A Combined Physical Activity and Multi-Micronutrient Supplementation Intervention in South African Primary Schools: Effects on Physical Activity, Fitness, and Cardiovascular Disease Risk Factors

TL;DR

A school-based program combining physical activity and micronutrient supplements in South Africa had mixed effects on children's fitness and heart health.

Contribution

This study evaluates the combined effects of physical activity and micronutrient supplementation on cardiovascular health in marginalized South African children.

Findings

Micronutrient supplementation improved cardiorespiratory fitness and reduced blood pressure.

The intervention was linked to adverse metabolic changes like increased triglycerides and decreased HDL.

Physical activity interventions alone did not significantly increase daily activity levels.

Abstract

What are the main findings?
School-based physical activity (PA) interventions, alone or combined with multi-micronutrient supplementation (MMNS), did not increase daily PA and showed mixed effects on cardiometabolic health in South African children aged 6–12 years.The MMNS improved cardiorespiratory fitness (CRF) and reduced blood pressure but was linked to adverse metabolic changes (triglycerides and high-density lipo-protein).

School-based physical activity (PA) interventions, alone or combined with multi-micronutrient supplementation (MMNS), did not increase daily PA and showed mixed effects on cardiometabolic health in South African children aged 6–12 years.

The MMNS improved cardiorespiratory fitness (CRF) and reduced blood pressure but was linked to adverse metabolic changes (triglycerides and high-density lipo-protein).

What are the implications of the main finding?
Nutritional supplementation may hold potential for improving CRF and blood pressure in school-age children, though possible metabolic trade-offs require careful consideration.PA interventions alone may be insufficient to change activity patterns in marginalised settings, highlighting the role of broader environmental and contextual barriers.

Nutritional supplementation may hold potential for improving CRF and blood pressure in school-age children, though possible metabolic trade-offs require careful consideration.

PA interventions alone may be insufficient to change activity patterns in marginalised settings, highlighting the role of broader environmental and contextual barriers.

Background/Objectives: Declining physical activity (PA) and cardiorespiratory fitness (CRF) in children are global public health concerns, particularly in populations experiencing urbanization and economic transition. This study investigated the effects of a school-based intervention on PA, CRF, and cardiovascular disease (CVD) risk factors in children aged 6–12 years from marginalized communities in Gqeberha, South Africa. Methods: A cluster randomized controlled trial was conducted in four schools, with participants randomly assigned to one of the following four arms: (i) PA and multi-micronutrient supplementation (MMNS); (ii) PA and placebo; (iii) MMNS; or (iv) placebo (control). A total of 1151 children were assessed at baseline (T1), 1003 at post-intervention (T2), and 549 at follow-up (T3). PA was measured using accelerometers. Secondary outcomes included CRF (20 m shuttle-run) and CVD risk factors (i.e., anthropometry, blood pressure, glycated hemoglobin [HbA1c], and lipid profile). Mixed linear models adjusted for baseline characteristics were used. Results: None of the interventions significantly improved daily PA. From T1 to T2, the MMNS arm significantly increased CRF, while PA + MMNS reduced HbA1c. However, MMNS alone increased triglycerides, and PA + placebo increased low-density lipoprotein (LDL). From post-intervention (T2) to follow-up (T3), the MMNS arms significantly reduced blood pressure. Yet, the PA + MMNS arm increased body fat percentage and decreased high-density lipoprotein (HDL). Conclusions: While MMNS showed promise for improving fitness and blood pressure and PA + MMNS reduced HbA1c, adverse metabolic changes emerged. The results should be interpreted with caution due to the short intervention span and COVID-19 disruptions during the second year of the intervention.