An egg a day may prevent stunted growth in infants

Behind the Headlines

Thursday June 8 2017

Babies can start eating mashed hardboiled eggs at around 6 months

Eggs are an excellent source of protein

"An egg a day appears to help young children grow taller," BBC News reports.

Research involving young children in Ecuador found babies given one egg a day for six months had improved growth compared with controls, as well as a reduced risk of stunted growth.

Stunted growth is when a child fails to meet the expected height or weight for their age. It can lead to long-term health problems, including difficulties affecting both physical and mental development. It's caused by malnutrition, repeated infection or, in some cases, both. 

The researchers point out that eggs – an excellent source of protein – are a relatively cheap and convenient way to ensure children are getting high-quality food, and could be an ideal intervention for at-risk children in the developing world.

In the study, babies who were given a daily egg also ate less sugary food, such as sweets and cakes. This suggests eating eggs might help reduce childhood obesity.

We don't know if the results would apply to children in the UK or elsewhere in the world, where stunted growth is much less common.

Previous scares about salmonella in eggs may have put some people off giving young children eggs, but advice from the Food Standards Agency says hen eggs produced in the UK under the Lion branding scheme are "very low" in risk, including for pregnant women and young children.

Babies should be exclusively breastfed until they're around 6 months of age. Mashed-up hardboiled eggs can be offered to babies when they're around 6-8 months old. 

Where did the story come from?

The study was carried out by researchers from Washington University, the University of Maryland and the University of California Davis in the US, and Universidad San Francisco de Quito in Ecuador.

It was funded by the Mathile Institute, a not-for-profit organisation that funds child nutrition research. 

The study was published in the peer-reviewed journal Pediatrics on an open access basis, so it's free to access online.

The Mail Online's headline suggests the study's main finding was that eggs "help babies stay healthy" – but the study primarily looked at babies' growth and weight, not their overall health.

Their news article also doesn't make it clear that the research may only apply to children in resource-poor communities, such as rural Ecuador.

BBC News carries a clearer story with a balanced overview.

What kind of research was this?

This was a randomised controlled trial. This is usually the best type of study to see whether one intervention (such as giving a child an egg every day) works.

What did the research involve?

Researchers recruited 163 mothers (or other caregivers) with a child aged 6-9 months who was in good health.

All the babies were weighed and measured, and information was taken from their caregivers at the start of the study and again after six months.

At the start of the study, the researchers asked about the situation at home – for example, access to clean water and sanitation, the baby's usual diet, and any recent illness.

Children with severe malnutrition, heart defects or egg allergies weren't included.

Families were visited weekly to monitor any ill health among the babies and for the families in the egg group to receive their eggs for the week.

At the end of six months, after adjusting their figures to take account of the children's age, sex and measurements at the start, researchers looked at whether children who'd been given eggs were less likely to be underweight or have stunted growth.

In randomised controlled studies of drugs, researchers usually try to ensure patients don't know whether they're taking the treatment or not. That obviously wasn't possible in this study.

The main outcome measures were children's length and weight for their age, and whether they were below a certain marker that suggests they were much shorter or lighter than other children their age. This was used to assess whether they were underweight or had stunted growth. 

What were the basic results?

At the start of the study, 26% of children in the control group and 37% in the egg group had stunted growth for their age.

By the end of the study, that had changed to 29% of children in the control group and 21% of those in the egg group.

Taking other factors into account, children given an egg daily were 47% less likely to be stunted at the end of the study (95% confidence interval [CI] 0.37 to 0.77).

They were also 74% less likely to be underweight (effect size 0.26, 95% CI 0.10 to 0.70), although far fewer children were underweight to start with.

In both groups, children were likely to be eating more sugar-sweetened drinks, cakes, chocolate, pastries, or biscuits at the end of the study than at the start.

However, those in the egg group ate 29% less sweet food than the control group (0.71, 95% CI 0.51 to 0.97).

There were no reports of egg allergy, although caregivers of children in the egg group were more likely to report that the children had experienced diarrhoea.

How did the researchers interpret the results?

The researchers say their results show including an egg a day as part of a baby's diet from 6 months of age "significantly improved linear growth and reduced stunting" in this population.

They go on to say that, "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." 

Conclusion

This study sounds like good news for undernourished children in parts of the world where stunted growth or being underweight are common, such as the Andean mountains of Ecuador.

The study showed that eggs seem to be a safe and practical way of boosting children's nutrition in this population.

But this research has some limitations. Adding one food to a diet is likely to affect the rest of the diet, too.

And caregivers for the children may have given them different foods in addition to the eggs, or treated them differently in some ways.

The children in the control group may also have eaten more eggs than they would have done had their caregivers not been involved in the study. 

But, more importantly, we don't know whether the results are applicable to a very different population, such as the UK, where most babies are well nourished and a wide variety of foods are available. Egg allergy may also be more common in the UK.

As long as your child doesn't have an egg allergy, there's no reason not to give them eggs. Eggs are a good source of protein and other nutrients that children need for a healthy, balanced diet.

As younger children are more vulnerable to the effects of food poisoning, it's important to store, handle and prepare eggs properly.

Analysis by Bazian

Edited by NHS Choices

Links to the headlines

An egg a day appears to help young children grow taller. BBC News, June 7 2017

They've cracked it! An egg a day helps babies stay healthy: Daily consumption reduces chance of stunted growth or being underweight. Daily Mail, June 7 2017

Links to the science

Iannotti LL, Lutter, CK, Stewart CP, et al. Eggs in Early Complementary Feeding and Child Growth: A Randomized Controlled Trial. Pediatrics. Published online June 6 2017

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