Constipation is one of the most common health problems in children and adults. Variation in the normal bowel habit and symptoms recognized as constipation has made it difficult to accurately diagnose the condition in children. In addition, overflow incontinence and encopresis, both symptoms of functional constipation (FC), are often considered simply as problematic bowel habits and not as symptoms of FC. Therefore, it is difficult to clarify the current state of FC in childhood. The Rome III criteria [
It is well known that dietary habit can affect defecation, and as such, regional disparity should be considered when determining the prevalence of constipation. Although increasing the intake of dietary fibre and water is often recommended as a dietary therapy for patients with constipation, the influence of total calories and individual nutrients on FC in childhood have not been clarified. A brief-type, self-administered, diet-history questionnaire (BDHQ) developed by Kobayashi et al. has been validated for dietary intake assessment in adults [
Study setting and participants.
Two types of questionnaire were distributed to the guardians of 2052 children attending 28 public or private nursery schools and 4451 children attending 1st or 2nd grade at 22 public elementary schools (6503 people in all) in Tsurumi Ward, Yokohama City, Kanagawa Prefecture, Japan, in September 2013. The questionnaires were collected between October and November 2013. One questionnaire assessed defecation and physical status, and the other was the BDHQ3y, which assessed total calories consumed and the intake of individual nutrients. The questionnaires were enclosed and concealed in envelopes by each guardian. The envelopes were collected at each school and sent back to the authors by a representative at each school.
This survey included questions on sex, age, height, weight, defecation frequency, fecal incontinence, withholding behaviour, painful defecation, stool consistency, and the presence of large-diameter stools. Guardians were required to answer questions regarding defecation frequency, stool consistency using the Bristol Stool Scale type, and frequency at 4 grades (always, sometimes, never, and hard to say) for other details related to defecation. Guardians had to choose the Bristol Stool Scale type that best represented their children’s stools using a picture chart. The picture chart was accompanied by descriptors that had been translated into Japanese.
The BDHQ3y is a four-page structured questionnaire that asks about the consumption frequency of selected foods commonly eaten in Japan, general dietary behaviour, and usual cooking methods. Estimates of the daily intake of different foods (66 items in total), total calories, and selected nutrients were calculated using an ad hoc computer algorithm for the BDHQ3y based on the Standard Tables of Food Composition in Japan [
The defecation status of each subject was classified according to the Rome III criteria (Table
Rome III criteria for functional constipation.
<4 years | ≥4 years |
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Must include at least 2 items for 1 month | Must include 2 or more items for at least 2 months before diagnosis |
(1) Two or fewer defecations per week | (1) Two or fewer defecations in the toilet per week |
(2) At least 1 episode per week of incontinence after the acquisition of toileting skills | (2) At least 1 episode of fecal incontinence per week |
(3) History of excessive stool retention | (3) History of retentive posturing or excessive volitional stool retention |
(4) History of painful or hard bowel movements | (4) History of painful or hard bowel movements |
(5) Presence of a large fecal mass in the rectum | (5) Presence of a large fecal mass in the rectum |
(6) History of large-diameter stools that may obstruct the toilet | (6) History of large-diameter stools that may obstruct the toilet |
Height, body weight, and body mass index (BMI) were evaluated based on the report of a national growth survey in preschool children [
The BDHQ3y calculates the intake amounts of 99 different types of food nutrients, including total calories, meal weight, water, protein, fat, carbohydrates, 15 food groups, and 78 ingredients based on an assessment of food-intake frequency per month. Inputting questionnaire data and conversion of the quantities of calories, nutrients, and food groups consumed were performed by the developer’s company (EBNJAPAN, Tokyo), and we then used the converted data for analysis. We analysed 15 items, including total amount per day of meal weight, total calories, water content in foods, protein, fat, carbohydrates, calcium, magnesium, phosphorus, soluble dietary fibre, insoluble dietary fibre, total dietary fibre, sodium chloride, juice, and water including tea. Twelve items, excluding juice and water, were analysed as the nutritional equivalent per 100 kcal.
This survey was approved by the Ethics Committee of Saiseikai Yokohama City Tobu Hospital (protocol number 201230). Response to the questionnaire was regarded as an agreement to participate, in accordance with Ethical Guidelines for Epidemiological Research published by the Ministry of Health, Labor and Welfare.
The prevalence of FC and the symptoms detailed in the Rome III criteria were examined using Pearson’s
A total of 3932 guardians returned the questionnaires which gave a collection rate of 58.7%. Overall, 3643 subjects answered both questionnaires. Of these, 14 subjects aged 9 years, 3 subjects who did not give their age, and 31 subjects who gave incomplete descriptions were excluded from further analysis. Thus, in total, 3595 subjects were analysed in this study. The characteristics of the analysed children (
Characteristics of the subjects.
FC | Non-FC |
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ANCOVA | ||
Boys : girls | 367 : 351 | 1439 : 1438 | 0.617 | ||
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Mean age (years) | All | 6.5 ± 1.3 | 6.4 ± 1.3 | 0.112 | |
Boys | 6.4 ± 1.4 | 6.4 ± 1.3 | 0.912 | ||
Girls | 6.6 ± 1.3 | 6.5 ± 1.3 | 0.015 | ||
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Mean height (cm) | All | 118.6 ± 10.0 | 118.5 ± 9.3 | 0.387 | 0.479 |
Boys | 118.6 ± 10.0 | 118.5 ± 9.3 | 0.863 | 0.362 | |
Girls | 118.3 ± 8.8 | 117.7 ± 8.8 | 0.287 | 0.315 | |
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Mean weight (kg) | All | 22.2 ± 4.9 | 21.8 ± 4.5 | 0.047 | 0.218 |
Boys | 22.5 ± 5.4 | 22.2 ± 4.6 | 0.149 | 0.133 | |
Girls | 21.9 ± 4.3 | 21.6 ± 4.4 | 0.238 | 0.467 | |
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Mean BMI (kg/m2) | All | 15.7 ± 1.9 | 15.5 ± 1.9 | 0.049 | 0.067 |
Boys | 15.8 ± 2.1 | 15.6 ± 1.9 | 0.033 | 0.193 | |
Girls | 15.5 ± 1.8 | 15.5 ± 1.9 | 0.554 | 0.588 | |
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Mean height |
All | −0.15 ± 1.14 | −0.08 ± 1.06 | 0.148 | 0.171 |
Boys | −0.07 ± 1.16 | −0.04 ± 1.09 | 0.722 | 0.296 | |
Girls | −0.22 ± 1.12 | −0.11 ± 1.02 | 0.078 | 0.454 | |
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Mean weight |
All | −0.22 ± 1.03 | −0.22 ± 0.99 | 0.911 | 0.806 |
Boys | −0.15 ± 1.16 | −0.26 ± 1.22 | 0.122 | 0.384 | |
Girls | −0.29 ± 1.01 | −0.25 ± 0.96 | 0.592 | 0.544 | |
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Mean BMI percentile | All | 45.47 ± 28.67 | 43.23 ± 28.11 | 0.057 | 0.042 |
Boys | 46.81 ± 29.42 | 43.91 ± 28.67 | 0.085 | 0.338 | |
Girls | 44.06 ± 27.84 | 42.54 ± 27.53 | 0.355 | 0.290 |
Data are shown as the mean ± standard deviation. ANCOVA: analysis with age as a covariate (Bonferroni).
Frequency of constipation symptoms including Rome III criteria.
All |
FC |
Non-FC |
|
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| |
≤2 defecations per week | 162 (4.6) | 111 (15.9) | 51 (1.8) |
Fecal incontinence | 488 (13.7) | 330 (46.3) | 158 (5.5) |
History of excessive stool retention | 785 (23.5) | 495 (73.6) | 290 (10.9) |
History of painful bowel movements | 774 (22.7) | 424 (61.5) | 350 (12.8) |
History of hard bowel movements | 675 (19.0) | 310 (43.6) | 365 (12.7) |
History of large-diameter stools that obstruct the toilet | 206 (5.8) | 149 (21.0) | 57 (2.0) |
Among the six items included in the Rome III criteria, “history of excessive stool retention” and “history of painful bowel movements” were frequently observed in the FC group (73.6% and 61.5%, resp.), with odds ratios as high as 24.5 and 11.0, respectively, and high sensitivity and specificity. The incidences of the items “≤2 defecations per week” and “history of large-diameter stools that obstruct the toilet” in the FC group were low (15.9% and 21.0%, resp.), although the specificity for both was 0.98.
The FC group had significantly greater fat intake than the non-FC group (45.9 ± 13.6 g and 44.4 ± 12.9 g, resp.,
Relationship between functional constipation and consumption of energy and nutrients.
Mean amount of intake per day | Unit | FC |
Non-FC |
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ANCOVA | ||||
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Total meal weight | g | 1606.3 ± 466.9 | 1616.2 ± 457.9 | 0.606 | |
Total calories | kcal | 1421.8 ± 417.0 | 1395.2 ± 385.6 | 0.122 | 0.128 |
Water content per meal | g | 1298.2 ± 393.7 | 1312.5 ± 390.8 | 0.380 | 0.378 |
Protein | g | 48.4 ± 14.0 | 48.1 ± 13.5 | 0.631 | 0.666 |
Fat | g | 45.9 ± 13.6 | 44.4 ± 12.9 | 0.005 | 0.007 |
Carbohydrates | g | 198.9 ± 70.2 | 196.2 ± 65.0 | 0.346 | 0.376 |
Calcium | mg | 529.6 ± 204.4 | 519.5 ± 198.1 | 0.272 | 0.269 |
Magnesium | mg | 176.6 ± 54.3 | 177.3 ± 52.6 | 0.779 | 0.736 |
Phosphorous | mg | 808.9 ± 257.2 | 801.7 ± 248.5 | 0.490 | 0.513 |
Soluble dietary fibre | g | 1.88 ± 0.7 | 1.92 ± 0.7 | 0.170 | 0.164 |
Insoluble dietary fibre | g | 5.97 ± 2.0 | 6.13 ± 2.0 | 0.062 | 0.057 |
Total dietary fibre | g | 8.02 ± 2.8 | 8.22 ± 2.8 | 0.074 | 0.069 |
NaCl | g | 9.22 ± 2.4 | 9.27 ± 2.4 | 0.614 | 0.605 |
Juice | g | 94.2 ± 127.5 | 80.9 ± 98.8 | 0.009 | 0.002 |
Water including tea | g | 301.6 ± 168.0 | 318.2 ± 168.4 | 0.018 | 0.015 |
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Total meal weight | g/100 kcal | 114.7 ± 20.6 | 117.3 ± 21.0 | 0.003 | 0.004 |
Water content per meal | g/100 kcal | 93.0 ± 20.4 | 95.5 ± 20.9 | 0.004 | 0.006 |
Protein | g/100 kcal | 3.4 ± 0.5 | 3.5 ± 0.5 | 0.090 | 0.111 |
Fat | g/100 kcal | 3.3 ± 0.6 | 3.2 ± 0.6 | 0.019 | 0.019 |
Carbohydrate | g/100 kcal | 13.9 ± 1.6 | 14.0 ± 1.5 | 0.127 | 0.123 |
Calcium | mg/100 kcal | 37.5 ± 10.9 | 37.3 ± 10.3 | 0.793 | 0.720 |
Magnesium | mg/100 kcal | 12.5 ± 2.0 | 12.8 ± 2.0 | 0.002 | 0.003 |
Phosphorous | mg/100 kcal | 57.3 ± 10.6 | 57.7 ± 9.9 | 0.346 | 0.395 |
Soluble dietary fibre | mg/100 kcal | 134.0 ± 3.6 | 138.7 ± 3.7 | 0.003 | 0.003 |
Insoluble dietary fibre | mg/100 kcal | 424.5 ± 9.1 | 442.3 ± 9.9 | 0.000 | 0.000 |
Total dietary fibre/day | mg/100 kcal | 570.3 ± 128.8 | 593.5 ± 138.4 | 0.000 | 0.000 |
NaCl | mg/100 kcal | 667.00 ± 137.9 | 680.7 ± 136.2 | 0.016 | 0.023 |
ANCOVA: analysis with age as a covariate (Bonferroni). Data are shown as the mean ± standard deviation.
Binomial logistic regression analysis of functional constipation.
Factor | Logistic regression coefficient | Standard error |
|
Odd ratio (95% confidence interval) |
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Age | 0.055 | 0.032 | 0.089 | 10.057 (0.992–1.126) |
BMI percentile | 0.003 | 0.001 | 0.063 | 1.003 (1.000–1.006) |
Juice | 0.001 | 0.000 | 0.008 | 1.001 (1.000–1.002) |
Fat/100 kcal | 0.196 | 0.076 | 0.010 | 1.216 (1.0476–1.412) |
Total dietary fibre/day/100 kcal | 0.001 | 0 | 0.001 | 0.999 (0.998–1.000) |
We could analyse 25.4% of the population of children aged 3 to 8 years in the survey area. Hence, our results reflect the prevalence of FC among children aged 3 to 8 years living in urban areas in Japan, which is approximately 20% regardless of age or sex. It should be noted that because the item in the Rome III criteria that asks about the presence of a large fecal mass in the rectum was not included in the questionnaires in this survey, the prevalence of childhood FC may be higher.
Asakura et al. conducted a school-based survey to examine the relationship between constipation and lifestyle factors, including dietary intake, among preschool-aged children in Japan [
In this study, a history of excessive stool retention and painful bowel movements were observed in 73.6% and 61.5% of the children in the FC group. In contrast, only 15.9% of the children in the FC group experienced 2 or less defecations per week. In previous studies, such differences between items in the Rome III criteria were not observed [
In this study, univariate analysis revealed that water intake, meal weight/100 kcal, water content per meal/100 kcal, magnesium intake/100 kcal, dietary fibre intake/100 kcal, and sodium chloride intake/100 kcal were all significantly lower in the FC group compared to the non-FC group, whereas the intake of juice was significantly higher. However, binomial logistic regression analysis showed that only fat per 100 kcal positively correlated with FC [odds ratio = 1.216, 95% confidence interval: 1.0476–1.412]. In mouse experiments, feeding of a high-fat diet resulted in intestinal dysbiosis and delayed colonic motility [
The main limitations of this study were that the Japanese questionnaire on defecation was not validated before its use and the question about the presence of large fecal mass in the rectum was omitted in the questionnaire. These factors could have influenced the prevalence of FC obtained in this study.
The current findings suggest that FC is common among children in preschool and early elementary school in urban areas in Japan. Decreased frequency of bowel movements is not a common symptom of FC in this population, and guardians should pay attention to other symptoms, including withholding defecation and painful defecation. Consumption of a high-fat diet should be avoided to prevent FC. A longitudinal study and an expanded study of additional age groups are also needed to determine whether FC in children aged 3 to 8 years persists into late childhood, adolescence, and adulthood.
The authors declare that they have no conflicts of interest.
The authors acknowledge Professor Satoshi Sasaki, Department of Social and Preventive Epidemiology, School of Public Health, the University of Tokyo, for giving them advice on the BHDQ3y. This study was supported by the grant of research for the area of nutritional education from The Japan Dietetic Association.