The sunshine vitamin needs no introduction when it comes to making your bones healthy and strong. Besides its well-known role in helping your body absorb calcium, vitamin D plays a crucial role in regulating both adaptive and innate immune system responses.
There is high-quality evidence suggesting vitamin D could reduce severe asthma attacks when taken along with standard asthma treatment. [1] A recent review also showed that vitamin D supplements may help prevent acute respiratory tract infections, known to aggravate asthma. [2]
Many studies are now finding a connection between low Vitamin D levels in expectant mothers and an increased risk of asthma and respiratory infections in new-born – suggesting that taking vitamin D supplements in pregnancy could be the key to preventing asthma in infants.
What new research tells us?
A new study published in the Journal of Allergy and Clinical Immunology found that intake of vitamin D during pregnancy positively influences the immune system of the foetus. This could reduce the risk of asthma and respiratory infections in a new-born. According to the researchers, asthma is usually diagnosed early in childhood, implying that the condition originates in foetus or early life.
Half the participants in the study group were given a high dose of 4,400 IU vitamin D3 per day during the second and third trimesters of pregnancy. The remaining participants took the recommended daily intake of 400 IU. The team analyzed the umbilical cord blood to test the response of innate as well as adaptive immune systems when the blood was exposed to simulated pathogens. Innate or natural immunity works short term whereas adaptive immunity utilizes specialized immune cells such as T lymphocytes to launch a more fierce attack against the pathogens, and provide long-term protection.
Not surprisingly, the researchers found that blood samples from babies born to women who took higher doses of vitamin D showed improved response to infections. The study concluded that “Vitamin D exposure during foetal development influences the immune system of the neonate, which can contribute to protection from asthma-related, including infectious, outcomes in early life.” [3]
Most of the evidence regarding low maternal vitamin D and risk of neonatal asthma is reported by observational and cohort studies. Though supportive, these studies are still considered inconclusive. Therefore, results from a randomized, double-blind, placebo-controlled clinical trial like this lend more weight and a flicker of positivity to the role of vitamin D in preventing asthma in early childhood and also to improve outcomes later in life.
The Lead researcher, Professor Catherine Hawrylowicz from King’s College London, said '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.' [4]
While the effect of maternal vitamin D supplementation on neonatal immunity seems really promising with this study, experts believe that more research is required to establish whether this dose can also help lower asthma related risks later in life.
However, these findings are very much in sync with what previous prenatal studies tell us regarding the impact of maternal vitamin D levels on respiratory health of the offspring.
A recent study published in Paediatrics Infectious Disease Journal also supports a preventive role of vitamin D during pregnancy on offspring wheeze and respiratory tract infections. [5]
Another analysis also concluded that maternal supplementation of vitamin D leads to a reduced rate of asthma and recurrent wheezing in young children, suggesting that “higher vitamin D status beginning in early pregnancy is necessary for asthma/recurrent wheeze prevention in early life.” [6]
What makes vitamin D tick? Vitamin D modulates the immune system, works as an anti-inflammatory and is involved in the production of antimicrobial proteins in the body that helps fight a range of bacterial and viral infections. All these properties make vitamin D supplementation a promising strategy in this area. Since vitamin D reserves of a new-born depend on maternal vitamin levels, notching up maternal intake could benefit new-borns, reducing their risk of recurrent wheezing, respiratory infections and asthma.
Considering vitamin D has a low toxicity index, supplementation may work as a safe and effective strategy for pregnant women, especially if they are deficient and are at a high risk of giving birth to a child with asthma.
References:
- Martineau et al. Vitamin D for the management of asthma. Cochrane Library. 2016.
- Martineau et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ, 2017
- E Hornsby et al. Vitamin D supplementation during pregnancy: Effect on the neonatal immune system in a randomized controlled trial. The Journal of Allergy and Clinical Immunology. 2017
- Vitamin D in pregnancy may help prevent childhood asthma. King’s College London. 2017
- Christensen N, Søndergaard J, Fisker N, Christesen HT. Infant Respiratory Tract Infections or Wheeze and Maternal Vitamin D in Pregnancy: A Systematic Review. Pediatr Infect Dis J. 2017
- Wolsk HM et al. Vitamin D supplementation in pregnancy, prenatal 25(OH)D levels, race, and subsequent asthma or recurrent wheeze in offspring: Secondary analyses from the Vitamin D Antenatal Asthma Reduction Trial. The Journal of Allergy and Clinical Immunology. 2017
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