The effects of one egg per day on vitamin A status among young Malawian children: A secondary analysis of a randomized controlled trial

Authors: WERNER, E.ROCHELLE - University Of California, Davis; HASKELL, MARJORIE - University Of California, Davis; ARNOLD, CHARLES - University Of California, Davis; Caswell, Bess; IANNOTTI, LORA - Washington University; LUTTER, CHESSA - Rti International, Usa; MALETA, KENNETH - University Of Malawi; STEWART, CHRISTINE - University Of California, Davis

Submitted to: Current Developments in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2023
Publication Date: 3/17/2023
Citation: Werner, E., Haskell, M.J., Arnold, C.D., Caswell, B.L., Iannotti, L.L., Lutter, C.K., Maleta, K.M., Stewart, C.P. 2023. The effects of one egg per day on vitamin A status among young Malawian children: A secondary analysis of a randomized controlled trial. Current Developments in Nutrition. 7(3). Article 100053. https://doi.org/10.1016/j.cdnut.2023.100053.
DOI: https://doi.org/10.1016/j.cdnut.2023.100053

Interpretive Summary: Vitamin A is an essential nutrient for growth, vision and immune function. Vitamin A deficiency is common in populations with limited consumption of foods high in vitamin A, such as animal products, dark green vegetables, dark orange fruits or vegetables or fortified foods and supplements. Young children may be at higher risk for vitamin A deficiency, especially in low- and middle-income countries. Eggs are a good source of retinol -- the form of vitamin A that is readily absorbed and used by the body. Therefore, providing eggs to children at risk of vitamin A deficiency may improve their vitamin A status. We tested the impact of providing eggs to 6- to 15-month-old children in rural Malawi. For six months, 330 children were provided with one egg per day to be added to their usual diet and a non-intervened control group of 329 children followed their usual diet. At the end of the study, the two groups of children did not differ in vitamin A status based on two different blood biomarkers of vitamin A. This may be due to a lower than expected percentage of children with vitamin A deficiency in this population. Children in rural Malawi may be protected from vitamin A deficiency by government programs providing vitamin A supplements to young children and mandating vitamin A fortification of foods such as sugar and oil. Provision of eggs may be of greater benefit in populations where vitamin A deficiency is more common.

Technical Abstract: Objectives: Vitamin A deficiency (VAD) is common in populations with limited dietary diversity and access to vitamin A-rich foods. The objective of this analysis was to determine the impact of supplementing children’s diets with 1 egg/day on the concentration of plasma retinol and retinol binding protein (RBP) and prevalence of VAD. Methods: Children age 6-9mo living in the Mangochi district of Malawi were individually randomized to receive 1 egg/day for 6mo (n=331) or continue their usual diet (n=329) in the Mazira trial (clinicaltrials.gov; NCT03385252). This secondary analysis measured plasma retinol by HPLC and RBP, c-reactive protein (CRP), and a-1-acid glycoprotein (AGP) by ELISA techniques at enrollment and 6mo follow-up. Retinol and RBP were adjusted for inflammation and mean concentrations were compared between groups using linear regression models. Prevalence ratios (PR) of VAD (retinol<0.7µmol/L) were compared between groups using log binomial or modified Poisson regression models. Results: After 6mo of study participation, 489 were assessed for retinol (egg: n=238; control: n=251) and 575 (egg: n=281; control: n=294) were assessed for RBP. Prevalence of inflammation (CRP>5mg/L or AGP>1g/L: 62%) and inflammation-adjusted VAD (7%) at enrollment did not differ between groups. At follow-up, the egg intervention group did not differ from the control in inflammation-adjusted retinol [(geometric mean (95%CI); egg: 1.10 µmol/L (1.07, 1.13); control: 1.08 (1.05, 1.12)], RBP [(egg: 0.99µmol/L (0.96, 1.02); control: 0.97 (0.94, 1.00)], or prevalence of VAD [egg: 6%; control: 3%; PR: 1.87 (0.83, 4.24)]. Conclusions: Provision of 1 egg/day did not impact VAD, plasma retinol, or RBP among young children in rural Malawi where the prevalence of VAD was low.