BackgroundEgg is a cheap source of essential micronutrients and high-quality protein, which can contribute to the daily nutritional needs of children, support their growth and brain development. Aim: The study evaluated the effectiveness of egg supplementation on nutritional status, physical fitness, and cognition of school-aged Children (8–12 Years) in Ho Municipality, Ghana. MethodsA school-based, double-blind randomized controlled trial design was adopted. Children aged 8 to 12 years from government-run primary schools were randomly allocated to receive either egg supplementation three times a week for three months or no supplementation at all for three months. Dietary intakes using a repeated 24-h dietary recall, Raven's cognition test, fitness level, BMI-for-age, and serum levels of ferritin, zinc, and albumin were assessed at baseline and after the intervention. ResultsAt pre-intervention, mean intake of several nutrients, including energy, CHO, protein, fat, iron zinc and folate were significantly higher in the intervention group. Post-intervention, these differences significantly increased for protein, fat, and iron, and reduced for energy, carbohydrate, folate, vitamin B6 and 12. Children on egg supplementation had a much higher increase in vitamin A intake (142.0 μg) than the controls (49.8 μg) between pre-and post-intervention. Regarding the physical fitness markers, pre-intervention mean handgrip, forward jump and total fitness scores were all higher in the intervention group and similar for the 50-m run. Post-intervention, the difference was lost while the total fitness score increased rather among controls (p < 0.001). For the biochemical markers, both serum ferritin (mean difference in control = 18.2 μg/L versus intervention= 20.1 μg/L) and zinc (mean difference in control 14.4 μg/L versus intervention 69.4 μg/L) increased more in the intervention than the controls. BMI-for-age z-score did not change between the intervention and control (p = 0.894) post-intervention, while the total cognition score improves slightly more in controls (4.8 points, p < 0.001) than in the intervention group (3.3 points, p < 0.001). ConclusionsThe results indicate that school children who consumed boiled eggs three times per week for three months had a higher mean intake of energy, carbohydrate, protein, iron, zinc, folate, and vitamins A and B6. The mean serum ferritin and albumin levels improved significantly higher in the experimental group. Egg supplementation did not significantly improve physical fitness and cognitive test scores of school-aged children. From this study, egg supplementation may improve some nutrients among school children but effects on congintion and physical fitness may require further study.