Early introduction of eggs boosts infant blood concentrations of several key indicators of brain development, a recent study in Ecuador found. The results could have implications for infant nutrition in both the developing and developed worlds.
Eggs pack a strikingly efficient nutritional punch relative to their size. For example, they are rich in protein, vitamins A and B12, fatty acids, and choline, a vitamin B-related nutrient.
Lora Iannotti, PhD, Associate Dean for Public Health and Associate Professor at the Brown School at Washington University in St. Louis, led a group of researchers who studied the nutritional efficacy of introducing eggs to Ecuadorian infants early during complementary feeding, when other foods begin to augment breast milk. The researchers, whose results were published in Pediatrics, randomly assigned 163 infants ages 6–9 months to an intervention group, in which the children received one egg per day for six months, or a control group that did not receive eggs. In the intervention cohort, eggs had a significant effect on growth — the prevalence of stunting decreased by 47 percent and underweight by 74 percent. That was eye-opening.
“The average effect size across other complementary feeding interventions around the world was only 0.39, compared with our effect size of 0.63,” says Iannotti, the study’s lead author. “That surprised us. Our effect size was almost 70 percent bigger.”
Body and Mind
Iannotti and her team did not hypothesize that eggs would have a beneficial effect only on growth — they also speculated that eggs would significantly enhance infants’ levels of choline and other brain development biomarkers.
And in fact, liquid chromatography-tandem mass spectrometry analysis of blood samples found that eating one egg per day had a sizable effect on choline and biomarkers in choline-associated pathways in brain development. In a separate analysis, which appeared in The American Journal of Clinical Nutrition, infants in the egg group had higher concentrations of choline than those in the control group, for a comparative effect size of 0.35.
“Too often, we focus on nutrition just for ... growth parameters, but I think it’s very important that we think about nutrition also for brain development.”
— Lora Iannotti, PhD, Associate Dean for Public Health and Associate Professor at the Brown School at Washington University in St. Louis
Chessa Lutter, PhD, Adjunct Research Professor of Family Science at the University of Maryland School of Public Health, Senior Nutrition Researcher in the Food Security and Agriculture Division at nonprofit RTI International, and a coauthor of the American Journal of Clinical Nutrition study, says choline is important during pregnancy and infancy for a host of reasons, including its contributions to the structural integrity of cell membranes and its role in the production of the neurotransmitter acetylcholine.
“Acetylcholine is necessary for memory, mood, muscle control, and other brain and nervous system functions,” Lutter says. “Choline is also known to play a role in the modulation of gene expression, cell membrane signaling, lipid transport and metabolism, and early brain development. Choline is important, but [the observed growth effects] were [about] much more than choline. The growth effects, I think, were due to multiple aspects of what’s in eggs.”
Infants in the intervention group not only had higher choline concentrations compared with the control, but they also had significantly higher concentrations of betaine, a metabolite of choline that is important to liver function; methionine, an amino acid that aids metabolism; and DHA, an omega-3 fatty acid that contributes to brain development in infants. Iannotti calls the findings about the DHA concentration “a wonderful surprise,” noting that the way eggs package DHA and other nutrients allows for effective absorption.
The Lulun (“egg” in Ecuador’s Kichwa language) Project was groundbreaking, Lutter says, because it was the first randomized, controlled longitudinal study to examine the effects of eggs on child growth and brain development biomarkers. Its results are already having an impact. The Ecuador Ministry of Health now recommends the introduction of eggs at age 7 months based on the results. Iannotti says that as a relatively affordable animal-sourced food, eggs can play an important role in children’s nutrition — and not just in the developing world.
“I think it’s OK to say that eggs can be promoted in most any context,” she says. “[W]e have some work to do about information around allergies and cholesterol, which are ... two lingering concerns with physicians and mothers. What the literature tells us is, eggs aren’t going to actually cause an allergy. The allergy is already there. In middle- and high-income countries, there has to be caution because there are more egg allergies present. The other kind of historic remnant of why people don’t eat eggs is their connection to cholesterol. The literature has not shown that eggs are going to increase cholesterol, and that’s true across all kinds of contexts. The bottom line is, I think [this study’s findings] are important for healthcare providers, mothers and fathers to appreciate and potentially adapt.”