The Mazira Project is a study of the effect of egg consumption on growth, development and gut health of infants in Malawi. The study randomly assigns infants to receive one egg per day over six months or to receive an equivalent value of food at the end of six months. Growth, achievement of developmental milestones, gut microbiome composition and other measures of nutritional status are compared between the two groups to determine whether regular egg consumption benefits Malawian infants.

The aim of the Mazira Project is to determine whether daily consumption of an egg improves the growth and development of infants in rural Malawi. In Malawi, 37% of children under five years old are stunted, or shorter than expected for their age (1). Most stunting occurs when children are less than 2 years old. Stunting is a sign of long-term undernutrition and is associated with delayed cognitive development. Eggs provide protein, fatty acids, vitamin B12, choline and other nutrients that may support healthy growth and cognitive development. In a previous trial in Ecuador, infants who were provided eggs for daily consumption showed improved growth and lower rates of stunting than infants who were not provided eggs (2).

Investigators are assessing whether children who consume eggs regularly over six months starting when they are 6 to 9 months old have higher height-for-age scores and lower rates of stunting than children who do not consume eggs regularly. Investigators are also assessing whether egg consumption improves Malawian infants' cognitive development. Because gut health is important for good nutrition, they are testing whether eggs have positive effects on measures of gut health and the gut microbiome. Finally, they are exploring the various metabolic pathways by which the nutrients available in eggs may influence infant growth and development.

Participants are individually, randomly assigned to the egg intervention group or the control group. The mothers of infants who are randomly assigned to the egg intervention group receive 14 eggs each week and are asked to feed the infant one egg each day. Extra eggs are provided because sharing of food is common in Malawian households. The mothers of infants who are randomly assigned to the control group receive a package of foods at the end of the study that is equal in value to the eggs. Each mother/infant pair participates in the study for six months.

When infants are enrolled, a baseline assessment is completed. This assessment includes a blood draw plus testing for anemia and malaria, anthropometric measurements, developmental assessments, 24-hour dietary recall interview, infant health history questionnaire. Mothers' heights and weights are also measured, and each mother is asked about socio-economic and demographic indicators and food security in her household. The anthropometric, dietary and development assessments are repeated after 3 months. At the end of the six month study period, anthropometric, dietary and development assessments are repeated, along with another blood draw.

Additional data collected during the course of the study include: repeat 24-hour dietary recalls and monthly stool sample collection among a subsample of 200 children; twice-weekly observations of the index infant's egg consumption in the egg group or short questionnaire about the index infant's most recent meal in the control group; weekly morbidity history and animal source food consumption questionnaire among all infants; and focus groups and key informant interviews about production, availability and consumption of eggs among communities in the study area.

Inclusion Criteria:

• Living in catchment area of Lungwena health center, Mangochi District, Malawi during the study enrollment period
• Singleton birth

Exclusion Criteria:

• Egg allergy
• History of anaphylaxis or any serious allergic reaction requiring emergency medical care
• Congenital or chronic condition impacting growth and development or ability to eat eggs
• Severe anemia (hemoglobin < 5 g/dL)
• Mid-upper arm circumference < 12.5 cm or presence of bipedal edema
• Acute illness or injury warranting hospital referral

De-identified data will be posted in a publicly accessible repository on the Open Science Framework website. Publicly shared data will include all the individual participant data that underlie the results in each publication.

The study protocol and statistical analysis plan for the primary outcome analysis will be posted before data analysis begins. Data and analytic code will be posted within 6 months after publication of the primary outcome results.

Published data will be made publicly accessible. Unpublished data may be requested by contacting the study Principal Investigator.

Participants will not be masked. Data collectors will not be informed of the participant's group assignments. Data analysis will be conducted on blinded datasets until the primary analysis is complete.