• Kurt Z Long, Johanna Beckmann, Christin Lang, Harald Seelig, Siphesihle Nqweniso, Nicole Probst-Hensch, Uwe Pühse, Peter Steinmann, RandtRosa duRDDepartment of Human Movement Science, Nelson Mandela University, Port Elizabeth, South Africa., Cheryl Walter, Jürg Utzinger, and Markus Gerber.
• Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland. Electronic address: kurt.long@swisstph.ch.
• Am J Prev Med. 2024 Jun 1; 66 (6): 107810881078-1088.

IntroductionPhysical activity (PA) promotion combined with multimicronutrient supplementation (MMNS) among school-age children may reduce fat mass accrual and increase muscle mass through different mechanisms and so benefit child health. This study determined the efficacy of combined interventions on body composition among South African schoolchildren and determined if micronutrients mediate these effects.Study DesignLongitudinal cluster randomized controlled trial of children followed from 2019 to 2021. Statistical analyses carried from 2022 to 2023.Setting/ParticipantsA total of 1,304 children 6-12 years of age recruited from public schools in Gqeberha, South Africa.InterventionChildren were randomized by classes to either: (a) a physical activity group (PA); (b) a MMNS group; (c) a physical activity + multimicronutrient supplementation group (PA + MMNS); and (d) a placebo control group.Main Outcome MeasuresTrajectories of overall and truncal fat free mass (FFM) and fat mass (FM) estimates in modeled at 9 and 21 months using latent growth curve models (LGCM). Changes in micronutrient concentrations at 9 months from baseline.ResultsAn increased FFM trajectory was found among children in the MMNS arm at 9 months (Beta 0.16, 95% CI = 0.12, 0.31). The PA and MMNS arms both had positive indirect effects on this trajectory at 9 months (Beta 0.66, 95% CI = 0.44, 0.88 and Beta 0.32 95% CI = 0.1 0.5, respectively) and similarly at 21 months when mediated by zinc concentration changes. A reduced FM trajectory was found among children in the PA promotion arm at 9 months when using this collection point as the referent intercept. This arm was inversely associated with the FM trajectory at 9 months when mediated by zinc changes.ConclusionsPA and MMNS promotion in school-based interventions directly contributed to reductions in FM and increased FFM among South African children and indirectly through changes in micronutrient status.Trial RegistrationISRCTN, ISRCTN29534081. Registered on August 9, 2018 Institutional review board: Ethikkommission Nordwest- und Zentralschweiz" (EKNZ, project number: Req-2018-00608). Date of approval: 2018.Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.

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