Background and Objectives: Cognitive performance is essential for children, given this is a critical stage of brain growth and development. This systematic review and meta-analysis aimed to ascertain if physical activity or micronutrients impact cognitive performance in children. Materials and Methods: Electronic databases (PubMed and Scopus^®) were searched for relevant articles published between 2012 and 2021. We emphasized randomized controlled trials (RCTs) that examined the effect of physical activity and micronutrients on cognitive performance. Data from eligible studies were gathered and evaluated using random-, fixed- or pooled-effects models with 95% confidence intervals (95% CI). Results: Physical activity appeared to improve both Mathematics (d = 1.12, 95% CI: 0.56, 1.67) and attention (d = 0.65, 95% CI: 0.15, 1.14) performances. The micronutrient vitamin B12 had a positive effect on Mathematics (d = 2.39, 95% CI: 0.79, 3.98), English (d = 5.29, 95% CI: 2.76, 7.83), Geography (d = 5.29, 95% CI: 2.76, 7.83), Science (d = 3.39, 95% CI: 2.62, 4.16) and Arts (d = 3.32, 95% CI: 1.84, 4.79). Zinc was found to positively affect English (d = 3.78, 95% CI: 0.44, 7.13), Geography (d = 4.77, 95% CI: 0.56, 8.98) and Arts (d = 2.39, CI: 0.33, 4.45). Iron positively affected Mathematics (d = 1.29, 95% CI: 0.54, 2.06), English (d = 1.29, 95% CI: 0.44, 7.13), Geography (d = 4.77, 95% CI: 0.56, 8.98) and Arts (d = 2.39, 95% CI: 0.33, 4.45). Conclusions: A more comprehensive intervention with a specific dose/level of physical activity, an increased range of cognitive performance, and a well-designed study design that accounts for dietary intake and other health outcomes are required for future studies.

Low cognitive performance is a major concern among fishermen's children in Malaysia. Thus, this study was aimed at assessing dietary intake, nutritional status, physical activity, and socio-economic status, and their associations with cognitive performance among fishermen's children in Terengganu, Malaysia. We also investigated the risk associated with low cognitive performance. This cross-sectional study included 94 children 7–11 years of age in Terengganu. Dietary adequacy was assessed with two 24-h dietary recall surveys. Anthropometric measurements were assessed by calculation of the body mass index (BMI)-for-age Z-score and height-for-age Z-score. In addition, median urinary iodine tests were conducted to determine iodine concentrations. Physical activity was measured with the Physical Activity Questionnaire for Children (PAQ-C). Raven's coloured progressive matrices were used to determine cognitive performance. Binominal logistic regressions were performed on factors associated with cognitive performance, to identify the risk factors with the strongest association with cognitive performance. The children of fishermen had adequate intake of all necessary nutrients except for fat, dietary fibre, thiamine, folate, vitamin C, vitamin E, calcium, zinc, and potassium. Most of the children had normal BMI-for-age [median = −0.86 (2.11)] and height-for-age (mean = −1.01 ± 1.03). However, more than half had iodine deficiency [median = 83.9 (102)]. In addition, 16% had low physical activity levels, and their cognitive performance was classified with a low average score [median = 80.0 (21.0)]. The mother's education level (p = 0.037), children's BMI-for-age (p = 0.012), protein (p = 0.020), and niacin (p = 0.032), exhibited significant relationships with cognitive performance (p < 0.05). Of these variables, BMI-for-age (OR = 0.290, p = 0.036) and fourth quartile protein intake (≥52.69 g) (OR = 7.565, p = 0.015) were significant risk factors for low cognitive performance among fishermen's children in Terengganu. A balanced diet and healthy lifestyle are crucial for children's cognitive development. Thus, interventions emphasising the promotion of healthy lifestyles, particularly focusing on BMI-for-age and protein intake, are advised.