JIA Hai Xian, HAN Jun Hua, LI Hu Zhong, LIANG Dong, DENG Tao Tao, and CHANG Su Ying

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Mineral Intake in Urban Pregnant Women from Base Diet, Fortified Foods, and Food Supplements: Focus on Calcium, Iron, and Zinc*

JIA Hai Xian1,2, HAN Jun Hua1,#, LI Hu Zhong1, LIANG Dong1, DENG Tao Tao1, and CHANG Su Ying3

1. China National Center for Food Safety Risk Assessment, Beijing 100022, China; 2. Institute of Nutrition and Food Hygiene, Beijing Center for Diseases Prevention and Control, Beijing 100013, China; 3. United Nations Children's Fund, Beijing 100600, China

In the Chinese national nutrition surveys, fortified foods were not investigated separately from the base diet, and the contribution of fortified foods to micronutrients intake is not very clear. This study investigated the diet, including fortified foods and food supplements, of urban pregnant women and analyzed the intake of calcium, iron, and zinc to assess the corresponding contributions of fortified foods, food supplements, and the base diet. The results demonstrated that the base diet was the major source of calcium, iron, and zinc, and was recommended to be the first choice for micronutrients intake. Furthermore, consumption of fortified foods and food supplements offered effective approaches to improve the dietary intake of calcium, iron, and zinc in Chinese urban pregnant women.

Mineral intake; Base diet; Fortified food; Food Supplements

The Rome Declaration on Nutrition in 2014 reported that over two billion people in the world experience deficiencies of micronutrients, in particular vitamin A, iodine, iron, and zinc[1], a view that was also mentioned in published guidelines on food fortification with micronutrients[2]. Chinese national nutrition surveys up to 2010 showed that the intake of calcium, iron, vitamin A, and folate in pregnant women was under the recommended intake level[3]. The strategies for the control of micronutrient malnutrition recommended by Food Agricultural Organization of the United Nations and the World Health Organization including food-based approaches such as dietary diversification and food fortification, nutrition education, public health and food safety measures, and food supplementation[2]. All of these strategies can be applied to prevent nutrient deficiencies, especially in women and children.

In China, with the continuous improvement of the food fortification standards, the National Food Safety Standard GB14880-2012, a standard for the use of nutritional fortification substances in foods[4], has been published and enforced. Various domestic or imported fortified products are introduced in the markets, which are communized to improve micronutrients intake for whom experiencing deficiencies. This standard permitted voluntary micronutrients fortification in some food categories such as dairy products, cereal products, and beverages. Following this standard, food for pregnant and lactating women can be fortified with micronutrients to give specific nutritional support[5]. A large number of pregnant women consume fortified foods such as pregnancy milk powder and they are also the primary consumers of food supplements. Calcium, iron, and zinc are common micronutrients fortified in pre-packaged foods and are often the ingredients of food supplements; therefore, the total intake of these three minerals along with the effects of fortification and food supplementation are a concern. However, since fortified foods were not investigated separately from the base diet in the national nutrition surveys, the contribution of fortified foods to micronutrients intake has not been reported. Therefore, the separate contributions of the base diet, fortified foods, and food supplements to the total intake of micronutrients should be evaluated, and the benefits and risks of fortified foods and food supplements should also be considered in order to provide references for reevaluating or revising relevant standards or regulations.

A survey was conducted on the dietary data in terms of the base diet and consumption of fortified foods and food supplements of urban pregnant women as well as demographic information and awareness of fortified foods and food supplements. The survey was aimed to identify the contributions of major minerals from the three sources and to conduct a preliminary evaluation of the benefits and risks of fortified foods and food supplements.

In this study, 298 mid-trimester urban pregnant women at the survey sites (Beijing in Northern China, Hefei in middle China, and Nanning in Southern China) were included. The food composition data used in this study were obtained from the Chinese Food Composition Table[6], and another database of the fortified foods and food supplements was built based on the product labels, so that the total intake of these three minerals could be calculated and compared with the Chinese dietary reference intake (DRI) values. The recommended nutrient intake (RNI) and tolerable upper intake level (UL) were used as cutoff points to estimate the prevalence of inadequate intake and the risk of excessive intake, respectively. The differences in nutrients intake before and after consuming fortified foods and food supplements were analyzed by Wilcoxon signed-rank test to determine the contribution of fortified foods and food supplements. Avalue < 0.05 was considered statistically significant.

Most (81.54%) of the pregnant volunteers in this study were between 25 and 35 years of age. Their approximate per capita monthly income was2,000-10,000, and monthly expenditure on food was500-2,000 per subject. Their gestational age was 23.17 ± 3.88 weeks, and the majority (83.6%) were experiencing their first pregnancy. Anemia and systremma occurred in 6.12% and 46.64%, respectively. Awareness of fortified foods was 76.85%, approximately 22% lower than that of food supplements. The percentages of subjectswho are very familiar with fortified foods and food supplements were both at low levels. Approximately 52.01% (155/298) of the subjects had consumed fortified foods during the past week (more than three times), mainly milk (29.87%) and milk powder (27.52%) and 71.14% (212/298) of the subjects had consumed food supplements during the past month (following the product instructions). Multivitamins and minerals were the main types of food supplements consumed (81.60%), with some consumption also of single minerals or vitamins.

Figure 1 shows that the base diet was the greatest contributor to the total intake of calcium, iron, and zinc (with an average contribution of 68.99%, 85.97%, and 80.57%, respectively), followed by food supplements (20.88%, 10.05%, and 15.39%, respectively), whereas fortified foods contributed the least (10.13%, 3.98%, and 4.04%, respectively). Some researches in other countries showed that fortified foods can play a certain role in improving nutritional status, whereas others reported adverse results[7-9]. In this study, to some extent, the contributions of fortified foods to mineral intake and the average contribution differed from results reported by European or other countries[7-9]as well as some Chinese data[10]. For instance, in this research, the contribution of calcium from fortified foods is higher than the result in Irish female adults (3.6%)[7], whereas the results for iron are lower. This may due to factors such as the different dietary models, fortification levels or scopes.

To address concerns about excess nutrients intake, the percentiles of calcium, iron, and zinc intake were calculated with/without fortified foods and food supplements and were compared with the latest Chinese DRIs. The results showed that fortified foods and food supplements increased the total intake of these three minerals. The median of calcium intake increased from 1058.99 mg to 1210.89 mg when fortified foods were added, and more obvious increases were found for food supplements. The percentage of adequate intake also increased significantly (< 0.01) (Table 1). The distribution of calcium, iron, and zinc intake in comparison with DRIs showed that for calcium, suitable intake (intake level between RNI and UL) increased by 18.45% and6.71% after the consumption of food supplements and fortified foods, respectively (Figure 2). However, for iron, owing to the increased number of subjects with an intake over the UL value, suitable intake decreased by 4% after the addition of food supplements. As discussed above, fortified foods and food supplements can play an important role in improving the status of mineral intake of the population. The contribution of food supplements is higher than that of fortified foods but much lower than that of the base diet. For some individuals, there is an increased risk of excess intake, especially for iron, because of the high concentration found in food supplements. When subjects consume both fortified foods and food supplements, the proportion that exceeds the UL value apparently increases, especially for calcium. Therefore, more guidance for the use of fortified foods and food supplements is suggested.

Figure 1. Average contribution of different sources to the intake of calcium, iron, and zinc.

In summary, the base diet was the main sourceof calcium, iron, and zinc in urban pregnant women, which was recommended to be the first choice for nutrients intake. Meanwhile, for urban pregnant women, consumption of fortified foods and food supplements can be an effective approach to improve the minerals intake when a calcium, iron, or zinc deficiency is encountered. However, the contribution of fortified foods for these three nutrients was still at a rather low level, indicating that the fortified values of GB 14880-2012 can be higher, based on more risk analysis data. For example, more micronutrients need to be evaluated, and the database of fortified foods needs to be improved. Meanwhile, further intensive studies concerning nutrients risk assessment re-assessment and risk-benefit analysis of fortificationis required.

Table 1. Percentiles of Calcium, Iron, and Zinc Intake before/after Addition of Fortified Foods and Food Supplements

BD, base diet; FF, fortified foods; FS, food supplements; RNI, recommended nutrient intake; UL, tolerable upper intake level. TOTAL = BD + FF + FS, TOTAL – FF = BD + FS, TOTAL – FS = BD + FF.Superscript letter–number combinations indicate significant differences:a1compared witha2,= -10.62,< 0.01;a1compared witha3,= -12.00,< 0.01;a2compared witha3,= -6.15,< 0.01;b1compared withb2,= -8.64,< 0.01;b1compared withb3, Z = -8.61,< 0.01;b2compared withb3,= -2.79,< 0.01;c1compared withc2,= -8.64,< 0.01;c1compared withc3,= -8.78,< 0.01;c2compared withc3,= -6.63,< 0.01.

Figure 2. Distribution of calcium, iron, and zinc intake in comparison with dietary reference intake values. BD, base diet; FF, fortified foods; FS, food supplements; RNI, recommended nutrient intake; UL, tolerable upper intake level.

We are grateful to all the subjects who participated in this study and to Academician CHEN Jun Shi, Professor HUO Jun Sheng, and Professor YANG Bao Ru for the help in reviewing and commenting on the paper. We also sincerely thank all the participants who worked on this study in the following institutes: China National Center for Food Safety Risk Assessment; School of Public Health, Peking University; School of Public Health, Anhui Medical University; and the Centers for Disease Control and Prevention, GuangXi Zhuang Autonomous Region.

1. FAO, WHO. Rome Declaration on Nutrition. Second International Conference on Nutrition (ICN2), 2014.http://www.fao.org/assets/infographics/FAO-infographic-ICN2-RomeDeclaration-en.pdf. [2016-07-22]

2. Allen L, Benoist DB, Dary O, et al. Guidelines on food fortification with micronutrients. WHO/FAO, 2006.http://www.who.int/nutrition/publications/micronutrients/9241594012/en/. [2016-07-22]

3. Wang J, Zhao LY, Piao JH, et al. Nutrition and health status of pregnant women in 8 provinces in China. J Hyg Res, 2011; 40, 201-3. (In Chinese)

4. National food safety standards. National food safety standard for the use of nutritional fortifier in foods (GB 14880-2012). China Standards Press, 2012. (In Chinese)

5. Das JK, Salam RA, Kumar R, et al. Micronutrient fortification of food and its impact on woman and child health: a systematic review. Syst Rev, 2013; 2, 67.

6. Yang YX, Wang GY, Pan XC. Chinese Food Composition (version 2002). Peking University Medical Press, 2002. (In Chinese)

7. Hannon EM, Kiely M, Flynn A. The impact of voluntary fortification of foods on micronutrient intake in Irish adults. Brit J Nutr, 2007; 97, 1177-86.

8. Hennessy á, Walton J, Flynn A. The impact of voluntary food fortification on micronutrient intake and status in European countries: a review. P Nutr Soc, 2013; 72, 433-40.

9. Flynn A, Hirvonen T, Mensink GM, et al. Intake of selected nutrients from foods, from fortification and from supplements in various European countries. Food Nutr Res, 2009; 12, 53.

10.Huang J, Sun J, Li WX, et al. Efficacy of different iron fortificants in wheat flour in controlling iron deficiency. Biomed Environ Sci, 2009; 22, 118-21.

#Correspondence should be addressed to HAN Jun Hua, PhD, Professor, Tel: 86-10-52165426, E-mail: hanjhua@163.com

Biographical note of the first author: JIA Hai Xian, male, born in 1988, public health physician, majoring in food safety and nutrition.

Accepted: November 30, 2016

10.3967/bes2016.120

August 18, 2016;

*The study was supported by UNICEF (Act No.32).