Our study provides a insight about the dietary intakes and nutrition status of the migrant children in Wuhan and other cities with similar economic level to Wuhan. Overall, the subjects in the present study confirms the characteristics what we assumed. Migrant children’s parents were generally with lower education levels, most parents only have a junior or high school diploma. Most migrant child was not the only child in the family. There is a higher incidence of overweight and obesity among them. In 2015, the overweight rate of children aged 6 ~ 17 in China was 9.6%, and the obesity rate was 6.4% , while in the current study, 12.9% of children are overweight and 8.8% are obese, which is higher than the general level. The prevalence of wasting among these children was 6.5%, which was lower than the detection rate of 9.2% for school-age children aged 7 ~ 18 in 2014 Chinese National Surveys on Students Constitution and Health . So the results confirms what we assumed that migrant children maybe easily get overweight or obesity due to improved economic condition, easily food availability and lacking of discipline from their busy parents.
Insufficient energy intake and unreasonable energy distribution
In terms of energy intake, 46.1% of boys and 44.4% of girls didn’t meet the recommendation. It may be related to the inadequate amount of food intake. China Society of Nutrition recommend the proportions of energy supply from three macronutrients were 13%~15% from protein, 25%~30% from fat, 55%~65% from carbohydrate for the school-aged children. While the present study indicated that the energy from protein was relatively low (11.1% for girls, 12.4% for boys), but the energy from fat was slightly higher, which was similar to Yang’s results . Intakes of animal and soybean protein (32.2% for girls, 43.3% for boys) were lower than that of Zhu’s research . With regard to food choice, respondents consumed fewer food of animal protein, such as fish, shrimp and eggs, while oil consumption was exceed, it suggested that schools and parents should moderately increase protein-rich food and reduce the use of cooking oil for pupils.
Unreasonable energy supply proportion of three meals and snacks
The Chinese Society of Nutrition recommends that the proportions of energy supplied by breakfast, lunch, and dinner for children are 25%-30%, 30%-40%, and 30%-35%, respectively . In the present study, the proportion of breakfast were lower than the recommendation value, while the proportion of supper were higher than that. This could be because that some children has the habit of skipping breakfast. On the field investigation, we found that some of the children said they didn’t eat anything at morning. In view of the frequent occurrence of the phenomenon, teachers should take action to promote the habit of breakfast consumption and increase awareness of nutritional quality of school breakfast programs . The vast majority of children eat supper at home, compare to the insipid meals in school canteens, the food prepared by parents are much more diverse and suit their taste, so children are prone to overeating. The results also confirmed that the energy proportion of dinner was over the recommended value. On the one hand, parents should pay attention to change the unreasonable eating regimen, and guide kids to eat more at breakfast and lunch but less at dinner. On the other hand, the school should make lunches more palatable under the conduction of a professional dietitian.
Snacks are an unavoidable part in children's diet . However, there are two extreme phenomena in public awareness of snacks. Some parents believe that children should not eat any snacks , while some other parents let their children indulge in snacks . In view of above two misconceptions, “Guide-lines on snacks for Chinese children and adolescents (GSCCAs)”  classified snacks into three ranks: rank 1 included snacks that were suitable for regular consumption, such as yogurts, fruits, soybeans and sweet potatoes; rank 2 was assigned to snacks that were suitable for moderate consumption, such as cookies and desserts; rank 3 items were suitable for limited consumption, such as instant noodles, candy, and deep-fried versions of puffed foods. According to the survey, the all-day energy ratios from snacks of boys and girls were 8.5% and 9.8%, which were lower than that of Huai’an city (10.5% for boys and 14.4% for girls) . We found that some children ate fried chips, instant noodles, spicy strip and drank beverages frequently which all were suitable for limited consumption by GSCCAs (not more than once a week). Consumption of junk foods for long period will lead to obesity, dental caries and nutritional deficiencies, and may also lead to underlying health risks for the future.
Inadequate intake of micronutrients
The most serious nutritional concern of the studied children was inadequate intake of micronutrients. Vitamins and minerals are essential for the growth and development of children. Lack of micronutrients will reduce the immunity, chronic deficiency will lead to malnutrition and micronutrient deficiencies, resulting in increased morbidity and mortality . Only few of these children whose daily intake of minerals and vitamins reached the EAR, which was similar to the other researches . More than 80% of children are deficient in vitamin B1, which may be related with a long-term consumption of over-refining white rice or flour and low consumption of grains, beans and nuts . The intake of vitamin B2, vitamin B3, and vitamin C were also relatively inadequate, which was closely related to the unreasonable dietary patterns of children. Girls were better than boys in the field of intake of vitamin A, but the proportion of insufficiency was still high (47.9% for girls and 60.4% for boys). Vitamin A deficiency can lead to dark adaptation extension or nyctalopia in some severe cases. Children are advised to increase take vitamin A-rich foods, such as animal liver, dark green vegetables, and carrots .
Inadequate calcium intake was the most serious, and the average mean value was only 20% of the RNI (1 200 mg), almost none child meet the recommendation (85% of RNI). The results were lower than that of children in Nanjing (741.4 mg) . The phenomenon of calcium deficiency is comparatively common among Chinese children. These data confirmed the study which had done by Liu . This could be attributed to the consumption of fewer milk and dairy products. In addition, the current study showed insufficient intake of zinc and selenium, which were important for prevent malnutrition, stunting, low immunity and mental retardation. Iron is one of the most essential micro-elements but easily to lack for human. Iron-deficiency anemia is the most common type of anemia in children . In the present study, the data showed that children’s total iron intake was relatively good, but the composition was questionable. The proportion of heme-iron is too low (12.6% of boys and 12.2% of girls), which is in agreement with recent study by Yu et al. . Children should be encouraged to take sufficient lean meat, fish and poultry to ensure the supply of heme-iron. And if the child not refuse, animal liver and blood will be a better choice.
Limited kinds of foods and unreasonable dietary patterns
It was showed that intakes of grains, meat and oils of migrant children met the recommendation of Dietary Guidelines for Chinese Residents. However, the intakes of all other kinds of food were not. More than 95% of children choose to have breakfast and lunch at school canteen from the investigation, so it implied that school shouldered important responsibilities of children’s nutritional status. But in fact, the breakfast and lunch provided by school were relatively simple and lack variety, which makes it common that students had very little appetite and unable to finish the food, just throw the leftovers into the trash, it is consistent with the other research . Deficiency of vegetables may be related to the poor habit of picky eating, for example, over 60% of participants don’t like to eat vegetables in this survey, especially green leaf vegetables. The situation of milk drinking was the worst, the average milk intakes were far away from the recommendation (300 ml), which were similar to the other domestic research results . In view of the problems of migrant children’s dietary pattern, it is essential to correct the children’s unhealthy eating behavior by health education, parents and schools should work together to improve the quality of children’s diet.
Limitations of the study
A few limitations to the present study should be acknowledged. The 24-hour recall was used to collecting the dietary data, as a self-report method, it contain inherent dietary reporting errors. In other words, the recalled data of food intake in the past 24 hours maybe higher or lower than the actual intakes. Additionally, the three days which were surveyed were all school days, which may overestimate the insufficiency of intakes. Therefore the results can’t be used to represent completely the dietary status of migrant children. But despite these shortcomings, the study on energy and nutrient intake of the group still provide the basic data of migrant children, it can be referenced by other cities with similar economic level to Wuhan.