Abstract
Impact statement
• Studies investigating nutritional literacy and its connection to obesity predominantly target the demographic of children and adolescents, a critical period when lifelong dietary habits are established. • Emerging trends highlight the increasing integration of digital media tools among this age group. Future studies are evolving based on these trends, recognizing the impact of digital platforms on nutritional awareness. • The obtained data underscore a scarcity of comprehensive studies on the subject within the existing literature. • Recommendations for future research advocate a concentrated focus on children and adolescents, particularly in the context of obesity. Prioritizing this age group in subsequent studies is essential for advancing our understanding and addressing the complexities of this critical public health issue.
Introduction
Food literacy (FL) is defined as the ability to acquire, understand, interpret and use relevant information in making food-related decisions. It has been reported that individuals with limited FL cannot make appropriate food choices to meet their daily nutritional requirements, exhibit unhealthy eating behavior and may adversely affect their health due to errors in the perception of healthy food.1,2 In the literature, it is stated that FL is a subcomponent of health literacy together with nutritional literacy. The definition of nutritional literacy is seen to be quite similar. This situation was also reported in a study on the subject. However, it has been emphasized that although food and nutrition literacy are used interchangeably in studies, they do not have the same meaning, and the relationship between them cannot be fully explained.1,3
Obesity, which has negatively affected both the country’s economy and the quality of life of people for many years. It is a public health problem that affects the whole world. Obesity is a preventable disease caused by changing eating habits. It is very important for the individual to understand the nutritional recommendations given by dietitians about nutrition and make them a lifestyle. 4 According to the WHO report in 2022, 5 obesity is a public health problem that greatly affects children, adolescents and adults in almost all regions of the world. Nutrition is a very important risk factor in the development and prevention of obesity. Nutrition is one of most important the changeable risk factors. Therefore, determining the deficiencies in this subject is crucial for the protection and development of public health. Although there are many studies on health literacy, studies on food and nutrition literacy are limited in number. The use of different expressions makes it difficult to evaluate the results obtained from the studies. Therefore, the aim of this study is to bring a macro perspective to scientific studies on food and nutrition literacy and obesity and to evaluate the focus of studies in this field. In addition, this study will determine the most influential authors, institutions, countries, and journals in the field and examine the areas where possible future studies on the subject can focus.
Research Questions (RQ):
Answering RQ1 would enable researchers to identify international collaborations and potential collaborators on “NL/FL in obesity”. This would help explore the spatial distribution of articles.
Answering RQ2 would be expected to facilitate scholars in finding suitable journals for publishing “NL/FL in obesity”-related papers quickly.
Answering RQ3 would not only help researchers recognize significant documents but also reveal influential and productive countries, organizations, and authors that are internally connected.
Methods
Data collection and search strategy
Web of Science Core Collection (WoSCC) is one of the most widely used scientific databases in literature searches. Many researchers have conducted studies examining the data coverage of WoSCC, the quality of journals, and its advantages and disadvantages. 6 Hou et al. (2015) state that the data needed for WoSCC bibliometric analysis, such as the number of cited references, affiliation, DOI, keywords and keywords plus, are obtained in this database in a more standardized and complete manner compared to other databases. In addition, in terms of high-level visualization, WoSCS is stated as the most suitable database in the studies conducted by Falagas et al. (2008) and Gan et al. (2022).7,8 For this reason, the WoSCC database was preferred for the literature review in this study.
Database review and analyses for bibliometric analysis were carried out on March 21, 2023. In the search carried out using the WoSCC database, “all fields” searches were included, and the keywords were determined as “food literacy AND obesity” and “nutrition literacy AND obesity”. “Article”, “article, early access” and “article, proceedings paper” studies were included. In the study, only studies in the English literature were used to ensure universality and similarity in terms of letters in keywords, keywordsplus and similar data. All other features were determined as exclusion criteria. In the screening process carried out by two authors, the articles were excluded from the study by reading the titles, abstracts and, if necessary, the full text. Between 21 March 2023 and 01 April 2023, the final work file was obtained. After the keyword search, a total of 881 publications were reached. A total of 114 of these studies were excluded because they were not “article”, “article, early access” and “article, proceedings papers”, and 12 of them were excluded because of language, dublication and nonrelated publications. All articles between 1995, when the first article on the subject was published, and 2023, when the analysis was carried out, were included in the study. A total of 755 publications were studied. The data collection methodology used for scientometric analysis is shown in Figure 1. A flowchart representing research design.
The Bibliometrix library in R Studio IDE was used for analysis. For
Structuring strategy of the research
The work carried out is structured in line with a certain systematic pattern. The structuring strategy for the main title and subtitles of the study, which was basically analyzed under six main titles, is shown in Figure 2. Structuring strategy.
Results
Analysis of metadata outputs
Completeness of bibliographics metadata.
aAria & Cuccurullo, 2017.
Descriptive analysis of metadata.
When the average annual number of articles and the number of citations of the articles are examined, it is possible to say that the annual productivity has increased as of 2007. It is seen that it has become a remarkable research area by researchers, especially in the period between 2014 and 2019. Figure 3 shows data on the annual average number of publications and citation values. Annual scientific production and avarege citiations per year (1995-2023 March).
Analysis of sources output
In this analysis, which includes the most influential journals in the field, journals were evaluated on parameters such as h-index, g-index or citation. These journals can be multidisciplinary journals that feed the field specifically, or they can be resources that only publish on specific topics. In this study, journals were ranked considering their h index scores. In the literature, it is stated that when comparing the most influential journals in the field, a ranking on the number of publications alone will not be sufficient, and this should be supported by the outputs of Bradford’s Law (9). Bradford’s Law defines the scattering or distribution of the literature on a particular subject into journals.
9
Hertzel (1987)
10
expresses this situation as follows: “If scientific journals are arranged in descending order of efficiency of articles published on a particular subject, the journals may be divided into a core group of journals that publish articles exclusively on that subject, and several groups or regions containing the same number of articles as the core group”.
In this study, the ranking according to the number of articles published in the related journals and the journal lists in Zone 1 according to Bradford’s Law rule show compatibility. In other words, the influential journals in the field related to the subject are seen as the journals in Figure 4. Bradford’s Law journal list.
Top 25 journal list (Bradford’s law / zone 1).
aTotal citiation.
bNumber of publication.
cPublication year start.
There are four journals with an h-index score of 10 and above in the top 25 most influential journals in the field. The number of journals with a g-index score of 10 and above, which is another productivity and impact score, is five. The h-index is a metric used to measure the productivity and citation impact of a scholar’s published work. It is defined as the maximum value of h such that the given author has published h papers that have each been cited at least h times. For example, an h-index of 10 means the researcher has 10 papers with at least 10 citations each. This index aims to capture both the quantity (number of publications) and quality (citations) of a researcher’s work, providing a more comprehensive assessment of their academic impact than simple citation counts or publication numbers alone. The g-index is a metric used to measure the productivity and citation impact of a scholar’s published work, similar to the h-index. However, the g-index gives more weight to highly-cited articles. It is defined as the highest number (g) of papers that together received g2 or more citations. In other words, a researcher with a g-index of 10 has published at least 10 papers that, combined, have received at least 100 citations. The g-index is designed to improve upon the h-index by better accounting for the citation distribution across a researcher’s publications, thus giving more importance to highly-cited papers.
The m-index, also known as the m-quotient, is a metric that adjusts the h-index to account for the length of a researcher’s career. It is calculated by dividing the h-index by the number of years the researcher has been publishing. The m-index provides a normalized measure of research impact, allowing for a fairer comparison between researchers at different stages in their careers. For example, a researcher with an h-index of 20 who has been publishing for 10 years would have an m-index of 2. This metric helps to highlight researchers who have consistently produced high-impact work over time. The total number of publications in 25 journals in the list was found to be 332. This number corresponds to 44% of the articles in the local data set. The total number of citations of the articles in these journals is 5912. This means that there are an average of 17.80 citations per article. The citation average of the total articles in the data set was 15.75 (Table 2).
Analysis of authors’ output
This section, which includes bibliometric data about the most productive and influential authors in the field, has been shaped under three headings. In line with this planning, first, quantitative data about the authors themselves, then the institutions they are affiliated with, and finally, the analysis results of the authors’ countries are included.
Author output
Publications on the subject were made by a total of 2402 authors (Table 2). Under this heading, quantitative data such as the impact scores, number of publications and citation numbers of the first 25 active authors are included.
Top 25 authors list.
aTotal citiation.
bNumber of publication.
cPublication year start.
Affiliations output
The most productive institutions in the field with 20 or more publications to which the authors are affiliated are given below (Figure 5). Affiliations list (NP ≥ 20).
There are a total of 12 universities that have published 20 or more articles from institutions that contribute to the field of obesity and nutritional literacy. Researchers at these universities fed the field academically with a total of 351 articles. This number, which corresponds to 46.5% of the articles in the data set, constitutes almost half of it in terms of contributing to the expansion of the field. The top three universities at the top of the list, Deakin University, The University of Sydney, and University of North Caroline, contributed 124 articles to the field.
Country output
Top 10 Most relevant country and Most cited country.
aSingle country publications.
bMultiple country publications.
cTotal cited.
dAverage Article Citations.
The list is almost the same as the previous list in terms of the total number of citations and the average citations per article of the countries where the corresponding authors are located. The remarkable point in the average number of citations is that the average of Chile is expressed as 168. The reason for this is that there are two publications in this country by researchers, and they are frequently cited in the literature.
Analysis of document output
Most global cited document.
aTotal citations.
bTotal citations per year.
cNormalized total citations.
Most local cited document.
aLocal Citations.
bGlobal Citations.
cNormalized Local Citations.
dNormalized Global Citations.
Most global and local cited document output
Table 6, which includes the global cited data, can also include the studies that are not included in the local data set. In fact, these studies can sometimes be publications that cover the field indirectly instead of being directly related to the field but that researchers prefer as a source. It is seen that it differs from Table 7, which already has similar information in the local data set. According to the data in Table 6, the most important source benefited by the researchers is the study named “
Among the studies directly related to the subject and included in the data set, the most important article benefited by the researchers is the study named “
Author’s keywords output
Keywords are the words that help us to have a general idea about the content of the study that is specifically mentioned in the articles at first glance. For an article, an uncomplicated title that adequately describes the content and choosing the right keywords suitable for the content are important criteria. This section includes the frequently used keywords in the articles in the local data set and data on how the keyword trends have changed over the years.
As can be understood from the word cloud, words such as obesity, overweight and literacy, which form the core of the study subject, stand out in a large and remarkable way because they are frequently repeated words. Likewise, words such as adolescents, children and childhold obesity also give an idea about the participant population on which the study subjects are focused. The words that seem smaller and ineffective compared to these two groups provide information about the data, such as the countries that the subject works with, wants to measure or addresses.
It is possible to examine the studies on obesity-related nutritional literacy in four periods, from the past to the present, in terms of the total number of publications (Figure 3). The first of these is the period between 1995 and 2007, the publication date of the first article. This period is the period when the subject has just begun to emerge, and the groundwork is prepared for the maturation of subtopics in terms of study areas. It refers to the time taken for the shaping and structuring of the subject rather than determining a specific field of study as of the period. The period between 2007 and 2014 was a bumpy period, in which the subject was preferred as a field of study with high popularity in some years and sometimes less preferred compared to the previous year. “Food label” and “policy”, which are the most frequently preferred keywords in this period, show that policies related to nutritional literacy have become more important, and research has been conducted on product label reading and similar issues. In addition, the words “ Word cloud (freq > 50).
The Sankey diagram in Figure 7, which is a summary of the journal, author and article analyses carried out thus far, contains information about the most frequently used keywords and preferred journals by the 20 most influential authors in the field. For example, Katz DL, who is at the top of the list of the most influential writers in the field, frequently used keywords such as “childhood obesity” and “nutrition education”. In addition, the same author preferred journals such as Journal of Nutrition Education and Behavior and Journal of School Health to publish the results of the research. Sankey diagram (author-centered).
Analysis of conceptual structure
In this section, where conceptual analysis of the subject is made, the relations of clustered subjects within themselves and with other clusters are included. In addition, there are analysis results such as the main study topics related to the field, the preferred topics in the current trend, those who work on the subject in more specific areas, and the emerging trends without the year limit.
The conceptual structure in Figure 8 is similar to the category that was previously divided into four historical periods (see Figure 9). Conceptual structure (keywords plus). Trend topics.
The subthemes preferred by researchers in the main theme of obesity and nutritional literacy and information on the features of these themes are given in Figure 10. Accordingly, the themes preferred as Basic Themes within the scope of the subject are seen as overweight, nutrition and prevention. In fact, this section is seen as the section that forms the basis of the subject and on which the studies are built. In addition, among the themes that are expressed as Motor Themes and are now in a trend position, there are areas such as risk, prevalence, and physical activity. There are two groups called Niche Themes that represent very specific areas. The first of these are researchers who prefer to develop or adapt scales such as validity, reality, and survey. Others are researchers who choose to work in a specific category, such as low-income countries. Another field that is likely to emerge in the literature in the coming years is that areas such as effect, dietary intake and exposure are among the study topics that are likely to appear frequently in the literature on the subject. Thematic map (healthcare and VR).
Intellectual structure
This section analyzes the intellectual background on the subject and its structure. This analysis refers to the centrality positions and academic power structures of the articles. Analysis, which can also be expressed as intellectual schools, are the resources that help researchers in shaping the field. These schools, which intellectually support the field, include not only the local data set but also the literature in the bibliography of the data set. In other words, they can also be expressed as schools that help to create the main idea and study areas of the subject.
According to the data in Figure 11, it is possible to say that three schools (red, blue, green) led the way in the formation of the field and supported it for new work areas. In these three schools, the school with the highest author participation and dense network is the blue school. Co-citiation network.
The blue schools, which cover a denser cluster in terms of the number of authors and network of relations, generally conduct questionnaires from development and studies related to children. In addition, it is possible to state that authors such as Vidgen HA and Velardo S, who are important representatives of this school, carried out studies covering the Australian region.
Representatives of the red group carried out studies focused on technology and fitness. Among the important representatives of this group, names such as Weiss BD and Rothman RL stand out.
Finally, it is seen that the group of authors who are outside of the field relationship circle and focus on more niche topics, as seen from Figure 11, work on media, advertising, and their relations with obesity.
Social structure
This section shows the relations of the authors with each other in terms of institution or country.
When the groups formed by two or more author groups are examined, it is possible to state that there is a similar structure to the intellectual groups in terms of shaping and supporting the field. When the cooperation network focused on institutions is examined, it is seen that the universities, which are at the top of the list of influential institutions in the field, both have a more frequent relationship with each other and are quite effective. In particular, Deakin University, Sydney University and Western Australia University frequently conduct studies with each other. In addition, it is possible to talk about the existence of institutions that carry out studies by maintaining relations with fewer institutions. (Figure 12). Collaboration network (institutions).
When the cooperation network developed between institutions is examined on a country basis, the existence of three countries that are in relations with many countries stands out. These are the USA, the United Kingdom and Australia. The tables that include the countries of the influential institutions and responsible authors also support this intellectual and social relationship network. Researchers who want to study the subject in the future can benefit from Figure 13 to conduct research with countries included in the cooperation network of their country. Collaboration netw.
Discussion
The purpose of this bibliometric analysis is to evaluate the scientific publications on nutritional literacy in obese individuals between 1995 and 2023 and to evaluate the trends in these publications. With this study, the databases scanned in the Web of Science were scanned, and whether there was an increase in the number of publications on the subject, whether the trends in different subjects changed, and, if so, which areas they were directed to were evaluated. In addition, professionals who specifically study nutritional literacy in obese individuals were identified for the first time. As a result of the literature review, it was seen that there are bibliometric analyses and meta-analyses for health literacy, but there is no bibliometric, meta-analysis or systematic review for NL/FL. This study is the first bibliometric analysis on nutrition literacy, which is an important component of health literacy, and obesity, which is one of the important problems of our age. Although systematic reviews on nutritional literacy have been made for different purposes (explanation of terms and the relationship between them, tools developed for determining literacy levels 11 and evaluation of nutritional literacy levels of school-age children, 12 it is planned to go further with this study. Not only was the number of scientific studies analyzed, but the relevant keywords and the level of association between authors and countries were also determined. At the same time, bibliometric analysis is an interesting approach because it gives an idea about the areas in which studies evaluating the relationship between nutritional literacy and obesity are concentrated, and it provides an idea for future publications on the subject.
Considering the number of articles published on the subject, it has been shown that there has been a rapid increase in the number of articles after 2007, but there has been a significant increase in the number of publications in the last 10 years. The rapid increase in the number of publications after 2013 decreased in 2020. The main reason for this may be due to the emergence of the COVID pandemic, which affects the whole world, and the fact that researchers and journals turn more toward COVID-related publications. In a study, it was reported that studies on health literacy, of which nutritional literacy is also a component, increased between 2020 and 2021. 13 It has been reported that the curfew and restrictions on other social areas caused by the COVID-19 pandemic greatly affect the mental, physical, and emotional health of children and adolescents. This situation has led to the fact that health literacy came to the fore more in this period. When nutrition is thought to be effective in the prevention of many infection-related diseases, the publication of nutrition and nutrition-related studies was delayed until 2021. According to the results obtained from this study, David L Katz, who is the most influential author on nutritional literacy, had seven publications on COVID-19 in 2020.
Considering the number of citations, the most cited author directly related to the subject is the article published by Velardo in 2015. Since this article is an article on the definition of nutritional literacy and was published during the period when the subject was widely studied, it is thought that it received more citations than other studies. 1 Similarly, it was shown in a study that Nutbeam’s study, in which the concept of health literacy was defined, received significantly more citations than other articles. 13 It was found that the most cited work in areas not directly related to the topic was the work on digital media by Chassiakos et al. Researchers working on nutritional literacy focus more on childhood obesity. Looking at the keywords, it has been shown that children and adolescents are frequently preferred. In connection with this, researchers often prefer digital media channels as an educational tool to increase nutritional literacy in childhood. This situation explains the fact that a publication related to digital media is cited most in other fields. It has been noted that the caregivers co-use of digital media tools facilitates learning, as it enables caregivers to prepare educational materials and present them in an age-appropriate manner for the child. However, despite these benefits, excessive use of digital tools is widely emphasized to have adverse effects on cognitive development. 14
Keywords are very important, as they provide information about the areas in which the studies are focused. This bibliometric analysis provides insight into what other areas of research on nutritional literacy and obesity are focusing on. According to the analysis, the words obesity, overweight and literacy, which present the direct content of the subject, are frequently repeated. It has been seen that the words child and adolescent are frequently preferred in the studies. Considering that it is often emphasized in studies that nutrition plays an important role in the prevention of childhood obesity, it is an expected result that studies will focus on this area. 15
When the keywords are examined according to the years, the ground was prepared for the understanding and maturation of the subject in the beginning years (1995-2007), and the subtitles were not preferred very often in these periods. In the following period (2007-2014), the keywords food label and policy, which are associated with studies on public health, were used more frequently. In addition, the words “
Analyses were performed to determine which subject the studies focused on, which field they focused on, and possible future study areas. Accordingly, it has been shown that the main theme, similar to the keywords, focuses on obesity, nutrition and prevention. In this period, it was found that studies on the subject were mostly associated with “prevalence”, “risk” and “physical activity”. It is estimated that future studies on obesity and nutritional literacy may be in the fields of “impact”, “dietary intake” and “exposure”.
When we look at the main focus of the leading authors in the field, it is the development of tools and questionnaires to determine nutritional literacy, which receives more citations in the local area, and the children are frequently preferred in keywords. Another important trend has been on “technology” and “fitness” by Rothman RL and Weiss BD, which received very high citations (234) among researchers who indirectly covered the subject. It was found that author groups studied the relationship between media and advertising and obesity less frequently.
It has been determined that Deakin University, University of Sydney and University of Western Australia are the institutions that frequently carry out studies on the subject together. The countries that prefer to cooperate more with each other are the USA, the United Kingdom and Australia. This situation provides information about which countries and institutions can cooperate with the authors who plan to work in this field, according to the fields they plan to work on.
This study has some limitations due to the nature of bibliometric analysis methodology. Despite being one of the most widely used scientific databases, articles related to the subject published in other databases have not been included in the study. Although the X software is considered reliable for bibliometric analyses, future studies should conduct comparisons using other bibliometric software such as R, Gephi, CiteSpace, and Bibliometrix. In the literature, it has been seen that some authors use nutrition education as a keyword instead of the concepts of nutrition/nutritional literacy. This may have led to the inability to find all articles on the subject. Another limitation is that the language of the articles included in the study was English. Articles published in other languages were not included in the study. This may have led to the concentration of work areas in certain countries. However, the acceptance of English as the language of science and alphabetic differences make it difficult to unite on a common point.
Developing nutrition literacy in childhood is essential for preventing future health issues. While digital media tools are a viable alternative, parental co-use is recommended due to children’s limited self-control. Assessing nutritional knowledge, identifying deficiencies, and implementing appropriate measures are necessary. Further comprehensive studies on nutrition and food literacy are required.
Footnotes
Authors’ contributions
Declaration of conflicting interests
Funding
ORCID iD
