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Abstract

Introduction/Objective:

In Asia, 42% of young children suffer from iron deficiency anemia. Children have an increased requirement for iron intake because of growth and physical activity. Education plays an important role in anemia prevention and in ensuring children are aware of appropriate iron intake and the iron content of different foods. As a tool for this purpose, we adapted the adult version of the Revised Iron Intake Scale (RIIS) to create the Child and Adolescent Version of the Iron Intake Scale (CIIS), using illustrations to help children recognize the foods listed in the CIIS. We aimed to evaluate the validity and reliability of this new scale.

Methods:

We conducted a cross-sectional study using a self-administered questionnaire to examine the criterion-related validity of the CIIS. We used Spearman’s rank correlation coefficient to compare iron intake estimated by the CIIS with that calculated by the Brief-type Diet History Questionnaire (BDHQ-15y), which assesses respondents’ dietary habits over the past month and is standardized among Japanese children. The survey was repeated twice to examine reliability.

Results:

We found a moderate positive correlation for iron intake between the CIIS and BDHQ-15y, with a correlation coefficient of .52 (n = 258, P < .001). Cronbach’s alpha coefficient was .718. The CIIS reproducibility test yielded a correlation coefficient of .67.

Conclusion:

Our results indicated that the CIIS was valid, reliable, and reproducible. We therefore believe that the scale can be used to improve education about iron deficiency anemia and thereby reduce anemia rates among children and adolescents.

Keywords

Iron Intake Scale anemia iron deficiency nutrition education

Introduction

The WHO Global Anemia Survey estimates that 269 million young children are exposed to serious health problems due to anemia.¹ Anemia rates are particularly high in Asia, where 42% of young children are considered to have iron deficiency anemia. It has been reported that anemia is associated with stroke and depression among adults,^2,3 and anemia in childhood affects cognitive development and growth.⁴

In children and adolescents, the demand for iron intake increases with physical growth, increased physical activity, and menstrual bleeding.^5,6 Although augmenting iron intake is essential for reducing iron deficiency anemia, it is noteworthy that in Japan, dietary iron intake has significantly declined among this age group. According to a National Institute of Health and Nutrition report, average daily dietary iron intake was 7.6 mg in 2019, compared with 13.9 mg in 1978, marking a 45.3% decrease over the past 4 decades.^7,8

It is imperative to focus on achieving adequate iron content in one’s diet, rather than solely relying on iron supplementation.⁹ The use of supplements is 1 method of compensating for insufficient dietary intake of iron; however, when a children’s hospital in Cambodia tried to reduce anemia in malnourished sick children by increasing iron intake through supplements, it was unsuccesful.¹⁰ Conversely, a boarding school in Indonesia reported 40% improvement in anemia rates by increasing iron intake through school lunches.¹¹ As in this case, to reduce anemia rates, it is necessary not only to increase iron intake but also to redress malnutrition, as well as increasing intake of protein and B vitamins, which have a similar hematopoietic role to iron.

To enhance one’s iron intake, it is essential to understand the iron content of different food items. Foods differ significantly in the amount of iron they contain and the rate at which it is absorbed by the body. For instance, heme iron, predominantly found in meats, exhibits high absorption rates. Conversely, other foods that are consumed in greater quantities can still make a significant contribution to iron intake, despite having lower iron content and absorption rates. For example, the iron content of rice, a staple food, is approximately one-tenth that of red meat; however, the contribution to total iron intake is higher when rice is consumed in larger amounts, such as 3 servings per day. Furthermore, during school years, when the demand for iron increases due to growth and physical activity, it is crucial to provide education focused on anemia prevention and appropriate iron intake. In Japan, school meals play a pivotal role as a model for good nutrition. Similarly, a study conducted by the National Homegrown School Feeding Program in Nigeria demonstrated that school meals provided 137% to 175% of the daily Recommended Nutrient Intake (RNI) for iron, thus supporting iron intake among schoolchildren.¹² These meals have been instrumental in enhancing children’s awareness of and attitudes toward food.

The authors of this study have previously measured iron intake in female university students following nutritional education aimed at increasing hemoglobin and iron intake,¹³ and have also investigated changes to iron intake among female high school students as a result of nutrition education activities that included cooking practice with parents.¹⁴ While implementing such nutrition education-related activities among children and adolescents, we recognized a need for an iron intake self-assessment tool tailored to this age group. The Brief-type Self-administered Diet History Questionnaire 15 Years (BDHQ-15y) is an existing dietary intake assessment tool that was designed to estimate the intake of approximately 30 nutrients, including iron, based on average dietary consumption over the previous month.¹⁵ This index has been validated for its accuracy in assessing nutrient intake and the consumption of different food groups when used among Japanese children. However, while the BDHQ-15y has the advantage of measuring the intake of a range of nutrients beyond iron, the requirement to calculate intake totals for so many nutrients makes evaluation challenging. Furthermore, because the questionnaire consists of 88 questions and fills both sides of an A3 sheet of paper, it is time-consuming to complete and can be a significant burden for children. For these reasons, we decided that it would be more prudent to adapt the existing adult version of the Revised Iron Intake Scale (RIIS) to children and adolescents.¹⁶ Hereafter, we refer to our newly adapted version as the Child and Adolescent Version of the Iron Intake Scale (CIIS), the development of which is described in this paper.

The objective of this study was to examine the validity, reliability, and reproducibility of the CIIS for use among children and adolescents in order to establish its suitability as a tool for nutrition education on anemia prevention in elementary and junior high schools.

Methods

This research comprised the following 3 steps: (1) developing the CIIS; (2) conducting a cross-sectional study using a self-administered questionnaire to examine the scale’s validity and reliability; and (3) conducting a longitudinal study to evaluate the scale’s reproducibility.

Development of the Child and Adolescent Version of the Iron Intake Scale (CIIS)

The CIIS was adapted from the RIIS developed by Okabe et al.¹⁶ The RIIS included food groups with group-specific daily iron intake of approximately 1.0 mg in the results of the 2013 National Health and Nutrition Examination Survey on nutrient intake. The RIIS is composed of the following food groups: (1) staple foods, (2) brown rice and soba noodles, (3) dark green vegetables, (4) raw vegetables, (5) other cooked vegetables, (6) dried foods, (7) shellfish and oily fish, (8) red meat, (9) liver (organ meats), (10) eggs and bean products, and (11) chocolate and confectionery. A score of 1 point on the frequency scale corresponds to 0.5 mg of iron content at the defined serving sizes for each food group.

Two educators specializing in nutrition education collaborated to develop the initial draft of the CIIS. In developing the CIIS, we added illustrations to facilitate children’s understanding of the serving sizes described in each question and of how it would typically be served as part of a meal. Additionally, we made adjustments to the wording used in the RIIS questionnaire items and the phrasing describing how to answer the questions. We also referred to the set list of Japanese Kanji characters learned by elementary and junior high school students to ensure that the Japanese text could be read and understood by fifth-graders (Supplemental File: Japanese version of the CIIS).

To examine the surface validity and accessibility of the tool, we engaged 10 fourth- to sixth-grade elementary school students as evaluators. The students belonged to the school lunch committee of an elementary school in Town A, Fukushima Prefecture. Elementary school students were selected as evaluators because it was assumed that if they could understand the questionnaire, junior high school students would also be able to do so. The students were asked to give feedback by underlining with a marker any sections they believed might be unclear or difficult for their peers to understand.

Validity and Reliability of the CIIS

The cross-sectional study was conducted using a self-administered questionnaire. The study targeted Town B, where a survey request was issued and cooperation secured. It encompassed all elementary and junior high schools within Town B (comprising 6 elementary schools and 2 junior high schools) and included all 134 fifth-grade students and all 145 eighth-grade students. The survey was conducted in September 2019.

The survey items included height, weight, health-, and lifestyle-related items such as complaints of fatigue, shortness of breath on stairs, stiff shoulders, headache, and dizziness, dietary items such as dieting and missing meals, degree of menstrual bleeding, history of anemia, and usage of iron supplements. The survey also asked for responses to the CIIS questionnaire developed as part of this research. Additionally, the survey included the BDHQ-15y, an 88-item questionnaire that evaluates the dietary habits of respondents over the previous month, which has previously undergone rigorous testing for reliability and validity specifically within the context of Japanese children.¹⁵

Regarding the survey procedures, a document describing the purpose and implementation of the study was distributed to parents, and their consent was obtained. Questionnaires were distributed at each school, and students were asked to take the questionnaires home and fill them out in cooperation with their parents. The students themselves were asked to read a written explanation of the implementation of the study by the teacher in charge. The explanation stated that cooperation in this study was voluntary, and that refusal to cooperate would not affect their school grades. This study was conducted after obtaining approval from the Koriyama Women’s University Ethics Committee (approval number: 2020-102).

Reproducibility of the CIIS

To examine the test-retest reliability of the CIIS, 2 surveys were administered to 26 fifth-graders and 27 sixth-graders at an elementary school in Town C. The selection of survey participants was conducted through an elementary school that has an established collaborative agreement with the first author’s university. The surveys were administered in May 2022 and 1 month later in June 2022. In both cases, the survey items comprised those questions on the CIIS questionnaire.

Statistical Analysis

For descriptive statistics, we reported means and standard deviations for continuous variables, and medians and 25th to 75th percentile ranges for categorical variables. To examine the criterion-related validity of the CIIS, we calculated Spearman’s rank correlation coefficients comparing iron intake estimated by the CIIS with that of the BDHQ-15y. Participants were excluded from the analysis if they had any missing responses to question items in either the BDHQ-15y or CIIS. To test the CIIS’s reliability, we calculated internal consistency using Cronbach’s alpha-coefficient, and to test reproducibility, we examined test-retest reliability by calculating Spearman’s rank correlation coefficients between 2 time points, 1 month apart. The statistical significance level was set at 5%. SPSS Statistics ver 26.0 (IBM Japan, Tokyo) was used for statistical analyses.

Results

Surface Validity and Accessibility of the CIIS

The 10 elementary school students who were asked to evaluate the draft version of the CIIS gave the following comments: (1) it was difficult to tabulate the scores, and (2) it was difficult to determine from the tabulated scores whether their daily dietary iron intake met the recommended amount. We had feared that the food items listed in the questionnaire might be difficult to understand, but when asked, the children said that the meanings were clear from the illustrations. We asked the 10 evaluators to highlight questionnaire items that were difficult to understand; however, no items were highlighted, indicating that all the students were able to comprehend the item descriptions. As a result of the comments received, we improved the CIIS to make it easier to calculate the total score by providing boxes to enter the score for each item. In addition, to help users interpret their own results, we added easy-to-understand scales showing recommended daily dietary iron intake for elementary, junior high, and high school students. Although high school students were not included in our survey this time, we added a recommendation for the amount of iron that high school students should consume to serve as a guide for iron intake in the future. Figure 1 shows the English translation of the finalized version of the CIIS.

Figure 1.

Child and Adolescent Version of the Iron Intake Scale (CIIS).

Validity and Reliability of the CIIS

The number of responses (and response rate) to the survey conducted as part of the cross-sectional study was 119 (88.8%) for elementary school students (out of 134 eligible students) and 144 (99.3%) for junior high school students (out of 145 eligible students). The number of valid responses (and valid response rate, defined as the number of valid responses divided by the number of responses collected) was 114 (95.8%) for elementary school students and 144 (100%) for junior high school students. Exclusions included 3 elementary school students who did not fully complete the BDHQ-15y, and 2 who did not fully complete the CIIS. The age (mean ± standard deviation) of the respondents was 10.4 ± 0.7 years for the fifth-grade students and 14.3 ± 0.6 years for the eighth-grade students. Symptoms similar to anemia, such as fatigue, stiff shoulders, and dizziness, were observed to increase in prevalence from elementary to junior high school in both boys and girls. Additionally, instances of skipped meals and a history of anemia were more commonly reported among junior high school students compared with elementary school students (Table 1). The median iron intake according to the CIIS was 5.5 mg for boys and 5.8 mg for girls in elementary school, and 6.3 mg for boys and 6.0 mg for girls in junior high school. The breakdown of iron intake for each food group is shown in Table 2.

Table 1.

Body Measurements and Health-, Lifestyle-, and Dietary-related Items for Male and Female Elementary and Junior High School Students.

	Boys				Girls
	Elementary school (n = 61)		Junior high school (n = 74)		Elementary school (n = 53)		Junior high school (n = 70)
	Mean or n	SD or %	Mean or n	SD or %	Mean or n	SD or %	Mean or n	SD or %
Height (cm, Mean ± SD)	139.9	6.0	166.4	6.3	142.1	7.7	156.1	4.6
Weight (kg, Mean ± SD)	35.7	8.8	54.9	8.8	35.8	5.6	50.0	7.2
Body type
Underweight	2	3.3	2	2.7	1	1.9	1	1.4
Normal	49	80.3	68	91.9	46	86.8	63	90.0
Overweight	10	16.4	4	5.4	6	11.3	6	8.6
Health-, lifestyle-, and dietary-related items	n = 61	%	n = 74	%	n = 53	%	n = 70	%
Complaints of fatigue	7	11.5	28	37.8	5	9.4	32	45.7
Shortness of breath on stairs	9	14.8	5	6.8	4	7.5	16	22.9
Stiff shoulders	5	8.2	21	28.4	5	9.4	30	42.9
Dizziness	6	9.8	36	48.6	3	5.7	36	51.4
Pale complexion	0	0.0	2	2.7	3	5.7	2	2.9
Craving to chew on ice	12	19.7	10	13.5	12	22.6	19	27.1
Dieting	4	6.6	4	5.4	2	3.8	9	12.9
Skip meals	1	1.6	6	8.1	1	1.9	6	8.6
History of anemia	2	3.3	5	6.8	1	1.9	8	11.4
Taking iron supplements	7	11.5	8	10.8	5	9.4	8	11.4
Menstruating	—	—	—	—	9	17.0	66	94.3
Heavy menstruation	—	—	—	—	1	1.9	26	37.1

Abbreviation: SD, standard deviation.

Table 2.

CIIS Responses: Total and Food Group-specific Daily Dietary Iron Intake (mg).

	Boys				Girls
	Elementary school (n = 61)		Junior high school (n = 74)		Elementary school (n = 53)		Junior high school (n = 70)
	Median	IQR	Median	IQR	Median	IQR	Median	IQR
Total daily iron intake	5.5	(4.5-6.5)	6.3	(4.7-8.0)	5.8	(4.8-6.8)	6.0	(5.0-7.5)
Daily iron intake by food group:
1. Staple foods (such as white rice, bread, or noodles)	2.0	(2.0-2.0)	2.0	(2.0-2.0)	2.0	(2.0-2.0)	2.0	(2.0-2.0)
2. Brown rice, buckwheat, or pasta	0.3	(0-0.25)	0.3	(0-0.3)	0.3	(0.3-0.3)	0.3	(0-0.3)
3. Dark green vegetables	0.3	(0.3-0.5)	0.5	(0.3-1.0)	0.3	(0.3-0.5)	0.3	(0.3-0.5)
4. Raw vegetables and salad	0.3	(0.3-0.5)	0.5	(0.3-1.0)	0.3	(0.3-0.5)	0.5	(0.3-0.5)
5. Cooked vegetables	0.3	(0.3-0.3)	0.3	(0-0.5)	0.3	(0-0.5)	0.3	(0.3-0.5)
6. Dried foods (such as dried daikon or dried tofu)	0.0	(0-0.3)	0.3	(0-0.25)	0.3	(0-0.3)	0.0	(0-0.25)
7. Shellfish or oily fish (such as mackerel or sardines)	0.5	(0.3-0.5)	0.5	(0.3-0.5)	0.3	(0.3-0.5)	0.5	(0.3-0.5)
8. Red meat (such as pork, beef, or chicken thighs)	1.0	(0.5-1.0)	1.0	(0.5-1.0)	1.0	(0.5-1.0)	1.0	(0.5-1.0)
9. Liver	0.0	(0-0)	0.0	(0-0)	0.0	(0-0)	0.0	(0-0)
10. Eggs, tofu, or other bean products	0.5	(0.5-1.0)	0.5	(0.4-1.0)	0.5	(0.5-1.0)	1.0	(0.5-1.0)
11. Red bean paste, sesame seeds, cocoa, or chocolate	0.3	(0.3-0.5)	0.3	(0.3-0.5)	0.3	(0.3-0.5)	0.3	(0-0.5)

Abbreviations: CIIS, Child and Adolescent Version of the Iron Intake Scale; IQR, interquartile range.

To examine the criterion-related validity of the CIIS, the association between the iron intake calculated by the CIIS and that calculated by the BDHQ-15y was examined using Spearman’s rank correlation coefficient. The correlation coefficient was .52 (n = 258, P < .001), indicating a moderate positive correlation. The median (25th-75th percentile range) values were 5.8 mg (4.8-7.3 mg) and 7.1 mg (5.5-9.1 mg) for the CIIS and BDHQ-15y, respectively (Table 2). To test reliability, we measured internal consistency, based on the same survey subjects and responses as above; Cronbach’s alpha coefficient was .718.

Reproducibility of the CIIS

For the reproducibility test, participants were excluded if they left any item of the CIIS incomplete in either round of the survey. In the first round, responses were obtained from 24 fifth-graders (92%) and 23 sixth-graders (85.2%), with a 100% valid response rate. The second round, conducted 1 month later, mirrored these results, maintaining a 100% valid response rate with the same number of participants from both grades. The median (and 25th-75th percentile range) values were 9.3 mg (7.0-13.0 mg) and 9.0 mg (6.8-11.5 mg) for the first- and second-round surveys, respectively, with a correlation coefficient of .67 (n = 47, P < .001) for reproducibility (Tables 3 and Table 4).

Table 3.

Correlation Between Daily Dietary Iron Intake Calculated by CIIS and That of BDHQ-15y.

Iron intake	n	Median (mg)	IQR (mg)	Correlation coefficient^a	P-value
CIIS	258	5.8	(4.8-7.3)	.52	<.01
BDHQ-15y	258	7.1	(5.5-9.1)	.52	<.01

Abbreviations: BDHQ-15y, Brief-type Diet History Questionnaire 15 Years; CIIS, Child and Adolescent Version of the Iron Intake Scale; IQR, interquartile range.

Spearman’s rank correlation coefficient.

Table 4.

Reproducibility of CIIS.

Iron intake	N	Median (mg)	IQR (mg)	Correlation coefficient^a	P-value
First CIIS survey	47	9.3	(7.0-13.0)	.67	<.001
Second CIIS survey^b	47	9.0	(6.8-11.5)	.67	<.001

Abbreviations: CIIS, Child and Adolescent Version of the Iron Intake Scale; IQR, interquartile range.

Spearman’s rank correlation coefficient.

Conducted 1 month later.

Discussion

In this study, we used the RIIS as a basis from which to develop the CIIS, adding illustrations of food items and revising expressions to make them easier for children to understand, particularly those relating to numerical information. A previous commentary on strategies to communicate health information to the public recommends using plain language to explain complex concepts, being attentive to numerical complexity, and collaborating with the intended audience.¹⁷ Instead of focusing only on plain language, we used illustrations to facilitate children’s understanding of food items in this case.¹⁸ For numerical information, we added boxes to the questionnaire to enable children to follow the step-by-step calculation of iron intake more easily. We also sought opinions from schoolchildren on the draft CIIS and made improvements accordingly. In Japan, school lunches are provided from the first grade of elementary school through to the third grade of junior high school, and these school lunches play a role in educating students about nutrition. In addition, the Home Economics curriculum for elementary school students requires fifth-graders to learn about the nutritional requirements of the body, and education on the nutritional characteristics and combinations of everyday foods is conducted throughout the school system.¹⁹ It can therefore be concluded that the food items listed and illustrated in the CIIS can be easily understood by students.

To confirm the validity of the CIIS, we tested the correlation between iron intake calculated by the CIIS and that calculated by the BDHQ-15y. According to a systematic review of food intake frequency surveys developed in Japan, a correlation coefficient of .5 or higher is considered to show validity, and 6 out of 25 articles examining iron levels were considered valid.²⁰ In the present study, the correlation coefficient was .52, confirming the validity of the CIIS. In terms of reliability, Cronbach’s alpha coefficient for the CIIS was .718, which is acceptable, and the correlation coefficient for rest-retest reliability was .67 when the CIIS was repeated after 1 month, which indicates reproducibility. Although the alpha coefficient was acceptable, the value of less than .8 (interpreted as “good”) might have resulted from including a questionnaire item about liver (organ meats), which is consumed infrequently, but has a high iron content and high absorption rate.

This survey revealed a trend of increasing nonspecific complaints similar to symptoms of anemia among both male and female junior high school students. Furthermore, instances of skipped meals and a history of anemia were found to be more common among junior high school students than among their younger elementary school counterparts. As adolescents enter junior high school, they commonly experience a life stage marked by rapid growth and increased engagement in sports, often coinciding with the onset of menstruation among girls. The body’s requirement for iron intake increases accordingly. Therefore, it is crucial to educate students about appropriate dietary choices for anemia prevention during, and ideally before, this period of their lives.

Food frequency questionnaires (FFQs), of which the BDHQ-15y is an example, are an effective method of assessing dietary intake and are widely used in research because they provide data for all the major nutrient groups. As seen in international contexts, FFQs are frequently employed for assessing iron intake. However, FFQs such as the BDHQ-15y are not commonly used in elementary and junior high schools because of the inconvenience of the computer processing of the responses, the time required for return, and the expense involved. The CIIS developed in the present study allows students to calculate their own iron intake by answering the questions and adding up the total, and to determine whether they are meeting the target intake by referring to the guidance at the bottom of the questionnaire (Figure 1). The average iron intake of elementary and junior high school students in the 7 to 14 years age group of the 2019 National Health and Nutrition Survey was 6.5 mg,⁸ which is almost the same as the average intake found in this study among junior high school students. By food item, staple foods provided the highest iron intake, followed by meat, and then eggs and bean products. Among the respondents to our survey, the consumption of liver, which is particularly rich in iron, was negligible.

There are several major methodological limitations to this study. Firstly, we have investigated correlation with iron intake as calculated by the BDHQ-15y. Due to the inability to compare with physiological indicators obtained through blood tests or similar means, there is a reliance on subjective memory, which may introduce potential errors. Secondly, the survey was self-administered, and the presence of anemia symptoms was based on the respondents’ subjective assessments. Consequently, this may limit our ability to evaluate the association between iron intake and anemia, especially in cases where individuals are asymptomatic. Validation of the prevalence of iron deficiency anemia and assessment of risk factors should be considered when applying the study to a larger population or universalizing the study.

Conclusion

We developed an iron intake scale for children and adolescents, called the CIIS, that enables them to determine their own dietary iron intake, and whether it is excessive or deficient, simply by answering a set of diet-related questions. Assessment of iron intake via the new scale showed a significant correlation with that calculated via the BDHQ-15y, an existing but more complex and computationally demanding FFQ. Analysis showed the CIIS to be reliable and reproducible. We hope that the CIIS will be used as an educational tool to empower children to understand and manage their own iron intake, fostering their ability to make healthier food choices, ultimately contributing to their long-term health and well-being.

Supplemental Material

sj-xlsx-1-jpc-10.1177_21501319241259410 – Supplemental material for Validity and Reliability of the Child and Adolescent Version of the Iron Intake Scale (CIIS) as an Educational Tool

Supplemental material, sj-xlsx-1-jpc-10.1177_21501319241259410 for Validity and Reliability of the Child and Adolescent Version of the Iron Intake Scale (CIIS) as an Educational Tool by Satoko Okabe, Shinya Ito, Akemi Kameta and Aya Goto in Journal of Primary Care & Community Health

Footnotes

Acknowledgements

We would like to express our sincere gratitude to the Board of Education of Town A, Fukushima Prefecture, the homeroom teachers of the elementary and junior high schools involved, and the children and their parents for their generous cooperation in this research. We also thank Oliver Stanyon for editing this manuscript and for translating the Japanese CIIS questionnaire into English.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was funded by a grant from the Cooperative Research Program of the Department of Radiation Medicine and a grant from the Kitasato University Research Grant for Young Researchers, Kagamiishi “Food and Health” Nutrition Education Project, JSPS Grants-in-Aid for Scientific Research (KAKENHI) Grant Numbers JP 19KK0060 and 23KK0045.

ORCID iDs

Satoko Okabe

Shinya Ito

Akemi Kameta

Aya Goto

Supplemental Material

Supplemental material for this article is available online.

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Supplementary Material

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