Vol.3, No.3, 135-140 (2011) Health
doi:10.4236/health.2011.33025
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
Prevalence and characterization of supplement use
among healthy children and adolescents in an urban
Japanese city
Nagisa Mori, Masaru Kubota*, Shoko Hamada, Ayako Nagai
Department of Human Life and Environment, Nara Women’s University, Nara, Japan;
*Corresponding Author: masaru_kubota@chime.ocn.ne.jp
Received 2 January 2011; revised 20 February 2011, accepted 28 February 2011.
ABSTRACT
Although there a re numerous studies on the use
of supplements in children and adolescents
from western countries, only a small number of
studies have been conducted in Asian countrie s.
This study was planned to determine the use of
supplements and their association with life-
styles in healthy Japanese children and ado-
lescents. This is a community-based cross-sec-
tional study conducted i n a Jap anes e urban city,
Nara, in 2008. A total of 681 children and ado-
lescents aged between 3 and 17 years were en-
rolled. The parents were asked to complete a
questionnaire on the use of supplement s among
their children. Demographic information, health
and nutrition status of children as perceived by
parents, sleep duration, and a family history of
supplement use were also collected. A total of
20.4% of children and adolescents are presently
using (in the past one month) or have used (in
the p as t one y ear excluding the past one month)
supplements. The types of supplements most
commonly used were minerals, followed by vi-
tamins and blueberry extracts. Univariate analy-
sis indicated that supplement use was associ-
ated with older age, poor perception of health
status, shorter sleep duration, and a positive
family history of supplement use. Multiple lo-
gistic regression analysis showed that age and
a positive family history affected supplement
use. Given the approximately 20% of prevalence
of supplement use in Japanese children and
adolescents, there is a need for further research
to examine the supplements’ effectiveness and
safety.
Keywords: Supplement; Child; Adolescence;
Japan; Lifestyle
1. INTRODUCTION
The use of supplements is expanding rapidly because
of a growing worldwide awareness of health promotion
[1]. The actual prevalence of supplement use differs
greatly from country to country, presumably due to the
diversity of cultural, nutritional, and economic condi-
tions. A series of nationwide surveys in the United States
indicated that the rates of supplement use in adults aged
18 years or older ranged from 32 to 52% [2-5]. In Euro-
pean [6,7] and Asian [8,9] countries, the reported rates
were lower, i.e. approximately between 15 and 30%.
These reports have also identified the characteristics of
supplement users from cultural, economic, and nutri-
tional points of view. In contrast, little is known about
the prevalence of supplement use in children and ado-
lescents except in the United States, where as high as
approximately 30-50% of children and adolescents have
been reported to use supplements [10-13]. Small cohort
studies from Europe showed that the frequencies of sup-
plement use were 25.8% for German children and ado-
lescents [14], and 37-50% for Finnish children aged 2
and 3 years [15]. The only comprehensive report on sup-
plement use in children in Asian countries, as far as we
know, was the investigation carried out by the National
Institute of Health and Nutrition in Japan, which found
that 15% of preschool children used supplements [16].
However, this survey only targeted preschool children.
Therefore, the purpose of the present study is to deter-
mine the prevalence of supplement use in healthy Japa-
nese children and adolescents, and to consider the rela-
tionships between supplement use and demographic and
lifestyle factors.
2. MATERIALS AND METHODS
2.1. Study Design and Subjects
This study was done in Nara city from April to May in
2008. Nara is an urban city in Japan with a population of
N. Mori et al. / Health 3 (2011) 135-140
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
136
approximately 370,000. Among them, the approximate
population of children and adolescents aged between 3
and 17 years was 45,000. The request for participation in
the present study was first sent to several kindergartens
or schools nearby. After obtaining consent by the princi-
pal, enrolled kindergartens or schools were decided by
random selection. The questionnaire that we devised for
the present study was distributed to the parents of the
participants through their kindergartens or schools. The
parents were then asked to complete the questionnaire at
home. A “supplement” was defined as a preparation that
provides various kinds of food substances in the form of
either tablet, capsule, powder, liquid or jelly [17]. 975
questionnaires were distributed, and responses were ob-
tained from 736 parents (recovery rate: 75.5%). After
responses with incomplete answers or those involving
reported supplements that did not meet the definition
given above, such as the over-the-counter medicines,
were excluded, a total of 681 children and adolescents
aged between 3 and 17 years were available for analysis.
These included 142 preschool children (3-6 years), 125
students in the 4th grade (9-10 years) and 109 students in
the 6th grade of elementary school (11-12 years), and 180
students in the 3rd grade (14-15 years), and 125 in the 2nd
grade of senior high school (16-17 years). There were
326 males and 355 females. We obtained consent from
all parents beforehand to use their children’s data in our
study. This project was approved by the ethical and epi-
demiological committee at Nara Women’s University.
2.2. Questionnaire
First, it was asked whether the child was given any
type of supplement in the past one month (present use)
or the past one year excluding the past one month (past
use). Also, data on types of used supplements, and the
family history of supplement use were collected. Demo-
graphic features, parents’ perceptions of children’s health
status and balance of diet, and average sleep hours per
day in the past one month were requested.
2.3. Statistics
Difference in supplement use according to age was
examined by one-way analysis of variance (ANOVA).
After the present and past users were combined into total
users, the association of supplement use with demo-
graphic features and various lifestyle elements was
evaluated; the chi-square test was used to determine as-
sociations with sex and family history, and the Kruskal-
Wallis test was used for age, health status, balance of
diet, and sleep hours. Multiple logistic regression analy-
sis for prediction of children’s supplement use was per-
formed by including variables of age, gender, health
status, food status, sleep hours, and family history of
supplement use. In the analysis, age and sleep hours
were categorized as indicated in Table 2. A statistical
analysis was made using “StatMate III” (ATMS, Tokyo,
Japan). P values less than 0.05 were considered signifi-
cant.
3. RESULTS
3.1. Supplement Use
Table 1 indicates the numbers of samples and sup-
plement users in relation to the age of the participants. A
total of 139 children (20.4 %) had experience using sup-
plements, including 72 (10.6%) present users, and 67
(9.8%) past users. In addition, the prevalence of total
users tended to increase with an increase of age (p <
0.001). There was no gender difference between sup-
plement users and non-users.
3.2. Association of Supplement Use with
Demographic Features and Lifestyles
Univariate analysis indicated that supplement use was
associated with age, health status, sleep duration, and
family history. However, multiple logistic regression
analysis revealed that only age and family history of
supplement use were associated with supplement use
(Table 2).
3.3. Types of Used Supplements
The types of supplement most frequently used were
minerals including iron, calcium, and zinc 54 (37%),
followed by vitamins including multi-vitamins, vitamin
B and vitamin C 42 (29%), and blueberry extracts 23
(16%) (Figure 1). As far as side effects were concerned,
only one case with a rash after receiving blueberry ex-
tracts was reported.
Table 1. Numbers of subjects and supplement users.
Total
number Supplement
user
Age Present Past Total
4-6 yr 142 4 (2.8%) 7 (4.9%) 11 (7.7%)
9-10 yr 125 7 (5.6%) 10 (8.0%) 17 (13.6 %)
11-12 yr109 16 (14.7%) 4 (3.7%) 20 (18.3%)
14-15 yr180 27 (15.0%) 32 (17.8%) 59 (32.8%)
16-17 yr125 18 (14.4%) 14 (11.2%) 32 (25.6%)
Total 681 72 (10.6%) 67 (9.8%) 139 (20.4%)
N. Mori et al. / Health 3 (2011) 135-140
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137
Table 2. Association between supplement use and demographic or lifestyle factors.
Supplement use
Number (-) (+) p value β coeffieint [95%CI]# p value
Total number (%) 681 542 (79.6) 139 (20.4)
Gender 0.78 0.29 [–0.12~0.72] 0.17
Male 326 (47.9)§ 258 (47.6) 68 (48.9)
Female 355 (52.1) 284 (52.4) 71 (51.1)
Age <0.001* 0.11 [0.03~0.19] <0.01
3-6 yr 141 (20.7) 133 (24.5) 8 (5.8)
9-10 yr 125 (18.4) 108 (19.9) 17 (12.2)
11-12 yr 109 (16.0) 88 (16.2) 21 (15.1)
14-15 yr 180 (26.4) 121 (22.3) 59 (42.4)
16-17 yr 126 (18.5) 92 (17.1) 34 (24.5)
Health status <0.01** 0.15 [–0.21~0.52] 0.41
Good 485 (71.2) 401 (74.0) 84 (60.4)
Moderate 169 (24.8) 119 (21.9) 50 (36.0)
Poor 27 (4.0) 22 (4.1) 5 (3.6)
Sleep duration <0.001** 0.28 [–0.61~0.04] 0.08
< 6 hrs/day 46 (6.8) 29 (5.4) 17 (12.2)
6 to < 7 hrs/day 216 (31.7) 154 (28.4) 62 (44.6)
7 to < 8 hrs/day 185 (27.2) 148 (27.3) 37 (26.6)
8 hrs/day 234 (34.3) 211 (38.9) 23 (16.6)
Balance of diet 0.11 0.35 [–0.03~0.72] 0.07
Good 334 (49.0) 275 (50.7) 59 (42.4)
Moderate 325 (47.7) 249 (45.9) 76 (54.7)
Poor 22 (3.3) 18 (3.4) 4 (2.9)
Family history of supplement use <0.001** 1.94 [1.46~2.42] <0.001
Negative 351 (51.5) 326 (60.1) 25 (18.0)
Positive 330 (48.5) 216 (39.9) 114 (82.0)
§ Numbers in parentheses indicate percentages. *Chi-square test. **Kruskal-Wallis test. # Logistic analysis.
4. DISCUSSION
Complementary and alternative medicine has become
popular throughout developed countries as the public’s
health awareness has increased [18]. Supplements be-
longing to the category of functional foods play a central
role in alternative and complementary medicine [18,19].
Although functional foods or supplements have not been
fully defined, these compounds are thought to benefi-
cially affect various functions in the body and to bring
about an improvement of health or well-being [19].
Therefore, the purposes of their use are twofold: 1) the
promotion or maintenance of health status, and 2) the
treatment of certain disorders related to shortages of
specific nutrients, especially in developing countries.
There have been numerous studies on the prevalence
of supplement use in healthy adult populations. The re-
sults of surveys differ depending upon the definition of
supplements, time of studies, and methods of surveys. In
addition, the regulation of health claims by official
N. Mori et al. / Health 3 (2011) 135-140
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138
Figure 1. Types of supplements used in the present study. Mul-
tiple answers were allowed. Bars indicate the total number of
each supplement users. Minerals included multi-minerals, cal-
cium, iron and zinc. Vitamins included multi-vitamins, vitamin
A, vitamin D, and ascorbic acid.
organization should be taken into consideration. In Japan,
for example, supplement-type foods are not allowed to
present health claims except “food with nutrient function
claims”. In the United States, however, health claims are
well regulated by the Food and Drug Administration
through provisions of the Food, Drug, and Cosmetic Act.
Such difference may have an effect on the attitude of
supplement consumers [20]. In the United States, a se-
ries of National Health and Nutrition Examination Sur-
vey (NHANES) demonstrated that the prevalence of
supplement use in adults in the past two decades has
ranged from 32.4 to 52% [2,4,5]. There is a slight in-
creasing trend with time. In these reports, supplement
use was mainly investigated in adults aged 18 years and
over during the past one month. Surveys from other
countries have reported lower prevalence: 22% for men
and 33% for women in Sweden [7], 11% for men and
16.4% for women in Japan [8], and 21.8% for men and
32% for women in Korea [9]. Notably, these reports in-
volved older populations or different observation periods.
In spite of the difference in prevalence found among the
surveys, these surveys have postulated that similar
demographic or lifestyle factors can be used for predict-
ing supplement use. Female gender, older age, higher
education, higher income, and good self-reported health
were found to be associated with higher use of supple-
ments [2-9]. Association of positive lifestyle factors with
supplement use is regarded to reflect the characteristics
of supplement users [21].
An earlier study by Kovar in 1981 demonstrated that
36% of children aged less than 18 years used vitamin or
mineral supplements within the past two weeks [22].
Subsequent studies in the United States involving sub-
jects of almost the same age group have shown similar
prevalence rates of 31.8-34% [12,13]. These values were
not very different from those of European reports
[14,15]. In a recent Japanese study targeting preschool
children, the rate of supplement use was 15% [16].
Demographic or lifestyle factors associated with sup-
plement use in children were consistent with those in
adults. However, no gender difference was found in most
studies [12, 14-16]. In addition, a positive family history
of supplement use, especially supplement use by the
mother, had an influence on children’s use [10,16,23].
Our study is, as far as we know, the first cross- sec-
tional study involving children aged 3-17 years in an
Asian country. The overall prevalence of supplement use
was 20.4% which was slightly higher than that found in
the report by Sato et al. [16]. The difference is presuma-
bly due to the age of the subjects. Older age and a posi-
tive family history were associated with higher supple-
ment use. Notably, a good lifestyle and a balanced diet,
even if these were determined only according to the
parent’s perception, were found to be not associated with
supplement use. Types of supplements commonly used
in this study were minerals and vitamins. This finding is
consistent with previous studies in children and adoles-
cents [10-16]. Third-ranked supplement, blueberry ex-
tracts, is thought to be specific to Japan. The reason for
its wide use is presumably the expectation that it has an
effect on visual acuity as advertised through mass media
[24], since the percentage of myopia in students is high
in Japan [25]. Concerning adverse effects, Timbo et al
reported that 4% of supplement users experienced ad-
verse effects [26], but only one case was reported in this
study.
There are several weaknesses in the present study.
First, generalization of our results as the representative
of children and adolescents in Japan should be careful
because of the limited number of subjects. Second, the
parent’s ability to accurately differentiate various sup-
plements was quite uncertain. In order to minimize this
problem, a direct interview method should be introduced.
Finally, important information about home income and
parent’s education level was not included. We omitted
such questions because we were afraid that including
them would cause a decrease in the response rate [16]. In
spite of these weaknesses, we believe our present study
to be important for understanding the present status of
supplement use in children and adolescents, and in es-
tablishing future plans of supplement use. Majority of
supplement users expect to receive adequate information
about the supplements they are using, expect the partici-
pation of the authorities and the safety of supplement
[27]. For these purposes, the future involvement of pro-
fessionals such as doctors, dietitians, co-medical staffs,
nutrition representatives as advisers of supplement use is
necessary.
N. Mori et al. / Health 3 (2011) 135-140
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139
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