Dietary Magnesium Intake in Relation to Fasting Blood Glucose and Insulin Concentrations and Body Mass Index in Middle School Students from the HEALTHY Study
Authors:   , Naseeb Manal , Volpe Stella L. 
Published: April 2022

Problem: Type 2 diabetes mellitus accounts for 8% to 45% of all new cases of diabetes mellitus among children and adolescents. In the United States (U.S.), for each year between 2002 and 2012, it has been reported that the rate of new cases of T2DM in individuals, 10 to 19 years of age, increased by about 5%. One of the keys to preventing T2DM in children and adolescents is through the prevention of obesity. Lifestyle modifications including healthy, well-balanced dietary habits and increased physical activity are required to reduce the prevalence of obesity and T2DM among children and adolescents. Healthy eating, characterized by a diet rich in fruit, vegetables, and whole grains may help prevent T2DM among children and adolescents. Magnesium is one of the key micronutrients found in these food sources. Magnesium is involved in the regulation of insulin signaling, the phosphorylation of insulin receptor kinase, and insulin-mediated cellular glucose uptake; a deficit of this element could lead to developing T2DM. The independent effect of magnesium has not been previously examined in a large population of children and adolescents who are at risk of T2DM. School-based interventions have been shown to improve students' health behaviors. The HEALTHY Study, a school-based intervention, was designed to reduce modifiable risk factors for T2DM in middle school students from 6th through 8th grades. The HEALTHY Study was a three-year, multi-component intervention that was conducted in a large population of middle school students. One of the HEALTHY Study goals was to increase intake of fruits and vegetables, which are good sources of magnesium. Therefore, the purpose of this study was to examine the relationship between dietary magnesium intake and the risk of T2DM in children and adolescents. Methods: A secondary data analyses of variables collected from the HEALTHY Study, including dietary magnesium intake, BMI percentile, and fasting plasma insulin and glucose concentrations were conducted. A total of 2,181 ethnically diverse students with completed dietary records, BMI percentile, and plasma insulin and glucose concentrations at baseline (6th grade) and end of study (8th grade) were included. Dietary magnesium intake was self-reported using the Block Kids Food Frequency Questionnaire. Hierarchical multiple regression model was used to determine the relationships between dietary magnesium intake, BMI percentile, and glycemic indices at baseline and end of the HEALTHY Study. Two-way mixed factorial analysis of covariance (ANCOVA) was used to determine whether there were changes in dietary magnesium intake between intervention and control schools and between 6th and 8th grade. Hierarchical multiple regression model was used to determine whether the difference in dietary magnesium intake, BMI percentile, plasma glucose and insulin concentrations from 6th to 8th grades were related. Results: Dietary magnesium intake was related to BMI percentile in middle school students at baseline and at the end of the HEALTHY Study (8th grade) ([beta]=-0.05, p= 0.05; [beta]=-0.07, p=0.004, respectively). The differences in dietary magnesium intake were related to changes in BMI percentile from 6th to 8th grade in the intervention schools and in the control schools (Intervention: [beta] =-0.07, p=0.03; Control: [beta] =-0.08, p=0.01, respectively). Moreover, dietary magnesium intake was inversely related to plasma glucose concentrations at the end of the HEALTHY Study in all BMI categories in the intervention schools (< 85th BMI percentile: p=0.003; [greater than or equal to] 85th BMI percentile: p=0.04). Conclusions: This study is the first and largest investigation found that dietary magnesium intake was related to BMI percentile and plasma glucose concentrations as risk factors of T2DM among children and adolescents, even though it is not clinically meaningful. Further research should focus on the extent to which dietary magnesium intake could be related to the risk of T2DM in children and adolescents.