"Eggs can be affordable and easily accessible," said Lora Iannotti, lead author of the study.

"They are also a good source of nutrients for growth and development in young children," she said. "Eggs have the potential to contribute to reduced growth stunting around the world."

The study, Eggs in Complementary Feeding and Growth, was published online 6 June in the journal Pediatrics.

Dr Iannotti and her co-authors conducted a randomized, controlled trial in Ecuador in 2015.

Children ages 6-9 months were randomly assigned to be given one egg per day for 6 months, versus a control group, which did not receive eggs.

Eggs were shown to increase standardized length-for-age score and weight-for-age score. Models indicated a reduced prevalence of stunting by 47 per cent and underweight by 74 per cent.

Children in the treatment group had higher dietary intakes of eggs and reduced intake of sugar-sweetened foods compared to control.

"We were surprised by just how effective this intervention proved to be," Dr Iannotti said. "The size of the effect was 0.63 compared to the 0.39 global average."

Eggs are a complete food, safely packaged and arguably more accessible in resource-poor populations than other complementary foods, specifically fortified foods, she said.

"Our study carefully monitored allergic reactions to eggs, yet no incidents were observed or reported by caregivers during the weekly home visits," Dr Iannotti said.

"Eggs seem to be a viable and recommended source of nutrition for children in developing countries."