30 May 2017 --- Taking vitamin D supplements during pregnancy can positively modify the immune system of the newborn baby, according to a study published in the Journal of Allergy and Clinical Immunology. A boost to the immune system could help protect the child against asthma and respiratory infections, a known risk factor for developing asthma in childhood.

The researchers from King's College London studied how taking a supplement of 4,400 IU vitamin D3 per day during the second and third trimesters of pregnancy, versus the recommended daily intake (RDI) of 400 IU/day, influenced the immune system of the newborn.

Participants were randomized at 10-18 weeks of pregnancy to high or low doses of vitamin D supplements. The team studied umbilical cord blood from 51 pregnant women to test the responsiveness of the newborn's innate immune system, which forms the body's first line of defense to infection, and T lymphocyte responses, which provide longer-lasting protection.

Blood samples from babies born to mothers supplemented with higher vitamin D3 were found to respond 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 the neonatal defense to infection.

The team believes the effect will likely lead to improved respiratory health in childhood because strong immune responses in early life have been linked to decreased development of asthma.

“The majority of all asthma cases are diagnosed in early childhood implying that the origin of the disease stems in fetal and early life,” says lead researcher, Professor Catherine Hawrylowicz from King's College London.

“Studies to date that have investigated links between vitamin D and immunity in the baby have been observational. For the first time, we have shown that higher Vitamin D levels in pregnancy can effectively alter the immune response of the newborn baby, which could help to protect the child from developing asthma. Future studies should look at the long-term impact on the immunity of the infant.”

“Vitamin D is a promising area of research for asthma. However, this study is just the first step of many needed to explore this topic. 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,” says Dr. Samantha Walker, Director of Research and Policy at Asthma UK.

Vitamin D is produced by the body through exposure to the sunshine or obtained from foods such as fatty fish and egg yolk, and helps the body control calcium and phosphate levels. Vitamin D levels have been linked to a range of health issues including cardiovascular disease and cancer. A recent study on vitamin D and male fertility has suggested that vitamin D has an effect on many aspects of fertility in both genders, including influencing production and maturation of sperm cells in men, egg cell and uterine lining maturation in women, and sex hormone production in both sexes.