program for veterans [
80] and the COPE [Creating Opportunities for Personal Empowerment] cognitive behavioral skills building TEEN [Thinking, Emotions, Exercise, and Nutrition] program designed for adolescents [
81]. Dietary change has been cited as having potential to improve mental wellbeing in undergraduate students, an important consideration for young adults [
82].
Findings revealing the differences and similarities in views of healthy eating in Chinese and American young adults hold implications not only for health professionals working with these populations in their home countries, but also for professionals addressing the needs of diverse populations. Dietitians in the U.S., for example, often work to address the needs of immigrant populations that are less acculturated in terms of adapting host country dietary customs, and must therefore understand the predominant views of health in the immigrants’ country of origin. The Asian population grew faster than any other race group in the U.S. between 2000 and 2010, with Chinese making up the largest component of this group [
83]. Given this, as well as the increase in obesity and related chronic conditions in the Chinese American community, researchers have highlighted the immediate need among health professionals to understand Chinese culture, with its specific beliefs, attitudes, and behaviors, as it relates to obesity risk [
14,
84]. Gaining this understanding will be particularly important not only in meeting the needs of Chinese American young adults, but also in serving Chinese international students in U.S. colleges and universities, a fast-growing population representing the majority of international students in the U.S [
85]. Given the particular nutrition-related challenges that college students face, the current study provides important information that may inform nutrition education interventions in a diverse at-risk group.
This study has several limitations. First, only 2 distinct groups of young adults representing 2 world areas were included. To further compare and contrast views on healthy eating in young adults, groups in other regions such as Europe, Africa or South America could be included. Secondly, participants included in the study were drawn from only one university in each country, and had self-selected into an introductory course on nutrition, limiting the generalizability of the results. The sample was, however, heterogeneous in terms of age and gender, and did allow for the discovery of important information regarding the diverse views of healthy eating in 2 distinct populations. Finally, the methods employed did not allow for examination of student responses in terms of whether students demonstrated complex thinking that linked multiple relevant concepts. Future studies may identify issues of complex thinking to provide greater depth of analysis.