Previous studies have pointed to an association between a high intake of sugary soft drinks and the onset of asthma in children aged 11. Consuming soft drinks with added sugar has been shown to considerably raise the risk of childhood asthma.
However, the link between maternal intake of sugar and her offspring's risk of asthma has not been sufficiently investigated.
This is why a team of researchers from Queen Mary University of London (QMUL), in collaboration with scientists from the University of Bristol, both in the United Kingdom, set out to examine whether there was such a link.
The research was led by Prof. Seif Shaheen of QMUL, and the findings were published in the European Respiratory Journal.
Sugar intake linked to allergic asthma
Prof. Shaheen and colleagues examined nearly 9,000 mother-child pairs, whose data had been recorded as part of the Avon Longitudinal Study of Parents and Children, which is a large cohort study carried out in the U.K. The study tracked the health of 14,500 children born to almost 9,000 mothers in Britain from 1991 to 1992.
The research carried out by Prof. Shaheen's team examined the links between pregnant mothers' consumption of free sugars (defined as monosaccharides and disaccharides that were added to foods and drinks, and sugars that occur naturally in honey, syrups, and fruit juices) and allergies.
The mothers were asked to fill in a food frequency questionnaire during their last trimester, and the offspring were tested for allergies when they were 7 years old, using positive skin tests to allergens such as dust mite, cats, and grass.
Prof. Shaheen and colleagues found that allergy and allergic asthma correlated strongly with the mothers' free sugar intake during pregnancy.
However, the study did not find enough evidence for an association between free sugar intake in pregnancy and asthma overall.
Next, the researchers compared the top 20 percent of mothers, who had consumed the most sugar, with the bottom 20 percent, who had consumed the least amount of sugar.
Here, they revealed a 38 percent increase in the risk of allergies, as well as a 101 percent increase in the risk of allergic asthma, for children whose mothers had the highest sugar intake.
Mothers should avoid too much sugar
The researchers adjusted the results for factors that may have influenced the results, such as the mother's diet and other maternal characteristics. Interestingly, the children's consumption of sugars in their early childhood had no bearing on the results.
Given the observational nature of the study, the researchers note that the findings cannot explain causality. However, they hypothesize that expectant mothers' high consumption of fructose may cause a "persistent postnatal allergic immune response leading to allergic inflammation in the developing lung."
"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."
Prof. Seif Shaheen
"The first step is to see whether we can replicate these findings in a different cohort of mothers and children," Prof. Shaheen adds. "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."
"In the meantime, we would recommend that pregnant women follow current guidelines and avoid excessive sugar consumption," he concludes.