Croup is a viral chest infection that affects young children. It causes a characteristic ‘barking’ cough, a hoarse voice and difficulty breathing. Croup is common and usually mild, but some children will need hospital treatment and breathing support.
“There is currently no vaccine against the pathogen that causes this disease. Therefore, other preventive strategies are needed, and measures initiated during pregnancy might be important since croup occurs in babies and young children,” explained Dr Nicklas Brustad, a clinician and postdoctoral researcher working on the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) at Copenhagen University Hospital, Denmark.
“For such purpose, there is evidence that both vitamin D and fish oil could have an influence on the immune system.”
The new trial, which study 736 pregnant women being cared for by COPSAC from 2010, was reportedly the first large study of its kind to investigate the effects of vitamin D and fish oil on croup.
Study details
The women were divided up into four groups: One group were given a high-dose (2,800 IUs per day) vitamin D supplement plus 2.4 grams per day of fish oil; the second group were given high-dose vitamin D and olive oil; the third group were given standard-dose vitamin D (400 IUs per day) plus fish oil; and the final group were given standard-dose vitamin D and olive oil. All the women took the supplements daily from their 24th week of pregnancy until one week after their babies were born.
Dr Brustad and his co-workers followed the children until they were three years old, during which time 97 cases of croup were confirmed amongst the children.
Overall, children whose mothers took the fish oil had an 11% risk of croup, compared to 17% in the children whose mothers took olive oil (a 38% decrease).
Children whose mothers took high-dose vitamin D had an 11% risk of croup, compared to an 18% risk in those whose mothers took the standard-dose vitamin D (a 40% decrease).
“Our findings suggest that vitamin D and fish oil could be beneficial against childhood croup in sufficiently high doses. These are relatively cheap supplements meaning that this could be a very cost-effective approach to improving young children’s health,” said Dr Brustad.
“We are not sure of the exact mechanisms behind the beneficial effects of vitamin D and fish oil, but it could be that they can stimulate the immune system to help babies and young children clear infections more effectively.”
The researchers said they will continue to follow the children in the study and plan to investigate why some children are more prone to infections in childhood than others.
“This could lead to new recommendations for supplementation during pregnancy”
Commenting independently on the research, Prof. Rory Morty from the University of Heidelberg and chair of European Respiratory Society’s lung and airway developmental biology group, said: “We know that lung health in babies and young children can be influenced during pregnancy. For example, babies whose mothers smoke tend to have worse lung health. We are increasingly seeing that elements of a mother’s diet can also help or hinder a baby’s lung development.
“This research suggests that taking vitamin D and fish oil supplements during pregnancy could have benefits for babies and young children. We would like to see further research in this area to support these findings as this could lead to new recommendations for supplementation during pregnancy. Pregnant women should always speak to their doctor before taking supplements.”
COPSAC is funded by The Lundbeck Foundation, The Danish Ministry of Health, and The Capital Region Research Foundation in Denmark.
Source: Abstract no: OA2189 “Fish oil and vitamin D supplementations in pregnancy protect against childhood croup”, by Nicklas Brustad et al; Presented in session, “Chronic and acute lung infections in children” on 5 September 2022.