High intake of sugar during pregnancy could increase risk of childhood allergy and allergic asthma, according to a new large-scale study.
The findings, published in the European Respiratory Journal, looked at data from almost 9,000 mother-child pairs to analyse associations between maternal intake of free sugars and asthma and allergy – as defined by positive skin tests to common allergens.
When comparing mothers with the highest sugar intake versus those with the lowest, there team found an increased risk of 38% for allergy in the offspring, and more than a doubled risk (101% increase) for allergic asthma.
Furthermore, the team found a 73% increased risk of allergy to two or more allergens when comparing the lowest and highest intakes of sugar during pregnancy.
No association was seen between sugar intake and eczema or hay fever, they added.
"We cannot say on the basis of these observations that a high intake of sugar by mothers in pregnancy is definitely causing allergy and allergic asthma in their offspring. However, given the extremely high consumption of sugar in the West, we will certainly be investigating this hypothesis further with some urgency,” said lead researcher Professor Seif Shaheen, from Queen Mary University of London (QMUL).
Independently commenting on the findings, Dr Rahul Chodhari, consultant paediatrician at the Royal Free London Foundations NHS Trust, and spokesperson for the Royal College of Paediatrics and Child Health (RCPCH), said it is well known that maternal health and wellbeing has ‘a profound impact’ on child health and this is impacted upon by a variety of factors, such as smoking and weight during pregnancy.
“Whilst links between asthma and high levels of sugar consumption by children have been suggested before, this is the first study to identify a potential association between sugar intake in pregnancy and allergy or allergic asthma in children and, as such, it is very interesting,” said Chodhari.
However, he noted that measuring sugar intake can be difficult, while there are a number of potentially confounding factors that may have an impact on the observations.
“We know that there are multiple factors associated with increased allergic disorders, such as long food chains, lack of exposure to common infections and pollution to name just a few,” he said.
Shaheen and colleagues used data from the Avon Longitudinal Study of Parents and Children (ALSPAC), also known as 'Children of the 90s', which recruited mothers who were pregnant in the early 1990s and has been following up their offspring ever since.
The researchers controlled for various potential confounders in the analyses, including background maternal characteristics, social factors and other aspects of maternal diet like foods and nutrients that have been previously linked to childhood asthma and allergy.
Importantly, the offspring's free sugar intake in early childhood was found to have no association with the outcomes seen in the analysis, said the team.
They speculate that the associations could be explained by a high maternal intake of fructose causing a persistent postnatal allergic immune response leading to allergic inflammation in the developing lung.
However, because the study is observational, it cannot not prove a causal link between maternal sugar intake and allergies or asthma – or provide any indication of mechanisms.
“We must therefore interpret the study’s findings very carefully and further research is needed to prove the association before changes to health policy can be supported,” said Shaheen.
"The first step is to see whether we can replicate these findings in a different cohort of mothers and children. If we can, then we will design a trial to test whether we can prevent childhood allergy and allergic asthma by reducing the consumption of sugar by mothers during pregnancy,” added the lead researcher.