Full
Outline
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.
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.
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/cm2 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).
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.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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