Impact of milk and egg supplementation on body composition and bone mineral density of rural primary school students in Yunnan Province
10.16835/j.cnki.1000-9817.2025288
- VernacularTitle:课间牛奶鸡蛋加餐对云南农村小学生体成分及骨密度的影响
- Author:
ZHANG Yan, ZHANG Wenbin, GONG Weiyan, SONG Chao, ZHOU Ying, DING Caicui, YUAN Fan, CHEN Zheng, QIU Yujie, LIU Ailing
1
Author Information
1. National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China
- Publication Type:Journal Article
- Keywords:
Food habits;
Intervention studies;
Body composition;
Bone density;
Students
- From:
Chinese Journal of School Health
2025;46(10):1401-1405
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the impact of milk and egg supplementation on body composition and bone mineral density of rural primary school students in Yunnan Province, so as to provide a reference for developing targeted nutritional intervention strategies.
Methods:In December 2023, a cluster sampling method was adopted to select students from grades one to three in four primary schools each from Jinggu and Shidian countys of Yunnan Province, as the intervention group (662 students). Additionally, two boarding primary schools were selected from each county based on the principle of matching scale and student numbers as the control group (455 students). Starting from April 2023, the intervention group received 200 mL milk and 50 g eggs during the break on school days for 8 months, while the control group maintained their usual diet behavior. Body composition was measured by using bioelectrical impedance analysis, and distal radial bone mineral density was assessed via dual energy X-ray absorptiometry in April and December 2023. The intervention effects were analyzed by using a difference in-differences approach.
Results:The final measurements of body fat percentage, skeletal muscle mass and fat free mass of the intervention group and the control group of primary school students were significantly higher than the baseline values, and the net effect of milk and egg intervention on these body composition indicators was not statistically significant ( P >0.05, both before and after adjustment). In contrast, bone mineral density increased significantly by 0.02 g/cm 2 in the intervention group. The net intervention effect on bone mineral density was statistically significant ( β=0.02, 95%CI =0.00-0.04), and remained significant after model adjustment ( β=0.02, 95%CI =0.00-0.04) (both P < 0.05). Subgroup analysis showed statistically significant effects of the intervention among girls ( β=0.02, 95%CI =0.00-0.04), day students ( β=0.04, 95%CI =0.01-0.07), and students with normal nutritional status ( β=0.02, 95%CI =0.00-0.04) (all P <0.05). No significant effect of milk and egg supplementation was observed on body composition indicators (all P <0.05).
Conclusions:Milk and egg supplementation can improve bone mineral density among rural primary school students in Yunnan Province. It is recommended that rural school aged children should increase intake of milk and eggs to support growth and development.
