[Changes in body composition of primary school students from Tianyang County, Guangxi Zhuang Autonomous Region after two years' nutrition intervention].

OBJECTIVE

To evaluate the effects of two years'nutrition intervention with eggs and milk on the body composition of rural primary school students in Tianyang County, Guangxi Zhuang Autonomous Region.

METHODS

Four intervention schools and four control schools were selected randomly from Tianyang County of Guangxi Zhuang Autonomous Region. Both intervention schools and control schools were similar in socialeconomic level, teaching standards, and school size. A total of 672 students(380students in the intervention group and 292 students in the control group)were recruited from the 2nd to the 4th Grade in primary school. Students in the intervention group were provided 200 g school milk and 50 g halogen eggs per school day. For students in the control group, no intervention was provided. Their height and weight were collected, and body composition was measured by bioelectrical impedance method at baseline, after oneyear and two-year intervention. The mixed linear model of repeated measurements was adopted for the comparison of each index. According to their weights by gender and age at baseline, students were divided into low weight group, medium weight group, and high weight group. Changes in body composition of students in each weight groups after two years'intervention were analyzed.

RESULTS

The increase of lean body mass of the male students in the intervention group was 0. 5 kg higher compared to those in the control group after one-year intervention(t=3. 66, P<0. 001). However, the difference was not significant between two groups after two years of intervention. In terms of body fat, the intervention group gained 0. 2 kg more body fat after one year(t=2. 12, P=0. 034)and0. 5 kg more after two years(t=3. 23, P=0. 001)compared to the control group. Differences in body fat or lean body weight in boys between intervention and control group were still present after controlling age, height and weight. At the same time, those effects on lean body mass were only found among boys with low and medium baseline weight level, and the effects on body fat were found among boys with high weight level. No effects were found in girls neither after one year or two years of intervention.

CONCLUSION

Two-year supplementation with eggs and milk had promoted lean body weight increase and body fat increase of poor rural primary school male students in Guangxi. However, no significant effects were found in female students.