Plasma mineral status after a six-month intervention providing one egg per day to young Malawian children: a randomized controlled trial

Background Mineral deficiencies are common in children living in low-resource areas. Eggs are a rich source of essential nutrients and have been shown to improve growth in young children, although little is known about their impact on mineral status. Methods Children aged 6–9 months (n = 660) were randomized to receive either one egg/day for 6-months or no intervention. Anthropometric data, dietary recalls, and venous blood were collected at baseline and 6-months follow-up. Quantification of plasma minerals (n = 387) was done using inductively coupled plasma-mass spectroscopy. Difference-in-difference mean plasma mineral concentrations was determined from baseline and follow-up values and assessed between groups by intention-to-treat using ANCOVA regression models. Results Prevalence of zinc deficiency was 57.4% at baseline and 60.5% at follow-up. Mean difference (MD) of plasma magnesium, selenium, copper, and zinc levels were not different between groups. Plasma iron concentrations were significantly lower in the intervention compared to the control group (MD = -9.29; 95% CI: -15.95, -2.64). Conclusions Zinc deficiency was widely prevalent in this population. Mineral deficiencies were not addressed with the egg intervention. Further interventions are needed to improve the mineral status of young children.