Vitamin D during pregnancy may prevent asthma in kids: study

Taking vitamin D supplements during pregnancy strengthens the babies' immune system, which may lower their risk of developing asthma and respiratory infections, a new study claims.
"The majority of all asthma cases are diagnosed in early childhood implying that the origin of the disease stems in foetal and early life," said Catherine Hawrylowicz, professor at King's College London in the UK.
Researchers looked at the effect that taking a supplement of 4,400 IU (International Units) vitamin D3 per day during the second and third trimesters of pregnancy versus the recommended daily intake (RDI) of 400 IU/day, had on the immune system of the newborn.

Participants were randomised at 10-18 weeks of pregnancy to high or low doses of vitamin D supplements.
The team then took umbilical cord blood from about 51 pregnant women to test the responsiveness of the newborn's innate immune system, which form the body's first line of defence to infection, and T lymphocyte (white blood cells) responses, which provide longer-lasting protection.
The team found that blood samples from babies born to mothers supplemented with higher vitamin D3 responded to mimics of pathogen stimulation by greater innate cytokine responses and greater IL-17A production in response to T lymphocyte stimulation.

Both types of response are predicted to improve neonatal defence to infection, researchers said.

Given the evidence for strong immune responses in early life being associated with decreased development of asthma, researchers believe the effect will likely lead to improved respiratory health in childhood.
"Vitamin D is a promising area of research for asthma. Although this study shows that vitamin D supplementation in pregnancy may improve immune responses, much more research is needed to prove whether this does in fact lead to reduced asthma rates later in life," Hawrylowicz said.
The study was published in the Journal of Allergy and Clinical Immunology.