Nutritional Status and Cardiac Autonomic Function: A Cross-Sectional Analysis of Heart Rate Variability in High Socioeconomic Status Schoolchildren

Introduction: The impact of nutritional status on cardiac autonomic function in adolescents from high socioeconomic status (SES) backgrounds, as defined by the Brazilian Economic Classification Criteria, remains unclear, particularly regarding heart rate variability (HRV) parameters. This study aimed to examine associations between nutritional categories (normal weight/overweight/obese) and HRV indices in adolescents from high-SES families. Methods: This cross-sectional study included 201 adolescents aged 11–14 years. HRV was assessed via RMSSD, pNN50, LF, HF, and LF/HF ratio. Data were analyzed using ANOVA and chi-square tests. Results: No significant HRV differences existed across nutritional status: RMSSD (normal: 193.49 ± 246.92ms vs. obese: 168.55 ± 162.43ms; p=0.605), pNN50 (33.39 ± 21.81% vs. 27.71 ± 20.67%; p=0.532), LF (55.85 ± 17.03nu vs. 61.74 ± 16.32nu; p=0.506), HF (155.27 ± 727.00nu vs. 38.10 ± 16.20nu; p=0.629), and LF/HF ratio (1.80 ± 1.57 vs. 2.03 ± 1.29; p=0.951). The values have been expressed as mean ± standard deviation. Chi-square tests confirmed no excess weight-HRV associations (all p>0.30). Discussion: The findings suggested that, among adolescents from high socioeconomic backgrounds, excess weight may not significantly impact cardiac autonomic modulation as measured by HRV. This challenges commonly held assumptions about early autonomic impairment in overweight youth and highlights the potential moderating role of lifestyle and environmental factors. Broader implications point to the need for context-specific cardiovascular risk assessments in pediatric populations. Conclusion: Nutritional status showed no association with HRV parameters in high-SES adolescents. Given the cross-sectional design and the relatively low number of obese participants, the findings of this study should be interpreted with caution. Nevertheless, they suggest preserved autonomic function regardless of nutritional status and emphasize potential protective lifestyle factors in this population.