**Prevalence of Dietary Supplement Use in Healthy Pre-School Chinese Children in Australia and China**

**Shu Chen 1 , Colin W. Binns 2,\*, Bruce Maycock 3 , Yi Liu 4 and Yuexiao Zhang <sup>5</sup>**


*Received: 13 December 2013; in revised form: 10 February 2014 / Accepted: 11 February 2014 / Published: 21 February 2014* 

**Abstract:** There is a growing use of dietary supplements in many countries including China. This study aimed to document the prevalence of dietary supplements use and characteristics of Chinese pre-school children using dietary supplements in Australia and China. A survey was carried out in Perth, Western Australia of 237 mothers with children under five years old and 2079 in Chengdu and Wuhan, China. A total of 22.6% and 32.4% of the Chinese children were taking dietary supplements in Australia and China, respectively. In China, the most commonly used dietary supplements were calcium (58.5%) and zinc (40.4%), while in Australia, the most frequently used types were multi-vitamins/minerals (46.2%) and fish oil (42.3%). In Australia, "not working", "never breastfeed", "higher education level of the mother" and "older age of the child" were associated with dietary supplement use in children. In China, being unwell and "having higher household income" were significantly related to dietary supplement usage. Because of the unknown effects of many supplements on growth and development and the potential for adverse drug interactions, parents should exercise caution when giving their infants or young children dietary supplements. Wherever possible it is preferable to achieve nutrient intakes from a varied diet rather than from supplements.

**Keywords:** dietary supplements; Chinese; calcium; zinc; migrants; child; nutrition

#### **1. Introduction**

Infant nutrition is important for short term and long term health. A balanced variety of nutritious foods are emphasized in the guidelines of the Australian and Chinese governments and other professional organizations as the best source of nutrition for healthy children [1–3]. However, the Chinese diet has been reported to be low in calcium, riboflavin, Vitamin A, and zinc [4,5]. A national survey in 2004 found that the average calcium intake among the city and suburban populations was 430 mg per day, well below the recommended intake [6]. The iron intake appears to be adequate in amount, but its bioavailability is very low and consequently the prevalence of iron deficiency and iron deficiency anemia was 43.7% and 7.8%, respectively, among children aged 1–3 years in 2001 [4,7].

The consumption of fortified foods and/or supplements can help some children meet their nutritional needs [8]. Examples of recommended use of supplements include the American Academy of Pediatrics' recommendation for oral Vitamin D supplementation for exclusively breastfed infants and, under certain conditions, for specific older infants and toddlers [9]. However, other countries, such as Australia, have different climatic conditions and do not recommend universal use of Vitamin D, and the excessive intakes of single nutrients may have the potential for adverse effects [10–12].

Dietary supplements enriched with vitamins, minerals, and other substances are increasingly consumed worldwide. The North America and the Asia Pacific regions are the dominant markets for vitamins and dietary supplements [13]. The prevalence of supplement use varies in different ethnic groups for a diversity of dietary and cultural reasons and economic conditions. Most published studies on the use of supplements in children have been conducted in the US and only a small number of studies have been conducted in Asian countries. It is reported that approximately 49% of the U.S. population take dietary supplements and the prevalence of supplement use was 35% among children aged 1–13 years [14,15]. In South Korea, approximately 34% of Korean children and adolescents were taking dietary supplements in a national survey in 2007–2009 [16]. A survey of urban Japanese found that 20.4% of children and adolescents between 3 and 17 years were using supplements, or had used them in the past year [17]. A cross-sectional survey carried out in Zhejiang Province, PR China in 1999 reported a prevalence of 18% of vitamin supplements and 31% of other nutritional supplements in adolescents [18]. A recent study from Taiwan reported that 34.9% of the infants had been given a dietary supplement before six months [19].

Australians have a high prevalence of taking dietary supplements. A representative population survey conducted in 2004 in South Australia reported the use of vitamin supplements by 39.2% respondents and mineral supplements by 13.6% of the population [20]. No recent data is available on the use of supplements by infants or young children in Australia.

Until recently, there have been no reported studies of dietary supplementation among Chinese young children in mainland China or overseas. The aim of this study was to document the prevalence of use of dietary supplements in these populations. A survey was carried out of Chinese mothers living in Perth, Australia and Chengdu and Wuhan, PR China.

#### **2. Methods**

This data was collected from October 2010 to October 2011 in Perth, Western Australia and from September to December 2011 in Chengdu and Wuhan, China. Participants in Perth were mothers who have at least one pre-school child under 5 years old. They were recruited from the Perth Chinese community, including Chinese schools and community organizations. Mothers interested in taking part in this study received an information sheet containing project details and were asked to sign the consent form. A total of 248 questionnaires were distributed in Perth and 237 mothers agreed to participate (response rate of 95.6%) and 230 mothers completed the dietary supplementation section of the questionnaire. The response rate to the dietary questionnaire was 95.6%. Participants in China were recruited from four kindergartens in four districts of Wuhan and 14 kindergartens in seven districts of Chengdu. Both private and public kindergartens were included. A total of 2400 questionnaires were distributed to mothers by kindergarten teachers and 2079 were returned, a response rate of 86.6%. The dietary supplementation questionnaire was completed by 1464 mothers in China with a response rate to the dietary questionnaire of 70.4%. The study was approved by the Curtin University Human Research Ethics Committee (approval number: HR 96/2010) and the local education authorities in China.

Demographic and dietary supplement use was collected using a validated and reliable questionnaire previously used in Chinese population studies [21]. Pre-coded questions were used to classify income into three groups using categories based on local annual household income surveys [22,23]. A Dietary Supplement Questionnaire is used to collect information on the participants' use of medicine, vitamins, minerals, herbals, and other supplements during the past two weeks. Detailed information about type, consumption frequency, and amount taken was collected for each reported dietary supplement use. Child's health status was collected using a translated version of the Australian National Health Survey Questionnaire [24].

Body mass index (BMI) was defined as weight (kg)/height (m)2 . The 2012 revised international child cut-offs developed by the International Obesity Task Force (IOTF) were used to classify thinness, overweightness and obesity in children in this study [25]. They are based on BMI data from six countries, corresponding to the body mass index (BMI) cut-offs at 18 years, which are BMI 25 (overweight), 30 (obesity) and 18.5 (underweight) [25].

All statistical analyses were performed using the IBM Statistical Package for Social Sciences (SPSS) Version 20.0. Independent samples' *t*-test was used to compare means between groups. Mann-Whitney U test was applied to compare the average age of children from two countries. Chi-VTXDUHȤ<sup>2</sup> ) test was used to compare basic characteristics of mothers and children in Australia and China. A multiple binary logistic regression model was used to evaluate the association between mother and child's characteristics and the use of dietary supplements. A backward elimination procedure was applied to obtain final models. *p* values <0.05 were considered statistically significant.

#### **3. Results**

A total of 230 Chinese mothers living in Perth, Australia and 1156 mothers living in Chengdu, Sichuan Province and 308 mothers living in Wuhan, Hubei Province, PR China completed the supplements questionnaire. The distribution analysis shows there were no differences between mothers who completed the supplements questionnaire and mothers who did not in age, education attainment, marital status, working status, family income status, breastfeeding initiation and duration. There was also no difference in education attainment, marital status, family income status, breastfeeding initiation and duration, between mothers in Chengdu and Wuhan. The only statistically significant difference between mothers in Wuhan and Chengdu was the average age (31.0 years in Chengdu and 30.8 years in Wuhan, *p* < 0.001). Because the difference is so small in Wuhan and Chengdu mothers, their data were pooled for further analysis.

The average age of Chinese mothers in Australia was older than mothers in China (33.8 ± 4.9 years compared to 31.0 ± 4.1 years, *p* < 0.001). The mothers in Australia also had higher education levels. The median age of the "index child" in the China study population (median age = 3.7 years, the interquartile range = 1.1 years) was older than in Perth (median age = 1.6 years, the interquartile range = 1.9 years, *p* < 0.001). More Perth Chinese children were underweight (22.7%) and fewer overweight and obese (8.0%) than children in China (11.6% underweight and 17.0% overweight and obese, *p* = 0.003) (Table 1).


**Table 1.** Characteristics of Chinese mothers and their children completing dietary questionnaires in Australia and China.


**Table 1.** *Cont.* 

**\*** The missing values vary for each variable in both countries.

A total of 22.6% of the Chinese children living in Perth were taking dietary supplements, including multi-vitamins/minerals, fish oil, protein, probiotics, colostrum, calcium, zinc and Vitamin AD (or cod liver oil) and Chinese herbs (Table 1). In Chengdu and Wuhan, China, 32.4% of young children were having dietary supplements, including multivitamins/minerals, calcium, zinc, iron, magnesium, fish oil, probiotics, Vitamin A and/or Vitamin D, Chinese herbs or other botanicals (Table 1). Compared to Chinese Australians, Chinese parents living in China were more likely to give their children dietary VXSSOHPHQWV Ȥ<sup>2</sup> = 9.2, df = 1, *p* = 0.002). However, in children aged over 12 months, there is no statistical difference in the prevalence of dietary supplements between Australia (28.6%) and China (32.7%, *p* = 0.284). A higher percentage of children over three years old living in Australia were taking dietary supplements (40.8%) compared to children living in China (31.5%).

In China, the use of calcium supplements was very common among supplement users (58.5%). About half of the Chinese children taking calcium supplements were also taking Vitamin D (*n* = 140, including the use of multi-vitamins). In Australia, only four children were given specific calcium supplements. The most common forms of supplemental calcium used in Chinese children up to five years old are gluconate (51.8%) and carbonate (37.5%). The dosage of calcium supplements ranged from 54–725 mg/day (Table 2). The average intake for calcium carbonate users (307.4 mg/day) is higher than gluconate calcium users (81 mg/day). When calculating the average intake, the intakes from multi-vitamins/minerals were also summed up if they were reported.


**Table 2.** Main dietary supplements used by Chinese children in Australia and China.

**\*** When calculated the average intake, the intakes from multi-vitamins/minerals were also summed if they were reported; \*\* IU/day, IU: international unit; NA: not available.

The prevalence of the use of zinc supplementation was also high in China. Nearly half of supplements users were using zinc supplements (40.4%). Almost all the zinc supplements were in the form of gluconate (93.2%) and the average intake of zinc was 4.4 mg/day (*n* = 166, range from 2.15–8.6 mg) (Table 2).

In Australia, the types most frequently used by supplement users were multi-vitamins/minerals (46.2%) and fish oil (42.3%). The average intake of fish oil was 859.6 mg per day (*n* = 13) with the range from 300 to 1000 mg per day (Table 2).

Chinese herbal supplements were used by children in both countries, especially in China, where 10.7% of supplements users were taking herb supplements (Table 2). Some herbal supplements were used for "better appetite" and some were believed to be beneficial to the immune system or to bring an improvement of health or well-being. In this study, traditional Chinese medicines including cinnabar, as arum, isatis root, kaladana, mangnolia officinalis, scaphium scaphigerum, coltsfoot, coptis chinensis and realgar were included as ingredients in children's dietary supplements or medicines for (preventing) coughs or colds. Excluding dietary supplements, 7.6% of children in China reported taking medicine during the last two weeks and 82.9% (*n* = 92, 6.3% of all the samples) were taking herbal products for medical reasons, such as cough or upper respiratory tract infection. In China, a total of 16.1% of supplements users (8.6% of the total sample) were using herbal products as dietary supplements or medicine and 7.7% of supplement users (2.2% of the total sample) in Australia reported taking herbal products.

In 4–5 year old children in Australia, nearly half (47.4%) were taking at least one dietary supplement 7DEOH,Q\$XVWUDOLDROGHUFKLOGUHQȤ<sup>2</sup> = 19.22, df = 4, *p* = 0.001), children who were QHYHU EUHDVWIHG Ȥ<sup>2</sup> = 4.32, df = 1, *p* < 0.05) and children who did regular physical exercises in pre-VFKRRORUDWKRPHȤ<sup>2</sup> = 10.88, df = 2, *p* = 0.001) were more likely to take dietary supplements than other children. Mothers who had migrated from other Asian regions (including Hong Kong) were more OLNHO\WRJLYHWKHLUFKLOGUHQGLHWDU\VXSSOHPHQWVWKDQPRWKHUVIURPPDLQODQG&KLQDȤ<sup>2</sup> = 4.47, df = 1, *p* < 0.05) (Table 3).


**Table 3.** Dietary supplement use by children: demographic variables.


**Table 3.** *Cont.* 

In China, the prevalence of dietary supplement use was higher in children who had been sick during WKH SDVW IRXUZHHNV Ȥ<sup>2</sup> = 6.97, df = 1, *p* <  DQG FKLOGUHQZKR KDG UHJXODU H[HUFLVH Ȥ<sup>2</sup> = 4.13, df = 1, *p* < 0.05) than in their counterparts. Higher household income was significantly related to WKHXVHRIFKLOGVXSSOHPHQWVȤ<sup>2</sup> = 19.29, df = 1, *p* < 0.001) (Table 3).

Mother's age, education level, working status, household income, the child's age, BMI, regular exercise, and "illness during the last month" were entered into a binary logistic regression model using backward elimination. After controlling for those potential confounding variables, the results of the binary logistic regression analysis showed that Chinese Australian mothers with higher education levels (OR = 2.51, 95% CI 1.19–5.27), older children (OR = 3.11, 95% CI 1.42–6.83), who were not employed (OR = 3.83, 95% CI 1.09–13.44), and never breastfed their children (OR = 6.75, 95% CI 1.29–35.31) were more likely to give their child dietary supplements. In China, higher household income (OR = 1.53, 95% CI 1.13–2.08) and "having illness during the past month" (OR = 1.44, 95% CI 1.05–1.97) were associated with dietary supplement use in children (Table 4).


**Table 4.** Odds ratios of factors for dietary supplement use in Chinese children in Australia and China.

**182** 

NS: not significant.
