Sick child resting

Sick child resting (© Tom Sickova -

COPENHAGEN, Denmark — Vitamin D and fish oil supplements could significantly help pregnant women keep their children from developing a common viral chest infection, a new study reveals.

Dr. Nicklas Brustad from Copenhagen University Hospital reports that women taking high doses of these supplements during pregnancy lowered the future risk that their children would develop croup by as much as 40 percent.

Croup is a chest infection that’s common among young children. Although most cases are mild, some toddlers may need hospitalization and mechanical support to breathe. Common symptoms of the illness are a “barking” cough, hoarse voice, and breathing issues.

“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. For such purpose, there is evidence that both vitamin D and fish oil could have an influence on the immune system,” Dr. Brustad says in a media release.

How much vitamin D should pregnant women take to keep croup away?

The study followed 736 pregnant women, recruited by the Copenhagen Prospective Studies on Asthma in Childhood in 2010. Researchers divided the mothers-to-be into four groups, one taking a high-dose vitamin D supplement (2800 international units daily) and fish oil containing long-chain n-3-polyunsaturated fatty acids (2.4 grams).

The second group took high-dose vitamin D and olive oil, while the third group received a standard dose of vitamin D (400 international units) and fish oil, and the final group took a standard dose and olive oil.

These women all continued taking the supplements from their 24th week of pregnancy until the week after delivery. The groups did not know the amount of vitamin D, fish oil, or olive oil they were taking. Researchers also monitored the children until their third birthday. A doctor formally diagnosed any children who may have been dealing with the symptoms of croup throughout that time. In total, there were 97 cases of croup during the study.

Results reveal that children whose mothers took high doses of vitamin D daily during pregnancy had an 11-percent risk of developing croup after birth. That risk increased to 18 percent if the child’s mother only took standard doses — a 40-percent difference.

Meanwhile, children whose mothers took fish oil supplements also had an 11-percent risk of croup. Those whose mothers took olive oil had a 17-percent risk, a 38-percent difference.

“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,” Dr. Brustad reports.

“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.”

“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,” adds Professor Rory Morty from the University of Heidelberg and chair of European Respiratory Society’s lung and airway developmental biology group.

“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.”

Prof. Morty did not take part in the research.

Dr. Brustad presented the findings at the European Respiratory Society International Congress.

About Chris Melore

Chris Melore has been a writer, researcher, editor, and producer in the New York-area since 2006. He won a local Emmy award for his work in sports television in 2011.

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