Eggs may crack stunting in children
Introduction of eggs during infancy appears to significantly enhance growth and reduce stunting in children in resource-poor settings, according to a study focused on rural, indigenous populations of the Ecuadorian highlands.
“Eggs are a complete food, safely packaged and arguably more accessible in resource-poor populations than other complementary foods, specifically fortified foods,” the authors said. “In our view, eggs have the potential to be an affordable and environmentally sustainable high-quality food source in populations at risk for both undernutrition and overweight and obesity.”
In a trial of 160 infants (mean age 7.6 months) randomly assigned to the arm fed one egg per day for 6 months (n=78; 39 percent female) or the control arm constituting usual feeding practices (n=82; 52 percent female), the authors found that the food-based intervention produced a “significant and biologically meaningful effect on child growth.”
At the end of the intervention, infants in the egg arm demonstrated a significant increase in the length-for-age (LAZ) and weight-for-age (WAZ) z scores compared with those in the control arm (LAZ effect size, 0.63; 95 percent CI, 0.38 to 0.88; WAZ effect size, 0.61; 0.45 to 0.77; p<0.001 for both). [Pediatrics 2017;doi:10.1542/peds.2016-3459]
Another notable observation is that the proportion of children who were stunted or underweight at baseline decreased substantially at 6 months in the egg arm (from 47 to 28 percent and from 13 to 5 percent, respectively) and increased marginally in the control arm (from 32 to 40 percent and from 5 to 7 percent, respectively). The food-based intervention reduced the prevalence of stunting by 47 percent (prevalence ratio [PR], 0.53; p=0.001) and underweight by 74 percent (PR, 0.26; p=0.008).
Compared with controls, children fed eggs had higher dietary intake of eggs (PR, 1.57) and reduced intake of sugar-sweetened foods (PR, 0.71). None developed immediate allergic reactions after consuming eggs throughout the study period.
The authors noted that the LAZ effect was a one-third or more increase in the global average effect size from other experimental trials of complementary foods in food-insecure populations. [Lancet 2013;382:452–477]
“Both egg yolk and egg whites contain constituents that might separately be linked to growth, although it was likely it was the combination of egg yolk and egg whites that produced the effect observed,” the authors said.
They pointed out that eggs are rich in choline, a nutrient previously found to promote growth in animal models, and contain high-quality amino acids that are not only necessary for muscle tissue accretion but also improve absorption kinetics for minerals and other essential nutrients. [Nutr Rev 2009;67:615–623]
However, the results of the study should be interpreted while keeping several limitations in mind, they added. First is the possibility of differences in growth trajectories or catch-up growth between the two feeding arms. Additionally, background stunting prevalence or cultural acceptability could limit the generalizability of the findings to other contexts, although well-designed social marketing campaigns may overcome problems of acceptability.
“Moving forward, there is a need for effectiveness studies to identify scalable strategies to increase egg availability and access to vulnerable households and promote eggs early in the complementary feeding period in different cultural contexts,” the authors said. “The efficacy of eggs might also be examined during pregnancy for impacts on foetal growth and maternal nutrition.”